Hepatocellular carcinoma biomarkers screening based on hydrogel photonic barcodes with tyramine deposition amplified ELISA.

Hepatocellular carcinoma (HCC), as one of the most lethal cancers, significantly impacts human health. Attempts in this area tends to develop novel technologies with sensitive and multiplexed detection properties for early diagnosis. Here, we present novel hydrogel photonic crystal (PhC) barcodes with tyramine deposition amplified enzyme-linked immunosorbent assay (ELISA) for highly sensitive and multiplexed HCC biomarker screening. Because of the abundant amino groups of acrylic acid (AA) component, the constructed hydrogel PhC barcodes with inverse opal structure could facilitate the loading of antibody probes for subsequent detection of tumor markers. By integrating tyramine deposition amplified ELISA on the barcode, the detection signal of tumor markers has been enhanced. Based on these features, it is demonstrated that the hydrogel PhC barcodes with tyramine deposition amplified ELISA could realize highly sensitive and multiplexed detection of HCC-related biomarkers. It was found that this method is flexible, sensitive and accurate, suitable for multivariate analysis of low abundance tumor markers and future cancer diagnosis. These features make the newly developed PhC barcodes an innovation platform, which possesses tremendous potential for practical application of low abundance targets.

Fluorometric "AND" logic gate for detection of tyramine and tyrosinase based on in-situ formation of silicon-containing nanoparticles.

BACKGROUND: Tyramine is an important index of food freshness degree, and tyrosinase that can specifically oxidized monophenolamine to catecholamine plays a crucial part in the occurrence and development of melanin-related skin diseases. Therefore, it is crucial to develop sensitive and efficient methods for the detection of tyramine and tyrosinase. RESULTS: In this work, encouraged by tyrosinase-triggered specific oxidation of tyramine to dopamine and the unique fluorescent reaction between dopamine and amino silane, we have developed a one-step synthetic strategy of silicon containing nanoparticles (Si CNPs) for "turn-on" detection of tyramine and tyrosinase. The Si CNPs formed with thoroughly studied mechanism exhibit uniform structure and robust yellow-green fluorescence. The low detection limits for tyramine (1.87 µM) and tyrosinase (0.0029 U/mL) demonstrate admirable sensitivity outstripping most methods. The proposed assay achieves satisfactory results in the determination of tyramine and tyrosinase activity in real samples. Furthermore, we leverage this new fluorescent assay to enable the fabrication of an "AND" Boolean logic gate. SIGNIFICANCE: The entire process can be completed at easily available temperature and pressure with rapid response, convenient operation and visual observation. This fluorescent assay featured with excellent sensitivity, selectivity and stability has considerable prospects in the application of biosensors and disease diagnosis.

Riparin II-type benzamides as novel antibiofilm agents against dermatophytes: chemical synthesis, in vitro, ex vivo and in silico evaluation.

BACKGROUND: The ability of dermatophytes to develop biofilms in host tissues confers physical and biochemical resistance to antifungal drugs. Therefore, research to find new compounds against dermatophyte biofilm is crucial. OBJECTIVES: To evaluate the antifungal activity of riparin II (RIP2), nor-riparin II (NOR2) and dinor-riparin II (DINOR2) against Trichophyton rubrum, Microsporum canis and Nannizzia gypsea strains. METHODS: Initially, we determined the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of benzamides. We evaluated the inhibitory effects on the development of dermatophyte biofilms using in vitro and ex vivo models. Finally, we built three-dimensional models of the sulphite pump Ssu1 to investigate the interactions with the benzamides by molecular docking. RESULTS: RIP2 showed a broad spectrum of activity against T. rubrum, M. canis and N. gypsea, whereas NOR2 and DINOR2 were more selective. Furthermore, the shortening of the carbon chain from RIP2 benzamide to NOR2 and DINOR2 homologs caused a decrease in the MIC values. The benzamides reduced biofilm production and viability in vitro (P < 0.05) at MIC. This result was similar ex vivo in human nail fragments tests, but NOR2 and DINOR2 showed significant results at 2xMIC (P < 0.05). We constructed a model of the Ssu1 protein for each dermatophyte with high similarity. Molecular docking showed that the benzamides obtained higher binding energy values than ciclopirox. CONCLUSIONS: Our study shows the antibiofilm potential for riparin II-type benzamides as new drugs targeting dermatophytes by inhibiting the Ssu1 protein.

Ultrasensitive fluorescence microRNA biosensor by coupling hybridization-initiated exonuclease I protection and tyramine signal amplification.

Tyramine signal amplification (TSA) has made its mark in immunoassay due to its excellent signal amplification ability and short reaction time, but its application in nucleic acid detection is still very limited. Herein, an ultrasensitive microRNA (miRNA) biosensor by coupling hybridization-initiated exonuclease I (Exo I) protection and TSA strategy was established. Target miRNA is complementarily hybridized to the biotin-modified DNA probe to form a double strand, which protects the DNA probe from Exo I hydrolysis. Subsequently, horseradish peroxidase (HRP) is attached to the duplex via the biotin-streptavidin reaction and catalyzes the deposition of large amounts of biotin-tyramine in the presence of hydrogen peroxide (H2O2), followed by the conjugation of signal molecule streptavidin-phycoerythrin (SA-PE), which generates an intense fluorescence signal upon laser excitation. This method gave broad linearity in the range of 0.1 fM - 10 pM, yielding a detection limit as low as 74 aM. An increase in sensitivity of 4 orders of magnitude was observed compared to the miRNA detection without TSA amplification. This biosensor was successfully applied to the determination of miR-21 in breast cancer cells and human serum. By further design of specific DNA probes and coupling with the Luminex xMAP technology, it could be easily extended to multiplex miRNA assay, which possesses great application potential in clinical diagnosis.

New aspects characterizing non-obese NAFLD by the analysis of the intestinal flora and metabolites using a mouse model.

Non-alcoholic fatty liver disease (NAFLD) is a major public health problem due to the high incidence affecting approximately one-third of the world's population. NAFLD is usually linked to obesity and excessive weight. A subset of patients with NAFLD expresses normal or low body mass index; thus, the condition is called non-obese NAFLD or lean NAFLD. However, patients and healthcare professionals have little awareness and understanding of NAFLD in non-obese individuals. Furthermore, preclinical results from non-obese animal models with NAFLD are unclear. Gut microbiota and their metabolites in non-obese/lean-NAFLD patients differ from those in obese NAFLD patients. Therefore, we analyzed the biochemical indices, intestinal flora, and intestinal metabolites in a non-obese NAFLD mouse model established using a methionine-choline-deficient (MCD) diet. The significantly lean MCD mice had a remarkable fatty liver with lower serum triglyceride and free fatty acid levels, as well as higher alanine transaminase and aspartate transaminase levels than normal mice. 16S RNA sequencing of fecal DNA showed that the overall richness and diversity of the intestinal flora decreased in MCD mice, whereas the Firmicutes:Bacteroidota ratio was increased. g_Tuzzerella, s_Bifidobacterium pseudolongum, and s_Faecalibaculum rodentium were the predominant species in non-obese NAFLD mice. Fecal metabolomics using liquid chromatography-tandem mass spectrometry revealed the potential biomarkers for the prognosis and diagnosis of non-obese NAFLD, including high levels of tyramine glucuronide, 9,12,13-TriHOME, and pantetheine 4'-phosphate, and low levels of 3-carbamoyl-2-phenylpropionaldehyde, N-succinyl-L,L-2,6-diaminopimelate, 4-methyl-5-thiazoleethanol, homogentisic acid, and estriol. Our findings could be useful to identify and develop drugs to treat non-obese NAFLD and lean NAFLD. IMPORTANCE: Patients and healthcare professionals have little awareness and understanding of NAFLD in non-obese individuals. In fact, about 40% of people with NAFLD worldwide are non-obese, and nearly one-fifth are lean. Lean NAFLD unfortunately may be unnoticed for years and remains undetected until hepatic damage is advanced and the prognosis is compromised. This study focused on the lean NAFLD, screened therapeutic agents, and biomarkers for the prognosis and diagnosis using MCD-induced male C57BL/6J mice. The metabolites tyramine glucuronide, 9,12,13-TriHOME, and pantetheine 4'-phosphate, together with the predominant flora including g_Tuzzerella, s_Bifidobacterium pseudolongum, and s_Faecalibaculum rodentium, were specific in non-obese NAFLD mice and might be used as targets for non-obese NAFLD drug exploration. This study is particularly significant for non-obese NAFLDs that need to be more actively noticed and vigilant.

[Metabolic Activities Catalyzed by Human Cytochrome P450 (CYP) 2D6 and CYP3A Subfamily Members and Effect of Various Compounds, Including Endogenous Steroid Hormones, on These Activities].

My research focused on the effects of various drugs on (1) dopamine formation from p-tyramine catalyzed by polymorphic cytochrome P450 (CYP or P450) 2D6 variants and (2) endogenous steroid hormone hydroxylation catalyzed by CYP3A subfamily members (CYP3A4, CYP3A5, CYP3A7). The activation (cooperativity) of metabolic reactions catalyzed by P450s was especially emphasized. The effects of various psychotropic agents on dopamine formation from p-tyramine, catalyzed by wild-type CYP2D6.1 and CYP2D6 variants, including CYP2D6.2 (Arg296Cys;Ser486Thr), CYP2D6.10 (Pro34Ser;Ser486Thr), and CYP2D6.39 (Ser486Thr) were compared. Michaelis (Km) and inhibition (Ki) constants of the psychotropic agents in the presence of CYP2D6.10 were higher than those observed in the presence of other CYP2D6 variants. Fluvoxamine, fluoxetine, milnacipran, and haloperidol activated CYP2D6-catalyzed dopamine formation [decreasing the Km and/or increasing the maximal velocity (kcat)], and this activation was CYP2D6 variant-dependent. Regarding the CYP3A subfamily, the effects of various compounds including endogenous steroid hormones on the 6ß-hydroxylation of steroid hormones, such as testosterone, progesterone, and cortisol, were determined; it was found that testosterone, dehydroepiandrosterone, and/or α-naphthoflavone activated 6ß-hydroxylation of cortisol and/or progesterone, but the effects varied in the presence of different CYP3A subfamily members. Further studies are required to confirm the mechanisms and therapeutic relevance of these activation phenomena.

Multi-crosslinked hydrogel built with hyaluronic acid-tyramine, thiolated glycol chitosan and copper-doped bioglass nanoparticles for expediting wound healing.

The migration of fibroblasts and endothelial cells is a critical determinant of wound-healing outcomes for skin injuries. Here, hyaluronic acid-tyramine (HAT) and thiolated glycol chitosan (TGC) conjugates were combined with copper-doped bioglass (ACuBG) nanoparticles to build a novel type of multi-crosslinked hydrogel for stimulating the migration of cells, and thus, expediting wound healing. The optimally devised HAT/TGC/ACuBG gels had markedly improved strength and stiffness compared to the gels built from either HAT or TGC while showing sufficient elasticity, which contributes to stimulating the migration of fibroblasts. The sustainable release of silicon and copper ions from the gels was found to jointly induce the migration of human umbilical vein endothelial cells. The results based on mouse full-thickness skin defects demonstrated that they were able to fully restore the skin defects with formation of complete appendages within two weeks, suggesting their promising potency for use in expediting wound healing.

Tyramine-Invertase Bioconjugate-Amplified Personal Glucose Meter Signaling for Ultrasensitive Immunoassay.

Highly sensitive and facile detection of low levels of protein markers is of great significance for the early diagnosis and efficacy monitoring of diseases. Herein, aided by an efficient tyramine-signal amplification (TSA) mechanism, we wish to report a simple but ultrasensitive immunoassay with signal readout on a portable personal glucose meter (PGM). In this study, the bioconjugates of tyramine and invertase (Tyr-inv), which act as the critical bridge to convert and amplify the protein concentration information into glucose, are prepared following a click chemistry reaction. Then, in the presence of a target protein, the sandwich immunoreaction between the immobilized capture antibody, the target protein, and the horseradish peroxidase (HRP)-conjugated detection antibody is specifically performed in a 96-well microplate. Subsequently, the specifically loaded HRP-conjugated detection antibodies will catalyze the amplified deposition of a large number of Tyr-inv molecules onto adjacent proteins through highly efficient TSA. Then, the deposited invertase, whose dosage can faithfully reflect the original concentration of the target protein, can efficiently convert sucrose to glucose. The amount of finally produced glucose is simply quantified by the PGM, realizing the highly sensitive detection of trace protein markers such as the carcinoembryonic antigen and alpha fetoprotein antigen at the fg/mL level. This method is simple, cost-effective, and ultrasensitive without the requirement of sophisticated instruments or specialized laboratory equipment, which may provide a universal and promising technology for highly sensitive immunoassay for in vitro diagnosis of diseases.

Enzymatic Dimerization-Induced Self-Assembly of Alanine-Tyramine Conjugates into Versatile, Uniform, Enzyme-Loaded Organic Nanoparticles.

Herein, we report a novel enzymatic dimerization-induced self-assembly (e-DISA) procedure that converts alanine-tyramine conjugates into highly uniform enzyme-loaded nanoparticles (NPs) or nanocontainers by the action of horseradish peroxidase (HRP) in an aqueous medium under ambient conditions. The NP formation was possible with both enantiomers of alanine, and the average diameter could be varied from 150 nm to 250 nm (with a 5-12 % standard deviation of as-prepared samples) depending on the precursor concentration. About 60 % of the added HRP enzyme was entrapped within the NPs and was subsequently utilized for post-synthetic modification of the NPs with phenolic compounds such as tyramine or tannic acid. One-pot multi-enzyme entrapment of glucose oxidase (GOx) and peroxidase (HRP) within the NPs was also achieved. These GOx-HRP loaded NPs allowed multimodal detection of glucose, including that present in human saliva, with a limit of detection (LoD) of 740 nM through fluorimetry. The NPs exhibited good cytocompatibility and were stable to changes in pH (acidic to basic), temperature, ultrasonication, and even the presence of organic solvent (EtOH) to a certain extent, since they are stabilized by intermolecular hydrogen bonding, π-π, and CH-π interactions. The proposed e-DISA procedure can be widely expanded through the design of diverse enzyme-responsive precursors.

Disposable biosensor based on ionic liquid, carbon nanofiber and poly(glutamic acid) for tyramine determination.

In this study, an electrochemical biosensor based on carbon nanofibers (CNF), ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (IL), poly(glutamic acid) (PGA) and tyrosinase (Tyr) modified screen printed carbon electrode (SPE) was constructed for tyramine determination. Optimum experimental parameters such as CNF and IL amount, polymerization conditions of glutamic acid, enzyme loading, pH of test solution and operating potential were explored. The construction steps of the Tyr/PGA/CNF-IL/SPE were pursued by scanning electron microscopy and cyclic voltammetry. The Tyr/PGA/CNF-IL/SPE biosensor exhibited linear response to tyramine in the range of 2.0 × 10-7 - 4.8 × 10-5 M with a low detection limit of 9.1 × 10-8 M and sensitivity of 302.6 µA mM-1. The other advantages of Tyr/PGA/CNF-IL/SPE include its high reproducibility, good stability and anti-interference ability. The presented biosensor was also applied for tyramine determination in malt drink and pickle juice samples and mean analytical recoveries of spiked tyramine were calculated as 100.6% and 100.4% respectively.

Gelatin-tyramine addition and low hydrogel density improves cell attachment, migration, and metabolic activity in vitro and tissue response in vivo in enzymatically crosslinkable dextran-hyaluronic acid hydrogels.

Hydrogels are receiving increasing attention for their use in 3D cell culture, tissue engineering, and bioprinting applications. Each application places specific mechanical and biological demands on these hydrogels. We developed a hydrogel toolbox based on enzymatically crosslinkable polysaccharides via tyramine (TA) moieties, allowing for rapid and tunable crosslinking with well-defined stiffness and high cell viability. Including gelatin modified with TA moieties (Gel-TA) improved the hydrogels' biological properties; 3 T3 fibroblasts and HUVECs attached to and proliferated on the enriched hydrogels at minute Gel-TA concentrations, in contrast to bare or unmodified gelatin-enriched hydrogels. Moreover, we were able to switch HUVECs from a quiescent to a migratory phenotype simply by altering the ligand concentration, demonstrating the potential to easily control cell fate. In encapsulation studies, Gel-TA significantly improved the metabolic activity of 3 T3 fibroblasts in soft hydrogels. Furthermore, we showed rapid migration and network formation in Gel-TA enriched hydrogels in contrast to a non-migratory behavior in non-enriched polysaccharide hydrogels. Finally, low hydrogel density significantly improves tissue response in vivo with large infiltration and low fibrotic reaction. Further development by adding ECM proteins, peptides, and growth factor adhesion sites will lead to a toolbox for hydrogels tailored toward their desired application.

Branched tyramides from males of the harvester ant, Pogonomyrmex badius.

Tyramides are produced in microgram quantities by males of species in the large Myrmicine ant sub-family (> 7000 species). Tyramides are transferred to female sexuals during mating where a specific female sexual evolved enzyme hydrolyzes the tyramides to the biogenic amine, tyramine. Tyramine is a ligand for receptors that rapidly activate reproductive development in the newly mated queen-previously reproductively inhibited by the mother queen. Without this elaborate biogenic amine precursor and co-evolved female sexual derived tyramide hydrolase, the defenseless newly mated queen's worker production would be delayed by up to 6 days, which could be lethal to the new queen. This is one of possibly several ant species separation mechanisms evolved to maintain species integrity. Here we report two methyl-branched tyramides from harvester ant, Pogonomyrmex badius, males, including one highly branched tyramide not previously reported.

Tyramine, one quorum sensing inhibitor, reduces pathogenicity and restores tetracycline susceptibility in Burkholderia cenocepacia.

Burkholderia cenocepacia is an opportunistic respiratory pathogen of particular relevance to patients with cystic fibrosis (CF), primarily regulating its biological functions and virulence factors through two quorum sensing (QS) systems (CepI/R and CciI/R). The highly persistent incidence of multidrug resistant Burkholderia cenocepacia poses a global threat to public health. In this study, we investigated the effects of tyramine, one biogenic amine, on the QS systems of Burkholderia cenocepacia. Genetic and biochemical analyses revealed that tyramine inhibited the production of N-hexanoyl-homoserine (AHL) signaling molecules (C8-HSL and C6-HSL) by blocking the CepI/R and CciI/R systems. As a result, the inhibition of QS systems leads to reduced production of various virulence factors, such as biofilm formation, extracellular polysaccharides, lipase, and swarming motility. Notably, as a potential quorum sensing inhibitor, tyramine exhibits low toxicity in vivo in Galleria mellonella larvae and is well characterized by Lipinski's five rules. It also shows high gastrointestinal absorption and the ability to cross the blood-brain barrier according to SwissADME database and ProTox-II server. Additionally, tyramine was found to enhance the efficacy of tetracycline in reducing the infectivity of Burkholderia cenocepacia in Galleria mellonella larvae infection model. Therefore, tyramine could be a promising candidate for combination therapy with traditional antimicrobials to improve their effectiveness against Burkholderia cenocepacia.

In silico investigation on interaction of small Ag6 nano-particle cluster with tyramine neurotransmitter.

The interaction of tyramine neurotransmitter with silver nano-particle (Ag6) cluster is explored in terms of the molecular structure, electronic properties and NBO analysis of tyramine-AgNPs bio-molecular conjugate. The adsorption mechanism of tyramine onto the Ag6 cluster has been investigated through computing of the electronic and geometrical properties in addition to the adsorption energies in various possible configurations. The magnitude of adsorption energy corresponding to the most favorable tyramine-Ag6 bio-molecular conjugate has been computed to be - 14.36 kcal/mol in the gas phase, which infers a good adsorption of tyramine with AgNPs cluster suggesting the practical applications of tyramine-AgNPs bio-molecular conjugates in bio-sensing, drug delivery, bio-imaging and other applications. Different electronic properties such as the energy gap of HOMO-LUMO, Fermi level and work function have been investigated in detail. Moreover, the effect of aqueous media on adsorption energy and electronic properties of the most favorable tyramine-AgNPs bio-molecular conjugate is investigated in order to understand the impact of the real biological situation.

Nutrigenomics: SNPs correlated to Food Preferences and Susceptibilities.

Background: Nutrigenomics explores the intricate interplay between single nucleotide polymorphisms (SNPs), food preferences, and susceptibilities. Methods: This study delves into the influence of SNPs on food sensitivities, allergies, tyramine intolerance, and taste preferences. Genetic factors intricately shape physiological reactions to dietary elements, with polymorphisms contributing to diverse sensitivities and immune responses. Results: Tyramine intolerance, arising from metabolic inefficiencies, unveils genetic markers exerting influence on enzyme function. SNPs transcend genetic diversity by exerting substantial impact on food sensitivities/allergies, with specific variants correlating to heightened susceptibilities. Genes accountable for digesting food components play pivotal roles. Given the rising prevalence of food sensitivities/allergies, understanding genetic foundations becomes paramount. In the realm of taste and food preferences, SNPs sculpt perception and choice, yielding variances in taste perception and preferences for sweetness, bitterness, and umami. This genetic medley extends its reach to encompass wider health implications. Conclusions: In this review article, we have focused on how polymorphisms wield significant sway over physiological responses, sensitivities, and dietary inclinations. Unraveling these intricate relationships illuminates the path to personalized nutrition, potentially revolutionizing tailored recommendations and interventions.

Tyramine and its Amtyr1 receptor modulate attention in honey bees (Apis mellifera).

Animals must learn to ignore stimuli that are irrelevant to survival and attend to ones that enhance survival. When a stimulus regularly fails to be associated with an important consequence, subsequent excitatory learning about that stimulus can be delayed, which is a form of nonassociative conditioning called 'latent inhibition'. Honey bees show latent inhibition toward an odor they have experienced without association with food reinforcement. Moreover, individual honey bees from the same colony differ in the degree to which they show latent inhibition, and these individual differences have a genetic basis. To investigate the mechanisms that underly individual differences in latent inhibition, we selected two honey bee lines for high and low latent inhibition, respectively. We crossed those lines and mapped a Quantitative Trait Locus for latent inhibition to a region of the genome that contains the tyramine receptor gene Amtyr1 [We use Amtyr1 to denote the gene and AmTYR1 the receptor throughout the text.]. We then show that disruption of Amtyr1 signaling either pharmacologically or through RNAi qualitatively changes the expression of latent inhibition but has little or slight effects on appetitive conditioning, and these results suggest that AmTYR1 modulates inhibitory processing in the CNS. Electrophysiological recordings from the brain during pharmacological blockade are consistent with a model that AmTYR1 indirectly regulates at inhibitory synapses in the CNS. Our results therefore identify a distinct Amtyr1-based modulatory pathway for this type of nonassociative learning, and we propose a model for how Amtyr1 acts as a gain control to modulate hebbian plasticity at defined synapses in the CNS. We have shown elsewhere how this modulation also underlies potentially adaptive intracolonial learning differences among individuals that benefit colony survival. Finally, our neural model suggests a mechanism for the broad pleiotropy this gene has on several different behaviors.

To efficiently navigate their environment, animals must pay attention to cues associated with events important for survival while also dismissing meaningless signals. The difference between relevant and irrelevant stimuli is learned through a range of complex mechanisms that includes latent inhibition. This process allows animals to ignore irrelevant stimuli, which makes it more difficult for them to associate a cue and a reward if that cue has been unrewarded before. For example, bees will take longer to 'learn' that a certain floral odor signals a feeding opportunity if they first repeatedly encountered the smell when food was absent. Such a mechanism allows organisms to devote more attention to other stimuli which have the potential to be important for survival. The strength of latent inhibition ­ as revealed by how quickly and easily an individual can learn to associate a reward with a previously unrewarded stimulus ­ can differ between individuals. For instance, this is the case in honey bee colonies, where workers have the same mother but may come from different fathers. Such genetic variation can be beneficial for the hive, with high latent inhibition workers being better suited for paying attention to and harvesting known resources, and their low latent inhibition peers for discovering new ones. However, the underlying genetic and neural mechanisms underpinning latent inhibition variability between individuals remained unclear. To investigate this question, Latshaw et al. cross-bred bees from high and low latent inhibition genetic lines. The resulting progeny underwent behavioral tests, and the genome of low and high latent inhibition individuals was screened. These analyses revealed a candidate gene, Amtyr1, which was associated with individual variations in the learning mechanism. Further experiments showed that blocking or disrupting the production the AMTYR1 protein led to altered latent inhibition behavior as well as dampened attention-related processing in recordings from the central nervous system. Based on these findings, a model was proposed detailing how varying degrees of Amtyr1 activation can tune Hebbian plasticity, the brain mechanism that allows organisms to regulate associations between cues and events. Importantly, because of the way AMTYR1 acts in the nervous system, this modulatory role could go beyond latent inhibition, with the associated gene controlling the activity of a range of foraging-related behaviors. Genetic work in model organisms such as fruit flies would allow a more in-depth understanding of such network modulation.

In situ photo-crosslinkable hyaluronic acid-based hydrogel embedded with GHK peptide nanofibers for bioactive wound healing.

A versatile hydrogel was developed for enhancing bioactive wound healing by introducing the amphiphilic GHK peptide (GHK-C16) into a photo-crosslinkable tyramine-modified hyaluronic acid (HA-Ty). GHK-C16 self-assembled into GHK nanofibers (GHK NF) in HA-Ty solution, which underwent in situ gelation after the wound area was filled with precursor solution. Blue light irradiation (460-490 nm), with riboflavin phosphate as a photoinitiator, was used to trigger crosslinking, which enhanced the stability of the highly degradable hyaluronic acid and enabled sustained release of the nanostructured GHK derivatives. The hydrogels provided a microenvironment that promoted the proliferation of dermal fibroblasts and the activation of cytokines, leading to reduced inflammation and increased collagen expression during wound healing. The complexation of Cu2+ into GHK nanofibers resulted in superior wound healing capabilities compared with non-lipidated GHK peptide with a comparable level of growth factor (EGF). Additionally, nanostructured Cu-GHK improved angiogenesis through vascular endothelial growth factor (VEGF) activation, which exerted a synergistic therapeutic effect. Furthermore, in vivo wound healing experiments revealed that the Cu-GHK NF/HA-Ty hydrogel accelerated wound healing through densely packed remodeled collagen in the dermis and promoting the growth of denser fibroblasts. HA-Ty hydrogels incorporating GHK NF also possessed improved mechanical properties and a faster wound healing rate, making them suitable for advanced bioactive wound healing applications. STATEMENT OF SIGNIFICANCE: By combining photo-crosslinkable tyramine-modified hyaluronic acid with self-assembled Cu-GHK-C16 peptide nanofibers (Cu-GHK NF), the Cu-GHK NF/HA-Ty hydrogel offers remarkable advantages over conventional non-structured Cu-GHK for wound healing. It enhances cell proliferation, migration, and collagen remodeling-critical factors in tissue regeneration. The incorporation of GHK nanofibers complexed with copper ions imparts potent anti-inflammatory effects, promoting cytokine activation and angiogenesis during wound healing. The Cu-GHK NF/hydrogel's unique properties, including in situ photo-crosslinking, ensure high customization and potency in tissue regeneration, providing a cost-effective alternative to growth factors. In vivo experiments further validate its efficacy, demonstrating significant wound closure, collagen remodeling, and increased fibroblast density. Overall, the Cu-GHK NF/HA-Ty hydrogel represents an advanced therapeutic option for wound healing applications.

Tyramine beta hydroxylase-mediated octopamine synthesis pathway in Litopenaeus vannamei under thermal, salinity, and Vibrio alginolyticus infection stress.

Stress responses impact the immune systems, growth, and reproduction of aquatic organisms. Neuroendocrine regulation involving biogenic amines, including octopamine (OA), plays a pivotal role in maintaining physiological balance during stress. This study focuses on the synthesis pathway of OA, particularly the role of tyramine beta hydroxylase (TBH), in Litopenaeus vannamei under stress. TBH catalyzes the conversion of tyramine to OA, a process critical for physiological responses. The present study demonstrated LvTBH at the protein level under different stress conditions during acute (0.5, 1, 2 h) and chronic stress (24, 72, 168 h) periods. LvTBH increased in thoracic ganglia within 2 h under hyperthermal stress, accompanied by elevated OA levels. Conversely, LvTBH decreased in the brain and circumesophageal connective tissues during acute and chronic hypothermal stress. Additionally, LvTBH increased in the brain and circumesophageal connective tissues under acute infection stress, coinciding with elevated OA levels. These findings collectively contribute to a more intricate understanding of the neuroendocrine dynamics within L. vannamei under stress, underscoring the role of TBH in orchestrating responses crucial for adaptation.

Methylglyoxal-derived hydroimidazolone, MG-H1, increases food intake by altering tyramine signaling via the GATA transcription factor ELT-3 in Caenorhabditis elegans.

The Maillard reaction, a chemical reaction between amino acids and sugars, is exploited to produce flavorful food ubiquitously, from the baking industry to our everyday lives. However, the Maillard reaction also occurs in all cells, from prokaryotes to eukaryotes, forming advanced glycation end-products (AGEs). AGEs are a heterogeneous group of compounds resulting from the irreversible reaction between biomolecules and α-dicarbonyls (α-DCs), including methylglyoxal (MGO), an unavoidable byproduct of anaerobic glycolysis and lipid peroxidation. We previously demonstrated that Caenorhabditis elegans mutants lacking the glod-4 glyoxalase enzyme displayed enhanced accumulation of α-DCs, reduced lifespan, increased neuronal damage, and touch hypersensitivity. Here, we demonstrate that glod-4 mutation increased food intake and identify that MGO-derived hydroimidazolone, MG-H1, is a mediator of the observed increase in food intake. RNAseq analysis in glod-4 knockdown worms identified upregulation of several neurotransmitters and feeding genes. Suppressor screening of the overfeeding phenotype identified the tdc-1-tyramine-tyra-2/ser-2 signaling as an essential pathway mediating AGE (MG-H1)-induced feeding in glod-4 mutants. We also identified the elt-3 GATA transcription factor as an essential upstream regulator for increased feeding upon accumulation of AGEs by partially controlling the expression of tdc-1 gene. Furthermore, the lack of either tdc-1 or tyra-2/ser-2 receptors suppresses the reduced lifespan and rescues neuronal damage observed in glod-4 mutants. Thus, in C. elegans, we identified an elt-3 regulated tyramine-dependent pathway mediating the toxic effects of MG-H1 AGE. Understanding this signaling pathway may help understand hedonistic overfeeding behavior observed due to modern AGE-rich diets.

Rethinking, reducing, and refining the classical oral tyramine challenge test of monoamine oxidase (MAO) inhibitors.

The oral tyramine challenge evaluates the safety of novel monoamine oxidase (MAO) inhibitors when taken with tyramine-containing food or drinks. In its current design, it comprises an extensive series of tyramine escalation steps until a blood pressure threshold is met. Due to the high variation in tyramine bioavailability, and thereby in blood pressure effect, this classical design has various limitations, including safety concerns. Based on data from a previously performed tyramine challenge study, the present study explored a reduced new design that escalates up to 400 mg, and evaluates the dose to a tyramine peak plasma concentration of ≥10 ng/mL, instead of a dose up to 800 mg, and to a blood pressure change of ≥30 mm Hg. Tested by trial simulation, the new design proves more efficient than the classical design in terms of better identifying tyramine sensitivity of test and reference treatments and reducing false-positive and false-negative rates in estimating tyramine sensitivity by more than 10-fold. Since it escalates over a lower tyramine dose range, the new design reduces risk to subjects associated with tyramine-induced blood pressure excursions, is less demanding for study participants, and is more efficient. By its focus on tyramine bioavailability as the primary concern for novel MAO inhibitors, the new tyramine challenge study provides better answers in a simplified and safer design compared with the classical design in trial simulation, warranting its use in future clinical studies.