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Cells are the basic unit of life. Electrochemical analysis of single cells/organelles is essential for uncovering the molecular mechanisms of physiological and pathological processes that are difficult to elucidate on a larger scale. This paper provides an overview of the commonly used fabrication methods for micro/nanoelectrodes applied in the investigations of single cells/organelles as well as the corresponding electrochemical measurements over the last four years including extracellular measurement, combination of extra and intracellular measurement, intracellular reactive oxygen species and reactive nitrogen species (ROS/RNS) measurement, and isolated organelles measurement. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to evaluate the value of tissue inhibitors of MMPs-2 (TIMP-2) to indicate 5-Fluorouracil (5-Fu) resistance status in colorectal cancer. Methods: The 5-Fu resistance of colorectal cancer cell lines was detected using Cell-Counting Kit-8 (CCK-8) and calculated using IC50. Enzyme-linked immunosorbent assay (ELISA) and real time-quantitative polymerase chain reaction (RT-qPCR) were used to detect TIMP-2 expression level in the culture supernatant and serum. Twenty-two colorectal cancer patients' TIMP-2 levels and clinical characteristics were analyzed before and after chemotherapy. Additionally, the patient-derived xenograft (PDX) model of 5-Fu resistance was used to evaluate the feasibility of TIMP-2 as a predictive biomarker of 5-Fu resistance. Results: Our experimental results display that TIMP-2 expression is elevated in colorectal cancer drug-resistant cell lines, and its expression level is closely related to 5-Fu resistance. Moreover, TIMP-2 in colorectal cancer patient serum undergoing 5-Fu-based chemotherapy could indicate their drug resistance status, and its efficacy is higher than CEA and CA19-9. Finally, PDX model animal experiments reveal that TIMP-2 can detect 5-Fu resistance in colorectal cancer earlier than tumor volume. Conclusion: TIMP-2 is a good indicator of 5-Fu resistance in colorectal cancer. Monitoring the serum TIMP-2 level can help the clinician identify 5-Fu resistance in colorectal cancer patients earlier during chemotherapy. [ABSTRACT FROM AUTHOR]

The concept of submodularity has wide applications in data science, artificial intelligence, and machine learning, providing a boost to the investigation of new ideas, innovative techniques, and creative algorithms to solve different submodular optimization problems arising from a diversity of applications. However pure submodular problems only represent a small portion of the problems we are facing in real life applications. In this paper, we further discuss the two-stage submodular maximization problem under a ℓ -matroid constraint. We design an approximation algorithm with constant approximation ratio with respect to the curvature, which improves the previous bound. In addition, we generalize our algorithm to the two-stage submodular maximization problem under a ℓ -exchange system constraint. [ABSTRACT FROM AUTHOR]