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Young and aged rats were treated chronically with ethanol or scopolamine. Muscarinic receptors were measured in cerebral cortex, hippocampus and striatum. Following scopolamine treatment muscarinic receptor density in cerebral cortex, hippocampus and striatum of young rats increased by 34, 57 and 27%, respectively; in brains of aged rats the increase was 41% in cerebral cortex, 43% in hippocampus and nil in striatum. Affinity of muscarinic receptors was not changed by scopolamine treatment. Following chronic ethanol administration there was a 48% increase in cortical muscarinic receptor density in young, but not aged rats. The density of muscarinic receptors in hippocampus and striatum of both young and aged rats was not affected by ethanol treatment. Affinity of receptors in hippocampus of aged, ethanol-treated rats was increased compared to age-matched controls. Adaptative responses of the muscarinic receptor/transducer system to neurotransmitter availability are present in both young and aged rats, both the ethanol-induced response is present only in young animals. This suggests differences in the mechanism of action of ethanol and receptor agonists and antagonists in modulating receptor plasticity.

The aggregation of gel-filtered human platelets induced by A23187 is very sensitive to inhibition by ethanol. Similarly when platelets preloaded with [3H]5-hydroxytryptamine ([3H]5HT) are studied in a superfusion system under conditions where aggregation is likely (high platelet density, presence of Ca2+) the rate of release of [3H]5HT induced by A23187 is reduced by the presence of ethanol. However when platelet aggregation is less likely (low platelet density, absence of Ca2+) ethanol does not reduce the rate of [3H]5HT efflux induced by A23187 in superfused platelets. In addition, in contrast to the effects of ethanol on platelet aggregation, the transformation of human red cells to echinocytes induced by A23187 is accelerated by the presence of ethanol. Similarly the increased efflux of 3H from superfused rat striatal slices preloaded with [3H]dopamine which is produced by A23187 is potentiated by ethanol. It is concluded that the inhibitory effect of ethanol on the action of A23187 may be confined to platelet aggregation. This may be because the mechanisms of action of either A23187 or ethanol on platelet aggregation differ from those on other cell functions.

Inositol monophosphatase can be modified at two sites by pyrene maleimide. These sites have been identified as Cys141 and Cys218. Stoichiometric addition of pyrene maleimide allows the sole modification of Cys218. The fluorescence of the pyrene moiety on the modified protein can be excited directly or by resonance energy transfer. The fluorescence properties of the pyrene group on Cys218 allows the interaction of ligands with the enzyme to be monitored. This feature has allowed dissociation constants for various metal ions to be determined and allowed the formation of various enzyme/ligand complexes to be observed. These studies have demonstrated that Mg2+ is required to support Pi binding and that Li+ interacts with a post‐catalytic complex which is only formed in the forward reaction.

The storage and transport of gases in coal is of tremendous importance in the utilisation of coalbeds, and in particular the recovery of methane. There is also increasing interest in the use of coal mines as sites for carbon dioxide sequestration to alleviate the potentially harmful effects of global warming. This paper demonstrates the use of magnetic resonance imaging to investigate the spatiotemporal dynamics of gas transport in coal. The presence of significant structural heterogeneities in the coal was observed. Dynamical effects displayed a broad range of time constants ranging from minutes to days.

Phospholipase C (PLC) activity was measured by the incorporation of [3H]-inositol into lipids and by the breakdown of [3H]-inositol-labelled phosphatidylinositols (PI) and polyphosphatidylinositols (PPI) to [3H]-inositol phosphates; phospholipase A2 (PLA2) activity by the breakdown of [3H]oleic acid-labelled phosphatidylcholine [( 3H]PC) to [3H]oleic acid and the enzymes of phospholipid base exchange (PLBE) by the incorporation of [14C]serine into membrane lipids. The activities of these enzymes in rat brain preparations were all increased by procedures which increase intracellular Ca2+, and were all inhibited to a varying extent by the presence of ethanol, 50 mM, in vitro. In contrast, the activities of PLA2 and PLBE enzymes were markedly increased in preparations from animals which had received ethanol chronically in vivo. Similarly, although the basal activity of PLC was only slightly increased in such preparations, depolarization induced the breakdown of a significantly greater fraction of radiolabelled PI than that which was obtained in control preparations. The results suggest compensatory alterations in the activity of Ca2+-activated enzymes of phospholipid metabolism in brain tissue during the continued presence of ethanol in vivo.

The dynamics of granular materials, particularly radial and axial segregation in horizontal rotating cylinders containing large and small particles, is studied by Magnetic Resonance Imaging (MRI). Stationary three-dimensional (3D) images and real-time two-dimensional (2D) structural images showing radial segregation, band formation, and band merging are reported. Quantitative local particle concentrations are measured in a noninvasive manner from the different magnetic resonance responses of the seeds throughout segregation. Data are acquired with sufficiently high temporal (300 ms for 2D images) and spatial resolutions (0.94 mm cubic voxels), to give insights into the underlying mechanisms of both radial and axial segregation. In particular, the increasing rate of the local particle concentration during radial segregation is quantified. Particle migration is observed in the bulk material of the 75% and 82% full cylinders during both radial and axial segregation, showing that this region beneath the avalanche layer does not behave as a solid body. We also provide direct experimental evidence to support recent numerical simulations of band merging.

The uptake of [14C]deoxyglucose by brains of rats that were given alcohol in drinking water for 7 months was investigated. There was a general, approximately 50%, increase in deoxyglucose uptake in brains of ethanol-treated rats with areas of the limbic system being particularly affected.

AbstractAlcohol taken regularly over a lengthy period of time has been claimed to cause to loss of neurons in both the adult and developing brain. However, it remains uncertain whether acute, as opposed to chronic, exposure to alcohol at specified periods can also cause disruption in the neuronal population of the developing brain. This question was investigated by exposing Wistar rat pups to 7.5 g/kg body weight of ethanol administered as a 10% solution via an intragastric cannula over an 8 hour period either on the 5th (PND5) or the 10th (PND10) postnatal day of age. Gastrostomy controls received a 5% sucrose solution substituted isocalorically for the ethanol. Another set of pups raised by their mothers was used as “suckle controls”. All surgical procedures were carried out under halothane vapour anaesthesia. After the artificial feeding regimes, all pups were returned to the lactating dams and weaned at 21 days of age. Between 52 and 54 days of age, the rats were anaesthetised with an intraperitoneal injection with Nembutal and killed by intracardiac perfusion with 3% glutaraldehyde in 0.1 M phosphate buffer. The relatively unbiased stereological procedure known as the “fractionator” method was used to estimate the total number of Purkinje cells in the cerebellum of each animal. The Purkinje cell nucleolus was used as the counting unit; it was assumed that each Purkinje cell contained only one nucleolus. PND10 ethanol‐treated rats and gastrostomy and suckle controls had between about 210,000‐232,000 Purkinje cells in the cerebellum. However, the PND5 ethanol‐treated rats had only about 137,000 Purkinje cells. Two‐way analysis of variance procedures revealed significant main effects of age at time of alcohol exposure and groups as well as a significant interaction between them. It is concluded that the Purkinje cell population numbers can be disrupted by acute exposure to alcohol on the 5th, but not the 10th, postnatal day of age. © 1995 Wiley‐Liss, Inc.