Sarcosine as a Potential Prostate Cancer Biomarker—A Review

Prostate cancer (CaP) is the most common type of tumour disease in men. Early diagnosis of cancer of the prostate is very important, because the sooner the cancer is detected, the better it is treated. According to that fact, there is great interest in the finding of new markers including amino acids, proteins or nucleic acids. Prostate specific antigen (PSA) is commonly used and is the most important biomarker of CaP. This marker can only be detected in blood and its sensitivity is approximately 80%. Moreover, early stages cannot be diagnosed using this protein. Currently, there does not exist a test for diagnosis of early stages of prostate cancer. This fact motivates us to find markers sensitive to the early stages of CaP, which are easily detected in body fluids including urine. A potential is therefore attributed to the non-protein amino acid sarcosine, which is generated by glycine-N-methyltransferase in its biochemical cycle. In this review, we summarize analytical methods for quantification of sarcosine as a CaP marker. Moreover, pathways of the connection of synthesis of sarcosine and CaP development are discussed.     

Voltammetry as a Tool for Characterization of CdTe Quantum Dots

Electrochemical detection of quantum dots (QDs) has already been used in numerous applications. However, QDs have not been well characterized using voltammetry, with respect to their characterization and quantification. Therefore, the main aim was to characterize CdTe QDs using cyclic and differential pulse voltammetry. The obtained peaks were identified and the detection limit (3 S/N) was estimated down to 100 fg/mL. Based on the convincing results, a new method for how to study stability and quantify the dots was suggested. Thus, the approach was further utilized for the testing of QDs stability.     

Use of electrochemical microsensors for hydrodynamics study in crossing microchannels

The study of microfluidic systems is an important research challenge related to the design of microdevices for chemical processes. The understanding of physical phenomena, such as flow behaviour and heat and mass transfer performance is needed in order to develop these microsystems for industrial applications as mixers, reactors or heat exchangers. This work aims at characterizing two flow pattern behaviours, by using an electrochemical method, in a microdevice composed of crossing microchannels. A nonintrusive electrodiffusion method involving an electrochemical reaction of active species on an electrode flush-mounted into a wall is used to investigate wall shear stress. The measured limiting diffusion current is related to the wall shear rate in the vicinity of the electrode. The experimental cell consists of two crossing microchannels intersecting at right angle. Two channels sections are investigated, respectively 500 and 833 μm in hydraulic diameter. In each case, the influence of the crossing on the flow behaviour and on the mixing performance are characterized locally by using microelectrodes implemented at several positions on the wall of the channels located after the crossing. The experimental results are analyzed and a comparison with the results of CFD simulations using Fluent is performed.     

Characterization of molecular structure of acrylic copolymers prepared via emulsion polymerization using A4F‐MALS technique

The study is primarily focused on the possibility to utilize organic asymmetric flow field‐flow fractionation (A4F) coupled to a multi‐angle light scattering (MALS) detector for the characterization of copolymers of methyl methacrylate with various acrylates prepared by emulsion polymerization. The effects of acrylate monomer type and content on the molar mass distribution and degree of branching of acrylic copolymers have been studied by A4F‐MALS using tetrahydrofuran as a carrier solvent. It has been found that the growing amount of acrylate results in the increase of molar mass, polydispersity, and branching degree as a result of chain transfer to polymer. Highly branched compact macromolecules with ultra‐high molar mass were identified in all copolymers containing a high level of acrylate. In contrast to size traditionally used exclusion chromatography, organic A4F‐MALS has been proved as a very efficient technique for the characterization of high molar mass acrylic emulsion copolymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40995.     

PIMT Binding to C-Terminal Ala459 of CAIX Is Involved in Inside-Out Signaling Necessary for Its Catalytic Activity

Human carbonic anhydrase IX (CAIX), a unique member of the α carbonic anhydrase family, is a transmembrane glycoprotein with high enzymatic activity by which CAIX contributes to tumorigenesis through pH regulation. Due to its aberrant expression, CAIX is considered to be a marker of tumor hypoxia and a poor prognostic factor of several human cancers. Hypoxia-activated catalytic function of CAIX is dependent on posttranslational modification of its short intracellular domain. In this work, we have identified that C-terminal Ala459 residue, which is common across CAIX of various species as well as additional transmembrane isoforms, plays an important role in CAIX activation and in pH regulation. Moreover, structure prediction I-TASSER analysis revealed involvement of Ala459 in potential ligand binding. Using tandem mass spectrometry, Protein-L-isoaspartyl methyltransferase (PIMT) was identified as a novel interacting partner, further confirmed by an in vitro pulldown assay and an in situ proximity ligation assay. Indeed, suppression of PIMT led to increased alkalinization of culture media of C33a cells constitutively expressing CAIX in hypoxia. We suggest that binding of PIMT represents a novel intracellular signal required for enzymatic activity of CAIX with a potential unidentified downstream function.     

Studies on the temperature distribution of a thick film transcutaneous oxygen sensor and its thermal influences on oxygen measurement

The partial pressures of gases, namely oxygen and carbon dioxide, in the arterial blood are important parameters for doctors to determine the respiratory conditions of patients. Currently in practice, there are a number of ways to measure these parameters, one of which is transcutaneous blood gas monitoring. This technique is a popular noninvasive measurement method for obtaining fast and relatively accurate responses. In this investigation, thick film technology has been employed to develop an amperometric oxygen sensor which consists of a heating module to elevate the temperature at the skin surface to transcutaneous levels. The heating module includes a heating element and its temperature is regulated by a temperature control circuit. Using an infrared camera, the transient and steady-state temperature distributions as well as the stability of the heating element have been analysed. The influence of temperature on the oxygen sensing module is also studied. In addition, a three-dimensional theoretical model is established to evaluate the thermal response of the sensor and subsequently compared with the results from the practical prototype. With this model, the design stages can be simplified and future heating modules for transcutaneous sensors could be generated and improved more easily and effectively.     

Investigation of electrocatalytic activity on a N-doped reduced graphene oxide surface for the oxygen reduction reaction in an alkaline medium

Today the search for new energy resources is a crucial topic for materials science. The development of new effective catalysts for the oxygen reduction reaction can significantly improve the performance of fuel cells as well as electrocatalytic hydrogen production. This study presents the scalable synthesis of nitrogen-doped graphene oxide for the oxygen reduction reaction. The combination of an ab initio theoretical investigation of the oxygen reduction reaction (ORR) mechanism and detailed electrochemical characterization allowed the identification of electrocatalytically active nitrogen functionalities. The dominant effect on electrocatalytic activity is the presence of graphitic and pyridinic nitrogen and also N-oxide functionalities. The overpotential of ORR for nitrogen-doped graphene oxide prepared by microwave-assisted synthesis outperformed the metal-doped graphene materials.     

SEDIMENTATION OF PARTICLES IN NON-NEWTONIAN FLUIDS

The influence of non-Newtonian flow behavior on sedimentation velocity of particles is investigated using an approximate solution for the motion of an assemblage of solid spheres presented previously by the authors. It is theoretically predicted that the pseudoplaslicity decreases the sedimentation velocity and its reduction is pronounced at large voidage. The present theory is discussed using the available empirical correlations.