Adenosine Triphosphate Degradation Research Articles

Effect of Specific Spoilage Organisms on the Degradation of ATP-Related Compounds in Vacuum-Packed Refrigerated Large Yellow Croaker (Larimichthys crocea)

This study examined the spoilage potential of specific spoilage organisms on the degradation of adenosine triphosphate (ATP)-related compounds in vacuum-packed refrigerated large yellow croaker. The total viable count (TVC), ATP-related compounds and related enzymes of vacuum-packed refrigerated large yellow croaker inoculated with different bacteria (Pseudomonas fluorescens and Shewanella putrefaciens) were characterized using the spread plate method, high-performance liquid chromatography and assay kits, respectively. Results indicated that the TVC for both control and Shewanella putrefaciens groups reached spoilage levels at days 9 and 15, respectively. The changes of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and adenosine deaminase activity across all groups showed no significant difference attributable to microbial growth. The results suggested that ATP to inosine monophosphate (IMP) degradation primarily occurs via fish’s endogenous enzymes, with minimal microbial involvement. On day 12, the IMP content in fillets inoculated with Pseudomonas fluorescens (0.93 μmol/g) was half higher than in those inoculated with Shewanella putrefaciens (0.57 μmol/g). Both spoilage organisms facilitated IMP degradation, with Shewanella putrefaciens making a more substantial contribution. Analysis of K values and correlation coefficients revealed that Shewanella putrefaciens was the primary factor in the freshness loss of refrigerated vacuum-packed large yellow croaker. These findings offer a reference for understanding quality changes in refrigerated large yellow croaker, especially regarding umami degradation at the microbial level.

Generation and characterization of antagonistic anti-human CD39 nanobodies.

CD39 is the major enzyme controlling the levels of extracellular adenosine triphosphate (ATP) via the stepwise hydrolysis of ATP to adenosine diphosphate (ADP) and adenosine monophosphate (AMP). As extracellular ATP is a strong promoter of inflammation, monoclonal antibodies (mAbs) blocking CD39 are utilized therapeutically in the field of immune-oncology. Though anti-CD39 mAbs are highly specific for their target, they lack deep penetration into the dense tissue of solid tumors, due to their large size. To overcome this limitation, we generated and characterized nanobodies that targeted and blocked human CD39. From cDNA-immunized alpacas we selected 16 clones from seven nanobody families that bind to two distinct epitopes of human CD39. Among these, clone SB24 inhibited the enzymatic activity of CD39. Of note, SB24 blocked ATP degradation by both soluble and cell surface CD39 as a 15kD monomeric nanobody. Dimerization via fusion to an immunoglobulin Fc portion further increased the blocking potency of SB24 on CD39-transfected HEK cells. Finally, we confirmed the CD39 blocking properties of SB24 on human PBMCs. In summary, SB24 provides a new small biological antagonist of human CD39 with potential application in cancer therapy.

ADP-mediated Modulation of Intracellular Calcium Responses in Chromaffin Cells: The Role of Ectonucleoside Triphosphate Diphosphohydrolase 2 on Rat Adrenal Medulla Function.

The present study investigated the localization and the adenosine 5'-triphosphate (ATP)-degrading function of the plasma membrane-bound ecto-nucleotidase, ectonucleoside triphosphate diphosphohydrolase 2 (NTPDase2), in the rat adrenal medulla. The effect of ATP degradation product, adenosine 5'-diphosphate (ADP), on carbachol (CCh)-induced intracellular Ca2+ ([Ca2+]i) responses in adrenal chromaffin cells was examined using calcium imaging. NTPDase2-immunoreactive cells were distributed between chromaffin cells. NTPDase2-immunoreactive cells were immunoreactive for glial fibrillary acidic protein and S100B, suggesting that they were sustentacular cells. NTPDase2-immunoreactive cells surrounded chromaffin cells immunoreactive for vesicular nucleotide transporter and P2Y12 ADP-selective purinoceptors. In ATP bioluminescence assays using adrenal medullary slices, ATP was rapidly degraded and its degradation was attenuated by the NTPDase inhibitors sodium polyoxotungstate (POM-1) and 6-N, N-diethyl-d-β,γ-dibromomethylene ATP (ARL67156). ADP inhibited CCh-induced [Ca2+]i increases of chromaffin cells in adrenal medullary slices. The inhibition of CCh-induced [Ca2+]i increases by ADP was blocked by the P2Y12 purinoceptor antagonist AZD1283. CCh-induced [Ca2+]i increases were also inhibited by the P2Y1, P2Y12, and P2Y13 purinoceptor agonist 2-methylthioadenosine diphosphate trisodium (2MeSADP), in combination with the P2Y1 purinoceptor antagonist MRS2179. These results suggest that sustentacular cells express NTPDase2 to degrade ATP released from adrenal chromaffin cells, and ADP modulates the excitability of chromaffin cells via P2Y12 purinoceptors to regulate catecholamine release during preganglionic sympathetic stimuli. (J Histochem Cytochem 72: 41-60, 2024).

Differential Influences of Endogenous and Exogenous Sensory Neuropeptides on the ATP Metabolism by Soluble Ectonucleotidases in the Murine Bladder Lamina Propria.

Bladder urothelium and suburothelium/lamina propria (LP) have prominent sensory and transducer functions with the active participation of afferent neurons and urothelium-derived purine mediators such as adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and adenosine (ADO). Effective concentrations of purines at receptor targets depend significantly on the extracellular degradation of ATP by ectonucleotidases (ENTDs). We recently reported the regulated release of soluble ENTDs (s-ENTDs) in the LP and the consequent degradation of ATP to ADP, AMP, and ADO. Afferent neurons in the LP can be activated by urothelial ATP and release peptides and other transmitters that can alter the activity of cells in their vicinity. Using a murine decentralized ex vivo detrusor-free bladder model, 1,N6-etheno-ATP (eATP) as substrate, and sensitive HPLC-FLD methodologies, we found that exogenous neuropeptides calcitonin gene-related peptide (CGRP), substance P (Sub P), neurokinin A (NKA), and pituitary adenylate cyclase-activating polypeptide [PACAP (1-38)] all increased the degradation of eATP by s-ENTDs that were released in the LP spontaneously and/or during bladder filling. Using antagonists of neuropeptide receptors, we observed that endogenous NKA did not modify the ATP hydrolysis by s-ENTDs, whereas endogenous Sub P increased both the constitutive and distention-induced release of s-ENTDs. In contrast, endogenous CGRP and PACAP (1-38) increased the distention-induced, but not the spontaneous, release of s-ENTDs. The present study puts forward the novel idea that interactions between peptidergic and purinergic signaling mechanisms in the LP have an impact on bladder excitability and functions by regulating the effective concentrations of adenine purines at effector cells in the LP.

Triggered metabolism of adenosine triphosphate as an explanation for the chemical heterogeneity of heterotopic ossification

Heterotopic ossification (HO), the pathological formation of bone in soft tissues, is a debilitating condition, as well as one of the few instances of de novo bone formation in adults. Chemical mapping of HO tissue showed distinct islands of calcium phosphate within phosphate-deficient, calcium-rich regions, suggesting a transition to apatitic bone mineral from a non-phosphatic precursor. The transition of amorphous calcium carbonate (ACC), a generally suggested bone-mineral precursor, in physiological conditions was thus investigated. Here, we show that adenosine triphosphate (ATP), present in high amounts in forming bone, stabilised ACC for weeks in physiological conditions and that enzymatic degradation of ATP triggered rapid crystallisation into apatite, through an amorphous calcium phosphate phase. It is suggested that this localised enzymatic degradation could explain the chemical heterogeneity seen in HO and may also represent a pathway to physiological bone mineralisation.

Efficient degradation of disodium adenosine triphosphate by Ca–Al-LDH-supported Fe-activated persulfate and in situ adsorption of the phosphate products

To efficiently treat organophosphorus pollutants and synchronously recover phosphorus resources, Fe-loaded layered double metal hydroxides (Fex/Ca–Al-LDHs) were successfully prepared via coprecipitation and impregnation. The effects of the Fex/Ca–Al-LDHs on the degradation of disodium adenosine triphosphate (5-ATP-Na2) in water and in situ separation of the oxidation product, PO43−, were analyzed. The amount of Fe impregnated into the Fex/Ca–Al-LDHs considerably influenced the capacity of the composite for the oxidative separation of 5-ATP-Na2. A 5-ATP-Na2 removal rate of 94.43% was achieved at pH 3 when the Fe content of the Fe0.4-LDHs, catalyst dosage, and potassium persulfate (PS) concentration were 0.4 mol L−1, 0.6 g L−1, and 0.8 mmol L−1, respectively. The removal rate of the Fex-LDHs/PS system was maintained at 71.81% after three oxidation adsorption−desorption cycles. The system was effective for the removal of other organophosphorus species and practical treatment of various sewage types. The activity of the catalyst is derived from the active Fe species (FeCl3, Fe(OH)2, and Fe2O3), which promoted the cyclic conversion of Fe(II) and Fe(III). An increase in the Fe(II) content promoted the activation of PS, enabling rapid pollutant degradation. The main pathway for 5-ATP-Na2 degradation involved oxidation by SO• 4− and •OH; the generated PO43− was primarily removed by adsorption on the Ca–Al-LDHs. The novel Fe-LDHs/PS catalytic adsorption system prepared in this study is an innovative platform for the efficient catalytic degradation of organophosphorus and simultaneous adsorption of the oxidation product, PO43−.

EVALUATION OF COMPONENTS OF THE EXTRACELLULAR PURINERGIC SIGNALING SYSTEM IN HUMAN SEPSIS.

Objective: Extracellular purines such as adenosine triphosphate (ATP), uridine triphosphate (UTP), and uridine diphosphate (UDP) and the ATP degradation product adenosine are biologically active signaling molecules, which accumulate at sites of metabolic stress in sepsis. They have potent immunomodulatory effects by binding to and activating P1 or adenosine and P2 receptors on the surface of leukocytes. Here we assessed the levels of extracellular purines, their receptors, metabolic enzymes, and cellular transporters in leukocytes of septic patients. Methods: Peripheral blood mononuclear cells (PBMCs), neutrophils, and plasma were isolated from blood obtained from septic patients and healthy control subjects. Ribonucleic acid was isolated from cells, and mRNA levels for purinergic receptors, enzymes, and transporters were measured. Adenosine triphosphate, UTP, UDP, and adenosine levels were evaluated in plasma. Results: Adenosine triphosphate levels were lower in septic patients than in healthy individuals, and levels of the other purines were comparable between the two groups. Levels of P1 and P2 receptors did not differ between the two patient groups. mRNA levels of ectonucleoside triphosphate diphosphohydrolase (NTPDase) 1 or CD39 increased, whereas those of NTPDase2, 3, and 8 decreased in PBMCs of septic patients when compared with healthy controls. CD73 mRNA was lower in PBMCs of septic than in healthy individuals. Equilibrative nucleoside transporter (ENT) 1 mRNA concentrations were higher and ENT2, 3, and 4 mRNA concentrations were lower in PBMCs of septic subjects when compared with healthy subjects. Concentrative nucleoside transporter (CNT) 1 mRNA levels were higher in PBMCs of septic versus healthy subjects, whereas the mRNA levels of CNT2, 3, and 4 did not differ. We failed to detect differences in mRNA levels of purinergic receptors, enzymes, and transporters in neutrophils of septic versus healthy subjects. Conclusion: Because CD39 degrades ATP to adenosine monophosphate (AMP), the lower ATP levels in septic individuals may be the result of increased CD39 expression. This increased degradation of ATP did not lead to increased adenosine levels, which may be explained by the decreased expression of CD73, which converts AMP to adenosine. Altogether, our results demonstrate differential regulation of components of the purinergic system in PBMCs during human sepsis.

Preparation and characterization of ATP-loaded chitosan/alginate nanoparticles for therapeutic applications

Adenosine triphosphate (ATP) is known as an energy source and is generated by mitochondria which is the powerhouse of the cell. The ATP supplies energy through the disassociation of the phosphate group by the cellular enzymes. The extracellular ATP in the extracellular environment acts as a signaling molecule and can act as an anti-inflammatory molecule, can promote cancer progression, and also can act as a pro-inflammatory molecule. The degradation of ATP is a major disadvantage by ectonucleotidases that attenuates the therapeutic property of ATP in the extracellular environment. We have formulated chitosan/alginate nanoparticles loaded with ATP for increasing their encapsulation efficiency and for sustained drug release. This encapsulation can avoid ATP degradation from ectonucleotidases. Nanoparticle characterization by DLS, FTIR, SEM, encapsulation efficiency, and cytotoxicity assay by XTT assay and Live-dead assay was monitored for the synthesized nano formulated ATP. Our results showed that the formulated ATP-loaded chitosan/alginate nanoparticle sized about 342 nm with the optimum encapsulation efficiency of about 92.03% with a sustained drug release profile. These nano formulated ATP could be used for calorie restriction conditions where ATP can be supplied as an extracellular source for bypassing oxidative phosphorylation, and we can circumvent the oxidant production during oxidative phosphorylation. The concept of avoiding oxidative stress by bypassing oxidative phosphorylation can open an avenue for healthy aging.

A conserved family of immune effectors cleaves cellular ATP upon viral infection

During viral infection, cells can deploy immune strategies that deprive viruses of molecules essential for their replication. Here, we report a family of immune effectors in bacteria that, upon phage infection, degrade cellular adenosine triphosphate (ATP) and deoxyadenosine triphosphate (dATP) by cleaving the N-glycosidic bond between the adenine and sugar moieties. These ATP nucleosidase effectors are widely distributed within multiple bacterial defense systems, including cyclic oligonucleotide-based antiviral signaling systems (CBASS), prokaryotic argonautes, and nucleotide-binding leucine-rich repeat (NLR)-like proteins, and we show that ATP and dATP degradation during infection halts phage propagation. By analyzing homologs of the immune ATP nucleosidase domain, we discover and characterize Detocs, a family of bacterial defense systems with a two-component phosphotransfer-signaling architecture. The immune ATP nucleosidase domain is also encoded within diverse eukaryotic proteins with immune-like architectures, and we show biochemically that eukaryotic homologs preserve the ATP nucleosidase activity. Our findings suggest that ATP and dATP degradation is a cell-autonomous innate immune strategy conserved across the tree of life.

Bi-enzyme competition based on ZIF-67 co-immobilization for real-time monitoring ofexocellular ATP.

Monitoring exocellular adenosine-5'-triphosphate (ATP) is a demanding task but the biosensor development is limited by the low concentration and rapid degradation of ATP. Herein, we developed a simple yet effective biosensor based on ZIF-67 loaded with bi-enzymes of glucose (GOx) and hexokinase (HEX) for effective detectionof ATP. In the confined space of the porous matrix, the bi-enzymes competed for the glucose substrate in the presence of ATP, facilitating the biosensor to detect low ATP concentrations down to the micromole level (3.75μM) at working potential of 0.55V (vs. Ag/AgCl). Furthermore, ZIF-67 with cobalt served as a porous matrix to specifically adsorb ATP molecules, allowing it to differentiate isomers with sensitivity of 0.53 nA/μM, RSD of 5.4%, and recovery rate of 93.3%. We successfully applied the fabricated biosensor to measure ATP secreted from rat PC12 cells in the pericellular space thus realizingtime-resolving measurement. This work paved the path for real-time monitoring of ATP released by cells, which will aid in understanding tumor cell glycolysis and immune responses.

Effects of post-mortem aging process on characteristic water-soluble taste-active precursors in yellow-feathered broilers

Chilled chicken has become the mainstream of chicken consumption. In order to explore the effect of post-mortem aging on water-soluble flavor precursors of chicken, pH, adenosine triphosphate (ATP) degradation, flavor nucleosides, free amino acids and water-soluble low molecular weight peptides were determined using Qingyuan partridge yellow-feathered broilers as material during 0–4 °C post-mortem aging in 48 h. The results showed that the pH value fell to the limit pH 5.64 (4 h) in chicken breast and 6.21 (3 h) in thigh. Regardless of chicken breast or thigh, ATP dropped rapidly within 3 h. It was found that the K-value in chicken thigh was the lowest at 2 h indicating the freshness was the best. Considering the equivalent umami concentration (EUC), the value at 3 h and 4 h was relatively high, but the corresponding electronic tongue umami value was not high, which further showed that the water-soluble low molecular taste peptide played an important role on the post-mortem aging process. Combined with cluster analysis and partial least squares discriminant analysis (PLS-DA), it was preliminarily inferred that the optimal time for chilled chicken during 0–4 °C post-mortem aging was 2 h, which could provide a theoretical basis for the further processing of fresh chicken.

The effects of tea polyphenol-ozonated slurry ice treatment on the quality of large yellow croaker (Pseudosciaena crocea) during chilled storage.

The aim of the current study was to evaluate the synergistic effects of tea polyphenol-ozonated slurry ice on the quality, physicochemical and protein characteristics of large yellow croaker (Pseudosciaena crocea) during chilled (4°C) storage. To 0.3% tea polyphenol combined with ozone water was added sodium chloride until the salt concentration reached 3.3% and with the use of an ice machine the mixture formed the tea polyphenol-ozonated slurry ice. Microbial [total viable count (TVC)], physicochemical [total volatile basic nitrogen (TVB-N), K value], myofibrillar fragmentation index (MFI), Ca2+ -ATPase activity, total sulfhydryl content, intrinsic fluorescence intensity (IFI), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were analyzed during chilled (4°C) storage for up to 20 days. The results showed that tea polyphenol-ozonated slurry ice could effectively inhibit the increase of TVC and TVB-N, reduce the degree of adenosine triphosphate (ATP) degradation. In addition, the tea polyphenol-ozonated slurry ice treatment could protect the integrity of myosin in myofibrillar proteins (MPs) by inhibiting the decrease of Ca2+ -ATPase activity and the content of total sulfhydryl. Furthermore, the tea polyphenol-ozonated slurry ice presented a superiorly protective effect on protein structure in MPs as manifested by the results of IFI, FTIR and SDS-PAGE. It was possible that due to the addition of tea polyphenol, the antioxidant activity of this complex was significantly improved. The tea polyphenol-ozonated slurry ice treatment can maintain the quality of large yellow croaker by decreasing the damage of MP caused by the interaction between microorganisms and endogenous enzymes. © 2022 Society of Chemical Industry.

The role of mitochondria in the recovery of neurons after injury.

The role of mitochondria in the recovery of neurons after injury.

Mechanosensitive Hydrolysis of ATP and ADP in Lamina Propria of the Murine Bladder by Membrane-Bound and Soluble Nucleotidases.

Prior studies suggest that urothelium-released adenosine 5′-triphosphate (ATP) has a prominent role in bladder mechanotransduction. Urothelial ATP regulates the micturition cycle through activation of purinergic receptors that are expressed in many cell types in the lamina propria (LP), including afferent neurons, and might also be important for direct mechanosensitive signaling between urothelium and detrusor. The excitatory action of ATP is terminated by enzymatic hydrolysis, which subsequently produces bioactive metabolites. We examined possible mechanosensitive mechanisms of ATP hydrolysis in the LP by determining the degradation of 1,N 6 -etheno-ATP (eATP) at the anti-luminal side of nondistended (empty) or distended (full) murine (C57BL/6J) detrusor-free bladder model, using HPLC. The hydrolysis of eATP and eADP was greater in contact with LP of distended than of nondistended bladders whereas the hydrolysis of eAMP remained unchanged during filling, suggesting that some steps of eATP hydrolysis in the LP are mechanosensitive. eATP and eADP were also catabolized in extraluminal solutions (ELS) that were in contact with the LP of detrusor-free bladders, but removed from the organ chambers prior to addition of substrate. The degradation of both purines was greater in ELS from distended than from nondistended preparations, suggesting the presence of mechanosensitive release of soluble nucleotidases in the LP. The released enzyme activities were affected differently by Ca2+ and Mg2+. The common nucleotidase inhibitors ARL67156, POM-1, PSB06126, and ENPP1 Inhibitor C, but not the alkaline phosphatase inhibitor (-)-p-bromotetramisole oxalate, inhibited the enzymes released during bladder distention. Membrane-bound nucleotidases were identified in tissue homogenates and in concentrated ELS from distended preparations by Wes immunodetection. The relative distribution of nucleotidases was ENTPD1 >> ENPP1 > ENTPD2 = ENTPD3 > ENPP3 = NT5E >> ENTPD8 = TNAP in urothelium and ENTPD1 >> ENTPD3 >> ENPP3 > ENPP1 = ENTPD2 = NT5E >> ENTPD8 = TNAP in concentrated ELS, suggesting that regulated ectodomain shedding of membrane-bound nucleotidases possibly occurs in the LP during bladder filling. Mechanosensitive degradation of ATP and ADP by membrane-bound and soluble nucleotidases in the LP diminishes the availability of excitatory purines in the LP at the end of bladder filling. This might be a safeguard mechanism to prevent over-excitability of the bladder. Proper proportions of excitatory and inhibitory purines in the bladder wall are determined by distention-associated purine release and purine metabolism.

Delivery of an ectonucleotidase inhibitor with ROS-responsive nanoparticles overcomes adenosine-mediated cancer immunosuppression.

Tumor evasion of immune destruction is associated with the production of immunosuppressive adenosine in the tumor microenvironment (TME). Anticancer therapies can trigger adenosine triphosphate (ATP) release from tumor cells, causing rapid formation of adenosine by the ectonucleotidases CD39 and CD73, thereafter exacerbating immunosuppression in the TME. The goal of this study was to develop an approach to facilitate cancer therapy-induced immunogenic cell death including ATP release and to limit ATP degradation into adenosine, in order to achieve durable antitumor immune response. Our approach was to construct reactive oxygen species (ROS)-producing nanoparticles that carry an ectonucleotidase inhibitor ARL67156 by electronic interaction and phenylboronic ester. Upon near-infrared irradiation, nanoparticle-produced ROS induced ATP release from MOC1 cancer cells in vitro and triggered the cleavage of phenylboronic ester, facilitating the release of ARL67156 from the nanoparticles. ARL67156 prevented conversion of ATP to adenosine and enhanced anticancer immunity in an MOC1-based coculture model. We tested this approach in mouse tumor models. Nanoparticle-based ROS-responsive drug delivery reprogramed the immunogenic landscape in tumors, eliciting tumor-specific T cell responses and tumor regression, conferring long-term survival in mouse models. We demonstrated that TME reprograming sets the stage for response to anti-programmed cell death protein 1 (PD1) immunotherapy, and the combination resulted in tumor regression in a 4T1 breast cancer mouse model that was resistant to PD1 blockade. Furthermore, our approach also induced immunological effects in patient-derived organotypic tumor spheroid model, suggesting potential translation of our nanoparticle approach for treating human cancers.

Astragalus polysaccharide (APS) exerts protective effect against acute ischemic stroke (AIS) through enhancing M2 micoglia polarization by regulating adenosine triphosphate (ATP)/ purinergic receptor (P2X7R) axis

ABSTRACT Clinically, the effective treatment for patients with acute ischemic stroke (AIS) is very limited. Therefore, this paper aims to investigate the mechanism how astragalus polysaccharide (APS) exerts protective effect against AIS and provide a new method for the treatment of AIS. Cell surface antigen flow cytometry and immunofluorescence were used to identify M1 and M2 microglia. Western blot was used to evaluate the expression of associated protein. Oxygen-glucose deprivation (OGD) was used to simulate the effect of AIS on rat microglia. The middle cerebral artery occlusion (MCAO) model was established to simulate the effect of AIS in vivo. Evans blue dye (EBD) was used to evaluate the permeability of blood–brain barrier (BBB). Western blot and cell surface antigen flow cytometry results showed that APS promoted the M2 polarization of rat microglia by inhibiting the expression of purinergic receptor (P2X7R). APS reversed the effect of OGD on the polarization of rat microglia M1/ M2 by regulating P2X7R. APS reversed the effect of MCAO on the polarization of rat microglia M1/ M2 in vivo. Furthermore, APS inhibited the expression of P2X7R by promoting the degradation of adenosine triphosphate (ATP) in the cerebral cortex of MCAO rats. In addition, APS contributed to maintain the integrity of BBB. Summarily, APS can reduce brain injury by promoting the degradation of ATP in microglia and inhibiting the expression of P2X7R after AIS.

Crowding within synaptic junctions influences the degradation of nucleotides by CD39 and CD73 ectonucleotidases

Synapsed cells can communicate using exocytosed nucleotides like adenosine triphosphate (ATP). Ectonucleotidases localized to synaptic junctions degrade nucleotides into metabolites like adenosine monophosphate (AMP) or adenosine. Oftentimes nucleotide degradation occurs in a sequential manner, of which ATP degradation by CD39 and CD73 is a representative example. Here, CD39 first converts ATP and adenosine diphosphate (ADP) into AMP, after which AMP is dephosphorylated into adenosine by CD73. Hence, the concerted activity of CD39 and CD73 can help shape cellular responses to extracellular ATP. In a previous study, we demonstrated that coupled CD39 and CD73 activity within synapse-like junctions is strongly controlled by the enzymes' co-localization, their surface charge densities, and the electrostatic potential of the surrounding cell membranes. In this study, we demonstrate that crowders within synaptic junctions, which can include globular proteins like cytokines and membrane-bound proteins, impact coupled CD39 and CD73 ectonucleotidase activity and, in turn, the availability of intrasynapse ATP. Specifically, we developed a spatially explicit, reaction-diffusion model for the coupled conversion of ATP → AMP and AMP → adenosine in a model synaptic junction with crowders that is solved via the finite element method. Our modeling results suggest that the association rate for ATP to CD39 is strongly influenced by the density of intrasynaptic protein crowders, as increasing crowder density generally suppressed ATP association kinetics. Much of this suppression can be rationalized based on a loss of configurational entropy. The surface charges of crowders can further influence the association rate, with the surprising result that favorable crowder-nucleotide electrostatic interactions can yield CD39 association rates that are faster than crowder-free configurations. However, attractive crowder-nucleotide interactions decrease the rate and efficiency of adenosine production, which in turn increases the availability of ATP and AMP within the synapse relative to crowder-free configurations. These findings highlight how CD39 and CD73 ectonucleotidase activity, electrostatics, and crowding within synapses influence the availability of nucleotides for intercellular communication.

The use of soluble gas stabilization technology on food – A review

Increasing the shelf life of perishable food products contributes to lower food waste and the possibility of widening distribution outreach in the food value chain. Soluble gas stabilization (SGS) technology is a pre-step process of dissolving carbon dioxide (CO2) into the product before packaging. This technology shows promising results on the lab-scale to limit microbial growth and other deteriorating mechanisms in food products. This review aims to gather available research results on the effects of combining SGS technology or dissolved CO2 with thermal and non-thermal processing technologies. The effects are structured according to the microbiological shelf life and safety as well as food quality parameters such as texture, color, drip loss, lipid oxidation, and adenosine triphosphate (ATP) degradation. This paper reviews the SGS effects alone and in combination with conventional food treatments on the parameters mentioned above. Improving thermal and non-thermal technologies efficacy meets the demand for better food quality while being more economically feasible. Combining dissolved CO2 with these treatments, as hurdle technology, considerably enhances the bacteriostatic effect of the treatments, mostly without compromising the product quality. However, it is highly dependent on the product kind, treatment method, experiment protocol, and composition and concentration of the product microbiota. Moreover, the extent of positive synergistic effects could be promoted by addressing specific problems such as gas layer formation during sous vide treatment. This paper provides a better understanding of the SGS effectiveness, performing beside conventional food processing technologies, for the full-scale implementation of the technology. • Consumer demand for minimally processed foods is rising. • Thermal and non-thermal methods tend to reduce food quality for extending shelf life. • Soluble gas stabilization technology improves conventional food treatments efficacy. • Soluble gas stabilization combined with conventional food treatments is reviewed.

Differentiation between fresh and frozen-thawed scallop adductor muscle as raw materials for sashimi during cold storage.

The changes of sensory and biochemical characteristics on the fresh and frozen-thawed scallop adductor muscle during storage at 4°C were discussed in this study. The Quality Index Method (QIM) scheme for evaluating scallop adductor muscle as raw materials for sashimi was proposed for the first time. The results of sensory evaluation showed that frozen-thawed scallop adductor muscle within zero to one day of refrigeration can be happily accepted by consumers, indicating the superiority of freezing for long-distance transportation, although the triangle test confirmed that there are still sensorial differences between fresh and frozen-thawed scallop adductor muscle. The microscopic observation of myofibrils extracted from scallop adductor muscle suggested that the myofibrillar protein which constitutes myofibrils has suffered some extent change due to freezing and thawing, even though the head region of myosin remained stable judging by the fact that there was no significant difference in Ca2+ -ATPase activity (p > 0.05). The changes of adenosine triphosphate (ATP) and its related compounds, and pH value during storage can be regarded as indicators to differentiate fresh and frozen-thawed scallop adductor muscle. The changes of Mg2+ -ATPase activity indicated that the interaction between myosin and actin was weakened by the freezing and thawing process. Practical Application: The QIM scheme can be used to evaluate the scallop adductor muscle as raw materials for sashimi. The mechanism of quality changes in the frozen-thawed scallop adductor muscle was discussed in combination with the destruction of myofibrils, ATP degradation and the decrease of pH value. This study has positive significance for improving the quality of frozen-thawed scallop adductor muscle by combining the changes of sensory and biochemical characteristics.

A pilot study on the biochemical effects of repeated administration of 24% oral sucrose vs. 30% oral dextrose on urinary markers of adenosine triphosphate degradation.

Premature neonates often receive oral sucrose or dextrose before tissue-damaging procedures (TDPs). Previous work showed that a single dose of sucrose, but not dextrose, increased cellular energy utilization and ATP degradation. This pilot study probes the effects of repeated administration of sucrose or dextrose on energy metabolism. Urinary markers of ATP metabolism (hypoxanthine, xanthine, uric acid) are measured in premature neonates randomized to receive: (a) standard of care, (b) 0.2 ml 24% oral sucrose, or (c) 0.2 ml 30% oral dextrose, before every painful procedure on days-of-life 3-7. Standard of care is associated with highest xanthine/creatinine and uric acid/creatinine, likely because of fewer pain treatments. Benefits of repeated oral sucrose are unclear. Neonates receiving oral dextrose had lower xanthine/creatinine and uric acid/creatinine. Repeated treatments of neonatal procedural pain with 30% oral dextrose are less energetically demanding. Larger clinical studies are needed for comparison with sucrose treatments.