Conformation of linear homo-oligoprolines

A conformational analysis of Piv-l-Pro-d-Pro-OMe was performed in the solid state using i.r. absorption and X-ray diffraction. The tertiary amide bond is in the trans conformation, whereas the tertiary peptide bond is in the cis conformation. The sequence of the, ø angles is F, F*. The preferred conformations of the pivaloylamino group, the pyrrolidine rings, and the ester moiety are also discussed.     

Ventricular Thrombosis During Permanent Endocardial Pacing in a Pediatric Patient with Hemorrheological Disorders

Thrombosis in the right atrium or ventricle is a rare complication of permanent endocardial pacing in adults. To the best of our knowledge, this complication has not been previously reported at all in the pediatric age group. We report on a case of a 7-year-old boy who had large left ventricular thrombi that occurred during permanent endocardial electrical stimulation. Subsequent pulmonary emboli complicated congestive heart failure in this patient. As a diagnostic approach, echocardiography and pulmonary perfusion scintigraphy were used. We comment on possible causes of this serious complication and suggest hemorrheological and platelet activation studies in patients with permanent endocardial pacing.     

"TWO-STEP" PEMPHIGUS INDUCTION BY ACE-INHIBITORS

Pemphigus lesions appeared in a 58-year-old man who was taking captopril for his hypertension. Drug withdrawal resulted in complete remission of the eruption. The subsequent use of enalapril as an antihypertensive agent caused a recurrence of pemphigus lesions along with onset of itching and dermographism. Intercellular antibodies were not found. Discontinuance of enalapril therapy had no effect on the clinical course. Steroid treatment was needed to resolve the eruption. Recently repeated immunofluorescent studies disclosed intercellular IgG antibodies in the serum at a low titer. Pemphigus induction could be initially related to the thiol acantholytic property of captopril. Subsequent production of intercellular antibodies and drug-activation of the kinin system could be responsible for relapsing.     

CONFORMATIONAL ANALYSIS OF N-(tert.-AMYLOXYCARBONY-l-PROLINE IN THE SOLID STATE AND IN SOLUTION

The solid-state conformational analysis of t-AOC-l -Pro-OH** has indicated that the molecules are not folded up to form an oxy-C₇ peptide conformation, but rather that they are held together through intermolecular O-H. 0 = C (urethane) hydrogen bonds. The tertiary amide bond is in the cis configuration. In solvents of high polarity strongly solvated species largely predominate. In cyclohexane solution non-associated and associated (involving the carboxyl C = O as the proton acceptor) species are simultaneously present. Obviously, the extent of association increases with increasing solute concentration. The amount of the oxy-C₇ form, if any, should be extremely small. It is also demonstrated that CD measurements alone can lead to an incorrect picture of the conformational preferences of amino acid derivatives and small peptides in solution.     

Long-Term Outcomes of CRT-PM Versus CRT-D Recipients

Objective: To compare the rates of all-cause mortality in recipients of cardiac resynchronization therapy devices without (CRT-PM) versus with defibrillator (CRT-D).
Methods: Between February 1999 and July 2004, 233 patients (mean age = 69 ± 8 years, 180 men) underwent implantation of CRT-PM or CRT-D devices. New York Heart Association (NYHA) heart failure functional class II was present in 11%, class III in 69%, and class IV in 20% of patients; mean left ventricle ejection fraction (LVEF) was 26.5 ± 6.5 %, 48% presented with idiopathic dilated cardiomyopathy and 49% with ischemic heart disease. Cox multiple variable regression analysis was performed in search of predictors of death.
Results: The clinical characteristics of the 117 CRT-PM and 116 CRT-D recipients were similar, except for LVEF (28.2 ± 6.2% vs 25.0 ± 6.5%, respectively; P < 0.001), and ischemic versus nonischemic etiology of heart failure (41% vs 56%, respectively P = 0.02). Over a mean follow-up of 58 ± 15 months, no significance difference in overall mortality rate was observed between the two study groups. Male sex, NYHA functional class IV, and atrial fibrillation at implant were significant predictors of death.
Conclusions: There was no difference in long-term survival rate among patients with CRT-D versus CRT-PM, although CRT-D more effectively lowered the sudden death rate. Male sex, NYHA functional class IV, and atrial fibrillation predicted the worst prognosis.     

Permanent Mechanical Catheter Ablation of an Accessory Pathway in a Child

Permanent mechanical ablation of an accessory atrioventricular pathway was observed in an infant during intracavitary electrophysiological mapping. The persistent lack of preexcitation was confirmed during a 15-month follow-up period.