Publications by authors named "Alexander Kostyuk"

The lack of oxygen (O2) causes changes in the cell functioning. Modeling hypoxic conditions in vitro is challenging given that different cell types exhibit different sensitivities to tissue O2 levels. We present an effective in vivo platform for assessing various tissue and organ parameters in Danio rerio larvae under acute hypoxic conditions.

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Reactive halogen species (RHS) are highly reactive compounds that are normally required for regulation of immune response, inflammatory reactions, enzyme function, etc. At the same time, hyperproduction of highly reactive compounds leads to the development of various socially significant diseases - asthma, pulmonary hypertension, oncological and neurodegenerative diseases, retinopathy, and many others. The main sources of (pseudo)hypohalous acids are enzymes from the family of heme peroxidases - myeloperoxidase, lactoperoxidase, eosinophil peroxidase, and thyroid peroxidase.

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The objective of the current review is to summarize the current state of optical methods in redox biology. It consists of two parts, the first is dedicated to genetically encoded fluorescent indicators and the second to Raman spectroscopy. In the first part, we provide a detailed classification of the currently available redox biosensors based on their target analytes.

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The need for innovative payment models for health technologies with high upfront costs has emerged due to affordability concerns across the world. Early technology adopter countries have been experimenting with delayed payment schemes. Our objective included listing potential barriers for implementing delayed payment models and recommendations on how to address these barriers in lower income countries of Central and Eastern Europe (CEE) and the Middle East (ME).

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Article Synopsis
  • - The study introduces a method for real-time monitoring of hydrogen peroxide and pH changes in rat stroke models using fiber-optic technology, allowing researchers to better understand the effects of ischemia on the brain.
  • - By utilizing advanced fluorescent protein sensors and reconnectable fiber probes, the framework enables detailed, multi-site analysis of oxidative stress and acidosis during stroke events, which are critical markers of the condition.
  • - The approach improves the accuracy of measurements by providing enhanced background noise reduction, making the results of in vivo stroke studies more reliable and statistically significant across different animal models.
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The lack of tools to monitor the dynamics of (pseudo)hypohalous acids in live cells and tissues hinders a better understanding of inflammatory processes. Here we present a fluorescent genetically encoded biosensor, Hypocrates, for the visualization of (pseudo)hypohalous acids and their derivatives. Hypocrates consists of a circularly permuted yellow fluorescent protein integrated into the structure of the transcription repressor NemR from Escherichia coli.

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Article Synopsis
  • * The study uses advanced genetically encoded biosensors to observe intracellular pH and reactive oxygen species (ROS) dynamics during these processes in both cultured neurons and experimental stroke in rats.
  • * Findings reveal a significant acidosis in the brain tissue almost immediately during the ischemic core, but notable ROS generation was only observed 24 hours later, indicating a disconnect between cell culture and actual metabolic processes in vivo.
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Redox reactions are of high fundamental and practical interest since they are involved in both normal physiology and the pathogenesis of various diseases. However, this area of research has always been a relatively problematic field in the context of analytical approaches, mostly because of the unstable nature of the compounds that are measured. Genetically encoded sensors allow for the registration of highly reactive molecules in real-time mode and, therefore, they began a new era in redox biology.

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Hypoxia is characterized by low oxygen content in the tissues. The central nervous system (CNS) is highly vulnerable to a lack of oxygen. Prolonged hypoxia leads to the death of brain cells, which underlies the development of many pathological conditions.

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Genetically encoded biosensors based on fluorescent proteins (FPs) are a reliable tool for studying the various biological processes in living systems. The circular permutation of single FPs led to the development of an extensive class of biosensors that allow the monitoring of many intracellular events. In circularly permuted FPs (cpFPs), the original N- and C-termini are fused using a peptide linker, while new termini are formed near the chromophore.

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Redox-sensitive fluorescent proteins (roFPs) are a powerful tool for imaging intracellular redox changes. The structure of these proteins contains a pair of cysteines capable of forming a disulfide upon oxidation that affects the protein conformation and spectral characteristics. To date, a palette of such biosensors covers the spectral range from blue to red.

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A wide variety of genetically encoded fluorescent biosensors are available to date. Some of them have already contributed significantly to our understanding of biological processes occurring at cellular and organismal levels. Using such an approach, outstanding success has been achieved in the field of redox biology.

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This policy research aims to map patient access barriers to biologic treatments, to explore how increased uptake of biosimilars may lower these hurdles and to identify factors limiting the increased utilisation of biosimilars. A policy survey was developed to review these questions in 10 Central and Eastern European (CEE) and Commonwealth of Independent States (CIS) countries. Two experts (one public and one private sector representative) from each country completed the survey.

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