Long-term microfluidic glucose and lactate monitoring in hepatic cell culture

Monitoring cellular bioenergetic pathways provides the basis for a detailed understanding of the physiological state of a cell culture. Therefore, it is widely used as a tool amongst others in the field of in vitro toxicology. The resulting metabolic information allows for performing in vitro toxicology assays for assessing drug-induced toxicity. In this study, we demonstrate the value of a microsystem for the fully automated detection of drug-induced changes in cellular viability by continuous monitoring of the metabolic activity over several days. To this end, glucose consumption and lactate secretion of a hepatic tumor cell line were continuously measured using microfluidically addressed electrochemical sensors. Adapting enzyme-based electrochemical flat-plate sensors, originally designed for human whole-blood samples, to their use with cell culture medium supersedes the common manual and laborious colorimetric assays and off-line operated external measurement systems. The cells were exposed to different concentrations of the mitochondrial inhibitor rotenone and the cellular response was analyzed by detecting changes in the rates of the glucose and lactate metabolism. Thus, the system provides real-time information on drug-induced liver injury in vitro.     

Two Views About Explicitly Teaching Nature of Science

Our focus is on the effects that dated ideas about the nature of science (NOS) have on curriculum, instruction and assessments. First we examine historical developments in teaching about NOS, beginning with the seminal ideas of James Conant. Next we provide an overview of recent developments in philosophy and cognitive sciences that have shifted NOS characterizations away from general heuristic principles toward cognitive and social elements. Next, we analyze two alternative views regarding ‘explicitly teaching’ NOS in pre-college programs. Version 1 is grounded in teachers presenting ‘Consensus-based Heuristic Principles’ in science lessons and activities. Version 2 is grounded in learners experience of ‘Building and Refining Model-Based Scientific Practices’ in critique and communication enactments that occur in longer immersion units and learning progressions. We argue that Version 2 is to be preferred over Version 1 because it develops the critical epistemic cognitive and social practices that scientists and science learners use when (1) developing and evaluating scientific evidence, explanations and knowledge and (2) critiquing and communicating scientific ideas and information; thereby promoting science literacy.     

What “ideas‐about‐science” should be taught in school science? A Delphi study of the expert community

Recent arguments in science education have proposed that school science should pay more attention to teaching the nature of science and its social practices. However, unlike the content of science, for which there is well‐established consensus, there would appear to be much less unanimity within the academic community about which “ideas‐about‐science” are essential elements that should be included in the contemporary school science curriculum. Hence, this study sought to determine empirically the extent of any consensus using a three stage Delphi questionnaire with 23 participants drawn from the communities of leading and acknowledged international experts of science educators; scientists; historians, philosophers, and sociologists of science; experts engaged in work to improve the public understanding of science; and expert science teachers. The outcome of the research was a set of nine themes encapsulating key ideas about the nature of science for which there was consensus and which were considered to be an essential component of school science curriculum. Together with extensive comments provided by the participants, these data give some measure of the existing level of agreement in the community engaged in science education and science communication about the salient features of a vulgarized account of the nature of science. Although some of the themes are already a feature of existing school science curricula, many others are not. The findings of this research, therefore, challenge (a) whether the picture of science represented in the school science curriculum is sufficiently comprehensive, and (b) whether there balance in the curriculum between teaching about the content of science and the nature of science is appropriate. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 692–720, 2003     

Developmental and Educational Perspectives on Theory Change: To Have and Hold,or To Have and Hone?

Eric Schwitzgebel presents an attractive argument for the use of affective indicators to both assess and extend the 'theory theory' research agenda. A key component of his argument is an account of explanation that can be applied to both children and adults, few of whom possess the attributes and behaviors that warrant being called scientists. The core features of his account include 1) regarding a set of propositions as a theory and 2) subscribing to a theory by accepting and employing this set of propositions to explain events within the theory's domain. We will argue that this account, while potentially helpful for guiding research on the affective content of explanations, requires elaboration because it (1) does not fully characterize what is distinctive and important about theoretical and scientific thinking, (2) raises questions about different kinds of explanations, such as seen in transitions from common-sense explanations to theoretical explanations; (3) favors individual theorizing to the exclusion of socially mediated theorizing, and (4) raises developmental questions about the nature of explanation-seeking and the capacity to apply evidence to evaluate theories.