Behavioral effects of subchronic inorganic manganese exposure in rats

Background: Manganese, an essential micronutrient, is a potential neurotoxicant in prolonged overexposure. Parkinson- like syndrome, motor deficit, disturbed psychomotor development are typical signs of neuropathological alterations due to Mn in humans. Methods: Young adult rats, in three groups of 16 each, received 15 and 59 mg/kg b.w. MnCl2, (control: distilled water) via gavage for 10 weeks, and were kept for further 12 weeks. Correlation of MnCl2 exposure to body and organ weights, neurobehavioral effects (spatial memory, exploratory activity, psychomotor performance, pre-pulse inhibition), and histopathological changes (gliosis) was sought. Results: By the end of treatment, Mn accumulated in blood, cortex, hippocampus, and parenchymal tissues. Body and organ weights were reduced in high dose rats. All treated rats showed hypoactivity, decreased memory performance, and diminished sensorimotor reaction. In the dentate gyrus of these, GFAP immunoreactivity increased. During the post-treatment period, body weight of the high dose group remained decreased, locomotor activity returned to control, but the lasting effect of MnCl2 could be revealed by amphetamine. Conclusion: Using complex methodology, new data were obtained regarding the relationship between the long-term effects of MnCl2 at neuronal and behavioral level. Š 2007 Wiley-Liss, Inc

Vezetőképesség moduláció ZnO nanoszálakon bioreceptorokkal = Conductivity Modulation of ZnO Nanowires by Bioreceptors (CoMoNano)

Kimutattuk, hogy az egyszerű és alacsony hőmérsékletű nedves kémiai eljárásban a vizes cinknitrát/hexametiltetramin oldat koncentrációjának csökkentésével csökken a növesztett ZnO nanoszálak vastagsága. Újszerű módszert dolgoztunk ki a nanoszál növesztésére, amelyben a ZnO magrétegre leválasztott Stöber szilika nanogömbök monorétegével nemcsak vékony de hosszabb nanoszálak is növeszthetőek. Kimutattuk, hogy az ilyen szálnak jobb az UV fénnyel történő modulálhatósági hatásfoka. Megmutattuk, hogy rendezett, lokalizált nanoszálak növeszthetők a magrétegre felvitt PMMA fedőrétegben kialakított nukleációablakokon keresztül. Az így növesztett nanoszálak rendezettsége, minősége inkább az alkalmazott magréteg kristályi minőségétől függ, semmint a felületi durvaságától. Eljárást dolgoztunk ki az IC planár technológiába jobban integrálható horizontális nanoszálak növesztésére. A kontaktusokról induló és oxidon tovább növő szálak lehetővé teszik az eszköz térvezérlésű tranzisztorként hátsó gate általi vezérelhetőségét, amivel növelhető a szál modulálhatósági hatásfokát, modulálási sebességét. Demonstráltuk a horizontális szálak modulálhatóságát UV fényre (kb. öt nagyságrend változás ) illetve az IgG fehérjére Z domén receptorokkal. A modulálás már nagyon kis IgG (25 nM) koncentrációnál megfigyelhető, de a koncentráció növekedésével telítési jelleget mutat. Ennek valószínűleg a szálon szabadon maradt receptorok csökkenő száma lehet az oka. | We have shown that in the chemical bath deposition the thickness of the grown ZnO nanowires (NWs) is reduced with decreasing concentration of the aqueous zinc nitrate and hexamethylentetramine. A novel route has been developed using a monolayer of silica nanospheres deposited on ZnO seedlayer to grow thin but much longer NWs than usual. Such NWs were observed to have better UV modulation property than those formed without nanosphere layer. We demonstrated that the selective growth of NWs could be well realized via the nucleation windows pre-formed in the PMMA cap-layer over the seed layer. The crystal quality and alignment of such NWs was determined by the dispersion in the crystallographic orientation of the seed layer while the role of its surface roughness was negligible. Method to grow horizontal NWs which is integrable into IC planar technology has been developed. Being nucleated from the electrodes then grown along oxide surface, the NWs can be gated by a back electrode as a field effect transistor, thus their modulation efficiency, speed can be further achieved. Modulation of the horizontal NWs has been demonstrated for UV illumination (five order of magnitude change) and IgG with Z domain receptors. The modulation effect of IgG can be observed even at very low concentration (25 nM), which showed a saturation tendency with increasing IgG concentration, probably due to the limitation of the available binding sites of the Z domains on the NW surface for the IgGs

Development and In-Depth Characterization of Bacteria Repellent and Bacteria Adhesive Antibody-Coated Surfaces Using Optical Waveguide Biosensing

Bacteria repellent surfaces and antibody-based coatings for bacterial assays have shown a growing demand in the field of biosensors, and have crucial importance in the design of biomedical devices. However, in-depth investigations and comparisons of possible solutions are still missing. The optical waveguide lightmode spectroscopy (OWLS) technique offers label-free, non-invasive, in situ characterization of protein and bacterial adsorption. Moreover, it has excellent flexibility for testing various surface coatings. Here, we describe an OWLS-based method supporting the development of bacteria repellent surfaces and characterize the layer structures and affinities of different antibody-based coatings for bacterial assays. In order to test nonspecific binding blocking agents against bacteria, OWLS chips were coated with bovine serum albumin (BSA), I-block, PAcrAM-g-(PMOXA, NH(2), Si), (PAcrAM-P) and PLL-g-PEG (PP) (with different coating temperatures), and subsequent Escherichia coli adhesion was monitored. We found that the best performing blocking agents could inhibit bacterial adhesion from samples with bacteria concentrations of up to 10(7) cells/mL. Various immobilization methods were applied to graft a wide range of selected antibodies onto the biosensor’s surface. Simple physisorption, Mix&Go (AnteoBind) (MG) films, covalently immobilized protein A and avidin–biotin based surface chemistries were all fabricated and tested. The surface adsorbed mass densities of deposited antibodies were determined, and the biosensor;s kinetic data were evaluated to divine the possible orientations of the bacteria-capturing antibodies and determine the rate constants and footprints of the binding events. The development of affinity layers was supported by enzyme-linked immunosorbent assay (ELISA) measurements in order to test the bacteria binding capabilities of the antibodies. The best performance in the biosensor measurements was achieved by employing a polyclonal antibody in combination with protein A-based immobilization and PAcrAM-P blocking of nonspecific binding. Using this setting, a surface sensitivity of 70 cells/mm(2) was demonstrated

Inhibition of ABCG2/BCRP-mediated transport–correlation analysis of various expression systems and probe substrates

BCRP / ABCG2 is a key determinant of pharmacokinetics of substrate drugs. Several BCRP substrates and inhibitors are of low passive permeability, and the vesicular transport assay works well in this permeability space. Membranes were prepared from BCRP-HEK293, MCF-7/MX, and baculovirus-infected Sf9 cells with (BCRP-Sf9-HAM), and without (BCRP-Sf9) cholesterol loading. Km values for three substrates - estrone-3-sulfate, sulfasalazine, topotecan - correlated well between the four expression systems. In contrast, a 10-20-fold range in Vmax values was observed, with BCRP-HEK293 membranes possessing the largest dynamic range. IC50 values of the different test systems were similar to each other, with 94.4% of pairwise comparisons being within 3-fold. Substrate dependent inhibition showed somewhat greater variation, as 81.4% of IC50 values in the BCRP-HEK293 membranes were within 3-fold in pairwise comparisons. Overall, BCRP-HEK293 membranes demonstrated the highest activity. The IC50 values showed good concordance but substrate dependent inhibition was observed for some drugs

Membrane Assays to Characterize Interaction of Drugs with ABCB1.

ATP-binding cassette sub-family B member 1 (ABCB1) [P-glycoprotein (P-gp), multidrug resistance protein 1 (MDR1)] can affect the pharmacokinetics, safety, and efficacy of drugs making it important to identify compds. that interact with ABCB1. The ATPase assay and vesicular transport (VT) assay are membrane based assays that can be used to measure the interaction of compds. with ABCB1 at a lower cost and higher throughput compared to cellular-based assays and therefore can be used earlier in the drug development process. To that end, we tested compds. previously identified as ABCB1 substrates and inhibitors for interaction with ABCB1 using the ATPase and VT assays. All compds. tested interacted with ABCB1 in both the ATPase and VT assays. All compds. previously identified as ABCB1 substrates activated ABCB1-mediated ATPase activity in the ATPase assay. All compds. previously identified as ABCB1 inhibitors inhibited the ABCB1-mediated transport in the VT assay. Interestingly, six of the ten compds. previously identified as ABCB1 inhibitors activated the basal ATPase activity in activation assays suggesting that the compds. are substrates of ABCB1 but can inhibit ABCB1 in inhibition assays. Importantly, for ATPase activators the EC50 of activation correlated with the IC50 values from the VT assay showing that interactions of compds. with ABCB1 can be measured with similar levels of potency in either assay. For ATPase nonactivators the IC50 values from the ATPase inhibition and VT inhibition assay showed correlation. These results demonstrate the utility of membrane assays as tools to detect and rank order drug-transporter interactions. [on SciFinder(R)

Estradiol-Induced Synaptic Remodeling of Tyrosine Hydroxylase Immunopositive Neurons in the Rat Arcuate Nucleus

Gonadal steroids induce synaptic plasticity in several areas of the adult nervous system. In the arcuate nucleus of adult female rats, 17β-estradiol triggers synaptic remodeling, resulting in a decrease in the number of inhibitory synaptic inputs, an increase in the number of excitatory synapses, and an enhancement of the frequency of neuronal firing. In the present paper, we studied the specificity of hormonal effects by determining the changes in synaptic connectivity of tyrosine hydroxylase (TH) immunoreactive (IR) neurons in the arcuate nucleus. We combined pre-embedding TH and post-embedding γ-aminobutyric acid (GABA) immunostaining, and performed unbiased stereological measurements in gonadectomized and 17β-estradiol-treated rats. We conclude that the synaptic connectivity of the TH-IR neurons is different from the other, nonlabeled population, and the response to estradiol is not uniform. TH-IR (dopaminergic) arcuate neurons of both male and female rats have more GABAergic (inhibitory) axosomatic inputs than the nondopaminergic population. Our study shows that the effect of 17β-estradiol is sex and cell specific in the sense that not all arcuate neurons are affected by the structural synaptic remodeling. In ovariectomized females hormone treatment decreased the numerical density of GABAergic axosomatic synapses on TH-IR, but not on nondopaminergic, neurons, whereas in orchidectomized males, 17β-estradiol treatment increased inhibitory synapses onto nondopaminergic neurons but did not affect the number of inhibitory terminals onto TH-IR neurons. The hormone-induced plastic changes in synaptic connectivity of TH-IR neurons may serve as the morphological basis for the cyclical regulation of the anterior pituitary