Tailored hydrogel composite membrane for the regulated crystallization of monosodium urate monohydrate within coffee's metabolites system.

Herein, a facile bionic research platform with fabricated hydrogel composite membrane (HCM) is constructed to uncover the effects of the main components of coffee's metabolites on MSUM crystallization. Tailored and biosafety polyethylene glycol diacrylate/N-isopropyl acrylamide (PEGDA/NIPAM) HCM allows the proper mass transfer of coffee's metabolites and can well simulate the process of coffee's metabolites acting in the joint system. With the validations of this platform, it is shown that chlorogenic acid (CGA) can hinder the MSUM crystals formation from 45 h (control group) to 122 h (2 mM CGA), which is the most likely reason that reduces the risk of gout after long-term coffee consumption. Molecular dynamics simulation further indicates that the high interaction energy (Eint) between CGA and MSUM crystal surface and the high electronegativity of CGA both contribute to the restraint of MSUM crystal formation. In conclusion, the fabricated HCM, as the core functional materials of the research platform, presents the understanding of the interaction between coffee consumption and gout control.

Differences in the Optical Response of MSU and CPP Crystals During Magnetic Orientation: Possibility of Diagnosing Gout and Pseudogout.

Pseudogout is crystalline arthritis. It has a similar clinical picture to that of gout, and it is difficult to distinguish the two diseases using conventional analysis methods. However, it is important to identify the different crystals responsible for these two cases because the treatment strategies are different. In a previous study, we reported magnetic orientation of monosodium urate (MSU) crystals, which are the causative agent of gout, at the permanent magnet level. In this study, we investigated the effect of an applied magnetic field on calcium pyrophosphate (CPP) crystals, which are the causative agent of pseudogout, and the difference in the magnetic responses of CPP and MSU crystals. We found that the CPP crystals were oriented in a magnetic field on milli-Tesla order because of the anisotropy of the diamagnetic susceptibility. In addition, the CPP crystals exhibited different anisotropic magnetic properties from those of MSU crystals, which led to a characteristic difference between the orientations of the two crystals. That is, we found that the causative agents of gout and pseudogout responded differently to a magnetic field. This report suggests that the discrimination between CPP and MSU by optical measurements is possible by application of magnetic fields appropriately. © 2023 Bioelectromagnetics Society.

An ultra-sensitive uric acid second generation biosensor based on chemical immobilization of uricase on functionalized multiwall carbon nanotube grafted palm oil fiber in the presence of a ferrocene mediator.

In this work, palm oil fiber (POF) grafted functionalized multiwall carbon nanotube (FMWCNT) decorated ferrocene (Fc) has been drop coated on a platinum electrode (Pt), in which uricase (UOx) has been chemically immobilized for sensitive and selective biosensing of uric acid (UA). Through the use of EDC/NHS, a stable bioelectrode (UOx/Fc/FMWCNT-POF/Pt) was obtained and characterized by FTIR/ATRIR, XRD, Raman, EA/EDX, TGA, SEM, TEM, CV, EIS, CA, and DPV. Results from DPV showed the rapid response of the developed bioelectrode towards UA (0.185 V) with high sensitivity (41.14 µA mM-1) and good limit of detection (19 µM) in the linear range 10-1000 µM. The low value of Michaelis-Menten constant (km = 31.364 µM) shows high affinity of the UA towards the enzyme at the electrode surface. The developed biosensor demonstrates good reproducibility, repeatability, and stability with a deviation of less than 2.5%, and was successfully applied for human blood sample analysis. The CA study revealed a fast response time (2 s) of the sensor. The work has pioneered a new addition to the class of tailorable chemical species for biosensor development and proven to be a promising new tool for point of care testing (POCT) applications.

Unusual shape-preserved pathway of a core-shell phase transition triggered by orientational disorder.

The ubiquitous presence of crystal defects provides great potential and opportunities to construct the desired structure (hence with the desired properties) and tailor the synthetic process of crystalline materials. However, little is known about their regulation role in phase transition and crystallization pathways. It was generally thought that a phase transition in solution proceeds predominantly via the solvent-mediated phase-transformation pathway due to energetically high-cost solid-state phase transitions (if any). Herein, we report an unprecedented finding that an orientational disorder defect present in the crystal structure triggers an unusual pathway of a core-shell phase transition with apparent shape-preserved evolution. In the pathway, the solid-state dehydration phase transition occurs inside the crystal prior to its competitive transformation approach mediated by solvent, forming an unconventional core-shell structure. Through a series of combined experimental and computational techniques, we revealed that the presence of crystal defects, introduced by urate tautomerism over the course of crystallization, elevates the metastability of uric acid dihydrate (UAD) crystals and triggers UAD dehydration to the uric acid anhydrate (UAA) phase in the crystal core which precedes with surface dissolution of the shell UAD crystal and recrystallization of the core phase. This unique phase transition could also be related to defect density, which appears to be influenced by the thickness of UAD crystals and crystallization driving force. The discovery of an unusual pathway of the core-shell phase transition suggests that the solid-state phase transition is not necessarily slower than the solvent-mediated phase transformation in solution and provides an alternative approach to constructing the core-shell structure. Moreover, the fundamental role of orientational disorder defects on the phase transition identified in this study demonstrates the feasibility to tailor phase transition and crystallization pathways by strategically importing crystal defects, which has broad applications in crystal engineering.

Natural products for the management of hyperuricaemia and gout: a review.

Hyperuricaemia is characterised by a high level of urate in the blood. The crystallisation of urate is considered a critical risk factor for the development of gout. Allopurinol and febuxostat have been commonly used medications to decrease the circulating urate levels. However, the use of these drugs is associated with undesired side effects. Therefore, the development of a new active, safety anti-hyperuricaemic and anti-inflammatory drug could be useful in gout therapy and is highly justified. Natural products have become a source of new pharmaceuticals due to their strong efficacy with less side effects, which relies on the comprising of complex bioactive compounds. There are a growing number of studies purporting decreasing serum urate with traditional medicines. This article was aimed to review these studies and identify which extracts promote urate reduction, along with their different mechanisms.

Isoorientin exerts a urate-lowering effect through inhibition of xanthine oxidase and regulation of the TLR4-NLRP3 inflammasome signaling pathway.

Isoorientin (ISO), a natural flavonoid compound, has been identified in several plants and its biological activity is determined and the study on lowering uric acid has not been reported. In view of the current status of treatment of hyperuricemia, we evaluated the hypouricemic effects of ISO in vivo and in vitro, and explored the underlying mechanisms. Yeast extract-induced hyperuricemia animal model as well as hypoxanthine and xanthine oxidase (XOD) co-induced high uric acid L-O2 cell model and enzymatic experiments in vitro were selected. The XOD activity and uric acid (UA) level were inhibited after the treatment of ISO in vitro and in vivo. Furthermore, serum creatinine (CRE) and blood urea nitrogen (BUN) levels were also significantly reduced and liver damage was recovered in pathological histology after the ISO administration in hyperuricemia animal model. The results of mechanism illustrated that protein expressions such as XOD, toll-like receptor 4 (TLR4), cathepsin B (CTSB), NLRP3, and its downstream caspase-1 as well as interleukin-18 (IL-18) were markedly downregulated by ISO intervention in vitro and in vivo. Our results suggest that ISO exerts a urate-lowering effect through inhibiting XOD activity and regulating TLR4-NLRP3 inflammasome signal pathway, thus representing a promising candidate therapeutic agent for hyperuricemia. Both animal models and in vitro experiments suggested that ISO may effectively lower uric acid produce. The mechanism might be the inhibition of XOD activity and NLRP3 inflammasome of upregulation.

Identification and characterization of N9-methyltransferase involved in converting caffeine into non-stimulatory theacrine in tea.

Caffeine is a major component of xanthine alkaloids and commonly consumed in many popular beverages. Due to its occasional side effects, reduction of caffeine in a natural way is of great importance and economic significance. Recent studies reveal that caffeine can be converted into non-stimulatory theacrine in the rare tea plant Camellia assamica var. kucha (Kucha), which involves oxidation at the C8 and methylation at the N9 positions of caffeine. However, the underlying molecular mechanism remains unclear. Here, we identify the theacrine synthase CkTcS from Kucha, which possesses novel N9-methyltransferase activity using 1,3,7-trimethyluric acid but not caffeine as a substrate, confirming that C8 oxidation takes place prior to N9-methylation. The crystal structure of the CkTcS complex reveals the key residues that are required for the N9-methylation, providing insights into how caffeine N-methyltransferases in tea plants have evolved to catalyze regioselective N-methylation through fine tuning of their active sites. These results may guide the future development of decaffeinated drinks.

[Role of drinking and dietary factors in effective dissolution therapy and recurrence prevention of uric acid kidney stones].

The use of alkaline mineral waters leads to alkalization of urine and an increase in level of urinary citrate, which represent important factor inhibiting the formation of urinary stones. Combination of alkaline mineral waters with citrates facilitates the achievement of target urine pH level not only during dissolution therapy, but also during recurrence prevention. Alkalization of urine and reducing of the influence of alimentary factor dont preclude drug therapy. Patients should be counselled about complex strategies aimed to modifiable risk factors for urinary stone disease.

Clinical observation of Qushi Xiezhuo formula in reducing monosodium urate crystal deposition in patients with axial spondyloarthritis.

OBJECTIVE: To investigate effect of Qushi Xiezhuo formula (QSXZF) on axial spondyloarthritis (AxSpA) with a high incidence of monosodium serum urate (MSU) crystal deposition. METHODS: In this prospective cohort study, 62 AxSpA patients diagnosed with MSU crystal deposition from October 2012 to July 2015 were recruited for follow-up observation for 1 year after discharge from the hospital. Patients were divided into a case group with QSXZF treatment and a control group without any interventions. X-ray and dual-energy computed tomography were used to assess structural damage in the pelvis and sacroiliac joint and the volume of the MSU crystals. The Wilcoxon rank-sum test and Fisher's exact test were used to compare the proportion and distribution between the groups. RESULTS: A decrease in C-reactive protein (CRP) level, relief from back pain, and an increase in MSU crystal depositions were found in control patients. Compared with the control group, QSXZF reduced CRP levels and back pain to a greater extent, as well as reduced erythrocyte sedimentation rate levels, serum uric acid levels, Ankylosing Spondylitis Disease Activity Score, morning stiffness and MSU crystal deposition. CONCLUSION: QSXZF can lower progress of radiogrphaic grade at sacroiliac joint in AxSpA/AS patients with MSU crystal deposition by decreasing the inflammation response and reducing the serum uric acid and volume of MSU crystal deposition in sacroiliac joint. The above process may be attributed to the relieving the Qi-movement disturbance in the body, and eliminating turbidity and dampness by QSXZF.

Direct Observation of Oxidation Reaction via Closed Bipolar Electrode-Anodic Electrochemiluminescence Protocol: Structural Property and Sensing Applications.

In this work, we developed an innovative closed bipolar electrode (BPE)-electrochemiluminescence (ECL) sensing strategy with generality for target detection. Based on charge balance and 100% current efficiency between the closed BPE poles and the driving electrodes, one of the driving electrodes in one cell of the closed BPE system was employed as ECL sensing surface to reflect the target on the BPE pole in the opposite cell. Compared with traditional BPE-ECL sensing method, which in general adopted the anodic ECL reagents such as Ru(bpy)32+ and its coreactant on one pole (anode) to reflect the target (occurring reduction reaction) on the other pole (cathode), the difference was that the targets occurring oxidation reaction could be detected by the anodic ECL reagents based on this strategy. To verify the feasibility of this strategy, the detection principle was stated first, and Fe(CN)64- as model target at anodic BPE pole were detected by anodic ECL reagents (Ru(bpy)32+ and TprA) on the driving electrode first. The ECL signals showed good performance for target detection. By changing the size and the material of the BPE pole where the targets were located, the detection of l-ascorbic acid (AA), uric acid (UA), and dopamine (DA) as other model targets with higher detection limit were accomplished. Visual and high-throughput detection of AA, UA, and DA were also successfully realized by an array of the closed BPE system. This closed BPE (array) system is an effective supplement of traditional BPE-ECL sensing and could greatly expand the scope of the detection target.

Effect of Consumption of Cocoa-Derived Products on Uric Acid Crystallization in Urine of Healthy Volunteers.

The purpose of this study was to determine the effects of consumption of different cocoa-derived products on uric acid crystallization in urine of 20 healthy volunteers. Participants were requested to select the specific diet that they wished to follow during the 12 h prior to collection of urine. The only restriction was that the diet could not include any product with cocoa, coffee, or caffeine. On the first day, each volunteer followed their selected diet, and an overnight 12 h urine sample was collected as the baseline urine. After seven days on an unrestricted diet, each volunteer repeated the same diet with 20 g of milk chocolate, chocolate powder, or dark chocolate during breakfast and another 20 g during dinner. Overnight 12 h urine samples were then collected. Urine volume, pH, oxalate, creatinine, uric acid, theobromine, and a uric acid crystallization test were determined for each sample. The results for all 20 patients show that uric acid crystallization was significantly lower following the consumption of chocolate powder or dark chocolate relative to baseline or following the consumption of milk chocolate. The results indicated that increased concentrations of urinary theobromine reduced the risk of uric acid crystallization.

HEMOLYMPH CHEMISTRY REFERENCE RANGES OF THE CHILEAN ROSE TARANTULA GRAMMOSTOLA ROSEA (WALKENAER, 1837) USING THE VETSCAN BIOCHEMISTRY ANALYZER BASED ON IFCC-CLSI C28-A3.

The use of invertebrate hemolymph chemistry analysis has the potential to become a major diagnostic tool. The goal of this study was to generate statistically sound hemolymph reference ranges from healthy tarantulas. Hemolymph was drawn from wild caught, acclimatized, and apparently healthy female Chilean rose tarantulas Grammostola rosea (Walkenaer, 1837) ( n = 43) using a modified technique. Hemolymph samples were separately analyzed using the Avian-Reptilian Profile Plus reagent rotor for VetScan® for the following chemistries: aspartate aminotransferase, bile acids, creatine kinase, uric acid, glucose, total calcium, phosphorus, total protein, albumin, potassium, and sodium. With this method the authors were able to establish statistically sound reference ranges for aspartate aminotransferase, creatine kinase, glucose, phosphorus, and total protein. Further in situ studies will determine the practical usability of these values in the evaluation of tarantula health.

Effect of corn supplementation on purine derivatives and rumen fermentation in sheep fed PKC and urea-treated rice straw.

This study investigated the effect of different levels of corn supplementation as energy source into palm kernel cake-urea-treated rice straw basal diet on urinary excretion of purine derivatives, nitrogen utilization, rumen fermentation, and rumen microorganism populations. Twenty-seven Dorper lambs were randomly assigned to three treatment groups and kept in individual pens for a 120-day period. The animals were subjected to the dietary treatments as follows: T1: 75.3% PKC + 0% corn, T2: 70.3% PKC + 5% corn, and T3: 65.3% PKC + 10% corn. Hypoxanthine and uric acid excretion level were recorded similarly in lambs supplemented with corn. The microbial N yield and butyrate level was higher in corn-supplemented group, but fecal N excretion, T3 has the lowest level than other groups. Lambs fed T3 had a greater rumen protozoa population while the number of R. flavefaciens was recorded highest in T2. No significant differences were observed for total bacteria, F. succinogenes, R. albus, and methanogen population among all treatment. Based on these results, T3 could be fed to lambs without deleterious effect on the VFA and N balance.

Mechanistic insights into the inhibition of quercetin on xanthine oxidase.

Quercetin, one of the most abundant flavonoid in the daily diet, was found to reversibly inhibit the generation of uric acid and superoxide radicals (O2-)catalyzed by xanthine oxidase (XOD) in a mixed-type manner with IC50 values of (2.74±0.04)×10-6 and (2.90±0.03)×10-6molL-1, respectively, and the inhibition of quercetin on O2- generation may be ascribed to the reduced form of XOD by a ping-pong mechanism. XOD had one high affinity binding site for quercetin with a binding constant of 4.28×104Lmol-1 at 298K, and the binding process was predominately driven by van der Waals forces and hydrogen bonds on account of the negative enthalpy and entropy changes. Moreover, molecular docking confirmed that the binding site for quercetin located in the isoalloxazine ring of the flavin adenine dinucleotide (FAD) domain of XOD, then the diffusion of O2- out of the FAD site was blocked in favor of another electron transferred from FADH2 to O2- to form hydrogen peroxide (H2O2). This study may clarify the role of quercetin on inhibiting XOD catalysis and provide a potential nutritional supplement for preventing gout and peroxidative damage.

Beneficial Properties of Phytochemicals on NLRP3 Inflammasome-Mediated Gout and Complication.

Gouty arthritis is characterized by the precipitation of monosodium urate (MSU) crystals in the joint. Pro-inflammatory cytokine IL-1ß is a critical manifestation in response to MSU crystals attack. IL-1ß secretion is dependent on the nucleotide-binding oligomerization domain-like receptor pyrin domain containing 3 (NLRP3) inflammasome. Abnormal activation of the NLRP inflammasome is related to cellular oxidative stress. However, recent studies have illustrated that phytochemicals with potent antioxidant activity exert inhibitory effects on NLRP3 inflammasome-mediated diseases. This review focuses on the current findings of studies on the NLRP3 inflammasome and the proposed mechanisms that MSU crystals trigger inflammation via activation of the NLRP3 inflammasome. We also summarized the potential use of phytochemicals on NLRP3 inflammasome-mediated diseases, suggesting that phytochemicals can further prevent acute gout attack.

Online Raman spectroscopy for structural biology on beamline ID29 of the ESRF.

Raman spectroscopy can probe the structure and conformations of specific chemical groups within proteins and may thus be used as a technique complementary to X-ray crystallography. This combined approach can be decisive in resolving ambiguities in the interpretation of enzymatic or X-ray induced processes. Here, we present an online Raman setup developed at the European Synchrotron that allows for interleaved Raman spectra acquisition and X-ray diffraction measurements with fast probe exchange and simple alignment while maintaining a high sensitivity over the entire spectral range. This device has been recently employed in the study of a covalent intermediate in the O2-dependent breakdown of uric acid by the cofactor-free enzyme urate oxidase and to monitor its decay induced by X-ray exposure.

Physiological concentrations of soluble uric acid are chondroprotective and anti-inflammatory.

High uric acid levels are a risk factor for cardiovascular disorders and gout; however, the role of physiological concentrations of soluble uric acid (sUA) is poorly understood. This study aimed to clarify the effects of sUA in joint inflammation. Both cell cultures of primary porcine chondrocytes and mice with collagen-induced arthritis (CIA) were examined. We showed that sUA inhibited TNF-α- and interleukin (IL)-1ß-induced inducible nitric oxide synthase, cyclooxygenase-2 and matrix metalloproteinase (MMP)-13 expression. Examination of the mRNA expression of several MMPs and aggrecanases confirmed that sUA exerts chondroprotective effects by inhibiting the activity of many chondro-destructive enzymes. These effects attenuated collagen II loss in chondrocytes and reduced proteoglycan degradation in cartilage explants. These results were reproduced in chondrocytes cultured in three-dimensional (3-D) alginate beads. Molecular studies revealed that sUA inhibited the ERK/AP-1 signalling pathway, but not the IκBα-NF-κB signalling pathway. Increases in plasma uric acid levels facilitated by the provision of oxonic acid, a uricase inhibitor, to CIA mice exerted both anti-inflammatory and arthroprotective effects in these animals, as demonstrated by their arthritis severity scores and immunohistochemical analysis results. Our study demonstrated that physiological concentrations of sUA displayed anti-inflammatory and chondroprotective effects both in vitro and in vivo.

Neutrophil Extracellular Traps and Microcrystals.

Neutrophil extracellular traps represent a fascinating mechanism by which PMNs entrap extracellular microbes. The primary purpose of this innate immune mechanism is thought to localize the infection at an early stage. Interestingly, the ability of different microcrystals to induce NET formation has been recently described. Microcrystals are insoluble crystals with a size of 1-100 micrometers that have different composition and shape. Microcrystals have it in common that they irritate phagocytes including PMNs and typically trigger an inflammatory response. This review is the first to summarize observations with regard to PMN activation and NET release induced by microcrystals. Gout-causing monosodium urate crystals, pseudogout-causing calcium pyrophosphate dehydrate crystals, cholesterol crystals associated with atherosclerosis, silicosis-causing silica crystals, and adjuvant alum crystals are discussed.

New synthesis of poly ortho-methoxyaniline nanostructures and its application to construct modified multi-wall carbon nanotube/graphite paste electrode for simultaneous determination of uric acid and folic acid.

Uric acid (UA) and folic acid (FA) are compounds of biomedical interest. In humans, about 70% of daily uric acid disposal occurs via the kidneys, and in 5-25% of humans, impaired renal (kidney) excretion leads to hyperuricemia. Folate is another form folic acid of which is known as, is one of the B vitamins. It is used as a supplement by women to prevent neural tube defects developing during pregnancy. Polyortho-methoxyaniline nanostructures (POMANS) was synthesized with a new two phase (organic-water) synthesis method. The POMANS was characterized using transmission electron microscopy (TEM) and Fourier transform IR (FTIR). This polymer was used to construct a modified multi-wall carbon nanotube, graphite paste electrode (POMANS-MWCNT/GPE). Linear sweep voltammograms (LSV), cyclic voltammetry (CV) and chronoamperometry were used to investigate the suitability of polyortho-methoxyaniline with multi-wall carbon nanotubes paste electrode as a modifier for the electrocatalytic oxidation of UA and FA in aqueous solutions with various pHs. The results showed that POMANS-MWCNT/GPE had high anodic peak currents for the electrooxidation of UA and FA in pH6.0.Under the optimized conditions, The catalytic peak currents obtained, was linearly dependent on the UA and FA concentrations in the range of 0.6-52 and 0.5-68µM with two segments and the detection limits 0.157 and 0.113µM for UA and FA were, respectively. Finally, the proposed method was also examined as a sensitive, simple and inexpensive electrochemical sensor for the simultaneous determination of UA and FA in real samples such as urine and serum.

Electrochemical Sensor Based on Fe Doped Hydroxyapatite-Carbon Nanotubes Composite for L-Dopa Detection in the Presence of Uric Acid.

A novel amperometric sensor based on iron doped hydroxyapatite (Fe-HA) and multiwalled carbon nanotubes (CNT) composite immobilized on a glassy carbon electrode (GCE) has been fabricated. The hybrid composite made of Fe-HA nanoparticles and CNT promotes electron transfer kinetics between the analyte levodopa (L-dopa) and the modified GC electrode. Under optimum conditions, the fabricated sensor gave a linear response range of 1.0 x 10(-7)-1.1 x 10(-6) M with the detection limit as low as 62 nM. The Fe-HA/CNT modified electrode showed good selectivity towards the determination of L-dopa in the presence of ascorbic acid (AA), uric acid (UA) and other common interferents. The sensor displays a high sensitivity, good reproducibility and long-term stability and it was successfully applied for the detection of L-dopa in pharmaceutical and medicinal plant samples.