Extreme stretching of high G:D ratio carbon nanotube fibers using super-acid

Few-wall carbon nanotube (CNT) textiles with unparalleled graphitic perfection and a solitary, prominent radial breathing mode (RBM) associated with metallic chirality have been mechanically stretched in chlorosulfonic acid (CSA) to a degree so far unseen in CNT textiles (150–250% of original length) with notably little tension required. This dramatically enhanced their microstructural alignment and density and, after most of the residual CSA was removed by a vacuum bake, the de-doped fiber's electrical conductivity was found to be 45% greater than single-crystal graphite – a significant milestone for CNT conductor development towards graphitic intercalation compounds (GICs) and traditional metals. Correlation tables and validated, multivariate statistical models show that conductivity is overwhelmingly linked to stretching degree, although eventually saturates near single-crystal graphite levels, implying the existence of a maximum undoped conductivity. The degree of stretching within CSA is correlated with the original mechanical properties (tenacity, elongation-to-break, and linear density); the Raman G’:G ratio and the upper-end oxidation temperature in thermogravimetric analysis also predict the best results. Less graphenically pristine CNT materials stretch to a lower degree in CSA, similar to previous reports. This study highlights the importance of post-synthesis processing to achieve superior performance in carbon nanotube textile materials

Parte A: Divide et impera: tramite uno screening in silico che targhetta l'omodimerizzazione del fattore di processività di HCMV, ppUL44, sono state identificate piccole molecole inibenti la replicazione virale. ParteB: Identificazione del proteoma nucleare di tutti i virus umani tramite un'analisi completa della localizzazione nucleare classica.

Human cytomegalovirus (HCMV) è un agente patogeno principale di molte malattie in persone immunosoppresse, inclusi pazienti affetti da AIDS e sottoposti a trapianto, e nascituri congenitamente infetti. Le terapie ed i farmaci antivirali utilizzati per il trattamento dell’infezioni da HCMV presentano una serie di limitazioni, tra cui la bassa biodisponibilità, tossicità, e l’insorgenza di ceppi virali farmaco resistenti, rendendo cruciale la necessità di identificare nuovi target terapeutici efficaci. Studi sulle interazioni tra proteine virali (PPI) si sono rivelati alleati importanti per lo sviluppo di nuovi farmaci antivirali, in quanto questi ultimi possono inibire il ciclo vitale del virus interferendo con le attività delle proteine virali. La dimerizzazione del fattore di processività della DNA polimerasi, ppUL44, di HCMV è essenziale per il ciclo vitale del virus infatti necessaria per la replicazione del DNA virale mediata da oriLyt e può essere quindi considerata come un potenziale target terapeutico. Pertanto, in precedenza, tramite uno screening in silico sono state identificate 18 piccole molecole (Small Molecules, SMs) potenzialmente capaci di interferire con la omodimerizazzione di ppUL44. Saggi antivirali delle 18 SMs sul virus ricombinante . In questo lavoro sono riuscita a caratterizzare l’effetto di questi composti sulla viabilità e crescita cellulare, e quindi cominciare un’analisi preliminare del loro meccanismo di azione. Tutte hanno compromesso la replicazione dei virus reporter AD169 di HCMV ed una sua controparte resistente al GCV in maniera simile. Tra le 4 SMs scelte, B3, ha mostrato il Selectivity Index (SI) più alto e quindi l’unico composto ad essere ulteriormente analizzato. Siamo riusciti a dimostrare che B3 efficientemente inibisce lo strain virale AD169 di HCMV in saggi di Plaque Reduction (PRA). Come misurato tramite qPCR, B3 ha specificatamente inibito la sintesi del DNA virale a partire da 72 ore post infezione, come anche l’espressiIl nostro Gruppo di ricerca ha precedentemente identificato il proteoma nucleare di tutti i virus infettanti l’essere umano, distinguendo tra proteine virali che traslocano all’interno del nucleo della cellula infetta in modo IMPα/β1 dipendente o meno, combinando analisi bioinformatiche estese anche alla caratterizzazione funzionale delle sequenze di localizzazione nucleare (NLS) virali. Questo studio presenta l’opportunità senza precedenti di comparare la diversa interazione tra virus differenti con l’apparato di trasporto al nucleo della cellula infetta, con importanti implicazioni sullo sviluppo di nuovi target terapeutici antivirali a largo spettro. Una profonda analisi funzionale sui classici NLS (cNLS) putative identificati ci ha portato alla scoperta di più di 500 proteine codificanti cNLS. Siamo riusciti anche a fare una prima caratterizzazione del processo di import nucleare delle proteine Large T antigen (LTA) dei Polyomavirus (HPyV) e delle cNLS coinvolte. Nonostante i LT di 14 HPyV presentavano cNLS funzionali, queste erano molto diverse tra di loro sia in termini di struttura che di attività. Le attività delle cNLS hanno riflesso I livelli di accumulo nucleare delle proteine full-length, con l’attività più bassa associata alla cNLS di HPyV7. Nonostante molti HPyV codificano per una o più cNLS monopartite, 4 di esse presentavano cNLS bipartita. Chiaramente queste differenze strutturali influenzano affinità verso l’apparato IMPα/β1 dipendente ed il tropismo del virus. Inoltre, 2 tra le 26 cNLS con il punteggio di cNLS mapper più alto identificate con i nostri studi, sono altamente conservate e presentano vari ortologhi di due proteine, A19 e N2, della famiglia dei Poxivirdae. Entrambe le proteine localizzano nel nucleo della cellula ospite, in un pathway attivo IMPα/β1 dipendente, e la loro traslocazione nucleare viene inibita in presenza di mutazioni sito-specifico.  Human cytomegalovirus (HCMV) is a leading cause of severe diseases in immunocompromised individuals, including AIDS patients and transplant recipients, and in congenitally infected newborns. The utility of available drugs is limited by poor bioavailability, toxicity, and emergence of resistant strains. Therefore, it is crucial to identify new targets for therapeutic intervention. Among the latter, viral protein–protein interactions are becoming increasingly attractive. Since dimerization of HCMV DNA polymerase processivity factor ppUL44 plays an essential role in the viral life cycle, being required for oriLyt-dependent DNA replication, it can be considered a potential therapeutic target. We therefore previously performed an in silico screening and selected 18 small molecules (SMs) potentially interfering with ppUL44 homodimerization. Antiviral assays using recombinant HCMV TB4-UL83-YFP in the presence of the selected SMs led to the identification of four active compounds. In this work I have characterized the effect of such compounds on cell viability and growth and began a preliminary analysis of their mode of action. All of them impaired replication of an AD169-GFP reporter virus and its ganciclovir-resistant counterpart to a similar extend. Among the 4 selected SMs compound B3 exhibited the highest selectivity index (SI) and was further investigated. We could show that it also efficiently inhibited HCMV AD169 strain in plaque reduction assays (PRAs). As assessed by qPCR by Western blotting experiments, B3 specifically reduced viral DNA synthesis starting from 72 h post infection, consistent with the inhibition of viral gene expression starting from 48 h post infection by Western blotting experiments. Therefore, our data suggest that inhibition of ppUL44 dimerization could represent a new class of HCMV inhibitors, complementary to those targeting the DNA polymerase catalytic subunit or the viral terminase complex. Our research group previously defined the nuclear proteome of all human viruses, discriminating between viral proteins translocated in an IMPα/β1 dependent or independent process by combining bioinformatics analysis with extensive functional characterization of viral cNLSs. This study represents an unprecedented opportunity to compare how viruses differently interact with the host cell nuclear transport machinery, with important implications for the development of broad-range host targeted antivirals. In depth functional validation of identified putative classical nuclear localization signals (cNLSs) led to the discovery of more than 500 novel viral cNLS. We also report the first characterization of the nuclear import process of Human Polyomaviruses (HPyVs) Large T antigens (LT) as well as of the cNLS involved. Although LT from all 14 HPyVs bear a functional cNLS, the latter are extremely heterogenous, both in terms of activity and structural organization. Importantly, cNLS activity mirrored the levels of nuclear accumulation of full-length proteins, with lowest activity associated to HPyV7. Surprisingly, while most HPyVs bear one or more monopartite cNLS, four of them bear a bipartite cNLS. Clearly, such structural differences suggest an important role in conferring binding abilities to specific IMPα isoforms with potential implication for viral tropism determination. Furthermore, among the 26 top ranked cNLS based on cNLS mapper score, two extremely well conserved cNLS in orthologues of Vaccinia Virus proteins A19 and N2 were identified. Both proteins localized in the cell nucleus via energy and IMPα/β-dependent process, and their nuclear import could be abolished by site specific mutagenesis of the cNLSs, thus A19 and N2 mutant derivatives failed to localize in the nucleus

Regulation of Glut-4 Expression in Skeletal Muscle cells: The Roles of Nuclear Respiratory Factor-1 and calcium/calmodulin dependent protein Kinase

GLUT4 protein is the major glucose transporter in skeletal muscle and is vital in the maintenance of euglycemia (17; 108). Underexpression of GLUT4 or impairement of its translocation from intracellular compartments to the cell surface, are linked to diminished glucose transport, hyperglycemia and type II diabetes (59; 61; 153). Type II diabetes can be alleviated by increasing GLUT4 expression (223). Previous reports have shown that overexpression of NRF-1 and activation of CaMKII increases GLUT4 expression but the mechanisms involved have not be characterized (10; 173). Therefore, the objective of this thesis was to investigate the molecular mechanisms by which NRF-1 and CaMK II regulate GLUT4 expression in C2C12 myocytes. We engineered C2C12 cells that overexpressed NRF-1 in response to doxycycline (Dox) using a Tet-On gene expression system and assessed the effects of NRF-1 overexpression on: a) MEF2A, GLUT4 and δALAS proteins by western blot, and b) the binding of NRF-1 to mef2a and δalas genes and MEF2A to the glut4 gene, by chromatin immunoprecipitation assay (ChIP). The importance of MEF2A in NRF-1-induced increase in GLUT4 expression was investigated by silencing MEF2A expression using small interference RNA (siRNA). CaMK II was activated in wild-type C2C12 myocytes using 10 mM caffeine and was inhibited by 25 μ M KN93. Acetylation of histones in the vicinity of NRF-1 and MEF2A binding sites on the mef2a and glut4 genes, respectively, were assessed by ChIP assay. HDAC5 nuclear export was assessed by immunocytochemistry and mRNA levels by qRT-PCR. Overexpression of NRF-1 resulted in ~3-fold increases in mef2a-bound NRF-1 and glut4 -bound MEF2A at 6 h and 8 h post Dox treatment, respectively. MEF2A and GLUT4 proteins were both increased ~1.6-fold at 6 h and 18 h post Dox treatment. Silencing of MEF2A caused a marked downregulation of GLUT4 expression in NRF-1-overexpressing cells

Preclinical evaluation of a novel drug delivery system for cisplatin

The aim of this body of work was to characterise a novel cisplatin drug delivery system and to develop new tools based on biophotonic imaging that could be used to enhance studies of drug delivery in vivo. Cucurbiturils (CB) are macrocycles which are formed by acid catalysed condensation of glycoluril and formaldehyde. The internal cavity of CB[7] encapsulates a single molecule of cisplatin and the hypothesis was that encapsulation would reduce thiol degradation of the drug. Drug sensitivity studies in vitro with the cisplatin-sensitive human ovarian cancer cell line, A2780, and a cisplatin-resistant derivative, A2780/cp70, showed that the CB[7] encapsulated cisplatin retained activity but that this encapsulation drug delivery system was not able to overcome resistance to platinum. However, when these cell lines were grown as subcutaneous xenografts in nu/nu mice, the encapsulated cisplatin was able to reduce the growth of A2780/cp70 tumours which are resistant to the maximum tolerated dose of cisplatin in vivo. One possible explanation of this observation is that encapsulation might alter the pharmacokinetics of cisplatin and a method for the detection of platinum in biological samples by ICP-MS was established and validated. This assay was sufficiently sensitive to detect the low levels of platinum present in mouse plasma 24 hours after administration of either free or encapsulated cisplatin. Plasma and tissue pharmacokinetics show that encapsulation had no effect on the peak plasma concentration of cisplatin but did reduce the rate at which cisplatin was cleared from the plasma. The increased plasma AUC of cisplatin resulted in a non-selective increase in the delivery of cisplatin to both tumour and normal tissues. However, there was no apparent increase in toxicity which could be explained by the fact that encapsulation, unlike an increase in the dose of free cisplatin, had no effect on the peak plasma concentration. Subcutaneous xenografts lack critical features of human tumours. The development of more complex models for use in drug development has been limited due to lack of a method for monitoring tumour growth. Biophotonic imaging was, therefore, investigated to determine whether it is sufficiently sensitive and reproducible to be able to evaluate growth of disseminated tumours in mice. The bioluminescent signal is dependent on the metabolism of luciferin by luciferase. Subcutaneous injection of luciferin was shown to produce a consistent signal in all injected mice. The bioluminescent signal was transient but reached a maximum intensity 6 minutes after injection and remained stable for about 4 minutes which defined the window during which measurements were taken. Sensitivity was shown to be dependent on the level of expression of luciferase by the cells. Injection of commercially available HCT116Luc cells, where the luciferase gene was inserted by a lentiviral system, was shown to allow detection of 10,000 cells in the lungs of mice. This sensitivity was about 10 fold greater than was obtained by lipofectamine based gene transfection. When HCT116Luc cells were grown as subcutaneous xenografts in mice, an exponential growth pattern was easily detected by bioluminescence imaging and the reproducibility between mice was comparable to that routinely obtained by calliper measurements. Activity of encapsulated cisplatin was determined in a model of disseminated ovarian cancer. Rab25, a member of the RAS oncoprotein superfamily, is up-regulated in around 80% of ovarian cancer samples compared to normal ovarian epithelium. Rab25 contributes to tumour progression by enabling the tumour cells to invade the extracellular matrix by altering the trafficking of integrin. Transfection of Rab25 into A2780 cells results in cells that can grow in the peritoneal cavity of mice. A2780-Rab25 cells were 4 fold resistant to cisplatin in vitro which confirms a previous observation that Rab25 expression in A2780 makes them less sensitive to the induction of apoptosis in response to stress. A2780-Rab25 cells that express the luciferase gene (A2780-Rab25Luc) were injected into the peritoneal cavity of mice and growth was measured by biophotonic imaging. Exponential growth was clearly apparent at a stage at which no obvious abdominal distension was apparent. The disseminated A2780-Rab25Luc tumour xenografts were less sensitive to cisplatin than are subcutaneous xenografts of A2780. This is the first study that suggests that Rab25 over-expression results in reduced drug sensitivity in vivo. In contrast, a very significant growth inhibition was observed when mice were treated with an equivalent dose of encapsulated cisplatin regardless of whether it was administered by the intraperitoneal or subcutaneous route. These results are very encouraging since they confirm the enhanced activity of encapsulated cisplatin and also demonstrate the value of biophotonic imaging for measurement of tumour growth in vivo. Pharmacodynamic measures of drug activity in vivo in animal models are often based either on measures of surrogate tissue response or on single measures on tumour tissue removed at the end of the experiment. Biophotonic imaging in vivo allows the translation of reporter assays used in cell lines in vitro to studies of tumour response in vivo. A plasmid was prepared that links the p53 transcriptional response element to the luciferase gene and it was then transfected in to A2780 cells which express wild type p53. Stable transfectants of A2780p53Luc were treated with cisplatin, doxorubicin and paclitaxel and induction of p53 determined by bioluminescence and confirmed by Western blotting. A very low bioluminescent signal was present in untreated cells and a clear dose dependent increase in bioluminescence was seen in response to all three drugs. When A2780p53Luc cells were grown as subcutaneous xenografts the bioluminescent signal was significant in untreated tumours but was markedly increased 24 hours after treatment of the mice with cisplatin. Induction of p53 in the tumours was confirmed by immunohistochemistry and this also confirmed significant expression of p53 in untreated tumours. The possible implications of these findings for the improved delivery of cisplatin are discussed