Photolysis and ozonolysis of (iso) desmosine-containing crosslinked peptides from porcine aorta elastin

This report describes the use of photolysis and ozonolysis as a means of achieving complete cleavage of the pyridinium ring of (iso)desmosine in crosslinked elastin peptides. Although photolysis leads to the opening of the ring with concomitant formation of lysine, the peptide chains remain attached. Subsequent ozonolysis is able to completely achieve the cleavage of the rest of the ring skeleton, thus leading to the separation of the peptide chains. Formation of new amino acids, i.e. α-aminoadipic and glutamic acids, is emphasized. Localization of these amino acids within the released peptides should be of help in structural investigations on the crosslinking zones involving either isodesmosine or desmosine. However, other amino acids such as tyrosine and phenylalanine are sensitive to this procedure and side reactions occur which are responsible for peptide bond cleavage with the formation of breakdown products.     

A Randomized‐Controlled Pilot Study Comparing ICD Implantation with and Without Intraoperative Defibrillation Testing in Patients with Heart Failure and Severe Left Ventricular Dysfunction: A Substudy of the RAFT Trial

Comparing ICD Implantation with and Without Intraoperative Defibrillation Testing. Introduction: The need to perform defibrillation testing (DT) at the time of implantable cardioverter defibrillator (ICD) insertion is controversial. In the absence of randomized trials, some regions now perform more than half of ICD implants without DT. Methods: During the last year of enrolment in the Resynchronization for Ambulatory Heart Failure Trial, a substudy randomized patients to ICD implantation with versus without DT. Results: Among 252 patients screened, 145 were enrolled; 75 randomized to DT and 70 to no DT. Patients were similar in terms of age (65.9 ± 9.3 years vs 67.9 ± 8.9 years); LVEF (24.7 ± 4.6% vs 23.6 ± 4.6%), QRS width (154.8 ± 23.5 vs 155.8 ± 23.6 ms), and history of atrial fibrillation (5% vs 6%). All 68 patients in the DT arm tested according to the protocol achieved a successful DT (≤25 J); 96% without requiring any system modification. No patient experienced perioperative stroke, myocardial infarction, heart failure (HF), intubation or unplanned ICU stay. The length of hospital stay was not prolonged in the DT group: 20.2 ± 26.3 hours versus 21.3 ± 23.0 hours, P = 0.79. One patient in the DT arm had a failed appropriate shock and no patient suffered an arrhythmic death. The composite of HF hospitalization or all‐cause mortality occurred in 10% of patients in the no‐DT arm and 19% of patients in the DT arm (HR = 0.53, 95% CI: 0.21–1.31, P = 0.14). Conclusions: In this randomized trial, perioperative complications, failed appropriate shocks, and arrhythmic death were all uncommon regardless of DT. There was a nonsignificant increase in the risk of death or HF hospitalization with DT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 1313‐1316, December 2012)     

A French Lawyer's View on Life & Death

The following excerpt from a book recently published in France raises some controversial issues in the medical ethics debate described above by Clarence Blomquist. The author, Francois Sarda, is a prominent Parisian lawyer.     

DOUBLE-BLIND RANDOMIZED MULTICENTRE TRIAL OF ACAMPROSATE IN MAINTAINING ABSTINENCE FROM ALCOHOL

A prospective placebo-controlled, randomized double-blind studyof Acamprosate at two dose levels in alcohol-dependent patientsfollowed up for 12 months was performed. After detoxification,each of the 538 patients included was randomly assigned to oneof three groups: 177 patients received placebo, 188 receivedAcamprosate at 1.3 g/day (low dose group) and 173 received 2.0g/day(high dose group) for 12 months. This was followed by a singleblind 6 month period on placebo. The patients' mean age was43.2 ± 8.6 years. Their mean daily alcohol intake washigh (nearly 200g/day) and of long duration (9.5 ± 7.1years). Abstinence figures followed the order high dose>lowdose>placebo. The difference was significant at 6 months(P     

Design and synthesis of novel inhibitors of prohormone convertases

Prohormone convertase-1 (PC1) and furin are subtilisin-like endopeptidases involved in the biosynthesis of peptide hormones. Five decapeptides representing the junction between the pro-region and the catalytic region of PC1 were prepared. The core sequence corresponded to D-Tyr-Arg-Ser-Lys-Arg-Xaa-Val-Gln-Lys-Asp where D-Tyr replaces the native Glu residue and Xaa, representing the P1′ position, corresponds to L-Ser, L-Leu or the unnatural amino acids, D-Ser, β-Ala, γ-Abu, β-Cha or γ-Hyp. Another analog incorporating an Orn residue in place of the Arg at the P1 site was also prepared. These peptides, synthesized by solid-phase Fmoc chemistry, were fully characterized by FAB-MS, ¹H-NMR and amino acid composition. Except for Orn, γ-Hyp, L/D-Ser and L-Leu containing analogs, the others were found to be moderate to potent competitive inhibitors of hPCl activity in the following order: γ-Abu>β-Cha>β-Ala, with K_i values ranging from 1 to 8.6 μM. Both L-Ser and L-Leu analogs were correctly cleaved at the acyl carbon COOH-terminal to the Lys-Arg pair by human PCl, whereas β-Cha, γ-Abu, β-Ala and D-Ser analogs proved to be very poor substrates. The Orn and γ-Hyp derivatives were not cleaved by the enzyme at all. The three analogs containing β-Cha, γ-Abu and β-Ala also proved to be potent inhibitors of the human furin activity in the following order: β-Ala>β-Cha> γ-Abu, with K₁ ranging from 0.8 to 2.2μM. Two more peptides, modified at the P1 position by addition of a semicarbazone (SC) moiety, were also synthesized by liquid-phase chemistry. These peptides, Arg-Ser-Lys-argininal-SC and Arg-Lys-Lys-argininal-SC, also proved to be potent competitive inhibitors of hPCl and exhibited K_i values 3.6 and 2.3 μM, respectively.