Superconductivity in a unique type of copper oxide

The mechanism of superconductivity in cuprates remains one of the big challenges of condensed matter physics. High-T c cuprates crystallize into a layered perovskite structure featuring copper oxygen octahedral coordination. Due to the Jahn Teller effect in combination with the strong static Coulomb interaction, the octahedra in high-T c cuprates are elongated along the c axis, leading to a 3dx 2-y 2 orbital at the top of the band structure wherein the doped holes reside. This scenario gives rise to 2D characteristics in high-T c cuprates that favor d-wave pairing symmetry. Here, we report superconductivity in a cuprate Ba2CuO4-y , wherein the local octahedron is in a very exceptional compressed version. The Ba2CuO4-y compound was synthesized at high pressure at high temperatures and shows bulk superconductivity with critical temperature (T c ) above 70 K at ambient conditions. This superconducting transition temperature is more than 30 K higher than the T c for the isostructural counterparts based on classical La2CuO4 X-ray absorption measurements indicate the heavily doped nature of the Ba2CuO4-y superconductor. In compressed octahedron, the 3d3z 2-r 2 orbital will be lifted above the 3dx 2-y 2 orbital, leading to significant 3D nature in addition to the conventional 3dx 2-y 2 orbital. This work sheds important light on advancing our comprehensive understanding of the superconducting mechanism of high T c in cuprate materials.

Lectin inspired polymers based on the dipeptide Ser-Asp for glycopeptide enrichment

Lectin inspired polymers polySD-SiO₂were prepared and applied to the high-efficiency enrichment of glycopeptides.

Phase I Trial of ISIS 5132, an antisense oligonucleotide inhibitor of c-raf-1, administered by 24-hour weekly infusion to patients with advanced cancer

Raf-1 is a serine/threonine kinase that functions as a critical effector of Ras-mediated signal transduction via the mitogen-activated protein kinase pathway. Constitutive activation of this pathway directly contributes to malignant transformation in many human tumors. A 20-base phosphorothioate oligonucleotide complementary to c-raf-1 mRNA (ISIS 5132; CGP 69846A) has been shown to specifically suppress Raf-1 expression both in vitro and in vivo. This Phase I trial, involving 22 patients with advanced cancer, was designed to evaluate the safety, feasibility, and maximum tolerated dose of ISIS 5132 administration as a weekly 24-h i.v. infusion. Pharmacokinetic analysis was performed, and c-raf-1 mRNA levels in peripheral blood mononuclear cells were assessed using quantitative reverse transcription-PCR. This trial defined a maximum tolerated dose of 24 mg/kg/week on this schedule. Two of four patients treated at 30 mg/kg/week had serious adverse events after the first dose of ISIS 5132, including acute hemolytic anemia and acute renal failure and anasarca. There were no major responses documented. Dose-dependent complement activation was demonstrated on this schedule, but not on previously evaluated schedules, of ISIS 5132 administration. In contrast to other trials of ISIS 5132, there appeared to be no consistent suppression of peripheral blood mononuclear cell c-raf-1 mRNA level on this schedule at any of the dose levels analyzed. These data suggest that the efficacy and toxicity profiles of antisense oligonucleotides may be highly dependent on the schedule of administration and support the analysis of the putative molecular target in the evaluation of novel therapeutics.

Pharmacokinetics of phosphorothioate antisense oligodeoxynucleotides

Phosphorothioate (PS) oligodeoxynucleotides represent the class of antisense drugs most advanced in development and clinical testing. Exploitation of antisense oligonucleotide technology for development of rationally designed therapeutic drugs has presented a unique set of challenges, some of which relate to their pharmacokinetic behavior in vivo. Pharmacokinetic studies of PS oligodeoxynucleotides demonstrate that they are well absorbed from parenteral sites, rapidly distributed broadly to all peripheral tissues, do not cross the blood-brain barrier, and are eliminated primarily by slow metabolism in tissues. In general, the pharmacokinetic properties of this class of compounds appear to be largely driven by chemistry rather than sequence.

Comparison of pharmacokinetics and tissue disposition of an antisense phosphorothioate oligonucleotide targeting human Ha-ras mRNA in mouse and monkey

The plasma pharmacokinetics and tissue disposition of ISIS 2503 were studied in mice following single and multiple bolus intravenous (iv) injections of 1-50 mg/kg, and in monkeys following single and multiple 2-h iv infusions of 1-10 mg/kg and bolus iv injections of 1 mg/kg of ISIS 2503. ISIS 2503 and its metabolites were measured in plasma, urine, and tissues using solid-phase extraction followed by capillary gel electrophoresis (CGE). In both species, the plasma clearance of ISIS 2503 was characterized by rapid distribution to tissues, and to a lesser extent, metabolism. The plasma clearance in mice was at least two-fold more rapid than in monkeys at equivalent doses. The plasma disposition (t1/2) increased with dose. The highest concentrations of oligonucleotide were consistently observed in the kidney and liver in both species. At equivalent doses, tissue concentrations in monkeys were much higher than tissue concentrations in mice. Urinary excretion of total oligonucleotide was a minor elimination pathway in both species at doses < 10 mg/kg. However, urinary excretion of total oligonucleotide in mice was increased to 12-29% as dose increased from 20 to 50 mg/kg.

Pharmacokinetics and pharmacodynamics of an antisense phosphorothioate oligonucleotide targeting Fas mRNA in mice

ISIS 22023 is a modified phosphorothioate antisense oligonucleotide targeting murine Fas mRNA. Treatment of mice with ISIS 22023 reduced Fas expression in liver in a concentration-dependent and sequence-specific manner, which completely protected mice from fulminant death induced by agonistic Fas antibody. In this study, we characterized the relationships in mice between total dose administered, dose to the target organ, and ultimately, the intracellular concentration within target cell types to the pharmacologic activity of ISIS 22023. After subcutaneous injection, ISIS 22023 distributed to the liver rapidly and remained in the liver with the t(1/2) ranging from 11 to 19 days, depending on dose. There were apparent differences in patterns of uptake and elimination in different types of liver cells. Oligonucleotide appeared within hepatocytes rapidly, whereas the peak concentrations in Kupffer cells were delayed until 2 days after dose administration. Hepatocytes cleared oligonucleotide the most rapidly, whereas Kupffer cells appeared to retain oligonucleotide longer. The reduction of Fas mRNA levels (pharmacodynamic response) paralleled the increase of oligonucleotide concentration in mouse liver with maximum mRNA reduction of 90% at 2 days after a single 50 mg/kg subcutaneous administration. Moreover, the pharmacodynamics of ISIS 22023 correlated better with the pharmacokinetics in hepatocytes, supporting the concept that the presence of oligonucleotide in target cells results in reductions in mRNA and, ultimately, pharmacologic activity. These results provide a comprehensive understanding of the kinetics of an antisense drug at the site of action and demonstrate that the reductions in mRNA induced by this antisense oligonucleotide correlate with its concentrations in cell targets.

Pharmacokinetics and tissue disposition in monkeys of an antisense oligonucleotide inhibitor of Ha-ras encapsulated in stealth liposomes

PURPOSE

This study examined the pharmacokinetics and tissue distribution of an antisense oligonucleotide ISIS 2503, formulated in stealth (pegylated) liposomes (encapsulated) or in phosphate-buffered saline (unencapsulated).

METHODS

Encapsulated or unencapsulated ISIS 2503 was administered to rhesus monkeys by intravenous infusion. The concentrations of ISIS 2503 and metabolites in blood, plasma, and tissue samples were determined by capillary gel electrophoresis.

RESULTS

Plasma concentrations of encapsulated ISIS 2503 decreased mono-exponentially after infusion with a mean half-life of 57.8 hours. In contrast, the concentration of unencapsulated ISIS 2503 in plasma decreased rapidly with a mean half-life of 1.07 hours. Both encapsulated and unencapsulated ISIS 2503 distributed widely into tissues. Encapsulated ISIS 2503 distributed primarily to the reticulo-endothelial system and there were few metabolites observed. In contrast, unencapsulated ISIS 2503 distributed rapidly to tissue with highest concentration seen in kidney and liver. Nuclease-mediated metabolism was extensive for unencapsulated oligonucleotide in plasma and tissues.

CONCLUSIONS

The data suggest that stealth liposomes protect ISIS 2503 from nucleases in blood and tissues, slow tissue uptake, and slow the rate of clearance from the systemic circulation. These attributes may make these formulations attractive for delivering oligonucleotides to sites with increased vasculature permeability such as tumors or sites of inflammation.