Publications by authors named "Rafael Franco"

Cannabidiol (CBD), a phytocannabinoid with pleiotropic effects, exhibits complex mechanisms of action that remain incompletely understood, particularly its role as an allosteric modulator of G protein-coupled receptor (GPCR) heteromers. Among these, the adenosine A-cannabinoid CB receptor heteromer (AR-CBR) is a functionally relevant complex implicated in diverse physiological processes. This study aimed to characterize the modulatory effects of CBD on AR-CBR heteromers.

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This study employs a machine learning approach to identify a small-molecule-based signature capable of predicting Alzheimer's disease (AD). Utilizing metabolomics data from the plasma of a well-characterized cohort of 94 AD patients and 62 healthy controls; metabolite levels were assessed using the platform. Data preprocessing involved removing low-quality samples, selecting relevant biochemical groups, and normalizing metabolite data based on demographic variables such as age, sex, and fasting time.

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Epigenetic alterations are key contributors to Alzheimer's disease (AD), driving age-related cognitive decline. This study explores the combined neuroprotective effects of G9a histone methyltransferase inhibition (via UNC0642) and cannabinoid receptor activation (CB1R: ACEA; CB2R: JWH133) in AD models. We used HEK-293T cells and hippocampal neurons to demonstrate that G9a inhibition selectively enhances CB1R-mediated ERK/cAMP signaling.

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Background: Cannabidiol (CBD), the second most abundant phytocannabinoid in Cannabis sativa, has garnered significant interest due to its non-psychoactive nature and diverse receptor interactions.

Methods: This study employs in vitro and in vivo methodologies to validate CBD's potential as a treatment for Alzheimer's disease (AD) by addressing key hallmarks of the condition and promoting neuroprotective effects on spatial memory.

Results: Our findings demonstrate CBD's ability to decrease pTau and Aβ aggregation and to mitigate their axonal transport between cortical and hippocampal neurons.

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Objectives: Human tear analysis holds promise for biomarker discovery, but its clinical utility is hindered by the lack of standardized reference values, limiting interindividual comparisons. This study aimed at developing a protocol for normalizing metabolomic data from human tears, enhancing its potential for biomarker identification.

Methods: Tear metabolomic profiling was conducted on 103 donors (64 females, 39 males, aged 18-82 years) without ocular pathology, using the AbsoluteIDQ™ p180 Kit for targeted metabolomics.

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Neuroinflammation is widely recognized as a key pathological hallmark of Alzheimer's disease (AD). Recently, inhibiting soluble epoxide hydrolase (sEH) has emerged as a promising therapeutic strategy for AD. sEH plays a pivotal role in neuroinflammation by hydrolyzing epoxyeicosatrienoic acids (EETs), which have anti-inflammatory and neuroprotective properties, into pro-inflammatory dihydroepoxyeicosatrienoic acids (DHETs).

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Article Synopsis
  • GPR88 is an orphan G protein-coupled receptor primarily found in the striatum, and its function is not well understood despite changes in its expression seen in Parkinson's disease models.
  • GPR88 was found to interact with the kappa-opioid receptor (KOR), and this interaction inhibits KOR-mediated signaling, as evidenced by experiments showing that GPR88 can modulate effects of KOR agonists in both cultured cells and primary striatal neurons.
  • The GPR88-KOR complexes were more common in specific neurons related to dopamine pathways, suggesting that understanding their relationship could have implications for conditions like neuropathic pain, Parkinson's disease, and neuropsychiatric disorders.
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  • Oliguria, a condition characterized by decreased urine output, may be misinterpreted as acute kidney injury (AKI) in patients post-surgery, despite being a potential adaptive response during surgery.
  • A study analyzing 1,476 patients revealed that 34.4% exhibited oliguria within the first 24 hours after surgery, with certain factors like vasopressor use and non-elective procedures linked to increased risk.
  • Although oliguria was associated with a higher rate of AKI development compared to non-oliguric patients, 87.6% of oliguric patients did not show kidney dysfunction based on serum creatinine levels, questioning the accuracy of oliguria as an indicator for AKI.
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  • - Calcium ion (Ca) homeostasis is essential for proper neuron function, and this study investigated how the CB receptor (CBR) interacts with the ATR receptor to regulate cytoplasmic Ca levels in CNS neurons.
  • - A specific type of interaction called AT-CB receptor heteromers (ATCBHets) was identified using bioluminescence resonance energy transfer (BRET) in lab cells and in the context of Parkinson's disease (PD).
  • - The study found that activation of ATR reduces Ca levels in the presence of cannabinoids, and in a rat model of PD, lower levels of ATCBHets were linked to lesioned neurons, suggesting that cannabinoids might help mitigate calcium imbalance related to levodopa-induced
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  • Olfactory receptors are essential for our sense of smell and influence behaviors like food preferences and emotional memories.
  • They have unique regenerative abilities that can provide insights into neural regeneration, which is crucial for addressing central nervous system injuries.
  • Exploring the ectopic expression of these receptors may lead to new therapeutic approaches for repairing neural damage and treating neurodegenerative diseases.
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  • Class A G protein-coupled receptors (GPCRs) are important for cell signaling and are major drug targets, yet over 60% of them remain untapped for therapeutic use.
  • Traditional GPCR drugs often have adverse effects, but biased signaling offers a new approach for discovering safer therapeutics by targeting specific receptor conformations.
  • The review outlines the landscape of GPCR-biased modulators, highlighting recent advancements, therapeutic relevance, and the variations in understanding their biological effects across different GPCR families.
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  • G protein-coupled receptors (GPCRs) are dynamic structures that can exist in different forms and are influenced by ligand binding, balancing between monomers and oligomers.
  • A new bivalent ligand, which contains two linked pharmacophore units, can affect the behavior of the cannabinoid CB receptor (CBR) by binding to both parts of its dimer form.
  • This binding leads to increased signaling potency and better recruitment of β-arrestin, suggesting that manipulating receptor dimerization could enhance therapeutic effects for treatments involving cannabinoid receptors.
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  • The text discusses the need for better tools to measure neuroprotection in Alzheimer's and Parkinson's diseases, emphasizing that current methods lack specific markers.
  • It outlines the main outcome measures used in clinical trials for these neurodegenerative diseases since 2018, noting that they do not specifically assess neuroprotection.
  • Finally, the text highlights the potential of metabolomics, utilizing body fluids to discover new biomarkers related to neuroprotection, thanks to recent advancements in technology that allow for better detection of relevant metabolites.
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  • Allosterism is a regulatory mechanism for G protein-coupled receptors (GPCRs) that can be affected by ligand binding or interactions between different GPCRs; the study focuses on the allosteric properties of A receptor and CB receptor when they form a heteromer.
  • Experimental techniques used include measuring cAMP levels, analyzing phosphorylation of kinases, and using dynamic mass redistribution methods, showing how disrupting the heteromer affects receptor activation.
  • Key findings reveal that the A receptor can inhibit signaling in the CB receptor by blocking essential structural components, and that certain antagonists can change the interaction dynamics to allow for receptor activation, highlighting a unique allosteric mechanism in GPCR signaling.
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  • Neuroinflammatory disorders are linked to mitochondrial dysfunction and transcriptional changes, particularly in activated microglia, which shows altered biogenesis and redox status.
  • This study utilized RNA sequencing to examine gene expression in microglia treated with adenosine A receptor modulators, revealing significant upregulation (over 40% of mitochondrial genes expressed differently) in response to treatment, highlighting their role in inflammation and oxidative stress.
  • The research also indicated improved mitochondrial function when using the adenosine A receptor antagonist in pro-inflammatory conditions, supporting the potential of targeting the adenosinergic system for therapeutic interventions in neuroinflammation.
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Bioluminescence and fluorescence resonance energy transfer (BRET and FRET) together with the proximity ligation method revealed the existence of G-protein-coupled receptors, Ionotropic and Receptor tyrosine kinase heterocomplexes, e.g., A2AR-D2R, GABAA-D5R, and FGFR1-5-HT1AR heterocomplexes.

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  • Multiple sclerosis (MS) is a serious autoimmune and neurodegenerative disease affecting the central nervous system, with no cure available, highlighting the need for new treatment options.
  • The endocannabinoid system (ECS) has a crucial role in brain functions, and recent studies have shown that cannabinoid receptor interactions (heteromers) are relevant in neurodegenerative diseases, but their specific role in MS remains unclear.
  • New research identified cannabinoid receptor complexes (CBR-GPR55) in the prefrontal cortex, showing increased presence in MS patients, suggesting these receptor complexes could be potential targets for future MS therapies.
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Alterations in olfactory functions are proposed as possible early biomarkers of neurodegenerative diseases. Parkinson's and Alzheimer's diseases manifest olfactory dysfunction as a symptom, which is worth mentioning. The alterations do not occur in all patients, but they can serve to rule out neurodegenerative pathologies that are not associated with small deficits.

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This paper aimed at devising an intelligence-based method to select compounds that can distinguish between open-angle glaucoma patients, type 2 diabetes patients, and healthy controls. Taking the concentration of 188 compounds measured in the aqueous humour (AH) of patients and controls, linear discriminant analysis (LDA) was used to identify the right combination of compounds that could lead to accurate diagnosis. All possibilities, using the leave-one-out approach, were considered through ad hoc programming and in silico massive data production and statistical analysis.

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  • The medial prefrontal cortex (mPFC) plays a crucial role in cognitive functions like working memory, and the astrocytic cannabinoid type 1 receptor (CB1R) affects calcium (Ca) signaling linked to neuronal activity.
  • Research shows that adenosine A1 and A2A receptors (AR, A2AR) can modulate CB1R function in mPFC astrocytes, influencing how calcium signaling operates in these cells.
  • The activation of CB1R enhances long-term potentiation (LTP) in the mPFC, which is regulated by A1 receptors, while in specific genetically modified mice lacking certain calcium responses, CB1R activation reduces LTP, suggesting a balanced
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  • - CBD is a phytocannabinoid that shows potential for treating various diseases and operates through cannabinoid and other receptors, including the adenosine A receptor.
  • - In lab experiments using CHO cells, CBD could not bind to the A receptor in the same way as a certain fluorescent probe but did influence the receptor’s response to a known agonist.
  • - The findings imply that CBD acts as a negative allosteric modulator of the adenosine A receptor, meaning it can inhibit the receptor’s function without directly competing for the binding site.
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  • * Using targeted metabolomics and mass spectrometry, this study identified 16 elevated compounds in the aqueous humor of PD patients, with putrescine emerging as a significant differentiator compared to healthy controls.
  • * The findings highlight a possible link between altered metabolite levels, particularly involving arginine metabolism, with a combination of putrescine, tyrosine, and carnitine effectively distinguishing PD patients from healthy individuals.
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  • Dopamine D-like receptors are the most common dopamine receptors in the brain and are significant for research on neurological diseases.
  • The study introduces new fluorescent ligands derived from the D R antagonist SCH-23390, especially one called UR-NR435, which shows high affinity and selectivity for D-like receptors.
  • UR-NR435 acts as a neutral antagonist, preventing receptor degradation and allowing for effective visualization in fluorescence microscopy, proving useful for analyzing these receptors in various experiments.
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