Facilitating acquisition and transfer of a continuous motor task in healthy older adults and patients with Alzheimer's disease.

This study examined the acquisition and transfer of a fine motor skill, namely the rotary pursuit, in 99 patients with Alzheimer's disease (AD) and 100 normal controls (NCs). To identify optimal learning strategies, the authors had participants practice the rotary pursuit under constant, blocked, random, or no training conditions. Transfer was assessed using speeds that were different from those practiced during acquisition. AD patients and NCs receiving constant practice outperformed their peers in the blocked and random conditions during acquisition. Whereas all 3 types of practice facilitated transfer in the NCs, AD patients only benefited from constant practice. The inability of the AD patients to benefit from variable practice suggests that these individuals may have difficulty accessing and/or forming motor schemas. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Die Isolierung der Sulfide aus unlegierten Stählen

Möglichkeiten zur Sulfidisolierung. Isolierung durch elektrolytische Auflösung der Stahlmatrix. Fehlerquellen durch leichte Oxidierbarkeit von Mangansulfid und Verlust kleinster Teilchen. Arbeitsvorschrift zur quantitativen elektrolytischen Isolierung und Sammlung der Isolate. Untersuchung der Sulfidzusammensetzung.     

The diurnal distribution of sleep propensity: experimental data about the interaction of the propensities for slow-wave sleep and REM sleep

The aim of the present study was to assess the diurnal variation of sleep propensity by evaluating the temporal distribution of sleep onset latency (SOL) and REM- and slow-wave sleep (SWS) parameters in systematically scheduled daytime naps for 12 young males. To reduce the effect of prior SWS on subsequent REM sleep, a double-nap technique was used, i.e. two adjacent naps A and B, which were separated by a 10-min break. Nap duration was adjusted in such a way that nap A allowed 30 min of sleep and nap B one complete NREM-REM cycle. EEG slow wave activity (SWA, power density from 0.5-4 Hz) was estimated from nap A and REM sleep parameters from nap B. The time span between 08.00 hours and 24.00 hours was covered by nine double-naps at 2 h intervals. The order of the nap sessions was systematically varied within and across subjects. For each subject, the time between successive double-nap recordings was at least three days. SOL was shortest in the time interval 12.00 hours to 16.00 hours and significantly longer between 20.00 hours and 24.00 hours. REM sleep duration and the percentage of sleep onset REM episodes decreased continuously from 08.00 hours to the interval 18.00-20.00 hours and increased thereafter, with a time course inversely related to the one of body temperature, which was also measured continuously. SWA showed a steady, threefold increase from 08.00 hours to 24.00 hours. The study offers new data on the diurnal variation of sleep propensity which seems to be a composite function of the drives for SWS and REM sleep.     

Comparability of in Vitro Tests for Bioactive Nanoparticles: A Common Assay to Detect Reactive Oxygen Species as an Example

The release of reactive oxygen species (ROS) during the electron transport of mitochondrial aerobic respiration is the major source of ROS. However, contact between cells and nanoparticles (NPs) can also induce release of ROS, leading to an imbalance towards the pro-oxidative state. At low levels of ROS production, cells initiate a protective response to guarantee their survival, but an excess of ROS can damage cellular compounds such as membranes and various organelles, or directly cause genotoxicity. Thus an elevated level of ROS is an important indicator of cellular stress and an accurate recording of this parameter would be very informative. ROS can be measured by various assays, but all known assays measuring and quantifying ROS possess certain weaknesses. The problems and challenges of quantitatively detecting ROS in vitro using the 2′,7′-dichlorodihydrofluorescein (DCF) assay is discussed as an example. In addition, we debate the difficulties in finding a suitable and stable chemical reaction control for the DCF assay (or other ROS-detecting assays). As a conclusion, we believe that using 3-morpholinosydnonimine hydrochloride (Sin-1) as a ROS inducer in the DCF assay is feasible only qualitatively. However, a quantitative measurement of the absolute amount of ROS produced and a quantitative comparison between experiments is (at the moment) impossible.     

PFG NMR and QENS diffusion study of n-alkane homologues in MFI-type zeolites

Recent methodological progress in pulsed field gradient (PFG) NMR and quasi-elastic neutron scattering (QENS) is exploited to enhance the range of diffusion measurement of the series of the n-alkane homologues in MFI-type zeolites (silicalite-1, ZSM-5) up to n-tetradecane. As observed already for the short-chain-length alkanes, the diffusivities are found to be intermediate between those for NaCaA and NaX, in agreement with the trend in the respective pore diameters. Similarly as in NaX, the diffusivities decrease monotonically with increasing chain length, in contrast to NaCaA, where recently for chain lengths above about six carbon atoms a remarkable deviation from this trend has been observed. Though agreeing in their trends, the diffusivities measured by PFG NMR are by up to one order of magnitude below the QENS data. This difference may be referred to internal diffusion barriers in the MFI-type zeolites: since PFG NMR monitors molecular displacements of typically micrometers the determined diffusivities are affected by these additional transport resistances, while these resistances are of no relevance for QENS, where much shorter displacements are recorded.     

Size and time dependent internalization of label-free nano-graphene oxide in human macrophages

Graphene oxide shows great promise as a material for biomedical applications,e.g.,as a multi-drug delivery platform.With this in view,reports of studies on the interaction between nanosized graphene oxide flakes and biological cells are beginning to emerge.However,the number of studies remains limited,and most used labeled graphene oxide samples to track the material upon endocytosis.Unfortunately,the labeling process alters the surface functionality of the graphene oxide,and this additional functionalization has been shown to alter the cellular response.Hence,in this work we used label-free graphene oxide.We carefully tracked the uptake of three different nanoscale graphene oxide flake size distributions using scanning/transmission electron microscopy.Uptake was investigated in undifferentiated human monocyte cells (THP-1) and differentiated macrophage cells.The data show clear size dependence for uptake,such that larger graphene oxide flakes (and clusters) are more easily taken up by the cells compared to smaller flakes.Moreover,uptake is shown to occur very rapidly,within two min of incubation with THP-1 cells.The data highlights a crucial need for cellular incubation studies with nanoparticles,to be conducted for short incubation periods as certain dependencies (e.g.,size and concentration) are lost with longer incubation periods.     

Pharmacological dissociation between the reinforcing, sensitizing, and response-releasing functions of reward in honeybee classical conditioning.

Reserpine depletes biogenic amines from their stores in the honeybee (Apis mellifera camica) brain and leads to impaired appetitive conditioning using sucrose as a reinforcer. Compensatory injection of octopamine or dopamine directly into the brain restores these behavioral losses. Dopamine rescues the slowing-down effect on motor patterns, but not sensitization or conditioning. Octopamine leaves the motor patterns as well as sensitization unchanged but rescues conditioning. Specifically, octopamine rescues acquisition but not retrieval. Serotonin has no significant effect on sensitization but impairs conditioning. The authors conclude that octopamine is involved in selectively mediating the reinforcing but not the sensitizing or response-releasing function of the sucrose reward, whereas dopamine is selectively involved in the expression of the motor response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fine structural characteristics of testicular cord formation in the developing rabbit gonad

This paper presents morphological (light- and electron-microscopical) evidence for the role of the mesonephros in contributing cells to the differentiating indifferent gonad and, after sexual differentiation, to the testis. A continuous process is revealed during which segregation of cells occurs from the developing and regressing mesonephros. Additionally, the complementary role of the coelomic epithelium in gonadal ridge and testis formation is demonstrated. The differentiation of testicular cords, their remodelling from a primary reticulum, and the composition and further change of the cellular content during the period after sexual differentiation is described using a computer-aided three-dimensional reconstruction system. Apart from these morphogenetic events, cytodifferentiation in the somatic cells of the indifferent gonad and of the early differentiated testis is demonstrated using indirect immunof luorescence in combination with monoclonal antibodies to the intermediate filament proteins keratin 8 and 18 and vimentin. The immunohistochemical results show that different forms of cytodifferentiation coexist among the somatic cells present in the indifferent gonad and in the testis early after sexual differentiation.