bluuebunny/crossref_metadata_2025 huggingface dataset:
An advance organizer for teaching bacterial metabolism
Authors: Barbosa Heloiza R. , Marques Marilis V. , Torres Bayardo B.
Published: February 2007

The metabolic versatility of bacteria is a source of learning difficulty for students in classical microbiology courses. To facilitate the learning process, the authors developed an advance organizer. It consists of a set of six diagrams of metabolic pathways describing the basic living requirements of several types of bacteria: energy, carbon sources, and oxidizable substrates that provide electrons for reductive biosyntheses. The students are presented with the six diagrams and at the same time with one problem that must be resolved using solely the set of diagrams, with no access to any textbook. This procedure aims at developing the skills necessary to analyze different (and perhaps more complex) metabolic processes than those represented by the diagrams.
The use of MERLOT in biochemistry and molecular biology education
Authors: Cooper Scott
Published: February 2007

The referatory, Multimedia Educational Resources for Learning and Online Teaching (MERLOT), contains links to 1300 electronic teaching resources in biology and chemistry. Approximately 20% have been peer reviewed, and most have user comments or assignments attached. In addition to being a source of educational resources, the MERLOT project seeks to strengthen the educational community by providing peer review and recognition of quality electronic learning objects.
Teaching intermediary metabolism linearly doesn't work
Authors: Glew Robert H. , Brass Eric
Published: February 2007

Despite the fact that knowledge of the major biochemical metabolic pathways is essential to understanding the pathophysiology, clinical presentation, and management of many human diseases, there is disagreement among medical educators regarding the relevance of intermediary metabolism to the practicing physician and the expectations for medical students to master the various metabolic pathways. One basis for the widespread cynicism that exists regarding the need to teach medical students metabolic reactions and pathways derives from the fact that too often these aspects of biochemistry are taught as if they were isolated, unrelated, and independent bits of information. We use medium‐chain acyl‐CoA dehydrogenase deficiency as an example of how it is both possible and fruitful to teach two important but seemingly unrelated pathways in an integrated fashion and in the context of a specific clinical problem. This example illustrates how imbedding multiple metabolic pathways in a realistic clinical scenario and demonstrating the intimate interrelatedness of those pathways can provide the insight and understanding that are required for informed and rational diagnostic and therapeutic decision making. This article concludes with a series of practical and realistic recommendations for improving the teaching of intermediary metabolism.
Can problem‐based learning address content and process?*
Authors: Hintz Mary McCarthy
Published: February 2007

Problem‐based learning was used to address the learning process and traditional content in a one semester nonmajors biochemistry course. Three different pedagogical strategies were evaluated in three versions of the course. The first version exclusively utilized literature‐based learning (analysis of primary literature articles in small groups) with almost no lectures from the instructor. Classroom assessment addressed the research process, not content. In the second version, literature‐based learning was supplemented with a 75‐min lecture by the instructor before each article was analyzed as well as additional lectures as deemed necessary. Classroom assessment addressed process (70%) over content (30%). The third version was lecture‐based, with the emphasis on traditional content; lectures were supplemented with literature analysis. Classroom assessment emphasized content, but about 10% of each exam focused on the research process. Student evaluations of the three versions of the course showed no significant difference in opinions about the format of the course. Postcourse interviews with students 1) confirmed previous studies that showed that the literature‐based format greatly increased the involvement of students in their own learning, 2) showed that literature‐based learning is compatible with an equal focus on content and process, and 3) showed that supplementing lecture‐based teaching with literature‐based learning does not empower students to manage their own learning, although student response to this instructional method was positive.
Molecular analysis of the causes of down syndrome in a family
Authors: Szeberenyi Jozsef
Published: February 2007

Terms to be familiar with before you start to solve the test: Down Syndrome (trisomy 21), karyotype, chromosome translocation, mosaicism, minisatellites, Southern blotting, DNA fingerprinting, nondisjunction, first and second meiotic division, homologous chromosomes, sister chromatids.
Comparison of student performance in cooperative learning and traditional lecture‐based biochemistry classes
Authors: Anderson William L. , Mitchell Steven M. , Osgood Marcy P.
Published: February 2007

Student performance in two different introductory biochemistry curricula are compared based on standardized testing of student content knowledge, problem‐solving skills, and student opinions about the courses. One curriculum was used in four traditional, lecture‐based classes (n = 381 students), whereas the second curriculum was used in two cooperative learning classes (n = 39 students). Students in the cooperative learning classes not only performed at a level above their peers in standardized testing of content knowledge and in critical thinking and problem‐solving tasks (p < 0.05), but they also were more positive about their learning experience. The testing data are in contrast to much of the medical school literature on the performance of students in problem‐based learning (PBL) curricula, which shows little effect of the curricular format on student exam scores. The reason for the improvement is undoubtedly multifactorial. We argue that the enhancement of student performance in this study is related to: 1) the use of peer educational assistants, 2) an authentic PBL format, and 3) the application of a multicontextual learning environment in the curricular design. Though educationally successful, the cooperative learning classes as described in this study were too resource intensive to continue; however, we are exploring incorporation of some of the “high context” aspects of the small‐group interactions into our current lecture‐based course with the addition of on‐line PBL cases.
Teaching microbial physiology using glucose repression phenomenon in baker's yeast as an example
Authors: Raghevendran Vijayendran , Nielsen Jens , Olsson Lisbeth
Published: February 2007

The yeast Saccharomyces cerevisiae has been used by human beings since ancient times for its ability to convert sugar to alcohol. Continual exposure to glucose in the natural environment for innumerable generations has probably enabled S. cerevisiae to grow in fermentative mode on sugars by switching off the genes responsible for respiration even under aerobic conditions. This phenomenon is referred to as the Crabtree effect. The present review focuses on glucose repression in S. cerevisiae from a physiological perspective. Physiological studies presented involve batch and chemostat experiments of the wild type and a mutant that lacks a trait partially responsible for the fermentative behavior. Various undergraduate student exercises have been (and can be) formulated to illustrate the concept of glucose repression.
DNA replication and transcription: An innovative teaching strategy
Authors: Fossey Annabel , Hancock Carolyn
Published: February 2007

First‐year students in genetics at the University of KwaZulu‐Natal, South Africa, attend two general biology modules, one in each semester. Teaching involves four formal lectures per week of 45 min each, one 3‐h practical, and one lecture period tutorial. These students, graduating from secondary education, are well schooled in rote leaning but are limited in critical thinking and find assessment questions belonging to the higher levels of Bloom's taxonomy difficult. All students attend the formal lectures together, up to 300 students, whereas for the tutorials they are grouped into small groups, no more than 40 students in a tutorial class, allowing for innovative teaching strategies. Students find the processes of DNA replication and transcription difficult because of the sequential steps involved in the processes together with limitations imposed by the enzymes involved. Furthermore, they find the significance and relationships between the different components of the processes very difficult. A tutorial was developed in which students are requested to demonstrate replication with line drawings, which are then used in various iterations of transcription. The tutorial is administered in the presence of a tutor that guides the step by step execution of the tutorial while stimulating active participation. In the past 2 years, the presentation of this and other similar tutorials in genetics has improved overall class performance on average by 15%. Furthermore, students seem to display a greater retention from the first year to the second, which was previously rather limited. A survey among first‐year students revealed that the implementation of this tutorial facilitated studying and recall by helping students to organize thoughts, picture the sequence of events, understand fundamental concepts, and create a feeling of confidence.
A series of enzymology‐based experiments designed to mimic an applied research project
Authors: Boyce Angela , Walsh Gary
Published: February 2007

Four mini‐practicals are described in which the effects of temperature and pH on phytase activity are assessed, as well as the enzyme's thermostability and the effect upon stability of simulated digestive tract conditions. Phytase is routinely incorporated into monogastric animal feed to ameliorate the negative nutritional and environmental consequences of its substrate, dietary phytic acid. In addition to illustrating selected basic concepts in enzymology, the combined experiments allow the students to determine the suitability of the test phytase for inclusion in animal feed. As such the practical mimics an applied research project and is particularly suited to biotechnology students undertaking courses in basic biochemistry. Students may be segregated into groups of 4, with each team member charged with undertaking one of the mini‐experiments. In this way students are given individual responsibility and learn to work as part of an integrated research grouping.
In Vitro synthesis and activity of reporter proteins in an Escherichia coli S30 extract system: An undergraduate experiment*
Authors: Higgins Pamela J.
Published: February 2007

This undergraduate laboratory experiment integrates multiple techniques (in vitro synthesis, enzyme assays, Western blotting) to determine the production and detection sensitivity of two common reporter proteins (β‐galactosidase and luciferase) within an Escherichia coli S30 transcription/translation extract. Comparison of the data suggests that luciferase is the more suitable reporter for this specific in vitro extract system. Simple modifications in the experimental design allow for flexibility in the use of materials and the time required to perform the study. Furthermore, extension into additional experiments and alternative techniques are also discussed.
The importance of visual literacy in the education of biochemists*
Authors: Schönborn Konrad J. , Anderson Trevor R.
Published: February 2007

Visualization is an essential skill for all students and biochemists studying and researching the molecular and cellular biosciences. In this study, we discuss the nature and importance of visualization in biochemistry education and argue that students should be explicitly taught visual literacy and the skills for using visualization tools as essential components of all biochemistry curricula. We suggest that, at present, very little pedagogical attention has been given to this vital component of biochemistry education, although a large diversity of static, dynamic, and multimedia visual displays continues to flood modern educational resources at an exponential rate. Based on selected research findings from other science education domains and our own research experience in biochemistry education, 10 fundamental guidelines are proposed for the promotion of visualization and visual literacy among students studying in the molecular and cellular biosciences.
A mechanistic foundation for instructor‐regulated collective learning
Authors: Brooks David W. , Markwell John
Published: February 2007

The theory of memory and the ability to influence learning with conscious and unconscious factors, both internal and external, is reviewed. From a connectionist view of memory, the interactive compensatory model of learning is introduced, with an emphasis on the plastic components (motivation, prior knowledge, and metacognition) that can be regulated. Expert students, but not naive students, have a considerable ability to self‐regulate their learning processes and improve performance in undergraduate courses. We propose that in a class situation, there are emergent opportunities for an instructor who understands the dynamics of the learning environment to provide regulation for collective learning of multiple students and improve group learning. There are three interfaces for instructor‐regulated collective learning, and examples are provided for each to suggest how instructors may effectively provide regulation.
Song: B‐DNA (to the tune of “YMCA”)*
Authors: Ahern Kevin
Published: February 2007

Text in regular type to be sung (and ideally danced) by professor. Underlined text to be sung by everyone (loudly).
Identification of highly prized commercial fish using a PCR‐based methodology
Authors: Morán Paloma , Garcia‐Vazquez Eva
Published: February 2007

We report a practical class designed for undergraduate students of Marine Sciences as a part of the Genetics course. The class can also be included in undergraduate studies of food technology. The exercise was designed to emphasize the application of molecular biology techniques to fish species authentication and traceability. After a simple and rapid protocol for DNA extraction, PCR was used to analyze variation in size of individual 5S ribosomal gene spacer sequences in eight commercially important fishes. The resulting fragments containing these sequences were separated on agarose gels and visualized under a UV lamp. Differences in fragment length can be used to differentiate between species. This method is particularly useful in the identification of larvae, eggs, and processed food including frozen and canned products.
The development of biotechnology education in China*
Authors: Zhou Xuanwei , Lin Juan , Zhang Lei , Chen Zhonghai , Yin Yizhou , Guo Binhui , Sun Xiaofen , Tang Kexuan
Published: February 2007

From the middle of the 20th century, Chinese scientists have been actively involved in biotechnology. However, biotechnology education in China is a relatively recent phenomenon. This subject has not been addressed at the undergraduate level in a serious way until recently. In the last decade, biotechnology education developed rapidly and reached a new level in Chinese universities. The Chinese scientific establishment is very much aware of the importance of biotechnology and has identified this subject as one of the priority areas. Some universities are taking positive steps toward enhancing biotechnology education. This article focuses on the emergence, as well as the problems and prospects, of biotechnology education in China.
The determination of the redox states and phosphorylation potential in living tissues and their relationship to metabolic control of disease phenotypes
Authors: Veech Richard L.
Published: February 2007

This paper reviews the development in the 1950s of methods to determine the redox states of the free [NAD+]/[NADH] in cytoplasm of yeast by Helmut Holzer and Feodore Lynen and in rat liver by Theodore Bucher and Martin Klingenberg. This work was extended in the 1960s in the laboratory of Hans Krebs, where the use of basic thermodynamic and kinetic principles allowed the extension of this approach to the determination of the free mitochondrial [NAD+]/NADH] in mitochondria and the redox state of the free NADP system in cytoplasm and mitochondria. This work also outlined the linkage between the redox states in the various couples to the phosphorylation state or the free [ATP]/[ADP][Pi] ratio, the central energy parameter of living cells. This work has since been extended to include other energy‐linked systems including the gradients of inorganic ions between extra and intracellular phases of the cell and the redox state of the co‐enzyme Q couple of mitochondria. This system of linked near‐equilibrium redox and phosphorylation potentials constitutes a framework of primitive metabolic control that is altered in a number of disease phenotypes. The alteration of such disease phenotypes by substrate availability is discussed, as well as the importance of a thorough grounding in basic kinetics and thermodynamics in designing new therapies to normalize the metabolic abnormalities that are the proximate cause of many common and some rare diseases states.
Engagement, exploration, explanation, extension, and evaluation (5E) learning cycle and conceptual change text as learning tools
Authors: Balci Sibel , Cakiroglu Jale , Tekkaya Ceren
Published: February 2007

The purpose of this study is to investigate the effects of the Engagement, Exploration, Explanation, Extension, and Evaluation (5E) learning cycle, conceptual change texts, and traditional instructions on 8th grade students' understanding of photosynthesis and respiration in plants. Students' understanding of photosynthesis and respiration in plants was measured using the test developed by Haslam and Treagust (F. Haslam, D. F. Treagust (1987) Diagnosing secondary students' misconceptions of photosynthesis and respiration in plants using a two‐tier multiple choice instrument, J. Biol. Educ. 21, 203–211). The test was administered as pre‐test and post‐test to a total of 101 8th‐grade students in three intact classes of the same school located in an urban area. The classes were randomly assigned as control and experimental groups. Students in the first experimental group (n = 33) received 5E learning cycle instruction, students in the second experimental group (n = 34) received conceptual change text instruction, and students in the control group (n = 34) received traditional instruction. Attitudes toward science and pre‐test scores were used as covariates. A quasi‐experimental design utilizing the analysis of covariance showed a statistically significant difference between the experimental and control groups in the favor of experimental groups after treatment. However, no statistically significant difference between two experimental groups (5E versus conceptual change text instruction) was found.
Molecular cloning and analysis of a DNA repetitive element from the mouse genome
Authors: Geisinger Adriana , Cossio Gabriela , Wettstein Rodolfo
Published: February 2007

We report the development of a 3‐week laboratory activity for an undergraduate molecular biology course. This activity introduces students to the practice of basic molecular techniques such as restriction enzyme digestion, agarose gel electrophoresis, cloning, plasmid DNA purification, Southern blotting, and sequencing. Students learn how to carry out a GenBank™ search as they are encouraged to compile most available information about their cloned sequence. The natural integration of the bench work with the use of the bioinformatics tools is considered a major advantage of this laboratory course.
Pentose phosphate and calvin cycles: Similarities and three‐dimensional views*
Authors: Sillero Antonio , Selivanov Vitali A. , Cascante Marta
Published: February 2007

The main object of this work is to present simplified and three‐dimensional views of the pentose phosphate and Calvin cycles, emphasizing their functional and chemical similarities.
Student understanding of pH: “i don't know what the log actually is, i only know where the button is on my calculator”
Authors: Watters Dianne J. , Watters James J.
Published: February 2007

In foundation biochemistry and biological chemistry courses, a major problem area that has been identified is students' lack of understanding of pH, acids, bases, and buffers and their inability to apply their knowledge in solving acid/base problems. The aim of this study was to explore students' conceptions of pH and their ability to solve problems associated with the behavior of biological acids to understand the source of student difficulties. The responses given by most students are characteristic of an atomistic approach in which they pay no attention to the structure of the problem and concentrate only on juggling the elements together until they get a solution. Many students reported difficulty in understanding what the question was asking and were unable to interpret a simple graph showing the pH activity profile of an enzyme. The most startling finding was the lack of basic understanding of logarithms and the inability of all except one student to perform a simple calculation on logs without a calculator. This deficiency in high school mathematical skills severely hampered their understanding of pH. This study has highlighted a widespread deficiency in basic mathematical skills among first year undergraduates and a fragmented understanding of acids and bases. Implications for the way in which the concepts of pH and buffers are taught are discussed.
Cognitive development and the complexities of the undergraduate learner in the science classroom*
Authors: Markwell John , Courtney Sean
Published: February 2007

Students' reactions to classroom learning and the mastery of science vary along a wide spectrum of attitudes and emotions. In particular, we argue here that how learners encounter and learn subject matter is a function of their level of cognitive development. We describe the stages of cognitive development based on the work of William Perry and demonstrate their relevance to the undergraduate science classroom. With examples drawn from biochemistry, we attempt to show that, depending on the student's developmental level, there will be different abilities to handle the range of assignments and activities s/he can expect to experience in the average classroom. The college science instructor can benefit from knowledge of these stages and can work through their implications to develop strategies and techniques to regulate collective student learning.
A descriptive analysis of computer‐assisted teaching and learning in molecular biological education
Authors: Li Guangxing , Yin Jiechao , Ren Yudong , Wang Binjie , Ren Xiaofeng
Published: February 2007

The role and importance of computer‐assisted teaching and learning in molecular biological‐related education and research has been emphasized and pinpointed. In this study, some benefit viewpoints and discussion are provided for applying the computer‐assisted teaching and learning more efficiently in the process of knowledge acquisition and information exchange. Meanwhile, several cultural and economic issues related to the role of computers in teaching and learning are addressed.
A course designed for undergraduate biochemistry students to learn about cultural diversity issues
Authors: Benore‐Parsons Marilee
Published: February 2007

Biology, biochemistry, and other science students are well trained in science and familiar with how to conduct and evaluate scientific experiments. They are less aware of cultural issues or how these will impact their careers in research, education, or as professional health care workers. A course was developed for advanced undergraduate science majors to learn about diversity issues in a context that would be relevant to them, entitled “Diversity Issues in Health Care: Treatment and Research.” Learning objectives included: developing awareness of current topics concerning diversity issues in health care; learning how research is carried out in health care, including pharmaceutical research, clinical trials, and social research; and learning about health care practices. Lectures and projects included readings on laboratory and clinical research, as well as literature on legal, race, gender, language, age, and income issues in health care research and clinical practice. Exams, papers, and a service learning project were used to determine the final course grade. Assessment indicated student understanding of diversity issues was improved, and the material was relevant.
Glyceroneogenesis, the pathway that almost wasn't
Authors: Hanson Richard W. , Ballard F. John , Reshef Lea
Published: February 2007

“What seest thou else in the dark, backward abysm of time.” Prospero in The Tempest

As is true in all aspects of human endeavor, a scientific concept can appear before its time and remain unappreciated before events catch up with the concept. Such was the case of the discovery of glyceroneogenesis and the establishment of its biological importance; it took almost 40 years before the significance of this pathway became apparent and the concept of triglyceride recycling was understood by the scientific establishment. Even that may be stretching a point, because today glyceroneogenesis is hardly a household word. In this essay, we will tell the story of the discovery of glyceroneogenesis and the thought processes that led us to propose this pathway. We will also speculate on why the pathway was not more widely embraced by scientists working in lipid metabolism and why that may finally be changing. The reader is warned, however, that this story is a reconstruction of past events and, like all such attempts, suffers from the patina of nostalgia that inevitably covers all things resurrected from memory. Others may view things differently, but this is our story as we remember it.
Microarrays (DNA chips) for the classroom laboratory
Authors: Barnard Betsy , Sussman Michael , BonDurant Sandra Splinter , Nienhuis James , Krysan Patrick
Published: February 2007

We have developed and optimized the necessary laboratory materials to make DNA microarray technology accessible to all high school students at a fraction of both cost and data size. The primary component is a DNA chip/array that students “print” by hand and then analyze using research tools that have been adapted for classroom use. The primary adaptation is the use of a simulated cDNA target. The low density DNA array we discuss here was used to demonstrate differential expression of several Arabidopsis thaliana genes related to photosynthesis and photomorphogenesis. The methods we present here can be used with any biological organism whose sequence is known. Furthermore, these methods can be adapted to exhibit a variety of differential gene expression patterns under different experimental conditions. The materials and tools we discuss have been applied in classrooms at West High School in Madison, WI. We have also shared these materials with high school teachers attending professional development courses at the University of Wisconsin‐Madison.
Glycobiology, how to sugar‐coat an undergraduate advanced biochemistry laboratory
Authors: McReynolds Katherine D.
Published: February 2007

A second semester biochemistry laboratory has been implemented as an independent projects course at California State University, Sacramento since 1999. To incorporate aspects of carbohydrate biochemistry, or glycobiology, into our curriculum, projects in lectin isolation and purification were undertaken over the course of two semesters. Through this modification in course content, this class now offers a diverse, hands‐on treatment of not only standard protein purification techniques but also carbohydrate techniques, specifically the study of carbohydrate‐protein interactions through hemagglutination assays, a novel commercial assay known as the Instant™Chek assay, and the generation and use of appropriate affinity chromatography matrices. Throughout the semester, the students are in charge of all aspects of their projects, from planning to execution and completion. Specific examples of student projects are highlighted such that the breadth of protein‐carbohydrate chemistry pursued in a 15‐week semester can be appreciated. The feedback of the course was very favorable, indicating that the students came away with skills necessary for them to be successful in their future careers. Most importantly, however, aspects of glycobiology have now been incorporated effectively into a mainstream undergraduate biochemistry laboratory class.
jAMVLE, A new integrated molecular visualization learning environment*
Authors: Bottomley Steven , Chandler David , Morgan Eleanor , Helmerhorst Erik
Published: February 2007

A new computer‐based molecular visualization tool has been developed for teaching, and learning, molecular structure. This java‐based jmol Amalgamated Molecular Visualization Learning Environment (jAMVLE) is platform‐independent, integrated, and interactive. It has an overall graphical user interface that is intuitive and easy to use. The application can be downloaded free from the internet at wabri.org.au/jamvle. A cohort of 28 third year undergraduate molecular biotechnology degree students evaluated the new application through an essay‐style project. These were analyzed to identify themes expressed by students in the content of their evaluations. Most students were positive about the new jAMVLE learning environment, and five major benefits emerged from the analysis. In particular, the students perceived that jAMVLE has an appealing interface, is interactive, provides a useful integrated environment, is user friendly, and is an excellent learning tool. Overall, students found that the jAMVLE application stimulated their interest, was a more active learning environment, provided better guidance, and made learning fun.
How far is England in the process of introducing a mandatory reporting system?
Authors: Munro Eileen , Parton Nigel
Published: February 2007

This article argues that England is in the process of introducing a mandatory reporting system, not based on the requirement to report child abuse but on the basis of ‘a cause for concern’ for a child's welfare. It describes Section 12 of the Children Act 2004, which is fundamental to the development, and the rationale upon which it is based. The second part of the article summarizes the key criticisms that have been made of mandatory reporting systems and discusses how these are likely to apply in the English situation. Copyright © 2007 John Wiley & Sons, Ltd.
Extraction of Radio‐Labelled Xanthine Derivatives by Artificial Receptors: Deep Insight into the Association Behaviour
Authors: Bomkamp Martin , Siering Carsten , Landrock Karin , Stephan Holger , Fröhlich Roland , Waldvogel Siegfried R.
Published: February 2007

Association constants for the interaction of almost insoluble substrates with triphenylene ketal‐based receptors in toluene have been determined by means of an extraction method employing the corresponding radio‐labelled substrates. Flexible and more polar receptors tend to aggregate and exhibit inferior extraction qualities. Binding constants in toluene were found to be in the range 105–107 m−1, which is significantly higher than in dichloromethane. X‐ray analyses indicate the direct participation of a water molecule in the binding process, which may account for the surprisingly small effect of moisture in the solvent on the stability of the complexes.
Description of the Ground‐State Covalencies of the Bis(dithiolato) Transition‐Metal Complexes from X‐ray Absorption Spectroscopy and Time‐Dependent Density‐Functional Calculations
Authors: Ray Kallol , DeBeer George Serena , Solomon Edward I. , Wieghardt Karl , Neese Frank
Published: February 2007

The electronic structures of [M(LBu)2]− (LBu=3,5‐di‐tert‐butyl‐1,2‐benzenedithiol; M=Ni, Pd, Pt, Cu, Co, Au) complexes and their electrochemically generated oxidized and reduced forms have been investigated by using sulfur K‐edge as well as metal K‐ and L‐edge X‐ray absorption spectroscopy. The electronic structure content of the sulfur K‐edge spectra was determined through detailed comparison of experimental and theoretically calculated spectra. The calculations were based on a new simplified scheme based on quasi‐relativistic time‐dependent density functional theory (TD‐DFT) and proved to be successful in the interpretation of the experimental data. It is shown that dithiolene ligands act as noninnocent ligands that are readily oxidized to the dithiosemiquinonate(−) forms. The extent of electron transfer strongly depends on the effective nuclear charge of the central metal, which in turn is influenced by its formal oxidation state, its position in the periodic table, and scalar relativistic effects for the heavier metals. Thus, the complexes [M(LBu)2]− (M=Ni, Pd, Pt) and [Au(LBu)2] are best described as delocalized class III mixed‐valence ligand radicals bound to low‐spin d8 central metal ions while [M(LBu)2]− (M=Cu, Au) and [M(LBu)2]2− (M=Ni, Pd, Pt) contain completely reduced dithiolato(2−) ligands. The case of [Co(LBu)2]− remains ambiguous. On the methodological side, the calculation led to the new result that the transition dipole moment integral is noticeably different for S1s→valence‐π versus S1s→valence‐σ transitions, which is explained on the basis of the differences in radial distortion that accompany chemical bond formation. This is of importance in determining experimental covalencies for complexes with highly covalent metal–sulfur bonds from ligand K‐edge absorption spectroscopy.
Further studies on the interaction of loperamide with capacitative calcium entry in Leukemic HL‐60 cells
Authors: Daly John W. , Camerini‐Otero Carol , Shapiro Craig A. , Ma Jingyuan , Ziffer Herman , Vélez Leykza , Harper Jacquie L.
Published: February 2007

Loperamide at 3–10 µM has augmentative effects on calcium levels elevated by capacitative calcium entry (CCE) in leukemic HL‐60 cells after release of intracellular calcium by ATP or thapsigargin (Harper et al. [1997] Proc Natl Acad Sci USA 94:14912–14917). The effect of loperamide on calcium levels was absent at a pH value of 6.8, a pH at which CCE is not active in HL‐60 cells. Further investigations of HL‐60 cells in recent years revealed a great reduction in the magnitude of the loperamide response. However, when preceded by a CCE blocker, namely N‐methylnitrendipine (MRS 1844) or N‐propargylnitrendipine (MRS 1845), loperamide caused a significant reversal of the blockade. Six structural analogs of loperamide were synthesized, but only two showed loperamide‐like activity. Drug Dev. Res. 67:842–851, 2006. Published 2007 Wiley‐Liss, Inc.
K201 Improves norepinephrine‐induced diastolic dysfunction with preserved ejection fraction
Authors: Kaneko Noboru , Matsuda Ryuko , Ohtani Naoyuki , Nakajima Takahide , Arikawa Takuo , Suzuki Hidehiko , Toyoda Shigeru , Kikuchi Migaku , Hata Yoshihito , Abe Shichiro , Taguchi Isao , Shimamoto Ken
Published: February 2007

Heart failure with preserved ejection fraction differs from systolic heart failure in pathogenesis, underlying disease, and prognosis; however, the onset mechanism of this type of heart failure remains unknown and there is no proven therapy. Recently, we showed that norepinephrine (NE) under Ca2+ loading induces severe diastolic dysfunction without a significant change in the left ventricular ejection fraction (LVEF), that is, increased left ventricular end‐diastolic pressure (LVEDP), norepinephrine‐induced diastolic contracture (NEIDC), and diastolic opening of the aortic valve. In this study, the effects of two benzothiazepine derivatives, K201 (JTV519) and diltiazem, on diastolic dysfunction were examined using this model. K201 significantly suppressed the increase in LVEDP, reduced the incidence of NEIDC, and significantly improved the Ea wave and DCT in a dose‐dependent manner, as well as reducing pulmonary hemorrhage. In contrast, diltiazem did not improve diastolic dysfunction and the mortality in the diltiazem group was 57%, compared to 0% in the K201 group. These results suggest that reduction of intracellular Ca2+ alone does not inhibit diastolic heart failure; in contrast, blocking of α‐adrenoceptors and regulation of proteins such as troponin I via protein kinase C are required for treatment of diastolic heart failure. These results also suggest that K201 may be an agent for treatment of diastolic heart failure. Drug Dev. Res. 67:852–861, 2006. © 2007 Wiley‐Liss, Inc.
Endothelin receptors as drug targets in chronic cardiovascular diseases: the rationale for dual antagonism
Authors: Clozel Martine , Flores Susan
Published: February 2007

Endothelin has been described as the most potent vasoconstrictor known. Recent research shows that it is also a growth factor, a promoter of fibrosis and inflammation, and a key initiator of endothelial dysfunction. Endothelin becomes, therefore, a candidate in the pathogenesis of many chronic cardiovascular and fibrotic diseases, and inhibition of endothelin function is a potential therapeutic approach for those diseases. Endothelin receptor antagonists are now established therapy in the treatment of pulmonary arterial hypertension, and present promising perspectives in diabetic nephropathy, peripheral arterial disease, hypertension, heart failure, and pulmonary diseases. Endothelin binds to two endothelin receptors, ETA and ETB, and their respective roles are actively debated. A major challenge lies in the understanding of what is the preferred profile for new drugs: selective ETA antagonism or dual ETA and ETB receptor antagonism. A number of cardiovascular diseases are characterized by an up‐regulation of smooth muscle cell ETB receptors mediating vasoconstriction and proliferation, and a down‐regulation of endothelial ETB receptors, as compared to the physiological state, creating a situation where both ETA and ETB receptors contribute to vasoconstriction and remodeling. When these two receptor subtypes co‐exist, a cross‐talk between them, probably a result of receptor heterodimerization, suggests that dual ETA/ETB receptor antagonism may be necessary to obtain maximal efficacy. Drug Dev. Res. 67:825–834, 2006. © 2007 Wiley‐Liss, Inc.
Sex differences in and hormonal regulation of Kv1 potassium channel gene expression in the electric organ: Molecular control of a social signal
Authors: Few W. Preston , Zakon Harold H.
Published: February 2007

Electric fish communicate with electric organ (EO) discharges (EODs) that are sexually dimorphic, hormone‐sensitive, and often individually distinct. The cells of the EO (electrocytes) of the weakly electric fish Sternopygus possess delayed rectifying K+ currents that systematically vary in their activation and deactivation kinetics, and this precise variation in K+ current kinetics helps shape sex and individual differences in the EOD. Because members of the Kv1 subfamily produce delayed rectifier currents, we cloned a number of genes in the Kv1 subfamily from the EO of Sternopygus. Using our sequences and those from genome databases, we found that in teleost fish Kv1.1 and Kv1.2 exist as duplicate pairs (Kv1.1a&b, Kv1.2a&b) whereas Kv1.3 does not. Using real‐time quantitative RT‐PCR, we found that Kv1.1a and Kv1.2a, but not Kv1.2b, expression in the EO is higher in high EOD frequency females (which have fast EO K+ currents) than in low EOD frequency males (which have slow EO K+ currents). Systemic treatment with dihydrotestosterone decreased Kv1.1a and Kv1.2a, but not Kv1.2b, expression in the EO, whereas treatment with human chorionic gonadotropin (hCG) increased Kv1.2a but not Kv1.1a or Kv1.2b expression in the EO. Thus, systematic variation in the ratios of Kv1 channels expressed in the EO is correlated with individual differences in and sexual dimorphism of a communication signal. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Activity‐dependent formation and functions of chondroitin sulfate‐rich extracellular matrix of perineuronal nets
Authors: Dityatev Alexander , Brückner Gert , Dityateva Galina , Grosche Jens , Kleene Ralf , Schachner Melitta
Published: February 2007

Extracellular matrix molecules—including chondroitin sulfate proteoglycans, hyaluronan, and tenascin‐R—are enriched in perineuronal nets (PNs) associated with subsets of neurons in the brain and spinal cord. In the present study, we show that similar cell type‐dependent extracellular matrix aggregates are formed in dissociated cell cultures prepared from early postnatal mouse hippocampus. Starting from the 5th day in culture, accumulations of lattice‐like extracellular structures labeled with Wisteria floribunda agglutinin were detected at the cell surface of parvalbumin‐expressing interneurons, which developed after 2–3 weeks into conspicuous PNs localized around synaptic contacts at somata and proximal dendrites, as well as around axon initial segments. Physiological recording and intracellular labeling of PN‐expressing neurons revealed that these are large fast‐spiking interneurons with morphological characteristics of basket cells. To study mechanisms of activity‐dependent formation of PNs, we performed pharmacological analysis and found that blockade of action potentials, transmitter release, Ca2+ permeable AMPA subtype of glutamate receptors or L‐type Ca2+ voltage‐gated channels strongly decreased the extracellular accumulation of PN components in cultured neurons. Thus, we suggest that Ca2+ influx via AMPA receptors and L‐type channels is necessary for activity‐dependent formation of PNs. To study functions of chondroitin sulfate‐rich PNs, we treated cultures with chondroitinase ABC that resulted in a prominent reduction of several major PN components. Removal of PNs did not affect the number and distribution of perisomatic GABAergic contacts but increased the excitability of interneurons in cultures, implicating the extracellular matrix of PNs in regulation of interneuronal activity. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Differential contribution of extracellular and intracellular calcium sources to basal transmission and long‐term potentiation in the sympathetic ganglion of the rat
Authors: Vargas R. , Cifuentes F. , Morales M.A.
Published: February 2007

Calcium involved in basal ganglionic transmission and long‐term potentiation (LTP) can arise either by influx from the extracellular medium or release from intracellular stores. No attempts have yet been made to concurrently explore the contributions of extracellular and intracellular Ca2+ to basal ganglionic transmission or LTP. Here, we investigate this subject using the superior cervical ganglion of the rat. To explore the extracellular Ca2+ contribution, we evaluated basal transmission and LTP at different extracellular Ca2+ concentrations. To assess intracellular Ca2+ release, we explored the contribution of the calcium‐induced calcium release process by overactivation or blockade of ryanodine‐sensitive Ca2+ receptor channel with caffeine, and also by blocking either IP3R with Xestospongin C or the sarco(endo)plasmic reticulum Ca2+‐ATPase pump with thapsigargin. Extracellular Ca2+ affected ganglionic basal transmission and LTP to different extents. While 25% of the physiological Ca2+ concentration supported 80% of basal transmission, 50% of normal Ca2+ was required to achieve 80% of LTP. Notably, disruption of intracellular Ca2+ release by all the drugs tested apparently did not affect basal ganglionic transmission but impaired LTP. We conclude that basal transmission requires only a small level of Ca2+ entry, while LTP expression not only requires more Ca2+ entry but is also dependent on Ca2+ release from intracellular stores. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Exposure to neonatal separation stress alters exploratory behavior and corticotropin releasing factor expression in neurons in the amygdala and hippocampus
Authors: Becker Katja , Abraham Andreas , Kindler Jennifer , Helmeke Carina , Braun Katharina
Published: February 2007

Evidence is accumulating that early emotional experience interferes with the development of the limbic system, which is involved in perception and regulation of emotional behaviors as well as in learning and memory formation. Limbic brain regions, as well as hypothalamic regions and other, nonlimbic areas contain specific neuron subpopulations, which express and release corticotropin releasing factor (CRF). Since these neurons serve to connect limbic function to endocrine, stress‐related responses, we proposed that stressful experience during early postnatal brain development should interfere with the development of CRF‐containing neurons, particularly in brain regions essential for emotional regulation. Applying neonatal separation stress (daily 1 h separation from the parents and litter mates) as stressor, the number of immunocytochemically identified CRF‐expressing neurons/fibers was quantified in the amygdala, hippocampus, paraventricular nucleus of the hypothalamus, piriform cortex, and the somatosensory cortex of 3‐week‐old stressed and nonstressed Octodon degus, a semi‐precocial rodent. Compared to controls neonatally stressed animals showed significantly lower levels of CRF‐positive fibers (−60%) in the central amygdala, significantly less CRF‐positive neurons in the dentate gyrus (−28%) and the CA1 region (−29%) and significantly lower CRF cell densities in the somatosensory cortex (−26%). On the other hand, we found significantly higher numbers of CRF‐immunoreactive neurons in the basolateral amygdaloid complex (+192%) of stressed animals compared to nonstressed controls. No differences in CRF‐immunoreactive cell densities were detected in the other regions. Additional behavioral analysis revealed significantly elevated exploratory behavior (+34%) in stressed animals compared to controls, which might indicate reduced anxiety in the stressed animals. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007
Regulatory T cells inhibit Fas ligand‐induced innate and adaptive tumour immunity
Authors: Simon Anna Katharina , Jones Emma , Richards Hannah , Wright Kate , Betts Gareth , Godkin Andrew , Screaton Gavin , Gallimore Awen
Published: February 2007

CD4+CD25+ regulatory T cells (Treg) are known to influence T cell responses to tumours. Here we have explored the role of Treg in inhibiting not only adaptive, but also innate immune responses to tumours. To this end we used a Fas ligand (FasL)‐expressing melanoma cell line in a mouse model. In this system, innate immunity is sufficient to reject the tumour. All mice depleted of Treg and challenged with FasL‐expressing melanoma remained tumour‐free. Investigation of the underlying cellular effector mechanisms revealed that depletion of Treg enhanced an NK cell response capable of tumour lysis. Furthermore, this initial innate immune response primed mice to make an effective adaptive immune response leading to complete rejection of challenge with the parental melanoma. Both antigen‐specific antibody and CD4+ T cells were implicated in protection via adaptive immunity. We conclude that removal of Treg and vaccination with whole tumour cells expressing FasL activates multiple arms of the immune system, leading to efficient tumour rejection. These findings highlight a novel role for FasL in inducing innate immune responses that are normally inhibited by Treg and uncover an adjuvant effect of FasL that can be used to stimulate tumour immunity after depletion of Treg.