The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform
Ian S. Blagbrough - One of the best experts on this subject based on the ideXlab platform.
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N ^1,N ^ 12 -Diacyl Spermines: SAR Studies on Non-viral Lipopolyamine Vectors for Plasmid DNA and siRNA Formulation
Pharmaceutical Research, 2009Co-Authors: Hassan M. Ghonaim, Ian S. BlagbroughAbstract:Purpose To study the efficiency of novel synthetic N ^1, N ^12-diacyl Spermines on DNA and siRNA binding, and to compare their transfection efficiency with viability in cell lines. Methods Five long chain N ^1, N ^12-diacyl lipopolyamines: N ^1, N ^12-[didecanoyl, dimyristoyl, dimyristoleoyl, distearoyl and dioleoyl]-1,12-diamino-4,9-diazadodecane were synthesized from the naturally occurring polyamine Spermine. Their abilities to condense DNA and to form nanoparticles were characterized. Transfection efficiencies were studied in FEK4 primary skin cells and in an immortalized cancer cell line (HtTA), and compared with N ^4, N ^9-regioisomers. Also, the abilities of these novel compounds to bind to siRNA-forming nanoparticles were studied using a RiboGreen intercalation assay, and their abilities to deliver fluorescein-tagged siRNA into cells were quantified and compared with TransIT-TKO. Results By incorporating two long aliphatic chains and varying their acylation position, length, and oxidation state in a stepwise manner, we show efficient p and siRNA formulation and delivery to primary skin and cancer cell lines. Although two C14 chains (both saturated or both mono- cis -unsaturated) were efficient transfecting agents, they were highly toxic. Conclusions N ^1, N ^12-Dioleoyl Spermine efficiently binds to and delivers pDNA and siRNA with high cell viability even in a primary skin cell line. It is a novel, efficient non-viral vector in the presence of serum.
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Design and Synthesis of N ^4,N ^9-Disubstituted Spermines for Non-viral siRNA Delivery – Structure-Activity Relationship Studies of siFection Efficiency Versus Toxicity
Pharmaceutical Research, 2009Co-Authors: Moustafa K. Soltan, Hassan M. Ghonaim, Mohamed Sadek, M. Abou Kull, Lubna Abd El-aziz, Ian S. BlagbroughAbstract:Purpose To study the effect of sequentially changing the chain length, oxidation level, and charge distribution in N ^4, N ^9-diacyl and N ^4, N ^9-dialkyl Spermines on siRNA formulation, and then to compare their lipoplex transfection efficiency in cell lines. Methods Eight N ^4, N ^9-diacyl polyamines: N ^4, N ^9-[didecanoyl, dilauroyl, dimyristoyl, dimyristoleoyl, dipalmitoyl, distearoyl, dioleoyl and diretinoyl]-1,12-diamino-4,9-diazadodecane were synthesized. Their abilities to bind to siRNA and form nanoparticles were studied using a RiboGreen intercalation assay and particle sizing. Two diamides were also reduced to afford tetraamines N ^4, N ^9-distearyl- and N ^4, N ^9-dioleyl-1,12-diamino-4,9-diazadodecane. Delivery of fluorescein-labelled Label IT® RNAi Delivery Control was studied in FEK4 primary skin cells and in an immortalized cancer cell line (HtTA), and compared with TransIT-TKO. Results The design, synthesis, and structure-activity relationship studies of a series of N ^4, N ^9-disubstituted Spermines as efficient vectors for non-viral siRNA delivery to primary skin and cancer cell lines is reported. These non-liposomal cationic lipids are promising siRNA carriers based on the naturally occurring polyamine Spermine showing that C-18 is a better chain length as shorter chains are more toxic. Conclusions N ^4, N ^9-Distearoyl Spermine and N ^4, N ^9-dioleoyl Spermine are efficient siRNA formulation and delivery vectors, even in the presence of serum, comparable to TransIT-TKO. However, four positive charges distributed as in Spermine was significantly more toxic.
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Very Long Chain N ^ 4 ,N ^ 9 -Diacyl Spermines: Non-Viral Lipopolyamine Vectors for Efficient Plasmid DNA and siRNA Delivery
Pharmaceutical Research, 2008Co-Authors: Hassan M. Ghonaim, Ian S. BlagbroughAbstract:Purpose To study the effect of increasing the chain length over C-18 and varying the oxidation level in synthesized N ^4, N ^9-diacyl Spermines on DNA and siRNA formulation, and then to compare their transfection efficiency in cell lines Methods The five novel very long chain N ^4, N ^9-diacyl polyamines: N ^4, N ^9-[diarachidoyl, diarachidonoyl, dieicosenoyl, dierucoyl and dinervonoyl]-1,12-diamino-4,9-diazadodecane were synthesized. The abilities of these novel compounds to condense DNA and to form nanoparticles were studied using ethidium bromide fluorescence quenching and nanoparticle characterization techniques. Transfection efficiency was studied in FEK4 primary skin cells and in an immortalized cancer cell line (HtTA), and compared with the non-liposomal transfection formulation Lipogen, N ^4, N ^9-dioleoyl-1,12-diamino-4,9-diazadodecane. Also, the abilities of these compounds to condense siRNA and to form nanoparticles were studied using a RiboGreen intercalation assay and their abilities to deliver siRNA into cells were studied in FEK4 and HtTA cells using fluorescein-labelled Label IT® RNAi Delivery Control, a sequenced 21-mer from Mirus. Results We show efficient pEGFP and siRNA formulation and delivery to primary skin and cancer cell lines. Conclusions Adding two C20 or C22 chains, both mono- cis -unsaturated, N ^4, N ^9-dieicosenoyl Spermine and N ^4, N ^9-dierucoyl Spermine, gave efficient siRNA delivery vectors, even in the presence of serum, comparable to TransIT-TKO and with excellent cell viability.
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Varying the Unsaturation in N^4,N^9-Dioctadecanoyl Spermines: Nonviral Lipopolyamine Vectors for More Efficient Plasmid DNA Formulation
Pharmaceutical Research, 2006Co-Authors: Osama A. A. Ahmed, Charareh Pourzand, Ian S. BlagbroughAbstract:Purpose The aim of the study is to analyze the effect of varying the degree of unsaturation in synthesized N ^4, N ^9-dioctadecanoyl Spermines on DNA condensation and then to compare their transfection efficiency in cell culture. Methods The N ^4, N ^9-di-C18 lipopolyamines—saturated (stearoyl), C9- cis - (oleoyl), and C9,12-di- cis - (linoleoyl)—were synthesized from the naturally occurring polyamine Spermine. The ability of these novel compounds to condense DNA and form nanoparticles was studied using ethidium bromide fluorescence quenching and nanoparticle characterization techniques. Transfection efficiency was studied in several primary skin cells (FEK4, FCP4, FCP5, FCP7, and FCP8) and in an immortalized cancer cell line (HtTA) and was compared with the commercially available nonliposomal transfection formulation Transfectam^® (dioctadecylamidoglycyl Spermine), which also contains two saturated C18 lipid chains. Results N ^4, N ^9-Dilinoleoyl Spermine (C18, di- cis -9,12) is efficient at circular plasmid DNA (pEGFP) condensation and gives the most effective transfection in a series of primary skin cells and cancer cell lines at low charge ratios of 5.5 (± ammonium/phosphate). Conclusions The dienoic fatty acyl Spermine conjugate N ^4, N ^9-dilinoleoyl Spermine efficiently condenses DNA and achieves the highest transfection levels among the studied lipopolyamines in cultured cells.
Kazuei Igarashi - One of the best experts on this subject based on the ideXlab platform.
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POLYAMINE-SENSITIVE MAGNESIUM TRANSPORT IN SACCHAROMYCES CEREVISIAE
Biochimica et biophysica acta, 1994Co-Authors: Takaharu Maruyama, Naoyuki Masuda, Yoshimi Kakinuma, Kazuei IgarashiAbstract:Abstract In Saccharomyces cerevisiae we found a toxic effect of polyamines, well-known metabolites important for cell proliferation; in magnesium-limited (50 μM Mg2+) synthetic medium, cell growth was severely inhibited by Spermine, spermidine and putrescine in descending order. In conjunction with a decrease in the growth rate by the addition of 0.5 mM Spermine, the internal Mg2+ content decreased and the Spermine content increased. When cell growth ceased, the Mg2+ content had finally decreased to about 40% of the value before the addition of Spermine (120–130 nmol/mg dry weight), and the Spermine content concomitantly increased 30-fold (from 1 to 30 nmol/mg dry weight); Spermine4+ apparently took the internal place of Mg2+ with a probable stoichiometry of 1:2. However, the total amount of Mg2+ retained in the cells remained constant even with the addition of Spermine, suggesting that Spermine blocks Mg2+ accumulation. In high (2 mM) Mg2+ medium, cell growth was hardly affected by polyamines, and an exchange of Spermine and Mg2+ was minimal. Energy-dependent Mg2+ uptake by whole cells was inhibited by Spermine, spermidine and putrescine in a similar manner as the growth rates. On the other hand, Mg2+ inhibited Spermine uptake. These results suggest that competition takes place between extracellular Spermine and Mg2+ for their accumulations. It is thus clear that polyamine-sensitive Mg2+ transport system is indispensable for the physiology of this organism.
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Correlation between Spermine stimulation of rat liver Ile-tRNA formation and structural change of the acceptor stem by Spermine
Biochemical and biophysical research communications, 1991Co-Authors: Kuniko Kusama-eguchi, Shin-ichi Watanabe, Mika Irisawa, Kazuko Watanabe, Kazuei IgarashiAbstract:Abstract We have recently reported that the interaction of Spermine with the acceptor and anticodon stems may be important for Spermine stimulation of rat liver Ile-tRNA formation [Peng, Z. et al . (1990) Arch. Biochem. Biophys. 279, 138–145]. To pinpoint which interaction of Spermine is more important for Spermine stimulation of Ile-tRNA formation, Ile-tRNA formation and ribonuclease V 1 sensitivity of tRNA Ile were studied using purified tRNAs Ile from rat liver, wheat germ, brewer's yeast, torula yeast and Escherichia coli . The results indicate that Spermine stimulation of rat liver Ile-tRNA formation correlated with the structural change of the acceptor stem by Spermine. The nucleotide sequence of wheat germ tRNA Ile was also determined.
David W. Hoffman - One of the best experts on this subject based on the ideXlab platform.
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The crystal structure of spermidine/Spermine N1-acetyltransferase in complex with Spermine provides insights into substrate binding and catalysis.
Biochemistry, 2008Co-Authors: Eric J. Montemayor, David W. HoffmanAbstract:The enzyme spermidine/Spermine N1-acetyltransferase (SSAT) catalyzes the transfer of acetyl groups from acetylcoenzyme A to spermidine and Spermine, as part of a polyamine degradation pathway. This work describes the crystal structure of SSAT in complex with coenzyme A, with and without bound Spermine. The complex with Spermine provides a direct view of substrate binding by an SSAT and demonstrates structural plasticity near the active site of the enzyme. Associated water molecules bridge several of the intermolecular contacts between Spermine and the enzyme and form a “proton wire” between the side chain of Glu92 and the N1 amine of Spermine. A single water molecule can also be seen forming hydrogen bonds with the side chains of Glu92, Asp93, and the N4 amine of Spermine. Site-directed mutation of Glu92 to glutamine had a detrimental effect on both substrate binding and catalysis and shifted the optimal pH for enzyme activity further into alkaline solution conditions, while mutation of Asp93 to asparagin...
Hassan M. Ghonaim - One of the best experts on this subject based on the ideXlab platform.
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N ^1,N ^ 12 -Diacyl Spermines: SAR Studies on Non-viral Lipopolyamine Vectors for Plasmid DNA and siRNA Formulation
Pharmaceutical Research, 2009Co-Authors: Hassan M. Ghonaim, Ian S. BlagbroughAbstract:Purpose To study the efficiency of novel synthetic N ^1, N ^12-diacyl Spermines on DNA and siRNA binding, and to compare their transfection efficiency with viability in cell lines. Methods Five long chain N ^1, N ^12-diacyl lipopolyamines: N ^1, N ^12-[didecanoyl, dimyristoyl, dimyristoleoyl, distearoyl and dioleoyl]-1,12-diamino-4,9-diazadodecane were synthesized from the naturally occurring polyamine Spermine. Their abilities to condense DNA and to form nanoparticles were characterized. Transfection efficiencies were studied in FEK4 primary skin cells and in an immortalized cancer cell line (HtTA), and compared with N ^4, N ^9-regioisomers. Also, the abilities of these novel compounds to bind to siRNA-forming nanoparticles were studied using a RiboGreen intercalation assay, and their abilities to deliver fluorescein-tagged siRNA into cells were quantified and compared with TransIT-TKO. Results By incorporating two long aliphatic chains and varying their acylation position, length, and oxidation state in a stepwise manner, we show efficient p and siRNA formulation and delivery to primary skin and cancer cell lines. Although two C14 chains (both saturated or both mono- cis -unsaturated) were efficient transfecting agents, they were highly toxic. Conclusions N ^1, N ^12-Dioleoyl Spermine efficiently binds to and delivers pDNA and siRNA with high cell viability even in a primary skin cell line. It is a novel, efficient non-viral vector in the presence of serum.
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Design and Synthesis of N ^4,N ^9-Disubstituted Spermines for Non-viral siRNA Delivery – Structure-Activity Relationship Studies of siFection Efficiency Versus Toxicity
Pharmaceutical Research, 2009Co-Authors: Moustafa K. Soltan, Hassan M. Ghonaim, Mohamed Sadek, M. Abou Kull, Lubna Abd El-aziz, Ian S. BlagbroughAbstract:Purpose To study the effect of sequentially changing the chain length, oxidation level, and charge distribution in N ^4, N ^9-diacyl and N ^4, N ^9-dialkyl Spermines on siRNA formulation, and then to compare their lipoplex transfection efficiency in cell lines. Methods Eight N ^4, N ^9-diacyl polyamines: N ^4, N ^9-[didecanoyl, dilauroyl, dimyristoyl, dimyristoleoyl, dipalmitoyl, distearoyl, dioleoyl and diretinoyl]-1,12-diamino-4,9-diazadodecane were synthesized. Their abilities to bind to siRNA and form nanoparticles were studied using a RiboGreen intercalation assay and particle sizing. Two diamides were also reduced to afford tetraamines N ^4, N ^9-distearyl- and N ^4, N ^9-dioleyl-1,12-diamino-4,9-diazadodecane. Delivery of fluorescein-labelled Label IT® RNAi Delivery Control was studied in FEK4 primary skin cells and in an immortalized cancer cell line (HtTA), and compared with TransIT-TKO. Results The design, synthesis, and structure-activity relationship studies of a series of N ^4, N ^9-disubstituted Spermines as efficient vectors for non-viral siRNA delivery to primary skin and cancer cell lines is reported. These non-liposomal cationic lipids are promising siRNA carriers based on the naturally occurring polyamine Spermine showing that C-18 is a better chain length as shorter chains are more toxic. Conclusions N ^4, N ^9-Distearoyl Spermine and N ^4, N ^9-dioleoyl Spermine are efficient siRNA formulation and delivery vectors, even in the presence of serum, comparable to TransIT-TKO. However, four positive charges distributed as in Spermine was significantly more toxic.
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Very Long Chain N ^ 4 ,N ^ 9 -Diacyl Spermines: Non-Viral Lipopolyamine Vectors for Efficient Plasmid DNA and siRNA Delivery
Pharmaceutical Research, 2008Co-Authors: Hassan M. Ghonaim, Ian S. BlagbroughAbstract:Purpose To study the effect of increasing the chain length over C-18 and varying the oxidation level in synthesized N ^4, N ^9-diacyl Spermines on DNA and siRNA formulation, and then to compare their transfection efficiency in cell lines Methods The five novel very long chain N ^4, N ^9-diacyl polyamines: N ^4, N ^9-[diarachidoyl, diarachidonoyl, dieicosenoyl, dierucoyl and dinervonoyl]-1,12-diamino-4,9-diazadodecane were synthesized. The abilities of these novel compounds to condense DNA and to form nanoparticles were studied using ethidium bromide fluorescence quenching and nanoparticle characterization techniques. Transfection efficiency was studied in FEK4 primary skin cells and in an immortalized cancer cell line (HtTA), and compared with the non-liposomal transfection formulation Lipogen, N ^4, N ^9-dioleoyl-1,12-diamino-4,9-diazadodecane. Also, the abilities of these compounds to condense siRNA and to form nanoparticles were studied using a RiboGreen intercalation assay and their abilities to deliver siRNA into cells were studied in FEK4 and HtTA cells using fluorescein-labelled Label IT® RNAi Delivery Control, a sequenced 21-mer from Mirus. Results We show efficient pEGFP and siRNA formulation and delivery to primary skin and cancer cell lines. Conclusions Adding two C20 or C22 chains, both mono- cis -unsaturated, N ^4, N ^9-dieicosenoyl Spermine and N ^4, N ^9-dierucoyl Spermine, gave efficient siRNA delivery vectors, even in the presence of serum, comparable to TransIT-TKO and with excellent cell viability.
Graham G. Shaw - One of the best experts on this subject based on the ideXlab platform.
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Effect of Spermine and N1-dansyl-Spermine on epileptiform activity in mouse cortical slices.
European journal of pharmacology, 2005Co-Authors: Brian P. Kirby, Graham G. ShawAbstract:Abstract N 1 -dansyl-Spermine is a novel polyamine analogue, which has been demonstrated to have an antagonist action at the stimulatory polyamine site on the N -methyl- d -aspartate (NMDA) receptor macrocomplex. Cortical wedges from genetically epilepsy-prone DBA/2 mice demonstrate spontaneous epileptiform activity when perfused with Mg 2+ -free artificial cerebrospinal fluid (aCSF). This epileptiform activity has been demonstrated to be primarily mediated through the NMDA receptor. N 1 -dansyl-Spermine reduced the spontaneous epileptiform activity at a high dose (100 μM) but had no effect at a lower dose (50 μM). The polyamine, Spermine (300 μM) caused an increase in the rate of the spontaneous epileptiform discharges. This effect of Spermine was antagonised by administration of the low dose of N 1 -dansyl-Spermine (50 μM). This further demonstrates the role of the NMDA receptor in the production of spontaneous epileptiform discharges in the cortical wedge preparation and clearly illustrates both the facilitatory action of Spermine and the polyamine antagonist action of N 1 -dansyl-Spermine at the stimulatory polyamine site on the NMDA receptor.
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Effect of L-type calcium channel antagonists on Spermine-induced CNS excitation in vivo
Neuroscience letters, 2005Co-Authors: Karen M. Doyle, Brian P. Kirby, Desiree Murphy, Graham G. ShawAbstract:The ability of nitrendipine, nisoldipine, verapamil and gabapentin to inhibit the development of CNS excitation induced by Spermine was assessed in mice. Injection of an excitotoxic dose of Spermine (100 microg, i.c.v.) in mice results in worsening tremor that culminates in the development of a fatal tonic convulsion within 8 h of Spermine administration. The dihydropyridines, nitrendipine and nisoldipine, which are L-type calcium channel antagonists acting at the alpha1 subunit, inhibited the development of Spermine-induced effects. Verapamil, which also acts at the alpha1 subunit of the L-type calcium channel, also inhibited the development of Spermine-induced CNS excitation. Gabapentin, a postulated L-type calcium channel antagonist interacting at the alpha2delta subunit, did not inhibit the development of Spermine-induced effects. These results show that antagonists of the alpha1 subunit of L-type calcium channels can effectively inhibit the effects of Spermine in vivo. This may highlight the importance of L-type calcium channels in Spermine action.
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N1-Dansyl-Spermine: a potent polyamine antagonist
Brain research, 2004Co-Authors: Brian P. Kirby, Sheila A. Ryder, Nikolaus Seiler, Jacques Renault, Graham G. ShawAbstract:The potential polyamine antagonist action of N1-dansyl-Spermine (a potent NMDA antagonist) was assessed in two in vivo mouse models of polyamine action. Co-administration of N1-dansyl-Spermine (2-10 microg, i.c.v.) with Spermine (100 microg, i.c.v.) resulted in a dose-dependent antagonism of the Spermine-induced CNS excitation (body tremor and fatal tonic convulsions). In addition, the same dose of N1-dansyl-Spermine antagonised Spermine's enhancement of NMDA-induced convulsions. These results suggest that N1-dansyl-Spermine is in vivo a potent antagonist of the CNS effects of Spermine and of its action at the positive polyamine modulatory site on the NMDA receptor.