Arthur I. Cederbaum

Bio: Arthur I. Cederbaum is an academic researcher from Icahn School of Medicine at Mount Sinai. The author has contributed to research in topics: Oxidative stress & Lipid peroxidation. The author has an hindex of 73, co-authored 375 publications receiving 26362 citations. Previous affiliations of Arthur I. Cederbaum include City University of New York & Rutgers University.

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

Abstract: In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure flux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation, it is imperative to target by gene knockout or RNA interference more than one autophagy-related protein. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways implying that not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular assays, we hope to encourage technical innovation in the field.

Alcohol, oxidative stress, and free radical damage

Abstract: Reactive oxygen species (ROS) are small, highly reactive, oxygen-containing molecules that are naturally generated in small amounts during the body's metabolic reactions and can react with and damage complex cellular molecules such as fats, proteins, or DNA. Alcohol promotes the generation of ROS and/or interferes with the body's normal defense mechanisms against these compounds through numerous processes, particularly in the liver. For example, alcohol breakdown in the liver results in the formation of molecules whose further metabolism in the cell leads to ROS production. Alcohol also stimulates the activity of enzymes called cytochrome P450s, which contribute to ROS production. Further, alcohol can alter the levels of certain metals in the body, thereby facilitating ROS production. Finally, alcohol reduces the levels of agents that can eliminate ROS (i.e., antioxidants). The resulting state of the cell, known as oxidative stress, can lead to cell injury. ROS production and oxidative stress in liver cells play a central role in the development of alcoholic liver disease.

Role of oxidative stress in alcohol-induced liver injury

Abstract: Reactive oxygen species (ROS) are highly reactive molecules that are naturally generated in small amounts during the body’s metabolic reactions and can react with and damage complex cellular molecules such as lipids, proteins, or DNA Acute and chronic ethanol treatments increase the production of ROS, lower cellular antioxidant levels, and enhance oxidative stress in many tissues, especially the liver Ethanol-induced oxidative stress plays a major role in the mechanisms by which ethanol produces liver injury Many pathways play a key role in how ethanol induces oxidative stress This review summarizes some of the leading pathways and discusses the evidence for their contribution to alcohol-induced liver injury Special emphasis is placed on CYP2E1, which is induced by alcohol and is reactive in metabolizing and activating many hepatotoxins, including ethanol, to reactive products, and in generating ROS

Apparent hydroxyl radical production by peroxynitrite: implications for endothelial injury from nitric oxide and superoxide.

Abstract: Superoxide dismutase reduces injury in many disease processes, implicating superoxide anion radical (O2-.) as a toxic species in vivo. A critical target of superoxide may be nitric oxide (NO.) produced by endothelium, macrophages, neutrophils, and brain synaptosomes. Superoxide and NO. are known to rapidly react to form the stable peroxynitrite anion (ONOO-). We have shown that peroxynitrite has a pKa of 7.49 +/- 0.06 at 37 degrees C and rapidly decomposes once protonated with a half-life of 1.9 sec at pH 7.4. Peroxynitrite decomposition generates a strong oxidant with reactivity similar to hydroxyl radical, as assessed by the oxidation of deoxyribose or dimethyl sulfoxide. Product yields indicative of hydroxyl radical were 5.1 +/- 0.1% and 24.3 +/- 1.0%, respectively, of added peroxynitrite. Product formation was not affected by the metal chelator diethyltriaminepentaacetic acid, suggesting that iron was not required to catalyze oxidation. In contrast, desferrioxamine was a potent, competitive inhibitor of peroxynitrite-initiated oxidation because of a direct reaction between desferrioxamine and peroxynitrite rather than by iron chelation. We propose that superoxide dismutase may protect vascular tissue stimulated to produce superoxide and NO. under pathological conditions by preventing the formation of peroxynitrite.

The NOX Family of ROS-Generating NADPH Oxidases: Physiology and Pathophysiology

Abstract: For a long time, superoxide generation by an NADPH oxidase was considered as an oddity only found in professional phagocytes. Over the last years, six homologs of the cytochrome subunit of the phag...

Nitric Oxide and Peroxynitrite in Health and Disease

Abstract: The discovery that mammalian cells have the ability to synthesize the free radical nitric oxide (NO) has stimulated an extraordinary impetus for scientific research in all the fields of biology and medicine. Since its early description as an endothelial-derived relaxing factor, NO has emerged as a fundamental signaling device regulating virtually every critical cellular function, as well as a potent mediator of cellular damage in a wide range of conditions. Recent evidence indicates that most of the cytotoxicity attributed to NO is rather due to peroxynitrite, produced from the diffusion-controlled reaction between NO and another free radical, the superoxide anion. Peroxynitrite interacts with lipids, DNA, and proteins via direct oxidative reactions or via indirect, radical-mediated mechanisms. These reactions trigger cellular responses ranging from subtle modulations of cell signaling to overwhelming oxidative injury, committing cells to necrosis or apoptosis. In vivo, peroxynitrite generation represents a crucial pathogenic mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, circulatory shock, chronic inflammatory diseases, cancer, and neurodegenerative disorders. Hence, novel pharmacological strategies aimed at removing peroxynitrite might represent powerful therapeutic tools in the future. Evidence supporting these novel roles of NO and peroxynitrite is presented in detail in this review.

Role of free radicals and catalytic metal ions in human disease: an overview.

Abstract: Publisher Summary This chapter discusses the role of free radicals and catalytic metal ions in human disease. The importance of transition metal ions in mediating oxidant damage naturally leads to the question as to what forms of such ions might be available to catalyze radical reactions in vivo . The chapter discusses the metabolism of transition metals, such as iron and copper. It also discusses the chelation therapy that is an approach to site-specific antioxidant protection. The detection and measurement of lipid peroxidation is the evidence most frequently cited to support the involvement of free radical reactions in toxicology and in human disease. A wide range of techniques is available to measure the rate of this process, but none is applicable to all circumstances. The two most popular are the measurement of diene conjugation and the thiobarbituric acid (TBA) test, but they are both subject to pitfalls, especially when applied to human samples. The chapter also discusses the essential principles of the peroxidation process. When discussing lipid peroxidation, it is essential to use clear terminology for the sequence of events involved; an imprecise use of terms such as initiation has caused considerable confusion in the literature. In a completely peroxide-free lipid system, first chain initiation of a peroxidation sequence in a membrane or polyunsaturated fatty acid refers to the attack of any species that has sufficient reactivity to abstract a hydrogen atom from a methylene group.