Electrophysiological dissociation of recency and recognition memory

Event-related brain potentials (ERPs) were recorded during the test phases of two experiments. In experiment 1, subjects first studied two consecutively presented word lists. At test, they were presented with pairs of words, and were required to judge which word had been presented most recently. The test pairs were composed of two previously studied words, one drawn from each list, (Old+Old pairs), one previously studied and one new word (Old+New pairs), or two unstudied words (New+New pairs). At temporo-parietal electrodes, ERPs to Old+Old and Old+New pairs were both reliably more positive-going than those to New+New pairs. At electrode sites overlying prefrontal cortex, ERPs to Old+Old pairs attracting correct recency judgements were more positive, from around 300 ms onwards, than those elicited by the other classes of item, which did not differ from one another. In experiment 2, the test task was changed to one that required discrimination between Old+New items on the one hand, and Old+Old and New+New pairs on the other. ERPs to Old+Old and Old+New pairs once again differed from those to New+New pairs at temporo-parietal sites, but no differences were evident between the ERPs from frontal electrode sites. In line with the evidence from lesion studies, these findings suggest that judgements of relative recency depend upon processes, supported by the prefrontal cortex, additional to those that are necessary for recognition memory. They further suggest that these processes are activated rapidly and selectively in response to pairs of studied items when these must be discriminated on the basis of their relative recency of occurrence.     

The role of DnaJ-like proteins in glucocorticoid receptor.hsp90 heterocomplex assembly by the reconstituted hsp90.p60.hsp70 foldosome complex

The glucocorticoid receptor (GR) is recovered from hormone-free cells in a heterocomplex with the molecular chaperone hsp90, which is required to produce the proper folding state for steroid binding. GR.hsp90 heterocomplexes are formed by a multiprotein system that appears to exist in all eukaryotic cells. Recently, we have reconstituted a receptor.hsp90 heterocomplex assembly system with purified rabbit hsp90 and hsp70 and bacterially expressed human p23 and p60. We have shown that hsp90, p60, and hsp70 form an hsp90.p60. hsp70 complex that converts the GR from a non-steroid binding to a steroid binding form (Dittmar, K. D., and Pratt, W. B. (1997) J. Biol. Chem. 272, 13047-13054). The resulting GR.hsp90 heterocomplex rapidly disassembles unless p23 is present to bind to the ATP-dependent conformation of hsp90 and stabilize its association with the receptor (Dittmar, K. D., Demady, D. R., Stancato, L. F., Krishna, P., and Pratt, W. B. (1997) J. Biol. Chem. 272, 21213-21220). In the current work, we show that the purified rabbit hsp70 utilized in prior studies is contaminated with a small amount of the rabbit DnaJ homolog hsp40. Elimination of the hsp40 from the purified GR.hsp90 assembly system reduces assembly activity, and the activity is restored by addition of the purified yeast DnaJ homolog YDJ-1. hsp40 is a component of the hsp90.p60.hsp70 foldosome complex isolated from reticulocyte lysate with antibody against p60. Under conditions that promote binding of p23 to hsp90 (elevated temperature, ATP, Nonidet P-40, molybdate), a five-membered (p23. hsp90.p60.hsp70.hsp40) complex of chaperone proteins is formed in reticulocyte lysate or from purified proteins. The hsp40-free, purified assembly system has a modest level of assembly activity that is maximally potentiated by YDJ-1 when it is present at about one-twentieth the concentration of hsp70. Although hsp40 is not in the final GR.hsp90 heterocomplex isolated from L cell cytosol, it is in the GR.hsp90 heterocomplex assembled in reticulocyte lysate. We conclude that hsp40 is a component of the multiprotein hsp90-based chaperone system where it potentiates GR.hsp90 heterocomplex assembly.     

Measurement of the tunnel rate in SIS' tunnel junctions as function of bias voltage

Cryogenic detectors with superconducting tunnel junctions can provide an energy resolution improved by at least one order of magnitude compared with standard semiconductor detectors. While the detection principle was already demonstrated many years ago, the past years were dedicated to the transition from the laboratory sample to practical detectors. Our most favored detector design gives rise to tunnel junctions with electrodes of unequal energy gaps. In such hetero tunnel junctions bias conditions can be established which cause a negative signal current. We report the experimental verification of this effect, and we discuss the yield of charge signal of cryogenic detectors based upon superconducting tunnel junctions.     

Superior mesenteric artery syndrome presenting with acute massive gastric dilatation

A 14-year-old girl presenting with acute massive gastric dilatation secondary to duodenal obstruction by the superior mesenteric artery is described. The diagnosis was facilitated by contrast-enhanced abdominal computerized tomography. She was successfully treated by gastrostomy and subsequent duodenal derotation. This unique presentation of the superior mesenteric artery syndrome is discussed.     

Sublethal effects of an organophosphate insecticide on the European eel, Anguilla anguilla

Recent research has found that family caregivers do not discuss their caregiving in terms of tasks but instead describe their care as shaped by concerns, commitments and goals. The purpose of this paper is to challenge the ways in which nurses approach the family caregiving process and to explore possibilities for evolving nursing knowledge by questioning existing practice in the light of developing insight into the ways in which being a family caregiver is meaningful. A critique of the philosophical orientations of rationalism and empiricism provides a platform to discuss the merits of a Heideggerian phenomenological approach in assisting nurses to better understand family caring experience. Such critique serves to support the notion of displacing the traditional scientific view as the prime means of disclosing truth, acknowledging alternative ways of knowing.