Evaluation of Redox Activity of Human Myocardium‐derived Mesenchymal Stem Cells by Scanning Electrochemical Microscopy

In this study the redox activity of human myocardium‐derived mesenchymal stem cells (hmMSC) were investigated by redox‐competition (RC‐SECM) and generation‐collection (GC‐SECM) modes of scanning electrochemical microscopy (SECM), using 2‐methylnaphthalene‐1,4‐dione (menadione, MD) as a redox mediator. The redox activity of human healthy and dilated hmMSCs was evaluated by measuring reduction of MD. Measurements were performed by approaching and retracting the UME from the surface of growing hmMSC cells. The current study shows that the RC‐SECM mode can be applied to investigate integrity of cell membranes, whereas the most promising results were observed by using the GC‐SECM mode and applying the Hill's equation for the calculation/fitting of dependencies of electrical current vs menadione concentration. The calculated apparent Michaelis constant (K_M) for the production of menadiol (MDH₂) in the pathological hmMSC cells was 14.4 folds higher compared to that of the healthy hmMSC revealing the lover redox activity of pathological cells. Moreover, the calculated Hill's coefficient n shows a negative cooperative binding between MD and healthy hmMSC and positive cooperative binding between MD and pathological hmMSC. It means that healthy hmMSC is of lower affinity to MD, which is also related to the better membrane integrity of healthy cells. Data of this study demonstrate that SECM can be applied to investigate intracellular redox and membrane changes ongoing in human dilated myocardium‐derived hmMSC in order to improve their functioning and further regenerative potential.     

A method of summation of multiple trigonometric series

Institute of Mathematics and Cybernetics, Academy of Sciences of the Lithuanian SSR. Translated from Litovskii Matematicheskii Sbornik (Lietuvos Matematikos Rinkinys), Vol. 29, No. 3, pp. 615–620, July–September, 1989.     

Sieving the Rationals

Lithuanian Mathematical Journal - J. Kubilius developed the model for transferring the problems related to the value distributions of arithmetical functions to those for independent random...     

Benchmark compounds. Structures of cobalt(II) complexes of triphenylphosphine- and triphenylarsine oxides

The structures of the Co(OPPh₃)₂Cl₂, Co(OPPh₃)₂Br₂, Co(OPPh₃)₂I₂, Co(OAsPh₃)₂Br₂ and Co(OAsPh₃)₂(NO₃)₂ complexes have been determined by X-ray diffraction methods; all have pseudo-tetrahedral co-ordination for cobalt.     

Special maps effected by harmonic functions

Institute of Mathematics and Cybernetics, Academy of Sciences of the Lithuanian SSR. Translated from Litovskii Matematicheskii Sbornik (Lietuvos Matematikos Rinkinys), Vol. 29, No. 4, pp. 819–825, October–December, 1989.