Pilocarpine-induced status epilepticus in rats involves ischemic and excitotoxic mechanisms

The neuron loss characteristic of hippocampal sclerosis in temporal lobe epilepsy patients is thought to be the result of excitotoxic, rather than ischemic, injury. In this study, we assessed changes in vascular structure, gene expression, and the time course of neuronal degeneration in the cerebral cortex during the acute period after onset of pilocarpine-induced status epilepticus (SE). Immediately after 2 hr SE, the subgranular layers of somatosensory cortex exhibited a reduced vascular perfusion indicative of ischemia, whereas the immediately adjacent supragranular layers exhibited increased perfusion. Subgranular layers exhibited necrotic pathology, whereas the supergranular layers were characterized by a delayed (24 h after SE) degeneration apparently via programmed cell death. These results indicate that both excitotoxic and ischemic injuries occur during pilocarpine-induced SE. Both of these degenerative pathways, as well as the widespread and severe brain damage observed, should be considered when animal model-based data are compared to human pathology.     

Hyaluronan as carrier of carboranes for tumor targeting in boron neutron capture therapy

Boron neutron capture therapy (BNCT) represents a promising approach for tumor therapy. A critical requirement for BNCT is tumor targeting, a goal that is currently addressed with the development of low and high molecular weight agents capable of interacting with receptors expressed by cancer cells. Here, we describe a new bioconjugate (HApCB) composed by n-propyl carborane linked to hyaluronan (HA) via an ester linkage for a degree of substitution of approximately 30%, leading to a water-soluble derivative. The structure and main physicochemical characteristics of the new HA derivative were determined by means of Fourier transform infrared, fluorescence, and 1H, 13C, and 10B NMR analysis and are herein reported in detail. As HA is recognized by the CD44 antigen, densely populating the surface of many tumor cells, HApCB is expected to deliver boron atoms from the locally released carborane cages directly to target cells for antitumor application in BNCT. In vitro biological experiments showed that HApCB was not toxic for a variety of human tumor cells of different histotypes, specifically interacted with CD44 as the native unconjugated HA, and underwent uptake by tumor cells, leading to accumulation of amounts of boron atoms largely exceeding those required for a successful BNCT approach. Thus, HApCB may be regarded as a promising new BNCT agent for specific targeting of cancer cells overexpressing the CD44 receptor.     

An analog of BIX-01294 selectively inhibits a family of histone H3 lysine 9 Jumonji demethylases

BIX-01294 and its analogs were originally identified and subsequently designed as potent inhibitors against histone H3 lysine 9 (H3K9) methyltransferases G9a and G9a-like protein. Here, we show that BIX-01294 and its analog E67 can also inhibit H3K9 Jumonji demethylase KIAA1718 with half-maximal inhibitory concentrations in low micromolar range. Crystallographic analysis of KIAA1718 Jumonji domain in complex with E67 indicated that the benzylated six-membered piperidine ring was disordered and exposed to solvent. Removing the moiety (generating compound E67-2) has no effect on the potency against KIAA1718 but, unexpectedly, lost inhibition against G9a-like protein by a factor of 1500. Furthermore, E67 and E67-2 have no effect on the activity against histone H3 lysine 4 (H3K4) demethylase JARID1C. Thus, our study provides a new avenue for designing and improving the potency and selectivity of inhibitors against H3K9 Jumonji demethylases over H3K9 methyltransferases and H3K4 demethylases.     

Draft Genome Sequence of the Volatile Organic Compound-Producing Antarctic Bacterium Arthrobacter sp. Strain TB23, Able To Inhibit Cystic Fibrosis Pathogens Belonging to the Burkholderia cepacia Complex

Arthrobacter sp. strain TB23 was isolated from the Antarctic sponge Lissodendoryx nobilis. This bacterium is able to produce antimicrobial compounds and volatile organic compounds (VOCs) that inhibit the growth of other Antarctic bacteria and of cystic fibrosis opportunistic pathogens, respectively. Here we report the draft genome sequence of Arthrobacter sp. TB23.     

Synthesis and comparison of antiplasmodial activity of (+), (−) and racemic 7-chloro-4-(N-lupinyl)aminoquinoline

Recently the N-(?)-lupinyl-derivative of 7-chloro-4-aminoquinoline ((?)-AM-1; 7-chloro-4-{N-[(1S,9aR)(octahydro-2H-quinolizin-1-yl)methyl]amino}quinoline) showed potent in vitro and in vivo activity against both Chloroquine susceptible and resistant strains of Plasmodium falciparum. However, (?)-AM-1 is synthesized starting from (?)-lupinine, an expensive alkaloid isolated from Lupinus luteus whose worldwide production is not sufficient, at present, for large market purposes. To overcome this issue, the corresponding racemic compound, derived from synthetic (±)-lupinine was considered a cheaper alternative for the development of a novel antimalarial agent. Therefore, the racemic and the 7-chloro-4-(N-(+)-lupinyl)aminoquinoline ((±)-AM-1; (+)-AM-1) were synthesized and their in vitro antimalarial activity and cytotoxicity compared with those of (?)-AM-1. The (+)-lupinine required for the synthesis of (+)-AM-1 was obtained through a not previously described lipase catalyzed kinetic resolution of (±)-lupinine. In terms of antimalarial activity, (±)-AM1 and (+)-AM1 demonstrated very good activity in vitro against both CQ-R and CQ-S strains of P. falciparum (range IC₅₀ 16–35 nM), and low toxicity against human normal cell lines (therapeutic index >1000), comparable with that of (?)-AM1. These results confirm that the racemate (±)-AM1 could be considered as a potential antimalarial agent, ensuring a decrease of costs of synthesis compared to (?)-AM1.     

An efficient and convenient microwave-assisted chemical synthesis of (thio)xanthones with additional in vitro and in silico characterization

Xanthones and their thio-derivatives are a class of pleiotropic compounds with various reported pharmacological and biological activities. Although these activities are mainly determined in laboratory conditions, the class itself has a great potential to be utilized as promising chemical scaffold for the synthesis of new drug candidates. One of the main obstacles in utilization of these compounds was related to the difficulties in their chemical synthesis. Most of the known methods require two steps, and are limited to specific reagents not applicable to a large number of starting materials. In this paper a new and improved method for chemical synthesis of xanthones is presented. By applying a new procedure, we have successfully obtained these compounds with the desired regioselectivity in a shorter reaction time (50s) and with better yield (>80%). Finally, the preliminary in vitro screenings on different bacterial species and cytotoxicity assessment, as well as in silico activity evaluation were performed. The obtained results confirm potential pharmacological use of this class of molecules.     

The R-Ras/RIN2/Rab5 complex controls endothelial cell adhesion and morphogenesis via active integrin endocytosis and Rac signaling

During developmental and tumor angiogenesis, semaphorins regulate blood vessel navigation by signaling through plexin receptors that inhibit the R-Ras subfamily of small GTPases. R-Ras is mainly expressed in vascular cells, where it induces adhesion to the extracellular matrix (ECM) through unknown mechanisms. We identify the Ras and Rab5 interacting protein RIN2 as a key effector that in endothelial cells interacts with and mediates the pro-adhesive and -angiogenic activity of R-Ras. Both R-Ras-GTP and RIN2 localize at nascent ECM adhesion sites associated with lamellipodia. Upon binding, GTP-loaded R-Ras converts RIN2 from a Rab5 guanine nucleotide exchange factor (GEF) to an adaptor that first interacts at high affinity with Rab5-GTP to promote the selective endocytosis of ligand-bound/active β1 integrins and then causes the translocation of R-Ras to early endosomes. Here, the R-Ras/RIN2/Rab5 signaling module activates Rac1-dependent cell adhesion via TIAM1, a Rac GEF that localizes on early endosomes and is stimulated by the interaction with both Ras proteins and the vesicular lipid phosphatidylinositol 3-monophosphate. In conclusion, the ability of R-Ras-GTP to convert RIN2 from a GEF to an adaptor that preferentially binds Rab5-GTP allows the triggering of the endocytosis of ECM-bound/active β1 integrins and the ensuing funneling of R-Ras-GTP toward early endosomes to elicit the pro-adhesive and TIAM1-mediated activation of Rac1.     

Polyamines and transglutaminase activity are involved in compatible and self-incompatible pollination of Citrus grandis

Pollination of pummelo (Citrus grandis L. Osbeck) pistils has been studied in planta by adding compatible and self-incompatible (SI) pollen to the stigma surface. The pollen germination has been monitored inside the pistil by fluorescent microscopy showing SI altered morphologies with irregular depositions of callose in the tube walls, and heavy callose depositions in enlarged tips. The polyamine (PA) content as free, perchloric acid (PCA)-soluble and -insoluble fractions and transglutaminase (TGase) activity have been analyzed in order to deepen their possible involvement in the progamic phase of plant reproduction. The conjugated PAs in PCA-soluble fraction were definitely higher than the free and the PCA-insoluble forms, in both compatible and SI pollinated pistils. In pistils, pollination caused an early decrease of free PAs and increase of the bound forms. The SI pollination, showed highest values of PCA-soluble and -insoluble PAs with a maximum in concomitance with the pollen tube arrest. As TGase mediates some of the effects of PAs by covalently binding them to proteins, its activity, never checked before in Citrus, was examined with two different assays. In addition, the presence of glutamyl-PAs confirmed the enzyme assay data and excluded the possibility of a misinterpretation. The SI pollination caused an increase in TGase activity, whereas the compatible pollination caused its decrease. Similarly to bound PAs, the glutamyl-PAs and the enzyme activity peaked in the SI pollinated pistils in concomitance with the observed block of the pollen tube growth, suggesting an involvement of TGase in SI response.