Undersulfated, low-molecular-weight glycol-split heparin as an antiangiogenic VEGF antagonist

Vascular endothelial growth factor (VEGF) represents a target for antiangiogenic therapies in a wide spectrum of diseases, including cancer. As a novel strategy to generate nonanticoagulant antiangiogenic substances exploiting binding to VEGF while preventing receptor engagement, we assessed the VEGF-antagonist activity of a low-molecular-weight (LMW) compound (ST2184, Mw = 5800) generated by depolymerization of an undersulfated glycol-split heparin derivative. The parental compound was obtained by introducing regular sulfation gaps along the prevalently N-sulfated heparin regions, followed by glycol-splitting of all nonsulfated uronic acid residues (approximately 50% of total uronic acid residues). ST2184 was endowed with a negligible anticoagulant activity after S.C. injection in mice. ST2184 binds VEGF165 as evaluated by its capacity to retard 125I-VEGF165 electrophoretic migration in a gel mobility shift assay and to prevent VEGF165 interaction with heparin immobilized onto a BIAcore sensor chip. Unlike heparin, ST2184 was unable to present 125I-VEGF165 to its high-affinity receptors in endothelial cells and inhibited VEGF165-induced neovascularization in the chick embryo chorioallantoic membrane. Undersulfated, LMW glycol-split heparins may therefore provide the basis for the design of novel nonanticoagulant angiostatic compounds.     

Water soluble prodrug of a COX-2 selective inhibitor suitable for intravenous administration in models of cerebral ischemia

A water soluble choline prodrug (17) of a COX-2 selective inhibitor (16) suitable for intravenous dosing in models of cerebral ischemia has been developed. Constant infusion studies using 17 demonstrate that extrapolated brain levels of 16 may be maintained for over 24h in rats.     

Shared and non-shared antigens from three different extracts of the metacestode of Echinococcus granulosus

Hydatid cyst fluid (HCF), somatic antigens (S-Ag) and excretory-secretory products (ES-Ag) of Echinococcus granulosus protoscoleces are used as the main antigenic sources for immunodiagnosis of human and dog echinococcosis. In order to determine their non-shared as well as their shared antigenic components, these extracts were studied by ELISA-inhibition and immunoblot-inhibition. Assays were carried out using homologous rabbit polyclonal antisera, human sera from individuals with surgically confirmed hydatidosis, and sera from dogs naturally infected with E. granulosus. High levels of cross-reactivity were observed for all antigenic extracts, but especially for ES-Ag and S-Ag. Canine antibodies evidenced lesser avidity for their specific antigens than antibodies from human origin. The major antigenic components shared by HCF, S-Ag, and ES-Ag have apparent molecular masses of 4-6, 20-24, 52, 80, and 100-104 kDa, including doublets of 41/45, 54/57, and 65/68 kDa. Non-shared polypeptides of each antigenic extract of E. granulosus were identified, having apparent masses of 108 and 78 kDa for HCF, of 124, 94, 83, and 75 kDa for S-Ag, and of 89, 66, 42, 39, 37, and 35 kDa for ES-Ag.     

Environmental temperature controls Cryptosporidium oocyst metabolic rate and associated retention of infectivity

Cryptosporidium is a significant cause of water-borne enteric disease throughout the world and represents a challenge to the water industry and a threat to public health. In this study we report the use of a cell culture-TaqMan PCR assay to measure oocyst inactivation rates in reagent-grade and environmental waters over a range of temperatures. While oocysts incubated at 4 degrees C and 15 degrees C remained infective over the 12-week holding period, we observed a 4 log(10) reduction in infectivity for both 20 and 25 degrees C incubation treatments at 12 and 8 weeks, respectively, for all water types examined, a faster rate of inactivation for oocysts than previously reported. This temperature-dependent inactivation was further investigated using a simple and rapid ATP assay described herein. Time course experiments performed in reagent-grade water at incubation temperatures of 4, 15, 20, 25, 30, and 37 degrees C identified a close relationship between oocyst infectivity and oocyst ATP content, demonstrating that temperature inactivation at higher temperatures is a function of increased oocyst metabolic activity. While water quality did not affect oocyst inactivation, biological antagonism appears to be a key factor affecting oocyst removal from environmental waters. Both the cell culture-TaqMan PCR assay and the ATP assay provide a sensitive and quantitative method for the determination of environmental oocyst inactivation, providing an alternative to the more costly and time-consuming mouse infection assay. The findings presented here relating temperature to oocyst inactivation provide valuable information for determining the relative risks associated with Cryptosporidium oocysts in water.     

Hyposmolarity-induced ErbB4 phosphorylation and its influence on the non-receptor tyrosine kinase network response in cultured cerebellar granule neurons

Exposure of cultured cerebellar granule neurons (24 h serum-starved) during 3 min to 30% hyposmotic medium activated the tyrosine kinase receptor ErbB4 in the absence of its ligand. Hyposmolarity also activated the non-receptor tyrosine kinases, Src, focal adhesion kinase (FAK), extracellular signal-regulated protein kinase (ERK)1/2, and the tyrosine kinase target phosphatidyl-inositol-3-kinase (PI3K). The hyposmotic-induced activation of these kinases required the prior phosphorylation of ErbB4 as shown by the effect of ErbB4 blockade with AG213 reducing by 85-95% the phosphorylation of FAK and ERK1/2, by 74% and 36% that of PI3K and Src, respectively. These results suggest a key role of ErbB4 as a signal integrator of events associated with hyposmolarity. PI3K seems to be an important connecting element in the signaling network evoked by the hyposmolarity/ErbB4 activation as: (i) the p85 regulatory subunit of PI3K co-immunoprecipitates with ErbB4 and with FAK; (ii) PI3K blockade with wortmannin reduced the hyposmotic activation of FAK (90%) and ERK1/2 (84-91%). Inhibition of Src with PP2 reduced ErbB4 phosphorylation and inhibited the subsequent cytosolic kinase activation with the same potency as ErbB4 blockade. These results point to Src and ErbB4 and as early targets of the hyposmotic stimulus and osmosignaling. The functional significance for cell volume regulation of the ErbB4-Src-PI3K signaling cascade is indicated by the 48-66% decrease of the hyposmotic taurine efflux observed by inhibition of these kinases.     

Molecular cloning and functional expression in bacteria of the potassium transporters CnHAK1 and CnHAK2 of the seagrass Cymodocea nodosa

The cDNAs CnHAK1 and CnHAK2, encoding K⁺ transporters, were amplified from the leaves of the seagrass Cymodocea nodosa. None of these transporters suppressed the K⁺ deficiency of a Saccharomyces cerevisiae mutant, but both suppressed the equivalent defect of an Escherichia coli mutant. Overexpression of the transporter CnHAK1, but not CnHAK2, mediated very rapid K⁺ or Rb⁺ influxes in the E. coli mutant. The concentration dependence of these influxes demonstrated that CnHAK1 is a low-affinity K⁺ transporter, which does not discriminate between K⁺ and Rb⁺. CnHAK1 expressed in E. coli worked in reverse when the external K⁺ concentrations were low, and we established the condition of a simple functional test of K⁺ loss for transporters of the Kup-HAK family. In comparison with its homologue barley transporter HvHAK2, CnHAK1 was insensitive to Na⁺.     

Synthesis and cytotoxic activity of pyridazino[1',6':1,2]pyrido[3,4-b]indol-5-inium derivatives as anti-cancer agents

Several new pyridazino[1',6':1,2]pyrido[3,4-b]indol-5-inium derivatives were synthesised from beta-carboline derivatives and their cytotoxic activity and effect on the cell cycle were evaluated against L1210 cancer cells.     

Carotenoids as protective response against oxidative damage in Dunaliella bardawil

In the present work the relation between carotenoids production and cell response mechanisms to oxidative damage was studied. High light intensity and nitrogen starvation, both conditions, which may increase the oxidative damage in microalgae, significantly increased total carotenoids content in Dunaliella bardawil, the effect of N-starvation being more noticeable when acting synergetically with light on carotenoid production. S-starvation stimulated carotenoids production as much as N-starvation. The use of norflurazon, inhibitor of phytoene desaturase that blocks formation of epsilon-carotene from phytoene, caused a decrease of carotenoid content down to 5% that of the control cells incubated without the inhibitor. The decrease in the oxygen consumption rate of D. bardawil cells exposed to norflurazon suggests a connection between carotenoids desaturation and chloroplastic oxygen species dissipation processes reported in the literature for other algae. It is an indication of the carotenoids involvement in chloroplastic response mechanisms to oxidative damage.     

Molecular cloning and characterization of a sodium-pump ATPase of the moss Physcomitrella patens

Physcomitrella patens grew slowly at 600 mm Na+, pH 6.0, affected by the low water potential but without signs of suffering Na+ toxicity. At pH 8.0, tolerance seemed to be lower but it grew at 200 mm Na+, again without signs of Na+ toxicity. The resistance of Physcomitrella cells to the toxic effects of Na+ can be accounted for by their capacity to keep high K+:Na+ ratios and to extrude Na+ by a system that is not dependent on DeltapH. Physcomitrella expresses two P-type ATPases similar in sequence to fungal ENA-type Na+-ATPases. A functional study in yeast demonstrated that one of these ATPases, PpENA1, is an Na+-pump. We also found that P. patens has a plant-type SOS1 Na+/H+ antiporter. We discuss that Na+-ATPases existed in early land plants but that they were lost during the evolution of bryophytes to flowering plants.