Thammasat University

About: Thammasat University is a education organization based out in Bangkok, Thailand. It is known for research contribution in the topics: Population & Catalysis. The organization has 3953 authors who have published 7034 publications receiving 93617 citations. The organization is also known as: TU & Mahawitthayalai Thammasat.

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.

Redox Regulation of Cell Survival

Abstract: Reactive oxygen species (ROS) and reactive nitrogen species (RNS) play important roles in regulation of cell survival. In general, moderate levels of ROS/RNS may function as signals to promote cell proliferation and survival, whereas severe increase of ROS/RNS can induce cell death. Under physiologic conditions, the balance between generation and elimination of ROS/RNS maintains the proper function of redox-sensitive signaling proteins. Normally, the redox homeostasis ensures that the cells respond properly to endogenous and exogenous stimuli. However, when the redox homeostasis is disturbed, oxidative stress may lead to aberrant cell death and contribute to disease development. This review focuses on the roles of key transcription factors, signal-transduction pathways, and cell-death regulators in affecting cell survival, and how the redox systems regulate the functions of these molecules. The current understanding of how disturbance in redox homeostasis may affect cell death and contribute to the development of diseases such as cancer and degenerative disorders is reviewed. We also discuss how the basic knowledge on redox regulation of cell survival can be used to develop strategies for the treatment or prevention of those diseases. Antioxid. Redox Signal. 10, 1343–1374.

Culture specific and cross-culturally generalizable implicit leadership theories: Are attributes of charismatic/transformational leadership universally endorsed?

Abstract: This study focuses on culturally endorsed implicit theories of leadership (CLTs). Although cross-cultural research emphasizes that different cultural groups likely have different conceptions of what leadership should entail, a controversial position is argued here: namely that attributes associated with charismatic/transformational leadership will be universally endorsed as contributing to outstanding leadership. This hypothesis was tested in 62 cultures as part of the Global Leadership and Organizational Behavior Effectiveness (GLOBE) Research Program. Universally endorsed leader attributes, as well as attributes that are universally seen as impediments to outstanding leadership and culturally contingent attributes are presented here. The results support the hypothesis that specific aspects of charismatic/transformational leadership are strongly and universally endorsed across cultures.

Geographically localized knowledge: spillovers or markets?

Abstract: I. INTRODUCTION Knowledge spillovers - positive externalities of scientific discoveries on the productivity of firms which neither made the discovery themselves nor licensed its use from the holder of intellectual property rights - play a central role in the literature as causes of both economic growth and geographic agglomeration.(1) Zvi Griliches [1992] has surveyed the importance of R&D spillovers as a major source of endogenous growth in recent "New Growth Theory" models and the difficult empirical search for their existence. While the search for spillovers has been difficult, there has been considerable success in finding their fingerprints by demonstrating statistically significant effects on a firm's productivity of being near great universities and other sources of scientific discovery - geographically localized knowledge spillovers. (See particularly, Adam B. Jaffe [1989], Jaffe, Manuel Trajtenberg, and Rebecca Henderson [1993], and Edwin Mansfield [1995].)(2) Providing further evidence of the empirical relevance of geographically localized knowledge spillovers in the case of biotechnology, Lynne G. Zucker, Michael R. Darby, and Marilynn B. Brewer [1997] have recently demonstrated that "intellectual human capital," measured operationally by where and when "star" scientists at the leading edge of basic bioscience are active, is a principal determinant of both the location and timing of the entry of new biotechnology enterprises in the United States.(3) Operationalizing Sherwin Rosen's [1981] superstar concept, Zucker, Derby, and Brewer [1997] relate geographically localized knowledge spillovers in the formative years of the biotech industry to a relatively small number of outstanding scientists (207 of whom ever worked in the U.S.) who combined brilliant scientific productivity with specific knowledge of the new techniques which formed the basis of industrial formation and transformation (see Data Appendix). In this paper, we further explore the technology by which apparent geographically localized knowledge spillovers operate. Case studies and interviews point to the fact that the star scientists are not simply located in the same geographic area with biotech firms, but in fact are frequently deeply involved in their operations as principals, employees, or consultants. We find empirically that what might appear using standard methodology and data sets as geographically localized external economies for enterprises located near university stars turn out to exist only for that much smaller set of enterprises which are linked to particular star professors by contract or ownership - that is, by market exchange, This same subset of firms with explicit ties to star scientists also appear to account for a disproportionately larger share of industry growth, measured here as number of products in development, number of products on the market, and employment growth between 1989 and 1994. Indeed, it seems to us that the source of geographically localized effects on firm performance is the same as the reason that much of the fruits of the biotechnological revolution was much more appropriable by the star scientists than by the universities which (typically) employed them.(4) These star scientists generally retain their university affiliations while involved in commercial applications within easy commuting distance of home or university, thus creating localized effects of university research. Here we examine the effects of one scientific breakthrough on a relatively small number of industries which experience a technological transformation as a result. If, as we will argue in section V may well be the case, other instances of geographically localized knowledge spillovers are in fact also instances of appropriation and market exchange by discoveting scientists, then both interpretation of prior studies and their strong policy implications need to be reexamined. Before drawing these conclusions, we must turn to the concrete analysis which suggested them. …

Authenticated Encryption: Relations among notions and analysis of the generic composition paradigm.

Abstract: An authenticated encryption scheme is a symmetric encryption scheme whose goal is to provide both privacy and integrity. We consider two possible notions of authenticity for such schemes, namely integrity of plaintexts and integrity of ciphertexts, and relate them (when coupled with IND-CPA) to the standard notions of privacy (IND-CCA,NM-CPA) by presenting implications and separations between all notions considered. We then analyze the security of authenticated encryption schemes designed by “generic composition,” meaning making blackbox use of a given symmetric encryption scheme and a given MAC. Three composition methods are considered, namely Encrypt-and-MAC, MAC-then-encrypt, and Encrypt-then-MAC. For each of these, and for each notion of security, we indicate whether or not the resulting scheme meets the notion in question assuming the given symmetric encryption scheme is secure against chosen-plaintext attack and the given MAC is unforgeable under chosen-message attack. We provide proofs for the cases where the answer is “yes” and counter-examples for the cases where the answer is “no.”