Development and testing of a transcatheter heart valve with reduced calcification potential.

Introduction: Patients from developing countries who require heart valve surgery are younger and have less access to open heart surgery than those from developed countries. Transcatheter heart valves (THVs) may be an alternative but are currently unsuitable for young patients because of their inadequate durability. We developed and tested a THV utilizing two new types of decellularized bovine pericardial leaflets in an ovine model. Methods: The two decellularized tissues [one with a very low dose (0.05%) of monomeric glutaraldehyde (GA) fixation and detoxification (DF) and the other without glutaraldehyde (DE)] were compared to an industry standard [Glycar-fixed with the standard dose (0.625%) of glutaraldehyde]. THVs were manufactured with the three tissue types and implanted in the pulmonary position of nine juvenile sheep for 180 days. Baseline and post-explantation evaluations were performed to determine the hemodynamic performance of the valves and their dynamic strength, structure, biological interaction, and calcification. Results: Heart failure occurred in one animal due to incompetence of its Glycar valve, and the animal was euthanized at 158 days. The gradients over the Glycar valves were higher at the explant than at the implant, but the DE and DF valves maintained normal hemodynamic performance throughout the study. The DF and DE tissues performed well during the mechanical testing of explanted leaflets. Glycar tissue developed thick pannus and calcification. Compared to Glycar, the DF tissue exhibited reduced pannus overgrowth and calcification and the DE tissue exhibited no pannus formation and calcification. All tissues were endothelialized adequately. There was a striking absence of host ingrowth in the DE tissue leaflets, yet these leaflets maintained integrity and mechanical function. Conclusion: In the juvenile sheep THV model, Glycar tissue developed significant pannus, calcification, and hemodynamic deterioration. Using a very low dose of monomeric GA to fix the decellularized bovine pericardium yielded less pannus formation, less calcification, and better hemodynamic function. We postulate that the limited pannus formation in the DF group results from GA. Bovine pericardium decellularized with our proprietary method resulted in inert tissue, which is a unique finding. These results justify further development and evaluation of the two decellularized tissue types in THVs for use in younger patients.

Catalysis of linear alkene metathesis by Grubbs-type ruthenium alkylidene complexes containing hemilabile α,α-diphenyl-(monosubstituted-pyridin-2-yl)methanolato ligands.

Four new Grubbs-type precatalysts [RuCl(H2IMes)(O^N)(=CHPh)], where [O^N = α,α-diphenyl-(3-methylpyridin-2-yl)methanolato, α,α-diphenyl-(4-methylpyridin-2-yl)methanolato, α,α-diphenyl-(5-methylpyridin-2-yl)methanolato and α,α-diphenyl-(3-methoxypyridin-2-yl)methanolato] were synthesized and tested for their activity, stability and selectivity in the 1-octene metathesis reaction. Overall the precatalysts showed good activity and high stability for the metathesis of 1-octene at temperatures above 80 °C and up to 110 °C. Selectivities towards the primary metathesis products, i.e., 7-tetradecene and ethene, above 85% were obtained with all the precatalysts at 80 and 90 °C. High selectivities were also observed at 100 °C for the 4-Me- and 3-OMe-substituted precatalysts. With an increase in temperature an increase in isomerisation products and secondary metathesis products were observed with the latter reaching values >20% for the 3-OMe- and 3-Me-substituted precatalysts at 110 and 100 °C, respectively. All the precatalysts exhibits first-order kinetics at 80 °C with the 3-substituted precatalysts the slowest. The behaviour of the 3-substituted precatalysts can be attributed to electronic and steric effects associated with the adjacent bulky phenyl groups.

Ipilimumab in Pretreated Patients With Advanced Malignant Melanoma: Results of the South African Expanded-Access Program.

PURPOSE: The primary objective of this study was to evaluate 1- and 2-year survival rates and durable remissions in pretreated patients with advanced (unresectable or metastatic) malignant melanoma treated with ipilimumab in a South African expanded-access program (SA-EAP). PATIENTS AND METHODS: This multicenter, retrospective study obtained data from pretreated patients with advanced malignant melanoma who were eligible for the ipilimumab SA-EAP. Ipilimumab was administered at a dose of 3 mg/kg intravenously every 3 weeks for four cycles to adults with advanced melanoma for whom at least one line of treatment for metastatic disease had failed. Data from the medical records of 108 patients treated within the SA-EAP were collected and statistically analyzed to determine overall (OS) and progression-free survival (PFS) at 1 and 2 years. RESULTS: In the population of 108 patients, a median OS of 8.98 months (95% CI, 7.47 to 10.79 months) was observed. One-year OS was 36% (95% CI, 26% to 45%), and 2-year survival was observed as 20% (95% CI, 12% to 27%). The median survival without progression (ie, PFS) was 3.44 months (95% CI, 2.98 to 4.16 months), and 1- and 2-year PFS were 22% (95% CI, 14% to 29%) and 14% (95% CI, 8% to 21%), respectively. The longest recorded survival was 3.4 years. No independent prognostic variables were identified to predict for OS by multivariate Cox proportional hazards model. CONCLUSION: In this multicenter South African setting, ipilimumab at a dose of 3 mg/kg was an effective treatment with long-term OS in a subset of patients with pretreated advanced malignant melanoma.

A bis(pyridyl)-N-alkylamine/Cu(i) catalyst system for aerobic alcohol oxidation.

Herein a bis(pyridyl)-N-alkylamine/CuI/TEMPO/NMI catalyst system is reported for aerobic oxidation of a variety of primary alcohols to the corresponding aldehydes using readily available reagents, at room temperature and ambient air as the oxidant. ESI-MS analysis of the reaction showed the formation of a [(L1)(NMI)CuII-OOH]+ species, which is a key intermediate in the alcohol oxidation reaction. Evaluation of the effect of reaction parameters on the initial rate of the reaction allowed us to obtain the optimum conditions for catalytic activity. The careful choice of reaction solvent allowed for the oxidation of 4-hydroxybenzyl alcohol, a substrate which proved problematic in previous studies. In the case of 2-pyridinemethanol as substrate, experimental evidence shows that catalytic activity is diminished due to competitive inhibition of the catalyst by the alcohol substrate.

Synthesis Characterization and Biological Activities of Coordination Compounds of 4-Hydroxy-3-nitro-2H-chromen-2-one and Its Aminoethanoic Acid and Pyrrolidine-2-carboxylic Acid Mixed Ligand Complexes.

Coordination compounds of 4-hydroxy-3-nitro-2H-chromen-2-one and their mixed ligand complexes with aminoethanoic acid and pyrrolidine-2-carboxylic acid were synthesized by the reaction of Cu(II) and Zn(II) salts in molar ratio 1 : 2 for the coumarin complexes and 1 : 1 : 1 for the mixed ligand complexes, in basic media. The compounds formed were characterized using infrared, Uv-vis spectrophotometric analyses, mass spectrometry, magnetic susceptibility measurements, and EDX analyses. It was concluded that 4-hydroxy-3-nitro-2H-chromen-2-one coordinated as a monobasic ligand for all the complexes; it also coordinated via the carbonyl moiety in the case of the Cu(II) mixed ligand complexes. Similarly it was proposed that the amino acids also coordinated in a bidentate fashion via their amino nitrogen and carboxylate oxygen atoms. The synthesized compounds were screened for their antimicrobial and cytotoxic activities. The complexes exhibited marginal antimicrobial activity but good cytotoxic activity.

A molecular modeling study of the changes of some steric properties of the precatalysts during the olefin metathesis reaction.

The productive self-metathesis of 1-octene with a series of new phosphine ligated Grubbs-type precatalysts was studied. The resulting structures were used to compare some steric properties of the new precatalysts with those of well-known precatalysts. The possibility of α-CC agnostic stabilization as well as the ability of the ligands to shield the metal was studied. A comparison of the obtained data, pointed to the unlikelihood that α-CC agostic stabilization is a major contribution to the stabilization of the various metallacyclobutane rings. The similarity in the ability of the ligands to shield the metal also raised questions about the comparison of experimentally observed trends with those obtained theoretically.

A comparison of low and high activity precatalysts: do the calculated energy barriers during the self-metathesis reaction of 1-octene correlate with the precatalyst metathesis activity?

The self-metathesis reaction of 1-octene with several well-known Grubbs-type precatalysts and the new Z-selective Grubbs precatalyst were studied with molecular modeling. The obtained Gibbs-free energy values for all the steps during the productive metathesis of 1-octene were compared to the values obtained for some low catalytic activity precatalysts. Determining how the Gibbs-free energy values of highly active precatalysts compare to that of low catalytic activity precatalysts gave a deeper insight into the mechanism. The questionable correlation of the theoretically observed trends with those obtained experimentally does point to the need to be very cautious when making assumptions from theoretical results without a sufficiently large dataset.

Phase II, double-blind, randomized trial of capecitabine plus enzastaurin versus capecitabine plus placebo in patients with metastatic or recurrent breast cancer after prior anthracycline and taxane therapy.

Capecitabine is frequently used in the treatment of recurrent/progressive metastatic breast cancer (MBC) after prior anthracycline and taxane therapy. With the intention of improving the efficacy of single agent capecitabine, we initiated a randomized, double-blind, placebo-controlled Phase II study of the novel serine/threonine kinase inhibitor enzastaurin in combination with capecitabine in a heavily pretreated patient population. Patients received capecitabine 1,250 mg/m(2) twice daily plus enzastaurin 500 mg/day, or capecitabine plus placebo. The capecitabine was administered for the first 14 days of each 21 day cycle. The primary outcome was progression-free survival (PFS) using the log-rank test (1-sided significance level of 0.20). Of 109 patients assessed for eligibility, 85 were enrolled, randomized, and treated (42 and 43 patients in each respective treatment group). The study was terminated early following a preplanned futility analysis. Median PFS (95% CI) was 2.8 (2.1-4.6) months with capecitabine plus enzastaurin versus 4.3 (2.9-6.2) months with capecitabine plus placebo (adjusted hazard ratio: 1.728 [1.00-2.97]; P = 0.048). Median overall survival (95% CI) was lower with capecitabine plus enzastaurin than with capecitabine plus placebo (9.9 [7.0-16.6] months vs 14.9 [9.9-19.3] months, P = 0.181). Grade 3/4 adverse events were more frequent with capecitabine plus enzastaurin (42.9% vs 32.6%). Given the lack of PFS benefit, capecitabine plus enzastaurin is unsuitable as therapy for patients with recurrent/progressive MBC after prior anthracycline and taxane therapy. This trial is registered on www.clinicaltrials.gov (identifier: NCT00437294).

DFT investigation of the 1-octene metathesis reaction mechanism with the Phobcat precatalyst.

The productive self-metathesis reaction of 1-octene in the presence of the Phobcat precatalyst [RuCl(2)(Phoban-Cy)(2)(=CHPh)] using density functional theory was investigated and compared to the Grubbs 1 precatalyst [RuCl(2)(PCy(3))(2)(=CHPh)]. At the GGA-PW91/DNP level, the geometry optimization of all the participating species and the PES scans of the various activation and catalytic cycles in the dissociative mechanism were performed. The formation of the catalytically active heptylidene species is kinetically and thermodynamically favored, while the formation of trans-tetradecene is thermodynamically favored.