Analytical tools for urocanic acid determination in human samples: A review

Urocanic acid is a chromophore found in the skin that has been identified as an important immunosuppressant and carcinogenesis mediator through its photoisomerization from trans to cis form induced by ultraviolet radiation. Research on analytical methods that explore urocanic acid isomerization is indispensable to fully understand the deleterious effects mediated by this biomarker. In this context, the current relevant analytical methods for determination of these isomers in human samples are summarized in this review. The methods presented here are applicable to human samples collected by noninvasive methods (or minimally invasive), encompassing an array of analytical techniques, including high‐performance capillary electrophoresis, confocal Raman spectroscopy, gas chromatography, high‐performance liquid chromatography, and mass spectrometry, among others. Developed high‐performance liquid chromatography methods have proven to be advantageous, allowing noninvasive collections for in vivo analysis and the confocal Raman, specially, for real‐time analysis. Among all these methods, high‐performance liquid chromatography is the most investigated one with mass spectrometry or ultraviolet detector, and the mass spectrometry detector being the most studied in the last years, demonstrating high sensitivity, very low detection limits, and accurate identification, especially for clinical investigations.     

Towards the Use of Adsorption Methods for the Removal of Purines from Beer

Beer corresponds to a fermented alcoholic beverage composed of several components, including purine compounds. These molecules, when ingested by humans, can be catabolized into uric acid, contributing to uric acid’s level increase in serum, which may lead to hyperuricemia and gout. To assure a proper management of this disease, physicians recommend restrictive dietary measures, particularly by avoiding the consumption of beer. Therefore, it is of relevance to develop efficient methods to remove purine compounds from alcoholic beverages such as beer. In this review, we provide an introduction on fermented alcoholic beverages, with emphasis on beer, as well as its purine compounds and their role in uric acid metabolism in the human body in relation to hyperuricemia and gout development. The several reported enzymatic, biological and adsorption methods envisaging purine compounds’ removal are then reviewed. Some enzymatic and biological methods present drawbacks, which can be overcome by adsorption methods. Within adsorption methods, adsorbent materials, such as activated carbon or charcoal, have been reported and applied to beer or wort samples, showing an excellent capacity for adsorbing and removing purine compounds. Although the main topic of this review is on the removal of purine compounds from beer, other studies involving other matrices rather than beer or wort that are rich in purines are included, since they provide relevant clues on designing efficient removal processes. By ensuring the selective removal of purine compounds from this beverage, beer can be taken by hyperuricemic and gouty patients, avoiding restrictive dietary measures, while decreasing the related healthcare economic burden.     

Cysteine as a Multifaceted Player in Kidney,the Cysteine-Related Thiolome and Its Implications for Precision Medicine

In this review encouraged by original data, we first provided in vivo evidence that the kidney, comparative to the liver or brain, is an organ particularly rich in cysteine. In the kidney, the total availability of cysteine was higher in cortex tissue than in the medulla and distributed in free reduced, free oxidized and protein-bound fractions (in descending order). Next, we provided a comprehensive integrated review on the evidence that supports the reliance on cysteine of the kidney beyond cysteine antioxidant properties, highlighting the relevance of cysteine and its renal metabolism in the control of cysteine excess in the body as a pivotal source of metabolites to kidney biomass and bioenergetics and a promoter of adaptive responses to stressors. This view might translate into novel perspectives on the mechanisms of kidney function and blood pressure regulation and on clinical implications of the cysteine-related thiolome as a tool in precision medicine.     

Hydraulic Fracturing of Soft and Hard Rocks: Part 1—Rock Behavior Due to Fluid Penetration Rate

Transport in Porous Media - Hydraulic fracturing (HF) can initiate, propagate, and coalesce cracks, by injecting fluids into rocks. Two papers provide experimental results on the performance of...     

Outlook on the phase equilibria of the innovative system of "protected glycerol": 1,4-dioxaspiro[4.5]decane-2-methanol and alternative solvents

Fundamental data on 1,4-dioxaspiro[4.5]decane-2-methanol are scarce. This work presents the foremost systematic data on the solubility of 1,4-dioxaspiro[4.5]decane-2-methanol in sustainable solvents such as water and ionic liquids accompanied by the interpretation of interactions occurring in such binary systems. 1,4-Dioxaspiro[4.5]decane-2-methanol, here called protected glycerol, has been synthesized in order to protect the two hydroxyl groups of glycerol, thus avoiding the formation of side products in a specific process. A series of imidazolium salts accompanied by pyridinium, phosphonium, and ammonium ones with various types of counterions were used in this study. The liquid-liquid and solid-liquid equilibrium measurements in binary systems were carried out by using a dynamic method at atmospheric pressure over the temperature range from 273.00 to 378.30 K or below the boiling point of the solvent. Among all tested sustainable solvents, protected glycerol exhibited limited solubility, with only a few of them in the temperature range studied. The majority of the examined ionic liquids, either hydrophilic or hydrophobic, showed complete miscibility with this monohydroxyol. The Fourier-transform infrared (FTIR) spectroscopy studies of solute and solvents showing a miscibility gap and of their mixtures were performed to obtain insight into major inter- and intramolecular interactions in the investigated systems. Furthermore, the differential scanning calorimetry was used for the first time to determine the melting point, the enthalpy of melting, and the temperature and enthalpy of the solid-solid phase transition of 1-allyl-3-methylimidazolium chloride [Amim][Cl]. The results for the solubility of protected glycerol in sustainable solvents can be used to design future alternative reactions, such as telomerization with protected glycerol in ionic liquids for more specific building blocks and extraction/or separation that involves these mixtures.     

Luminescent columnar liquid crystals based on tristriazolotriazine

Five discotic molecules comprising a tris[1,2,4]triazolo[1,3,5] triazine core were designed and synthesized to obtain luminescent and charge-transporting columnar liquid crystalline materials. With the exception of one compound containing terminal hydroxyl groups all compounds presented a wide thermal range and stable columnar liquid crystalline phase, characterized by differential scanning calorimetry, polarized optical microscopy, and X-ray diffraction (XRD) techniques. The phase formation appeared to be associated to some extent with interdigitation of the alkoxy and benzylalkoxy portion, as suggested by the XRD results. All compounds have a strong blue luminescence in solution and solid phase. At the temperature at which the compounds enter in the mesophase the luminescence decreases significantly. This result suggests that entrance into the Col(h) phase is accompanied by a better π-stacking of the peripheral phenyl rings compared to the solid phase, consistent with the intramolecular distances (3.5 ?) observed in the XRD analysis. These compounds based on tristriazolotriazine are quite robust with good optical and thermal properties for application as solid state emitters, and we anticipate that they may provide an interesting alternative to other discotic molecules based on N-heterocycles, which generally present a high-temperature Col(h) phase.     

Spherical f-Tilings by Scalene Triangles and Isosceles Trapezoids, Ⅱ

The study of the dihedral f-tilings of the sphere S ² whose prototiles are a scalene triangle and an isosceles trapezoid was initiated in a previous work. In this paper we continue this classification presenting the study of all dihedral spherical f-tilings by scalene triangles and isosceles trapezoids in some cases of adjacency.     

Validity of extracellular water assessment with saliva samples using plasma as the reference biological fluid

Extracellular water (ECW) assessment is based on dilution techniques, commonly using blood sampling. However, plasma collection is an invasive procedure. We aimed to validate the use of saliva for ECW estimation by the bromide dilution technique using plasma as the reference method, in a sample of elite athletes. A total of 89 elite athletes with a mean age of 20.4 ± 4.4 years were evaluated. Baseline samples were collected before sodium bromide oral dose administration, and enriched samples were collected 3 h post‐dose administration. The bromide concentration was assessed by high‐performance liquid chromatography. Comparison of means, concordance coefficient correlation (CCC), multiple regression and Bland–Altman analysis were performed. The ECW from saliva explained 91% of the variance in ECW by plasma with a standard error of estimation of 0.91 kg. The CCC between alternative and reference methods was 0.952. No significant trend was observed between the mean and difference of the methods, with limits of agreement ranging between ?1.5 and 2.1 kg. These findings reveal that bromide dilution volume calculated from saliva samples is a valid noninvasive method for ECW assessment in elite athletes. Copyright © 2012 John Wiley & Sons, Ltd.     

Full Permanent Memory Effect in PDLC Films

Permanent memory effect in polymer dispersed liquid crystal (PDLC) films prepared by thermal polymerization induced phase separation (PIPS) were studied. New trimethylolpropane trimethacrylate (TMP3MA)/poly(propylene glycol) methacrylate (PPGMA375)/E7/AIBN and pentaerythritol tetraacrylate (PE4A)/poly(propylene glycol) acrylate (PPGA475)/E7/AIBN PDLC films showed 86% permanent memory effect with E90 = 6 V/μm and memory state contrast of 70% and full permanent memory effect with E90 = 3 V/μm and total memory state contrast, respectively. These materials with two stable states (opaque and transparent) seem to be promising for the development of a new class of optical memories as they can be used for electrically write information, optically read the written information and they can be thermally erased back to the initial scattered state.