Value and limits of μ-CT for nondemineralized bone tissue processing

An experimental approach was performed on 20 giant rabbits to establish the possibilities and limitations of μ-CT for routine processing of nondemineralized bone tissue. Hydroxyapatite (HA) or β-tricalciumphosphate (β-TCP) bead implants or a melange of both, microchambered and solid, were implanted into a standardized and precise defect in the patellar groove. The bone-healing phase was chosen for the histology considering 1 or 2 days, and 2, 3, and 6 weeks. Normal X-ray and μ-CT were applied on all specimens; five specimens in the 6-week stage were additionally processed according to the full range of conventional nondemineralized bone processing methods. μ-CT increased the possibilities of nondemineralized histology with respect to bone morphometry and a complete sequence of sections, thus providing a complete analysis of the bone response. μ-CT was limited in differentiating bone quality, cell analyses, and mineralization stages. The investigation based on normal X-rays is limited to defining integration and excluding the fibrous and bony encapsulation of loose implants. μ-CT allows a 3D evaluation of newly formed bone which is clearly marked against the ceramic implant. It does not allow, however, for the differentiation between woven and lamellar bone, the presentation of the canalicular lacunar system, or on the cell level, revealing canaliculi or details of the mineralization process which can be documented by high-resolution microradiography. Titer dynamics of bone formation remains the domain of polychromatic sequential labeling. The complete sequence of μ-CT slices enhances the possibilities for routine histology, tremendously allowing to the focus on detail histology to topographically well-defined cuts, thus providing more precise conclusions which take into consideration the whole implant.     

Influence of photoperiod on carbon dioxide and methane emissions from two pilot-scale stabilization ponds

Greenhouse gas (GHG) emissions (CO(2), CH(4)) from pilot-scale algal and duckweed-based ponds (ABP and DBP) were measured using the static chamber methodology. Daylight and nocturnal variations of GHG and wastewater characteristics (e.g. chemical oxygen demand (COD), pH) were determined via sampling campaigns during midday (12:30-15:30) and midnight (00:30-03:30) periods. The results showed that under daylight conditions in ABP median emissions were -232 mg CO(2) m(-2) d(-1) and 9.9 mg CH(4) m(-2) d(-1), and in DBP median emissions were -1,654.5 mg CO(2) m(-2) d(-1) and 71.4 mg CH(4) m(-2) d(-1), respectively. During nocturnal conditions ABP median emissions were 3,949.9 mg CO(2) m(-2) d(-1), 12.7 mg CH(4) m(-2) d(-1), and DBP median emissions were 5,116 mg CO(2) m(-2) d(-1), 195.2 mg CH(4) m(-2) d(-1), respectively. Once data measured during daylight were averaged together with nocturnal data the median emissions for ABP were 1,566.8 mg CO(2) m(-2) d(-1) and 72.1 mg CH(4) m(-2) d(-1), whilst for DBP they were 3,016.9 mg CO(2) m(-2) d(-) and 178.9 mg CH(4) m(-2) d(-1), respectively. These figures suggest that there were significant differences between CO(2) emissions measured during daylight and nocturnal periods (p < 0.05). This shows a sink-like behaviour for both ABP and DBP in the presence of solar light, which indicates the influence of photosynthesis in CO(2) emissions. On the other hand, the fluxes of CH(4) indicated that DBP and ABP behave as net sources of CH(4) during day and night, although higher emissions were observed from DBP. Overall, according to the compound average (daylight and nocturnal emissions) both ABP and DBP systems might be considered as net sources of GHG.     

A VNS heuristic for escaping local extrema entrapment in normalized cut clustering

Normalized cut is one of the most popular graph clustering criteria. The main approaches proposed for its resolution are spectral clustering methods and a multilevel approach of Dhillon et al. (TPAMI 29:1944–1957, 2007), called graclus. Their aim is to obtain good solutions in a small amount of time for large instances. Metaheuristics are general frameworks for stochastic searches often employed in global optimization to improve the solutions obtained by other heuristics. Variable neighborhood search (VNS) is a metaheuristic which exploits systematically the idea of neighborhood change during the search. In this paper, we propose a VNS heuristic for normalized cut segmentation. Computational experiments show that in most cases this VNS heuristic improves significantly, and in moderate time, the solutions obtained by the current state-of-the-art algorithms, i.e., graclus and a spectral method proposed by Yu and Shi (ICCV, 2003).     

A Java simulator of Rescorla and Wagner's prediction error model and configural cue extensions

In this paper we present the "R&W Simulator" (version 3.0), a Java simulator of Rescorla and Wagner's prediction error model of learning. It is able to run whole experimental designs, and compute and display the associative values of elemental and compound stimuli simultaneously, as well as use extra configural cues in generating compound values; it also permits change of the US parameters across phases. The simulator produces both numerical and graphical outputs, and includes a functionality to export the results to a data processor spreadsheet. It is user-friendly, and built with a graphical interface designed to allow neuroscience researchers to input the data in their own "language". It is a cross-platform simulator, so it does not require any special equipment, operative system or support program, and does not need installation. The "R&W Simulator" (version 3.0) is available free.     

Modelling and characterization of AlN-actuated microcantilevers vibrating in the first in-plane mode

The characterization of the first in-plane mode of aluminum nitride-actuated piezoelectric microcantilevers was carried out by using electrical and optical techniques. The top electrode of the cantilever was specifically designed to allow for an efficient electrical actuation of these in-plane modes. In order to confirm the in-plane nature of the modal vibration, the detection of the electrically induced movement was performed optically with the help of a stroboscopic microscope. In parallel, resonances were also measured electrically by means of an impedance analyzer. The quality factor and the resonant frequencies of the in-plane modes were estimated from the corresponding measurement data when applying both detection techniques. Our results show quality factor values as high as 3,000 for the first in-plane mode in air.     

Mental Health of Lesbian, Gay, Bisexual, and Heterosexual Siblings: Effects of Gender, Sexual Orientation, and Family.

Self-identified lesbian, gay male, and bisexual (LGB) individuals were recruited via convenience sampling, and they in turn recruited their siblings (79% heterosexual, 19% LGB). The resulting sample of 533 heterosexual, 558 lesbian or gay male, and 163 bisexual participants was compared on mental health variables and their use of mental health services. Multilevel modeling analyses revealed that sexual orientation predicted suicidal ideation, suicide attempts, self-injurious behavior, use of psychotherapy, and use of psychiatric medications over and above the effects of family adjustment. Sexual orientation was unrelated to current psychological distress, psychiatric hospitalizations, and self-esteem. This is the 1st study to model family effects on the mental health of LGB participants and their siblings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Opposing Effects of D? and D? Receptor Activation on Odor Discrimination Learning.

Dopaminergic modulation of cortical activity has been implicated in the formation of reward associations. There is abundant evidence for dopaminergic effects on olfactory processing. Using an olfactory discrimination task, the authors show that D? and D? dopamine receptors can regulate rats' olfactory discrimination capacities and that the effects of receptor activation functionally oppose one another. Injection of either the D? agonist SKF 38393 (10 mg/kg) or the D? antagonist spiperone (0.62 mg/kg) facilitated the discrimination of similar odorants but had no effect on the discrimination of dissimilar odorants, whereas both the D, antagonist SCH 23390 (0.025 mg/kg) and the D? agonist quinpirole (0.2 mg/kg) significantly impaired rats' ability to discriminate similar and dissimilar odorants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Immunohistochemistry of neuronal nitric oxide synthase and protein nitration in the striatum of the aged rat

To ascertain the possible implications of the nitric oxide (NO*) producing system in striatal senescence, and by using immunohistochemistry and image-processing approaches, we describe the presence of the enzyme nitric oxide synthase (NOS), the NADPH-diaphorase (NADPH-d) histochemical marker, and nitrotyrosine-derived complexes (N-Tyr) in the striatum of adult and aged rats. The results showed neuronal NOS immunoreactive (nNOS-IR) aspiny medium-sized neurons and nervous fibres in both age groups, with no variation in the percentage of immunoreactive area but a significant decrease in the intensity and in the number of somata with age, which were not related to the observed increase with age of the striatal bundles of the white matter. In addition, NADPH-d activity was detected in neurons with morphology similar to that of the nNOS-IR cells; a decrease in the percentage of area per field and in the number of cells, but an increase in the intensity of staining for the NADPH-d histochemical marker, were detected with age. The number of neuronal NADPH-d somata was higher than for the nNOS-IR ones in both age groups. Moreover, N-Tyr-IR complexes were observed in cells (neurons and glia) and fibres, with a significant increase in the percentage of the area of immunoreaction, related to the increase of white matter, but a decrease in intensity for the aged group. On the other hand, we did not detect the inducible isoform (iNOS) either in adult or in aged rats. Taken together, these results support the contention that NADPH-d staining is not such an unambiguous marker for nNOS, and that increased protein nitration may participate in striatal aging.     

Reusable abstractions for modeling languages

Model-driven engineering proposes the use of models to describe the relevant aspects of the system to be built and synthesize the final application from them. Models are normally described using Domain-Specific Modeling Languages (DSMLs), which provide primitives and constructs of the domain. Still, the increasing complexity of systems has raised the need for abstraction techniques able to produce simpler versions of the models while retaining some properties of interest. The problem is that developing such abstractions for each DSML from scratch is time and resource consuming.     

Alteration in the Synaptic and Extrasynaptic Organization of AMPA Receptors in the Hippocampus of P301S Tau Transgenic Mice

Tau pathology is a hallmark of Alzheimer’s disease (AD) and other tauopathies, but how pathological tau accumulation alters the glutamate receptor dynamics driving synaptic dysfunction is unclear. Here, we determined the impact of tau pathology on AMPAR expression, density, and subcellular distribution in the hippocampus of P301S mice using immunoblot, histoblot, and quantitative SDS-digested freeze-fracture replica labeling (SDS-FRL). Histoblot and immunoblot showed differential regulation of GluA1 and GluA2 in the hippocampus of P301S mice. The GluA2 subunit was downregulated in the hippocampus at 3 months while both GluA1 and GluA2 subunits were downregulated at 10 months. However, the total amount of GluA1-4 was similar in P301S mice and in age-matched wild-type mice. Using quantitative SDS-FRL, we unraveled the molecular organization of GluA1-4 in various synaptic connections at a high spatial resolution on pyramidal cell spines and interneuron dendrites in the CA1 field of the hippocampus in 10-month-old P301S mice. The labeling density for GluA1-4 in the excitatory synapses established on spines was significantly reduced in P301S mice, compared to age-matched wild-type mice, in the strata radiatum and lacunosum-moleculare but unaltered in the stratum oriens. The density of synaptic GluA1-4 established on interneuron dendrites was significantly reduced in P301S mice in the three strata. The labeling density for GluA1-4 at extrasynaptic sites was significantly reduced in several postsynaptic compartments of CA1 pyramidal cells and interneurons in the three dendritic layers in P301S mice. Our data demonstrate that the progressive accumulation of phospho-tau is associated with alteration of AMPARs on the surface of different neuron types, including synaptic and extrasynaptic membranes, leading to a decline in the trafficking and synaptic transmission, thereby likely contributing to the pathological events taking place in AD.