The effects of memantine on prepulse inhibition.

Reduced prepulse inhibition (PPI) of startle provides evidence of deficient sensorimotor gating in several disorders, including schizophrenia. The role of NMDA neurotransmission in the regulation of PPI is unclear, due to cross-species differences in the effects of NMDA antagonists on PPI. Recent reports suggest that drug effects on PPI differ in subgroups of normal humans that differ in the levels of baseline PPI or specific personality domains; here, we tested the effects of these variables on the sensitivity of PPI to the NMDA antagonist, memantine. PPI was measured in male Sprague-Dawley rats, after treatment with memantine (0, 10 or 20 mg/kg, s.c.). Baseline PPI was then measured in 37 healthy adult men. Next, subjects were tested twice, in a double-blind crossover design, comparing either (1) placebo vs 20 mg of the NMDA antagonist memantine (n=19) or (2) placebo vs 30 mg memantine (n=18). Tests included measures of acoustic startle amplitude, PPI, autonomic indices and subjective self-rating scales. Memantine had dose- and interval-dependent effects on PPI in rats. Compared with vehicle, 10 mg/kg increased short-interval (10-20 ms) PPI, and 20 mg/kg decreased long-interval (120 ms) PPI. In humans, memantine caused dose-dependent effects on psychological and somatic measures: 20 mg was associated with increased ratings of happiness, and 30 mg was associated with increased ratings of dizziness. PPI at the 120 ms prepulse interval was increased by 20 mg, but not 30 mg of memantine. Subgroups most sensitive to the PPI-enhancing effects of memantine were those with low baseline PPI, or with personality scale scores suggestive of high novelty seeking, high sensation seeking, or high disinhibition. NMDA blockade with memantine appears to have dose- and interval-dependent effects on sensorimotor gating in rats and humans, particularly among specific subgroups of normal human subjects. These findings are discussed as they relate to consistencies across other studies in humans, as well as apparent inconsistencies in the NMDA regulation of PPI across species

Somatostatin in inflammatory bowel disease

Intestinal inflammation is controlled by various immunomodulating cells, interacting by molecular mediators. Neuropeptides, released by enteric nerve cells and neuroendocrine mucosa cells, are able to affect several aspects of the general and intestinal immune system, with both pro- as well as anti-inflammatory activities. In inflammatory bowel disease (IBD) there is both morphological as well as experimental evidence for involvement of neuropeptides in the pathogenesis. Somatostatin is the main inhibitory peptide in inflammatory processes, and its possible role in IBD is discussed

Diminished nitroprusside-induced relaxation of inflamed colonic smooth muscle in mice.

The dextran sodium sulphate (DSS) induced colitis in mice was used as a experimental model to study the contractility of murine longitudinal colonic smooth muscle during inflammation. Smooth muscle segments of proximal, middle and distal colon were mounted in organ baths. Smooth muscle contraction was induced by carbachol showing an aboral increase in activity, whereas in the inflamed middle colonic segment a marked decrease in activity was observed. The dilatative effect of sodium-nitroprusside (SNP) as a nitric oxide donor was investigated after precontraction by carbachol. Both in normal and DSS segments administration of SNP to isolated mouse colonic smooth muscle preparations caused regional differences in relaxation, the highest relaxation seen in normal proximal colonic tissue. However, this relaxation was markedly reduced in inflamed proximal preparations, associated with a diminished cGMP contents

Didactisch handelen : een terreinverkenning in verband met de practische scholing van aanstaande leraren

Insufficient knowledge of the nature of the teaching profession in general and of the act of teaching as one of its aspects in particular makes the search for ways to achieve a better pedagogic-didactic training of the student teacher an extremely difficult one. Research activities aiming at an improvement of training methods for prospective teachers should be considered of vital interest, the more so in view of the efforts which are being made to obtain a more adequate classroom climate in our schools. To teach or to be taught includes more than just the rational-technical component on which one in search for gains in efficiency is perhaps inclined to lay more stress than on the socio-emotional part which, especially in respect of classroom teaching, should be considered essential.Assuming the growing need for research and theory as regards the problems of teaching and how to learn to teach, this study pays attention to the work of a number of researchers whose aim it is to apply their findings in the field of group dynamics and educational psychology to concepts that regard the practice of teaching. In addition to psychological aspects of learning groupdynamic points of view in particular are considered to be of importance for constructing a theory of instruction. The didactic interaction between learning and teaching activities takes place under circumstances in which the socio-emotional climate of the classroom does not only influence the scope and contents of intellectual learning results but affects also the emotional-volitional aspects of personality development. At the core of our study is the supposititon, based on general experience, that the teacher plays an important part in the formation of the socio-emotional climate of the classroom.Being a teacher implies inter alia a complex body of didactic skills. Traditional training methods usually confront the student teacher simultaneously with exercises of divergent skills. The question as to whether it would not be preferable to introduce the potential teacher gradually to the various skills involved in teaching and classroom management has led to a development in which it is attempted to define more closely the act of teaching and to break it down into its constituent elements. Despite its preliminary character the materials presented here may well prove to contain valuable suggestions for a better theoretical basis of the act of teaching.Although not entirely, the act of teaching may to a large extent be looked upon as a verbal affair manifesting itself in a monologue or dialogue: a lecture to the class or a talk with the class.Particularly in the United States of America this verbal character of the act of teaching is made the subject of investigations into teachers behavior. Basing themselves on the assumption that verbal transactions as a function of a special objective - in this case a didactic objective - can be looked upon as a 'game' the rules of which must be known in order to be able to participate successfully in said transactions, some researchworkers concentrate on the analysis of the verbal interaction between teacher and class. This research has produced a number of analytical categories that can be considered to be of importance for the description of the act of teaching. As is clear form WINNEFELD's system of didactic tendencies, in Germany too useful work is done with reference to teacher behaviour.Seen from the point of view of those engaged in the practical pedagogic-didactic training of future teachers, a system of analysis with reference to the act of teaching is particularly interesting if it can be used as an instrument for the evaluation of the teacher contact with the class. For this reason much space is given in this study to the system of didactic interaction analysis as developed by FLANDERS. Each of the categories which together form the abovementioned system is discussed separately and a number of alternative systems are considered. The FLANDERS system is based mainly on groupdynamic ideas regarding the role of the teacher as the leader within the classroom and it is concerned to a high degree with the way in which such phenomena - important both from a pedagogic and didactic point of view - as authority, goal-orientation, and social access function within the framework of the classroom. In FLANDERS' conception these phenomena are directly subject to the didactic strategies and tactics used by the teacher. FLANDERS introduces the in our opinion useful notion of flexibility as a category to describe the control of interaction structures exercised by the teacher. An important feature of the FLANDERS system is the possibility to transform the data obtained from direct observation into matrices. The technique to be used is explained in this study. In our opinion this technique can be applied successfully so as to give feedback to teachers with regard to certain aspects of their way of teaching.With a view to the application of the techniques of analysis in teacher training, some investigations that trace the influence of feedback data obtained through interaction analysis on the act of teaching are examined. The results have a provisional character and will, it is hoped, lead to replicate work in a field which in the Netherlands is almost unexplored. Lessons recorded on tape and analysed by us are used as examples of matrix interpretation. These examples refer to lessons given by prospective teachers at agricultural and horticultural schools. The results of the matrix interpretation in question are compared on the basis of the dimension direct-indirect teacher behavior. Interaction analysis and the processing of matrices are comparatively time-consuming activities. This seems to us to be a disadvantage, especially with a view to their application in research and training programmes. Mention is made of the application of electronic devices to eliminate to a large extent this difficulty. Thanks to a close collaboration between the TECHNICALand PHYSICALENGINEERINGRESEARCHSERVICE, the COMPUTERCENTREOF THEDEPARTMENT OFMATHEMATICS, and the DEPARTMENT OFEDUCATION OF THEAGRICULTURALUNIVERSITYthis electronic equipment will soon become available.In order to stimulate the search for new ways in the practical training of teachers, a fusion of research and training by way of interaction research is recommended. Intention, action and feedback are mentioned in this connection as the basis of a training model