The eco‐friendly biosynthesis of silver nanoparticles (AgNPs), using starch as reducing agent, was addressed in this work. Starch solutions with three different concentrations (0.5, 1.0, and 1.5% w/v), heated at 90°C for 12 h and stabilized with 100 µL of NaOH 0.1 M were used during the synthesis process. AgNPs were characterized by UV–visible (UV–Vis) spectrophotometry, SEM equipped with energy dispersive spectrometer and TEM. The antibacterial activity of the AgNPs was evaluated on Staphylococcus aureus using the disc diffusion technique (Kirby–Bauer method) relative to enrofloxacin antibiotic. Solutions containing AgNPs developed a yellow color and presented UV–Vis spectra characteristic for AgNPs, with surface plasmon resonance peaks between 411 and 414 nm. Spherical‐shape AgNPs were observed by TEM with sizes between 10 and 30 nm. These silver nanoparticles displayed an antimicrobial activity against S. aureus in colloidal state and films.

This research presents a noninvasive method for the acquisition of brain electrical signal in rat. Was used an electroencephalography (EEG) system developed for bovine and adapted to rats. The bipolar electrode system (needle electrodes (0,

No abstract

FERRARI, R. Effects of indole-3-acetic acid (IAA) administration on metabolism parameters and electro encephalic on rats. 2008 107f. Thesis (Doctorate)

Tryptophan is an essential amino acid precursor of neurotransmitter serotonin and triptamine. During its metabolism, indole-3-acetic acid (IAA) is generated; this substance presents both antioxidant and prooxidant effects in different biological systems in addition to hipoglicemic effects. To date, electroencephalography (EEG) has been used to evaluate the temporal effect of several substances in neurotransmission. The goal of this study was to characterize the effect of IAA in the brain by analysing the EEG signal and evaluate the oxidative status by means of biochemical parameters. The EEG was acquired by using a noninvasive method, and the brain electric signal was analysed by advanced digital signal processing techniques to determinate the energy signal filtered in different band frequencies. Furthermore, the oxidative status of the brain was investigated by measuring the activity of antioxidant enzymes and lipid peroxidation as well as blood glucose rates of the animals treated with different doses of IAA. Our results showed the relationship of IAA administration with changes in EEG signals. The oxidative status of the brain was modified by IAA after 14 days of treatment.

Guanidine has been used with some success to treat myasthenia gravis and myasthenic syndrome because it increases acetylcholine release at nerve terminals through K+, Na+ and Ca2+ channels-involving mechanisms. Currently, guanidine derivatives have been proposed for treatment of several diseases. Studies aimed at providing new insights to the drug are relevant. Experimentally, guanidine (10 mM) induces on mouse phrenic nerve-diaphragm (PND) preparations neurotransmission facilitation followed by blockade and a greatest secondary facilitation after its removal from bath. Herein, we hypothesized that this peculiar triphasic response may differ in muscles with distinct twitch/metabolic characteristics. Morphological alterations and contractile response of PND, extensor digitorum longus (EDL) and soleus (SOL) preparations incubated with guanidine (10 mM) for 15, 30, 60 min were analyzed. Guanidine concentrations of 5 mM (for PND and EDL) and 1 mM (for EDL) were also tested. Guanidine triphasic effect was only observed on PND regardless the concentration. The morphological alterations in muscle tissue varied along time but did not impede the PND post-wash facilitation. Higher doses (20–25 mM) did not increase EDL or SOL neurotransmission. The data suggest a complex mechanism likely dependent on the metabolic/contractile muscle phenotype; muscle fiber types and density/type of ion channels, sarcoplasmic reticulum and mitochondria organization may have profound impact on the levels and isoform expression pattern of Ca2+ regulatory membrane proteins so reflecting regulation of calcium handling and contractile response in different types of muscle.