Micellar effects and analytical applications of nitro substitution in 4-Nitro-N-alkyl-1,8-naphthalimide by cysteine derivatives.

The aromatic nucleophilic substitution reactions of the nitro group of 4-Nitro-N-alkyl-1,8-naphthalimides by thiolate anions produce fluorescent derivatives and their rates are strongly accelerated by micelles of hexadecyltrimethylammonium chloride even at low pH. Acceleration factors of this reactions can reach million-fold. As the products are oxidant-insensible, this reaction allows the determination of SH- containing compounds such as cysteine, glutathione or proteins even in oxidative conditions. Limits of detection are as low as 5 × 10-7 M, ten times lower than the limit for the classic 5,5'-dithiobis-(2-nitrobenzoic) acid method. Moreover, this reaction can be developed at pHs between 6.5 and 7.5 thereby diminishing the rate of spontaneous oxidation of the thiols. In addition, we demonstrated that 4-Nitro-N-alkyl-1,8-naphthalimides can be used to evidence SH groups in peptides, proteins and living cells.

Where do we aspire to publish? A position paper on scientific communication in biochemistry and molecular biology.

The scientific publication landscape is changing quickly, with an enormous increase in options and models. Articles can be published in a complex variety of journals that differ in their presentation format (online-only or in-print), editorial organizations that maintain them (commercial and/or society-based), editorial handling (academic or professional editors), editorial board composition (academic or professional), payment options to cover editorial costs (open access or pay-to-read), indexation, visibility, branding, and other aspects. Additionally, online submissions of non-revised versions of manuscripts prior to seeking publication in a peer-reviewed journal (a practice known as pre-printing) are a growing trend in biological sciences. In this changing landscape, researchers in biochemistry and molecular biology must re-think their priorities in terms of scientific output dissemination. The evaluation processes and institutional funding for scientific publications should also be revised accordingly. This article presents the results of discussions within the Department of Biochemistry, University of São Paulo, on this subject.

Where do we aspire to publish? A position paper on scientific communication in biochemistry and molecular biology

The scientific publication landscape is changing quickly, with an enormous increase in options and models. Articles can be published in a complex variety of journals that differ in their presentation format (online-only or in-print), editorial organizations that maintain them (commercial and/or society-based), editorial handling (academic or professional editors), editorial board composition (academic or professional), payment options to cover editorial costs (open access or pay-to-read), indexation, visibility, branding, and other aspects. Additionally, online submissions of non-revised versions of manuscripts prior to seeking publication in a peer-reviewed journal (a practice known as pre-printing) are a growing trend in biological sciences. In this changing landscape, researchers in biochemistry and molecular biology must re-think their priorities in terms of scientific output dissemination. The evaluation processes and institutional funding for scientific publications should also be revised accordingly. This article presents the results of discussions within the Department of Biochemistry, University of São Paulo, on this subject.

Allantoin as an independent marker associated with carotid intima-media thickness in subclinical atherosclerosis.

Allantoin is the main product of uric acid oxidation and was found to be augmented in atherosclerotic plaque in human autopsy and in animal models of atherosclerosis. Uric acid is abundant in human plasma and is prone to oxidation in inflammatory conditions such as atherosclerosis. In this study, we found a significant increase in plasma uric acid (P=0.002) and allantoin (P=0.025) in participants of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) that presented common carotid intima-media thickness (c-IMT) within the 75th percentile (c-IMT≥P75). Multiple linear regression showed an association of c-IMT with uric acid (ß=0.0004, P=0.014) and allantoin (ß=0.018, P=0.008). This association was independent of age, the traditional risk factor LDL/HDL ratio, and non-traditional risk factors: pulse pressure, neck circumference, and the inflammatory marker myeloperoxidase. The independent and strong association of allantoin with c-IMT shows that it might be a useful marker, along with other traditional risk factors, to evaluate an early stage of atherosclerosis.

Allantoin as an independent marker associated with carotid intima-media thickness in subclinical atherosclerosis

Allantoin is the main product of uric acid oxidation and was found to be augmented in atherosclerotic plaque in human autopsy and in animal models of atherosclerosis. Uric acid is abundant in human plasma and is prone to oxidation in inflammatory conditions such as atherosclerosis. In this study, we found a significant increase in plasma uric acid (P=0.002) and allantoin (P=0.025) in participants of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) that presented common carotid intima-media thickness (c-IMT) within the 75th percentile (c-IMT≥P75). Multiple linear regression showed an association of c-IMT with uric acid (β=0.0004, P=0.014) and allantoin (β=0.018, P=0.008). This association was independent of age, the traditional risk factor LDL/HDL ratio, and non-traditional risk factors: pulse pressure, neck circumference, and the inflammatory marker myeloperoxidase. The independent and strong association of allantoin with c-IMT shows that it might be a useful marker, along with other traditional risk factors, to evaluate an early stage of atherosclerosis.

Inflammatory muscle pain is dependent on the activation of kinin B1 and B2 receptors and intracellular kinase pathways.

BACKGROUND AND PURPOSE: B(1) and B(2) kinin receptors are involved in pain transmission but they may have different roles in the muscle pain induced by intense exercise or inflammation. We investigated the contribution of each of these receptors, and the intracellular pathways involved, in the initial development and maintenance of the muscle pain associated with inflammation-induced tissue damage. EXPERIMENTAL APPROACH: Mechanical hyperalgesia was measured using the Randall-Selitto apparatus after injecting 5% formalin solution into the gastrocnemius muscle in mice treated with selective antagonists for B(1) or B(2) receptors. The expression of kinin receptors and cytokines and the activation of intracellular kinases were monitored by real-time PCR and immunohistochemistry. KEY RESULTS: The i.m. injection of formalin induced an overexpression of B(1) and B(2) receptors. This overexpression was associated with the mechanical hyperalgesia induced by formalin because treatment with B(1) receptor antagonists (des-Arg(9) [Leu(8)]-BK, DALBK, and SSR240612) or B(2) receptor antagonists (HOE 140 and FR173657) prevented the hyperalgesia. Formalin increased myeloperoxidase activity, and up-regulated TNF-α, IL-1ß and IL-6 in gastrocnemius. Myeloperoxidase activity and TNF-α mRNA expression were inhibited by either DALBK or HOE 140, whereas IL-6 was inhibited only by HOE 140. The hyperalgesia induced by i.m. formalin was dependent on the activation of intracellular MAPKs p38, JNK and PKC. CONCLUSIONS AND IMPLICATIONS: Inflammatory muscle pain involves a cascade of events that is dependent on the activation of PKC, p38 and JNK, and the synthesis of IL-1ß, TNF-α and IL-6 associated with the up-regulation of both B(1) and B(2) kinin receptors.

TRPA1 antagonists as potential analgesic drugs.

The necessity of safe and effective treatments for chronic pain has intensified the search for new analgesic drugs. In the last few years, members of a closely-related family of ion channels, called transient receptor potential (TRP) have been identified in different cell types and their functions in physiological and pathological conditions have been characterized. The transient receptor potential ankyrin 1 (TRPA1), originally called ANKTM1 (ankyrin-like with transmembrane domains protein 1), is a molecule that has been conserved in different species during evolution; TRPA1 is a cation channel that functions as a cellular sensor, detecting mechanical, chemical and thermal stimuli, being a component of neuronal, epithelial, blood and smooth muscle tissues. In mammals, TRPA1 is largely expressed in primary sensory neurons that mediate somatosensory processes and nociceptive transmission. Recent studies have described the role of TRPA1 in inflammatory and neuropathic pain. However, its participation in cold sensation has not been agreed in different studies. In this review, we focus on data that support the relevance of the activation and blockade of TRPA1 in pain transmission, as well as the mechanisms underlying its activation and modulation by exogenous and endogenous stimuli. We also discuss recent advances in the search for new analgesic medicines targeting the TRPA1 channel.

The selective and competitive N-methyl-D-aspartate receptor antagonist, (-)-6-phosphonomethyl-deca-hydroisoquinoline-3-carboxylic acid, prevents synaptic toxicity induced by amyloid-ß in mice.

The toxicity of amyloid ß (Aß) is highly associated with Alzheimer's disease (AD), which has a high incidence in elderly people worldwide. While the current treatment for moderate and severe AD includes blockage of the N-methyl-d-aspartate receptor (NMDAR), the molecular mechanisms of its effect are still poorly understood. Herein, we report that a single i.p. administration of the selective and competitive (NMDAR) antagonist LY235959 reduced Aß neurotoxicity by preventing the down-regulation of glial glutamate transporters (glutamate-aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1)), the decrease in glutamate uptake, and the production of reactive oxygen species (ROS) induced by Aß(1-40). Importantly, the blockage of NMDAR restored the Aß(1-40)-induced synaptic dysfunction and cognitive impairment. However, LY235959 failed to prevent the inflammatory response associated with Aß(1-40) treatment. Altogether, our data indicate that the acute administration of Aß promotes oxidative stress, a decrease in glutamate transporter expression, and neurotoxicity. Our results reinforce the idea that NMDAR plays a critical regulatory action in Aß toxicity and they provide further pre-clinical evidence for the potential role of the selective and competitive NMDAR antagonists in the treatment of AD.

Protective role of aryl and alkyl diselenides on lipid peroxidation.

The concept that selenium-containing molecules may be better nucleophiles (and therefore antioxidants) than classical antioxidants has led to the design of synthetic organoselenium compounds. In the present study we appraised the antioxidant potential, thiol peroxidase activity, and rate of dithiotreitol and reduced glutathione oxidation of simple organodiselenide compounds in rats and mice. The present results demonstrate that alkyl and aryl diselenides are antioxidant compounds. We verified that the substitution on the aromatic moiety of diphenyl diselenide or the replacement of on aryl group by an alkyl substitute on diselenides changes their antioxidant and thiol peroxidase-like properties. The diaryl diselenides (PhSe)(2) and (p-ClPhSe)(2) presented higher thiol peroxidase activity and demonstrated better antioxidant potential than the other diselenides tested. In fact, the results revealed that alkyl diselenides, at low concentrations, were prooxidants and that aryl diselenides did not present this effect. Alkyl diselenides [(C(2)H(5)Se)(2) and (C(3)H(7)Se)(2)] demonstrated a higher potential for -SH group oxidation than aryl diselenides. In addition, this study demonstrated that diselenide protection against lipid peroxidation was different in mice and rats. The compounds tested acted more as antioxidants in the brains of mice than in the brains of rats.

Potential renal and hepatic toxicity of diphenyl diselenide, diphenyl ditelluride and Ebselen for rats and mice.

The occupational importance of tellurium and selenium is growing rapidly, but the biochemistry of exposure is poorly understood. Here we report the potential toxic effects of diphenyl diselenide (PhSe)(2), diphenyl ditelluride (PhTe)(2) and Ebselen in rats and mice. The results suggest that (PhTe)(2) is more toxic in rats than mice. (PhSe)(2), (PhTe)(2) and Ebselen are more toxic by intraperitoneal (i.p.) than subcutaneous (s.c.) route. Calculated LD(50) for (PhTe)(2), i.p., was 0.65 micromol/kg in rats and 150 micromol/kg in mice, and LD(50), s.c., was 0.9 micromol/kg in rats and >500 micromol/kg in mice. Calculated LD(50) for Ebselen, i.p., was 400 micromol/kg in rats and 340 micromol/kg in mice and LD(50), s.c., was >500 micromol/kg in both mice and rats. (PhTe)(2) at small doses increased 2-fold serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in rats. LD(50) for all organochalcogens administrated in mice inhibited blood delta-ALA-D activity. The present study provides evidence for liver and renal toxicity of (PhTe)(2).

Investigations into the potential neurotoxicity induced by diselenides in mice and rats.

It is well known that selenium is highly toxic to several species of mammals. Here we report the potential neurotoxicity of diselenides, as measured by the manifestation of seizures. The modulation of various neurotransmitter systems potentially involved in seizure episodes and death was also evaluated. The results of the present investigation suggest that toxicity of diselenides depends on the route of administration as well the species (rats or mice). These data show that modulation of more than one neuronal system can account for diselenide-induced seizures in mice. Additionally, changes in structure of diselenides, such as to introduce a functional group, influence the appearance of seizure episode. Conversely, all allosteric modulators tested did not protect dipropyl diselenide-induced seizures, indicating that aliphatic is more toxic than aromatic diselenides. Acute treatment with dipropyl diselenide inhibited [3H]-glutamate uptake to the crude synaptosomes. In contrast animals injected with diphenyl diselenide did not inhibit [3H]-glutamate uptake.