Synthesis, structure, theoretical and experimental in vitro antioxidant/pharmacological properties of α-aryl, N-alkyl nitrones, as potential agents for the treatment of cerebral ischemia

The synthesis, structure, theoretical and experimental in vitro antioxidant properties using the DPPH, ORAC, and benzoic acid, as well as preliminary in vitro pharmacological activities of (Z)-??-aryl and heteroaryl N-alkyl-nitrones 6-15, 18, 19, 21, and 23, is reported. In the in vitro antioxidant activity, for the DPPH radical test, only nitrones bearing free phenol groups gave the best RSA (%) values, nitrones 13 and 14 showing the highest values in this assay. In the ORAC analysis, the most potent radical scavenger was nitrone indole 21, followed by the N-benzyl benzene-type nitrones 10 and 15. Interestingly enough, the archetypal nitrone 7 (PBN) gave a low RSA value (1.4%) in the DPPH test, or was inactive in the ORAC assay. Concerning the ability to scavenge the hydroxyl radical, all the nitrones studied proved active in this experiment, showing high values in the 94-97% range, the most potent being nitrone 14. The theoretical calculations for the prediction of the antioxidant power, and the potential of ionization confirm that nitrones 9 and 10 are among the best compounds in electron transfer processes, a result that is also in good agreement with the experimental values in the DPPH assay. The calculated energy values for the reaction of ROS (hydroxyl, peroxyl) with the nitrones predict that the most favourable adduct-spin will take place between nitrones 9, 10, and 21, a fact that would be in agreement with their experimentally observed scavenger ability. The in vitro pharmacological analysis showed that the neuroprotective profile of the target molecules was in general low, with values ranging from 0% to 18.7%, in human neuroblastoma cells stressed with a mixture of rotenone/oligomycin-A, being nitrones 18, and 6-8 the most potent, as they show values in the range 24-18.4%.     

pH sensing in living cells using fluorescent microspheres

Intracellular pH in living cells is measured in real time at the single cell level using fluorescently covalently loaded microspheres as efficient carrier systems and stable sensors. The use of these sensors immobilized covalently onto polymeric particles allows analysis of intracellular pH flux over long period of time and eliminates the disadvantages such as dilution within the cell, elimination via leakage or compartmentalization.     

CD154: the atherosclerotic risk factor in rheumatoid arthritis?

Atherosclerosis, now regarded as a chronic inflammatory disease of the arterial wall, and its clinical manifestations have increasingly been associated with rheumatoid arthritis (RA), supporting the notion that autoimmune diseases and vascular disorders share common etiological features. Indeed, evidence pertaining to this matter indicates that inflammation and its multiple components are the driving force behind the pathogenesis of these disorders. Interestingly, CD154 and its receptors have emerged as major players in the development of RA and atherosclerosis, which raises the possibility that this axis may represent an important biological link between both complications. Indeed, CD154 signaling elicits critical inflammatory responses that are common to the pathogenesis of both diseases. Here, we provide an overview of the traditional and disease-related interrelations between RA and vascular abnormalities, while focusing on CD154 as a potential mediator in the development of atherosclerotic events in RA patients.     

Microvessel vascular smooth muscle cells contribute to collagen type I deposition through ERK1/2 MAP kinase, alphavbeta3-integrin, and TGF-beta1 in response to ANG II and high glucose

This study determines that vascular smooth muscle cell (VSMC) signaling through extracellular signal-regulated kinase (ERK) 1/2-mitogen-activated protein (MAP) kinase, alphavbeta(3)-integrin, and transforming growth factor (TGF)-beta1 dictates collagen type I network induction in mesenteric resistance arteries (MRA) from type 1 diabetic (streptozotocin) or hypertensive (HT; ANG II) mice. Isolated MRA were subjected to a pressure-passive-diameter relationship. To delineate cell types and mechanisms, cultured VSMC were prepared from MRA and stimulated with ANG II (100 nM) and high glucose (HG, 22 mM). Pressure-passive-diameter relationship reduction was associated with increased collagen type I deposition in MRA from HT and diabetic mice compared with control. Treatment of HT and diabetic mice with neutralizing TGF-beta1 antibody reduced MRA stiffness and collagen type I deposition. Cultured VSMC stimulated with HG or ANG II for 5 min increased ERK1/2-MAP kinase phosphorylation, whereas a 48-h stimulation induced latent TGF-beta1, alphavbeta(3)-integrin, and collagen type 1 release in the conditioned media. TGF-beta1 bioactivity and Smad2 phosphorylation were alphavbeta(3)-integrin-dependent, since beta(3)-integrin antibody and alphavbeta(3)-integrin inhibitor (SB-223245, 10 microM) significantly prevented TGF-beta1 bioactivity and Smad2 phosphorylation. Pretreatment of VSMC with ERK1/2-MAP kinase inhibitor (U-0126, 1 microM) reduced alphavbeta(3)-integrin, TGF-beta1, and collagen type 1 content. Additionally, alphavbeta(3)-integrin antibody, SB-223245, TGF-beta1-small-intefering RNA (siRNA), and Smad2-siRNA (40 nM) prevented collagen type I network formation in response to ANG II and HG. Together, these data provide evidence that resistance artery fibrosis in type 1 diabetes and hypertension is a consequence of abnormal collagen type I release by VSMC and involves ERK1/2, alphavbeta(3)-integrin, and TGF-beta1 signaling. This pathway could be a potential target for overcoming small artery complications in diabetes and hypertension.     

Catalase and Lipid Peroxidation Values in Serum of Tunisian Patients with Pemphigus Vulgaris and Foliaceus

Pemphigus is an autoimmune disorder resulting from the interaction between autoantibodies and desmoglein. Oxidative stress seems to be responsible for the onset/aggravation of many human diseases. Actually, it is considered as one of the several factors for the etiopathogenesis of pemphigus. The present study aims to evaluate the oxidative state in the sera of pemphigus vulgaris and pemphigus foliaceus patients by assessing lipid peroxidation, proteins oxidation, and antioxidant enzyme activity. This study included 36 pemphigus vulgaris and 42 pemphigus foliaceus patients as well as a group of controls consisting of 78 healthy volunteers. Malondialdehyde levels (p?<?0.001) and catalase activity (p?<?0.001) are higher in both groups of patients than in the control group. The two groups of patients showed a nonsignificant decrease in the thiol groups compared with the healthy one. A nonsignificant difference was shown between pemphigus vulgaris and pemphigus foliaceus patients, except for the catalase which shows an increase in the pemphigus vulgaris group. We have also found significant correlations between serum oxidative stress marker levels and serum anti-desmoglein antibody levels in the two pemphigus groups. These findings underline the implication of oxidative stress in the physiopathology of pemphigus by the increase in the autoantibodies?? reactivity.     

ALIX Is Recruited Temporarily into HIV-1 Budding Sites at the End of Gag Assembly

Polymerization of Gag on the inner leaflet of the plasma membrane drives the assembly of Human Immunodeficiency Virus 1 (HIV-1). Gag recruits components of the endosomal sorting complexes required for transport (ESCRT) to facilitate membrane fission and virion release. ESCRT assembly is initiated by recruitment of ALIX and TSG101/ESCRT-I, which bind directly to the viral Gag protein and then recruit the downstream ESCRT-III and VPS4 factors to complete the budding process. In contrast to previous models, we show that ALIX is recruited transiently at the end of Gag assembly, and that most ALIX molecules are recycled into the cytosol as the virus buds, although a subset remains within the virion. Our experiments imply that ALIX is recruited to the neck of the assembling virion and is mostly recycled after virion release.     

Synthesis and biological evaluation of 3,6-diamino-1H-pyrazolo[3,4-b]pyridine derivatives as protein kinase inhibitors

The synthesis and biological evaluation of a number of differently substituted 3,6-diamino-1H-pyrazolo[3,4-b]pyridine derivatives are reported. From the inhibition results on a selection of disease-relevant protein kinases [IC₅₀ (μM) DYRK1A = 11; CDK5 = 0.41; GSK-3 = 1.5] we have observed that 3,6-diamino-4-phenyl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (4) constitutes a potential new and simple lead compound in the search of drugs for the treatment of Alzheimer’s disease.     

Design and synthesis of acyclic nucleoside analogs with chlorinated imidazo[1,2-a]pyridine bases

A series of acyclic C-nucleoside analogs of 2,6-dichloro- and 2,6,7-trichloroimidazo[1,2-a]pyridine were synthesized and tested for antiviral activity. The appropriate hydroxymethyl-substituted heterocycles were treated successively with thionyl chloride, an appropriate nucleophile, then diisopropylethylamine to obtain the desired acyclic nucleoside analogs. These compounds were evaluated for activity against human cytomegalovirus and herpes simplex virus, type 1. Two of the dichloro analogs, but none of the trichloro analogs demonstrated slight antiviral activity (IC50's = 20-45 microM) at non-cytotoxic concentrations.     

Cdk1/cyclin B1 controls Fas-mediated apoptosis by regulating caspase-8 activity

Caspase activation is a hallmark of apoptosis. However, the molecular mechanisms underlying the regulation of caspase-8 activation within the extrinsic death pathway are not well understood. In this study, we demonstrate that procaspase-8 is phosphorylated in mitotic cells by Cdk1/cyclin B1 on Ser-387, which is located at the N terminus of the catalytic subunit p10. This phosphorylation of procaspase-8 on Ser-387 occurs in cancer cell lines, as well as in primary breast tissues and lymphocytes. Furthermore, RNA interference-mediated silencing of cyclin B1 or treatment with the Cdk1 inhibitor RO-3306 enhances the Fas-mediated activation and processing of procaspase-8 in mitotic cells. A nonphosphorylatable procaspase-8 (S387A) facilitates Fas-induced apoptosis during mitosis. Our findings suggest that Cdk1/cyclin B1 activity shields human cells against extrinsic death stimuli and unravel the molecular details of the cross talk between cell cycle and extrinsic apoptotic pathways. Finally, this new mechanism may also contribute to tumorigenesis.