The multi-disciplinary role of 'pion factories'

The multi-disciplinary role of intermediate energy proton accelerators in pure and applied nuclear physics is discussed with particular reference to the experimental programmes at LAMPF (Los Alamos Meson Physics Facility) and SIN (Swiss Institute for Nuclear Research, Zurich).     

Haemodynamic shear stress activates a K+ current in vascular endothelial cells

The endothelial lining of blood vessels is subjected to a wide range of haemodynamically-generated shear-stress forces throughout the vascular system. In vivo and in vitro, endothelial cells change their morphology and biochemistry in response to shear stress in a force- and time-dependent way, or when a critical threshold is exceeded. The initial stimulus-response coupling mechanisms have not been identified, however. Recently, Lansman et al. described stretch-activated ion channels in endothelial cells and suggested that they could be involved in the response to mechanical forces generated by blood flow. The channels were relatively nonselective and were opened by membrane stretching induced by suction. Here we report whole-cell patch-clamp recordings of single arterial endothelial cells exposed to controlled levels of laminar shear stress in capillary flow tubes. A K+ selective, shear-stress-activated ionic current (designated Ik.s) was identified which is unlike previously described stretch-activated currents. Ik.s varies in magnitude and duration as a function of shear stress (half-maximal effect at 0.70 dyn cm-2), desensitizes slowly and recovers rapidly and fully on cessation of flow. Ik.s activity represents the earliest and fastest stimulus-response coupling of haemodynamic forces to endothelial cells yet found. We suggest that localized flow-activated hyperpolarization of endothelium involving Ik.s may participate in the regulation of vascular tone.     

Antibiotic inhibition of group I ribozyme function

The discovery of catalytically active RNA has provided the basis for the evolutionary concept of an RNA world. It has been proposed that during evolution the functions of ancient catalytic RNA were modulated by low molecular weight effectors, related to antibiotics, present in the primordial soup. Antibiotics and RNA may have coevolved in the formation of the modern ribosome. Here we report that a set of aminoglycoside antibiotics, which are known to interact with the decoding region of the 16S ribosomal RNA of Escherichia coli, inhibit the second step of splicing of the T4 phage-derived td intron. Thus catalytic RNA seems to interact not only with a mononucleotide and an amino acid, but also with another class of biomolecules, the sugars. Splicing of other group I introns but not group II introns was inhibited. The similarity in affinity and specificity of these antibiotics for group I introns and rRNAs may result from recognition of evolutionarily conserved structures.     

The institution as an “Ideological system”: How morals maketh organization

A dominant current view of institutions sees them as task-performing entities and hence views improvements and change as functional in nature. Systems views of managing change in institutions are particularly guilty of adopting this view. Recommendations for change take the form of improving the task and organization structures to make the functions more efficient and effective in performance. This paper argues that such a functionalist view of an institution is limited and can be dangerous when considering recommendations for change. A different view of an institution is proposed. This view is interpretivist and uses the notion of organizational culture to show how institutions may be usefully viewed through the notion of “ideological system.” The theoretical framework for this notion is that of institutional members sharing and developing a common interpretive schema and exploiting this in their making of judgments about appropriate and inappropriate actions and change. This framework is then developed into the view that ideologies express the morals of institutional life and that so-called functional activities can be seen as essentially moral in action and intention. It is the symbolic nature of such moralities that allows the institutional life to be understood by its members and decisions to be made about what is appropriate and inappropriate behavior. The argument is made that this view of organizations is fundamentally important in analysis so that prioritization decisions can be understood and appropriate recommendations for change can be made. This paper shows how systems approaches can be used from this framework but that a different notion of institution, and hence change, needs to be adopted. An interpretative approach to organizational analysis is then developed and presented. Reference is made to various cases to illustrate the argument.     

Studies on lysosomes in rat heart cell cultures. II. The effect of exogenous lysosomes

Zusammenfassung Isolierte Lysosomen wie auch intakte Monozyten hatten keinen zytopathischen Einfluss auf Herzmuskelzellen von Ratten, gezüchtet im Medium mit pH 7,2. Ein erniedrigtes Medium wie auch Nachbehandlungen der Kulturen mit Vitamin A nach Chlorpromazin 10^–4 konnten keinen synergistisch zerstörenden Einfluss auf die Herzkulturen hervorrufen.

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Supported by Grant No. HE-05739 from the National Institutes of Health, U.S. Public Health Service.