Measurement of Spin Dynamics in a Layered Nickelate Using X-Ray Photon Correlation Spectroscopy: Evidence for Intrinsic Destabilization of Incommensurate Stripes at Low Temperatures.

We study the temporal stability of stripe-type spin order in a layered nickelate with x-ray photon correlation spectroscopy and observe fluctuations on timescales of tens of minutes over a wide temperature range. These fluctuations show an anomalous temperature dependence: they slow down at intermediate temperatures and speed up on both heating and cooling. This behavior appears to be directly connected with spatial correlations: stripes fluctuate slowly when stripe correlation lengths are large and become faster when spatial correlations decrease. A low-temperature decay of nickelate stripe correlations, reminiscent of what occurs in cuprates as a result of a competition between stripes and superconductivity, hence occurs via loss of both spatial and temporal correlations.

Hyperinsulinaemic hypoglycaemia and diabetes mellitus due to dominant ABCC8/KCNJ11 mutations.

AIMS/HYPOTHESIS: Dominantly acting loss-of-function mutations in the ABCC8/KCNJ11 genes can cause mild medically responsive hyperinsulinaemic hypoglycaemia (HH). As controversy exists over whether these mutations predispose to diabetes in adulthood we investigated the prevalence of diabetes in families with dominantly inherited ATP-sensitive potassium (K(ATP)) channel mutations causing HH in the proband. METHODS: We studied the phenotype of 30 mutation carriers (14 children and 16 adults) from nine families with dominant ABCC8/KCNJ11 mutations. Functional consequences of six novel missense mutations were examined by reconstituting the K(ATP) channel in human embryonic kidney 293 (HEK293) cells and evaluating the effect of drugs and metabolic poisoning on the channels using the (86)Rb flux assay. RESULTS: The mutant channels all showed a lack of (86)Rb efflux on exposure to the channel agonist diazoxide or metabolic inhibition. In the families, dominant ABCC8/KCNJ11 mutations were associated with increased birthweight (median + 1.56 SD score [SDS]). Fourteen children had HH and five adults were reported with HH or hypoglycaemic episodes (63%). Progression from hypoglycaemia to diabetes mellitus occurred in two individuals. Eight adults had a history of gestational diabetes in multiple pregnancies or were diabetic (diagnosed at a median age of 31 years). Within these families, none of the 19 adults who were not carriers of the ABCC8/KCNJ11 mutation was known to be diabetic. CONCLUSIONS/INTERPRETATION: The phenotype associated with dominant ABCC8/KCNJ11 mutations ranges from asymptomatic macrosomia to persistent HH in childhood. In adults, it may also be an important cause of dominantly inherited early-onset diabetes mellitus.

Spatial constraints underlying the retinal mosaics of two types of horizontal cells in cat and macaque.

Most types of retinal neurons are spatially positioned in non-random patterns, termed retinal mosaics. Several developmental mechanisms are thought to be important in the formation of these mosaics. Most evidence to date suggests that homotypic constraints within a type of neuron are dominant, and that heterotypic interactions between different types of neuron are rare. In an analysis of macaque H1 and H2 horizontal cell mosaics, Wässle et al. (2000) suggested that the high regularity index of the combined H1 and H2 mosaic might be caused by heterotypic interactions during development. Here we use computer modeling to suggest that the high regularity index of the combined H1 and H2 mosaic is a by-product of the basic constraint that two neurons cannot occupy the same space. The spatial arrangement of type A and type B horizontal cells in cat retina also follow this same principle.

The fate of ingested glyceran esters of condensed castor oil fatty acids [polyglycerol polyricinoleate (PGPR)] in the rat.

Samples of the emulsifier polyglycerol polyricinoleate (PGPR) were synthesized using the radiolabelled precursors [1-14C]glycerol ([14C]polyglycerol PGPR), [9,10-3H] or [12-3H]ricinoleic acid ([3H] PGPR) or [1-14C]stearic acid ([14C]stearyl PGPR). The absorption, tissue distribution, metabolism and excretion of these 14C- or tritium-labelled PGPR samples administered to rats was studied. The effects of intestinal and porcine pancreatic lipases on PGPR preparations were examined. Rats were dosed with [1-14C]glycerol, [14C]polyglycerol and ([14C]polyglycerol)PGPR by gavage and their urine. faeces and expired CO2 monitored for 14C. The results from the [1-14C]glycerol treated animals showed extensive metabolism of glycerol. For [14C]polyglycerols, the lower polyglycerols were preferentially absorbed from the intestine and were excreted unchanged in the urine while the higher polyglycerols were found in the faeces. After 4 days, 93% of the dose of polyglycerols was recovered, of which some 30% was found in the urine and 60% in the faeces. Traces of 14C activity were found in depot fat and liver. The excretory pattern and urinary metabolites from ([14C]polyglycerol) PGPR was very similar to that of [14C]polyglycerol. Analysis of urinary and faecal 14C material indicated that the PGPR polymer was digested to give free polyglycerol and polyricinoleic acid. PGPR was synthesised incorporating [1-14C]stearic into polyricinoleic acid which was then esterified with polyglycerol. The resulting [14C]PGPR or [1-14C] stearic acid in a dietary slurry was administered to groups of fed or starved rats by gavage. The results indicated complete digestion of PGPR and absorption of the fatty acids. The 14C-material absorbed was extensively laid down in depot fat and some metabolism to 14CO2 was demonstrated. The fate of the stearic acid was similar whether dosed alone or incorporated into the PGPR polymer. Samples of PGPR were synthesized containing 3H-labelled ricinoleic acid. The resulting [3H]PGPR was intubated into rats as a component of a dietary slurry. The results indicated that the polymer is extensively digested and 90% of the administered tritium is absorbed. The absorbed material was extensively metabolized within 24 hr so that large amounts of tritium were present in the aqueous phase of the tissues examined. After 24 hr, less than 5% of the administered material was present as lipid material, of which a large proportion was as non-hydroxy fatty acids. No traces of polymer material were found in the tissues examined. In vitro digestion of PGPR by porcine pancreatic lipase and rat intestinal fractions was demonstrated. The results indicate very extensive digestion of the PGPR polymer to polyglycerols and fatty acids. The fatty acids are metabolized extensively. The mono-, di- and triglycerols are extensively absorbed from the intestinal tract and rapidly excreted in the urine unchanged but the hexa-, penta- and higher polyglycerols are essentially not absorbed and excreted in the faeces unchanged.

The effects of complexity on confidence ratings in linguistic integration.

Bransford and Franks (1971) introduced a paradigm for the study of linguistic integration. Their primary measure was subjects' rated confidence in their responses. The present paper considers the appropriateness of this dependent variable, and concludes that the relation between sentence complexity and rated confidence is too small and unstable to justify the emphasis which confidence ratings have received. Further, certain differences between concrete and abstract sentences were obscured by a confidence analysis. The proportion of old responses is championed as a more appropriate dependent variable. Finally, it is shown that increasing the amount of specific memory necessarily decreases the size of the complexity effect.