Journals
2009 EN
Joel A. Drewry · Steven Fletcher · Peibin Yue
+8 more
We report the first application of coordination complexes as functional proteomimetics of the Src homology 2 (SH2) phosphopeptide-binding domain. As a proof-of-concept, functionalized bis-dipicolylamine (BDPA) copper(ii) complexes are shown to disrupt oncogenic Stat3-Stat3 protein complexes and elicit promising anti-tumour activity.
Royal Society of Chemistry
Journals
2009 EN
Stuart J. Williams · Aloke Kumar · Nicolas G. Green
+1 more
We demonstrate an optically induced electrokinetic technique that continuously concentrates nanoparticles on the surface of a parallel plate electrode that is biased with an AC signal. A highly focused beam of near-infrared light (1064 nm) was applied, inducing an electrothermal microfluidic vortex that carried nanoparticles to its center where they were accumulated. This technique was demonstrated with 49 nm and 100 nm fluorescent polystyrene particles and characterized as a function of applied AC frequency and voltage. With this technique the location and shape of colloidal concentration was reconfigured by controlling the optical landscape, yielding dynamic control of the aggregation. Colloidal concentration was demonstrated with a plain parallel plate electrode configuration without the need of photoconductive materials or complex microfabrication procedures.
Royal Society of Chemistry
Journals
2009 EN
Dhivyaa Alagappan · Deborah A. Lazzarino · Ryan J. Felling
+3 more
There is an increase in the numbers of neural precursors in the SVZ (subventricular zone) after moderate ischaemic injuries, but the extent of stem cell expansion and the resultant cell regeneration is modest. Therefore our studies have focused on understanding the signals that regulate these processes towards achieving a more robust amplification of the stem/progenitor cell pool. The goal of the present study was to evaluate the role of the EGFR [EGF (epidermal growth factor) receptor] in the regenerative response of the neonatal SVZ to hypoxic/ischaemic injury. We show that injury recruits quiescent cells in the SVZ to proliferate, that they divide more rapidly and that there is increased EGFR expression on both putative stem cells and progenitors. With the amplification of the precursors in the SVZ after injury there is enhanced sensitivity to EGF, but not to FGF (fibroblast growth factor)-2. EGF-dependent SVZ precursor expansion, as measured using the neurosphere assay, is lost when the EGFR is pharmacologically inhibited, and forced expression of a constitutively active EGFR is sufficient to recapitulate the exaggerated proliferation of the neural stem/progenitors that is induced by hypoxic/ischaemic brain injury. Cumulatively, our results reveal that increased EGFR signalling precedes that increase in the abundance of the putative neural stem cells and our studies implicate the EGFR as a key regulator of the expansion of SVZ precursors in response to brain injury. Thus modulating EGFR signalling represents a potential target for therapies to enhance brain repair from endogenous neural precursors following hypoxic/ischaemic and other brain injuries.
Journals
2009 EN
Steven Ball · Gilles Peltier
The complex endosymbiotic history of algal plastids has generated a high degree of diversity within their metabolic pathways. The shaping and merging of pathways from various combinations of hosts and endosymbionts is responsible for important biochemical innovations such as those exemplified by the emergence of starch metabolism. Green algae, such as Chlamydomonas reinhardtii, contain an oxygen-sensitive high-specific-activity hydrogenase that, in special circumstances, can generate molecular hydrogen directly from photosynthesis, or indirectly through the storage of photosynthetic energy in starch. The challenge now facing biochemists studying these pathways is to make use of these organisms to produce molecular hydrogen in a sustainable and efficient fashion.
Journals
2009 EN
Steven B. Rossington
This article describes the construction of a giant protein (‘Boris’) and illustrates how by making molecular models secondary school and college students can learn hands on how drug systems and proteins interact in drug therapy treatments within the human body.
Journals
2009 EN
Martin D. Rees · Steven E. Bottle · Kathryn E. FairfullSmith
+3 more
Tissue damage resulting from the extracellular production of HOCl (hypochlorous acid) by the MPO (myeloperoxidase)-hydrogen peroxide-chloride system of activated phagocytes is implicated as a key event in the progression of a number of human inflammatory diseases. Consequently, there is considerable interest in the development of therapeutically useful MPO inhibitors. Nitroxides are well established antioxidant compounds of low toxicity that can attenuate oxidative damage in animal models of inflammatory disease. They are believed to exert protective effects principally by acting as superoxide dismutase mimetics or radical scavengers. However, we show here that nitroxides can also potently inhibit MPO-mediated HOCl production, with the nitroxide 4-aminoTEMPO inhibiting HOCl production by MPO and by neutrophils with IC50 values of approx. 1 and 6 microM respectively. Structure-activity relationships were determined for a range of aliphatic and aromatic nitroxides, and inhibition of oxidative damage to two biologically-important protein targets (albumin and perlecan) are demonstrated. Inhibition was shown to involve one-electron oxidation of the nitroxides by the compound I form of MPO and accumulation of compound II. Haem destruction was also observed with some nitroxides. Inhibition of neutrophil HOCl production by nitroxides was antagonized by neutrophil-derived superoxide, with this attributed to superoxide-mediated reduction of compound II. This effect was marginal with 4-aminoTEMPO, probably due to the efficient superoxide dismutase-mimetic activity of this nitroxide. Overall, these data indicate that nitroxides have considerable promise as therapeutic agents for the inhibition of MPO-mediated damage in inflammatory diseases.
Journals
2009 EN
Shane C. Hardin · Clayton T. Larue · ManHo Oh
+2 more
The mechanisms involved in sensing oxidative signalling molecules, such as H2O2, in plant and animal cells are not completely understood. In the present study, we tested the postulate that oxidation of Met (methionine) to MetSO (Met sulfoxide) can couple oxidative signals to changes in protein phosphorylation. We demonstrate that when a Met residue functions as a hydrophobic recognition element within a phosphorylation motif, its oxidation can strongly inhibit peptide phosphorylation in vitro. This is shown to occur with recombinant soybean CDPKs (calcium-dependent protein kinases) and human AMPK (AMP-dependent protein kinase). To determine whether this effect may occur in vivo, we monitored the phosphorylation status of Arabidopsis leaf NR (nitrate reductase) on Ser534 using modification-specific antibodies. NR was a candidate protein for this mechanism because Met538, located at the P+4 position, serves as a hydrophobic recognition element for phosphorylation of Ser534 and its oxidation substantially inhibits phosphorylation of Ser534 in vitro. Two lines of evidence suggest that Met oxidation may inhibit phosphorylation of NR-Ser534 in vivo. First, phosphorylation of NR at the Ser534 site was sensitive to exogenous H2O2 and secondly, phosphorylation in normal darkened leaves was increased by overexpression of the cytosolic MetSO-repair enzyme PMSRA3 (peptide MetSO reductase A3). These results are consistent with the notion that oxidation of surface-exposed Met residues in kinase substrate proteins, such as NR, can inhibit the phosphorylation of nearby sites and thereby couple oxidative signals to changes in protein phosphorylation.
Journals
2009 EN
Yan Qiu · Coralie HoareauAveilla · Sebastian Oltean
+2 more
Anti-angiogenic VEGF (vascular endothelial growth factor) isoforms, generated from differential splicing of exon 8, are widely expressed in normal human tissues but down-regulated in cancers and other pathologies associated with abnormal angiogenesis (cancer, diabetic retinopathy, retinal vein occlusion, the Denys-Drash syndrome and pre-eclampsia). Administration of recombinant VEGF(165)b inhibits ocular angiogenesis in mouse models of retinopathy and age-related macular degeneration, and colorectal carcinoma and metastatic melanoma. Splicing factors and their regulatory molecules alter splice site selection, such that cells can switch from the anti-angiogenic VEGF(xxx)b isoforms to the pro-angiogenic VEGF(xxx) isoforms, including SRp55 (serine/arginine protein 55), ASF/SF2 (alternative splicing factor/splicing factor 2) and SRPK (serine arginine domain protein kinase), and inhibitors of these molecules can inhibit angiogenesis in the eye, and splice site selection in cancer cells, opening up the possibility of using splicing factor inhibitors as novel anti-angiogenic therapeutics. Endogenous anti-angiogenic VEGF(xxx)b isoforms are cytoprotective for endothelial, epithelial and neuronal cells in vitro and in vivo, suggesting both an improved safety profile and an explanation for unpredicted anti-VEGF side effects. In summary, C-terminal distal splicing is a key component of VEGF biology, overlooked by the vast majority of publications in the field, and these findings require a radical revision of our understanding of VEGF biology in normal human physiology.
Journals
2009 EN
S K Steven Houston · T David Bourne · M Beatriz S Lopes
+1 more
Massive retinal gliosis (MRG) is a rare, benign intraocular condition that may develop in association with long-standing eye conditions including chronic inflammation, vascular disorders, glaucoma, trauma, or congenital abnormalities. It is thought to represent a nonneoplastic reactive tissue response to retinal injury. Here, we describe an unusual case of bilateral MRG in association with retinopathy of prematurity. To our knowledge, this may be the first report of such an occurrence. The differential diagnosis of MRG is discussed with specific emphasis on its relationship to vasoproliferative tumor of the retina and presumed acquired retinal hemangiomas. In addition, we hypothesize that MRG, vasoproliferative tumor of the retina, and presumed acquired retinal hemangiomas may represent different phenotypes along a spectrum of the same disease process.
Journals
2009 EN
Amy P. Teoh · Steven B. Chin
The phonological systems of children with cochlear implants may include segment inventories that contain both target and nontarget speech sounds. These children may not consistently follow phonological rules of the target language. These issues present a challenge for the clinical speech-language pathologist who uses phonetic transcriptions to evaluate speech production skills and to develop a plan of care. The purposes of this tutorial are to (a) identify issues associated with phonetic transcriptions of the speech of children with cochlear implants and (b) discuss implications for assessment.
American Speech–Language–Hearing Association