Neurotoxicity and Underlying Mechanisms of Endogenous Neurotoxins

Endogenous and exogenous neurotoxins are important factors leading to neurodegenerative diseases. In the 1980s, the discovery that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) contributes to Parkinson’s disease (PD) symptoms led to new research investigations on neurotoxins. An abnormal metabolism of endogenous substances, such as condensation of bioamines with endogenous aldehydes, dopamine (DA) oxidation, and kynurenine pathway, can produce endogenous neurotoxins. Neurotoxins may damage the nervous system by inhibiting mitochondrial activity, increasing oxidative stress, increasing neuroinflammation, and up-regulating proteins related to cell death. This paper reviews the biological synthesis of various known endogenous neurotoxins and their toxic mechanisms.     

Synthesis of polypyrrole/Fe-kanemite nanocomposite through in situ polymerization: effect of iron exchange,acid treatment,and CO<Subscript>2</Subscript> adsorption properties

This paper focuses on the synthesis of polypyrrole/Fe-kanemite nanocomposites by in situ polymerization of pyrrole. Different percentages of PPy/Fe-kan have been prepared and tested for the CO₂ adsorption. Fe-exchanged kanemite was prepared using various iron contents and used as an oxidant for the preparation of PPy/Fe-kan nanocomposite. The obtained materials were characterized using various techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, ultraviolet–visible (UV–vis), thermogravimetric analysis TGA, energy dispersive X-ray analysis, scanning and transmission electronic microscopy (SEM, TEM). Based on the XRD and UV–vis analysis, the exchange process leads to the formation of various iron species on the external and internal surface. The thermal stability of PPy/Fe-kan was improved and increased in the following order PPy/Fe-kan (1%) > PPy/Fe-kan (3%) > PPy/Fe-kan (5%) > PPy/Fe-kan (10%) > PPy. SEM and TEM analysis show that the nanocomposite particles have spherical morphology with a high dispersion of the Fe-kanemite in the polymer matrix. CO₂ adsorption at 0 and 15 °C was carried using a volumetric method, and the recorded isotherm indicated that the CO₂ adsorption capacity of PPy/Fe-kan can be enhanced through modification by polypyrrole. The unmodified Na-kanemite has low CO₂ adsorption capacity around 0.05 mmol g^?1 at 15 °C, while the PPy/Fe-kan (5%) nanocomposite presented the best CO₂ adsorption capacity around 1.7 mmol g^?1 at 0 °C under low pressure that is mainly attributable to physical adsorption.     

Naloxone, but not flupenthixol, disrupts the development of conditioned ejaculatory preference in the male rat.

Male rats display a conditioned preference to ejaculate with a female bearing an odor paired previously with copulation to ejaculation. The present study examined the role of endogenous opioid and dopamine systems in this preference. Male rats received saline, the opioid receptor antagonist naloxone, or the dopamine receptor antagonist flupenthixol prior to 10 conditioning trials in a pacing chamber with an almond-scented female. On the final test, all males were injected with saline and given access to 2 females, 1 scented and the other unscented, in an open field. Only males injected with naloxone during training failed to manifest a conditioned ejaculatory preference. These findings suggest that activation of opioid, but not dopamine, systems during sexual interaction are necessary for conditioned ejaculatory preference in male rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structure Analysis and Classification of Precipitation Cells by Fractal Geometry

This paper analyzes the possibility to discriminate between convective precipitation and stratiform precipitation.This study aims to improve the measurement of rainfall from teledetection data obtained both on the ground and in space.For this,two parameters,fractal dimension and fractal lacunarity,are considered.To calculate the fractal dimension,we use the approach of box-counting and show that the fractal dimension differs between convectives cells and stratiforms ones.And then the fractal lacunarity parameter is calculated by using the sliding boxes algorithm.The study for all the regions shows that precipitation cells can be described by different lacunarities whatever the scale of analysis.We deduce that the two parameters,fractal dimension and fractal lacunarity,can be used to classify precipitations in convective regime and stratiform regime.     

Context-dependent acquisition of copulatory behavior in the male rat: Role of female availability.

The effect of the environment in which sexual experience is acquired was examined on patterns of male rat copulatory behavior. Males trained in a pacing chamber with a 4-hole partition had significantly shorter ejaculation latencies compared with males trained in chambers with a 1-hole partition. Those differences persisted when males were switched into the other pacing condition, suggesting that the pattern of copulation in these males had become "fixed." In the second experiment, males were trained to associate an almond odor with copulation in either the 1-hole or 4-hole condition. Males ejaculated preferentially with females associated with the 4-hole pacing condition. Copulatory behavior in male rats is sensitive to female availability, and females associated with greater availability are preferred. (PsycINFO Database Record (c) 2010 APA, all rights reserved)