Multivalent cyclic RGD conjugates for targeted delivery of small interfering RNA.

We have designed, synthesized, and tested conjugates of chemically modified luciferase siRNA (Luc-siRNA) with bi-, tri-, and tetravalent cyclic(arginine-glycine-aspartic) (cRGD) peptides that selectively bind to the αvβ3 integrin. The cellular uptake, subcellular distribution, and pharmacological effects of the cRGD-conjugated Luc-siRNAs compared to those of unconjugated controls were examined using a luciferase reporter cassette stably transfected into αvβ3 positive M21(+) human melanoma cells. The M21(+) cells exhibited receptor-mediated uptake of cRGD-siRNA conjugates but not of unconjugated control siRNA.

Unconventional internalization mechanisms underlying functional delivery of antisense oligonucleotides via cationic lipoplexes and polyplexes.

There is mounting interest in developing antisense and siRNA oligonucleotides into therapeutic entities; however, this potential has been limited by poor access of oligonucleotides to their pharmacological targets within cells. Transfection reagents, such as cationic lipids and polymers, are commonly utilized to improve functional delivery of nucleic acids including oligonucleotides. Cellular entry of large plasmid DNA molecules with the assistance of these polycationic carriers is mediated by some form of endocytosis; however, the mechanism for delivery of small oligonucleotide molecules has not been well established.

Integrin targeted delivery of gene therapeutics.

Integrins have become key targets for molecular imaging and for selective delivery of anti-cancer agents. Here we review recent work concerning the targeted delivery of antisense and siRNA oligonucleotides via integrins. A variety of approaches have been used to link oligonucleotides to ligands capable of binding integrins with high specificity and affinity.

Cellular delivery of siRNA and antisense oligonucleotides via receptor-mediated endocytosis.

Introduction: There is great potential for antisense and siRNA oligonucleotides to become mainstream therapeutic entities thanks to their high specificity and wide therapeutic target space compared with small molecules. Despite this potential, the pharmacological targets within the cells are less accessible to oligonucleotides that are hydrophilic and often charged. Oligonucleotides access their intracellular targets mainly by means of endocytosis, but only a fraction of them reach their targets, as delivery requires functional synergy of cellular uptake and intracellular trafficking.

Efficient synthesis of the tRNA nucleoside preQ0, 7-cyano-7-deazaguanosine, via microwave-assisted iodo→carbonitrile exchange.

The naturally occurring tRNA nucleoside preQ(0), 7-cyano-7-deazaguanosine, which is a central intermediate for other natural occurring 7-deazapurine nucleosides was synthesized via a copper(I)-ion-mediated iodo→carbonitrile exchange. The reaction was performed on the easily accessible 7-iodo-7-deazaguanosine under microwave conditions. The overall reaction yield was 30% starting with the glycosylation reaction of the nucleobase.

Retention prediction and hydrophobicity estimation of weak acidic compounds by reversed-phase liquid chromatography using acetic and perchloric acids as ion suppressors.

Simple acids are usually applied to suppress the ionization of weakly ionizable acidic analytes in reversed-phase liquid chromatography. The purpose of this study is to investigate the retention behavior of various weak acidic compounds (monoprotic, diprotic, triprotic, and tetraprotic acids) using acetic or perchloric acid as ion suppressor in a binary hydroorganic mobile phase. The apparent n-octanol-water partition coefficient (K(ow)") was proposed to calibrate the n-octanol-water partition coefficient (K(ow)) of weak acidic compound.

Intracellular delivery of an antisense oligonucleotide via endocytosis of a G protein-coupled receptor.

Gastrin-releasing peptide receptor (GRPR), a member of the G protein-coupled receptor superfamily, has been utilized for receptor-mediated targeting of imaging and therapeutic agents; here we extend its use to oligonucleotide delivery. A splice-shifting antisense oligonucleotide was conjugated to a bombesin (BBN) peptide, and its intracellular delivery was tested in GRPR expressing PC3 cells stably transfected with a luciferase gene interrupted by an abnormally spliced intron. The BBN-conjugate produced significantly higher luciferase expression compared to unmodified oligonucleotide, and this increase was reversed by excess BBN peptide.

Targeted intracellular delivery of antisense oligonucleotides via conjugation with small-molecule ligands.

Selective delivery of antisense or siRNA oligonucleotides to cells and tissues via receptor-mediated endocytosis is becoming an important approach for oligonucleotide-based pharmacology. In most cases receptor targeting has been attained using antibodies or peptide-type ligands. Thus, there are few examples of delivering oligonucleotides using the plethora of small-molecule receptor-specific ligands that currently exist.

Broadband tunable optical delay based on real-time Fourier transformation and ramp-type phase modulation.

A new tunable optical delay scheme based on real-time Fourier transformation and ramp-type phase modulation is proposed and experimentally demonstrated. A linearly chirped fiber Bragg grating is adopted to implement the real-time Fourier transformation, and tunable delay is realized by changing the ramp-type modulating signal's period. Experimental results agree well with the theory.

100Gb/s PolMux-NRZ-AOS-OFDM transmission system.

A novel high speed transmission system using all-optical sampling orthogonal frequency multiplexing (AOS-OFDM) technique is proposed and demonstrated. By utilizing polarization multiplexing (PolMUX) and non-return-to-zero (NRZ) format, the total bit rate is 100 Gb/s with high spectral efficiency of 1.6.

Studies on the glycosylation of pyrrolo[2,3-d] pyrimidines with 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-D-ribofuranose: the formation of regioisomers during toyocamycin and 7-deazainosine syntheses.

Glycosylation of silylated 4-amino-6-bromo-5-cyano-7H-pyrrolo[2,3-d]pyrimidine (9) with 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-D-ribofuranose (10) under "one-pot" glycosylation conditions (MeCN, TMSOTf) yielded the N-7 isomer 11 together with the N-1 compound 13 (ratio = 2:1). When the same conditions were applied to 4-hydroxy-7H-pyrrolo[2,3-d]pyrimidine (21) the N-3 isomer 22 was the only glycosylation product formed in almost quantitative yield.

Code extraction from encoded signal in time-spreading optical code division multiple access.

A vulnerability that allows eavesdroppers to extract the code from the waveform of the noiselike encoded signal of an isolated user in a standard time-spreading optical code division multiple access communication system using bipolar phase code is experimentally demonstrated. The principle is based on fine structure in the encoded signal. Each dip in the waveform corresponds to a transition of the bipolar code.

The biological effect of an antisense oligonucleotide depends on its route of endocytosis and trafficking.

We demonstrate that the biological effect of an oligonucleotide is influenced by its route of cellular uptake. Utilizing a splice-switching antisense oligonucleotide (SSO) and a sensitive reporter assay involving correction of RNA splicing, we examined induction of luciferase in cells treated either with various concentrations of an unconjugated ("free") SSO or an SSO conjugated to a bivalent RGD ligand that promotes binding to the alphavbeta3 integrin (RGD-SSO). Under conditions of equal accumulation in cells, the RGD-SSO consistently had a greater effect on luciferase induction than the unconjugated SSO.

Optical ultra-wide-band pulse bipolar and shape modulation based on a symmetric PM-IM conversion architecture.

A simple and feasible technique for ultra-wide-band (UWB) pulse bipolar modulation (PBM) and pulse shape modulation (PSM) in the optical domain is proposed and demonstrated. The PBM and PSM are performed using a symmetric phase modulation to intensity modulation conversion architecture, including a couple of phase modulators and an optical bandpass filter (OBPF). Two optical carriers, which are separately phase modulated by two appropriate electrical pulse patterns, are at the long- and short-wavelength linear slopes of the OBPF spectrum, respectively.

Role of basolateral efflux transporter MRP4 in the intestinal absorption of the antiviral drug adefovir dipivoxil.

Adefovir dipivoxil is a diester prodrug of the antiviral drug adefovir, with much greater oral bioavailability than adefovir. Evidence shows that the prodrug is metabolized to adefovir in the enterocytes during intestinal absorption. However, it is unknown how the highly charged and hydrophilic adefovir crosses the basolateral membrane in the intestine.

Chromatographic retention prediction and octanol-water partition coefficient determination of monobasic weak acidic compounds in ion-suppression reversed-phase liquid chromatography using acids as ion-suppressors.

Although simple acids, replacing buffers, have been widely applied to suppress the ionization of weakly ionizable acidic analytes in reversed-phase liquid chromatography (RPLC), none of the previously reported works focused on the systematic studies about the retention behavior of the acidic solutes in this ion-suppression RPLC mode. The subject of this paper was therefore to investigate the retention behavior of monobasic weak acidic compounds using acetic, perchloric and phosphoric acids as the ion-suppressors. The apparent octanol-water partition coefficient (K" ow) was proposed to calibrate the octanol-water partition coefficient (K(ow)) of these weak acidic compounds, which resulted in a better linear correlation with log k(w), the logarithm of the hypothetical retention factor corresponding to neat aqueous fraction of hydroorganic mobile phase.

Stacked optical code label for multicasting in optical packet switching networks.

Stacked optical code (OC) label and its en/decoder based on fiber Bragg gratings (FBG) are proposed and experimentally demonstrated. This kind of label can carry several nodes' address information simultaneously in optical packet switching networks, so it can be employed in optical multicasting and simplify the node's structure a lot. The en/decoder is fabricated with high precision by our FBG techniques, and the experiment results show that the stacked OC label can support optical multicasting very well.

Transport of dicationic drugs pentamidine and furamidine by human organic cation transporters.

The antiparasitic activity of aromatic diamidine drugs, pentamidine and furamidine, depends on their entry into the pathogenic protozoa via membrane transporters. However, no such diamidine transporter has been identified in mammalian cells. The goal of this study is to investigate whether these dicationic drugs are substrates for human organic cation transporters (hOCTs, solute carrier family 22A1-3) and whether hOCTs play a role in their tissue distribution, elimination, and toxicity.

Azide-alkyne "click" reaction performed on oligonucleotides with the universal nucleoside 7-octadiynyl-7-deaza-2'-deoxyinosine.

Oligonucleotides containing 7-substituted 7-deaza-2'- deoxyinosine derivatives bearing alkynyl groups were prepared. The octa-1,7-diynyl derivative was functionalized with the non-fluorescent 3- azidocoumarin by the Huisgen-Sharpless-Meldal cycloaddition to afford a highly fluorescent oligonucleotide conjugate. The ambiguous base pairing character and the clickable side chain allows the incorporation of almost any reporter molecule to DNA.

7-Deaza-2'-deoxyinosine: a nucleoside showing ambiguous base-pairing properties against the four canonical DNA constituents.

The title compound [systematic name: 7-(2-deoxy-beta-D-erythro-pentofuranosyl)-3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-one], C(11)H(13)N(3)O(4), represents an acid-stable derivative of 2'-deoxyinosine. It exhibits an anti glycosylic bond conformation, with a chi torsion angle of 113.30 (15) degrees .

7-Fluorotubercidin: a halogenated derivative of a naturally occurring nucleoside antimetabolite.

The title compound [systematic name: 4-amino-5-fluoro-7-(beta-D-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine], C(11)H(13)FN(4)O(4), exhibits an anti glycosylic bond conformation, with a chi torsion angle of -124.7 (3) degrees. The furanose moiety shows a twisted C2'-endo sugar pucker (S-type), with P = 169.

2'-Deoxyimmunosine: stereoselective synthesis, base pairing and duplex stability of oligonucleotides containing 8-oxo-7-thiaguanine.

Oligonucleotides containing 7-thia-8-oxoguanine represent a new class of molecules in which sulfur replaces the 7-nitrogen of a purine base. The monomeric 7-thia-8-oxoguanine 2'-deoxyribonucleoside (2'-deoxyimmunosine, 4) was prepared by nucleobase anion glycosylation in a regio- and stereoselective way employing 5-{[(di-n-butylamino)methylidene]amino}thiazolo[4,5-d]pyrimidine-2,7(3H,6H)-dione (18) and 1-chloro-2-deoxy-3,5-di-O-p-toluoyl-alpha-d-erythro-pentofuranose (6). The nucleoside was converted into the phosphoramidite and oligonucleotides were prepared by solid-phase synthesis.

Mechanistic photodissociation of CO-ligated neuroglobin and subsequent rebinding processes: a theoretical study.

In the present work, density functional theory (QM) and molecular mechanics (MM) method were used to study mechanistic photodissociation of CO-ligated neuroglobin (Ngb-CO). It was found that all the electronic states investigated here are bound with respect to the Fe-CO separation, except for a couple of near-degenerate states (1E) that are repulsive. Irradiation of Ngb-CO at 533 nm leads to the system in the lowest two excited singlet states (1Q), where non-adiabatic CO dissociation proceeds with high efficiency through the intersection between 1Q and 1E.

Fluorinated 7-deazapurine 2'-deoxyribonucleosides: modification at the nucleobase and the sugar moiety.

7-Deaza-7-fluoro-purine 2'-deoxynucleosides as well as 2'-deoxy-2'-fluoroarabinofuranosyl nucleosides 1-8 were synthesized. The fluorine atom was introduced on the base level with Selectfluor. Nucleobase-anion glycosylation was then employed to form the nucleosides.

2'-Deoxyimmunosine: a thiazolo[4,5-d]pyrimidine nucleoside adopting the syn conformation.

The title compound [systematic name: 5-amino-3-(2-deoxy-beta-D-erythro-pentofuranosyl)thiazolo[4,5-d]pyrimidine-2,7-(3H,6H)-dione], C(10)H(12)N(4)O(5)S, exhibits a syn glycosylic bond conformation, with a torsion angle chi of 61.0 (3) degrees. The furanose moiety adopts the N-type sugar pucker ((3)T4), with P = 33.