Effect of angiotensin-converting enzyme inhibitor therapy in mitral regurgitation with normal left ventricular function.

Mitral regurgitation (MR) is a common, frequently asymptomatic valvulopathy that can ultimately lead to left ventricular failure. With the objective of forestalling MR progression, a prospective, placebo controlled, double-blind study was conducted. It measured the effectiveness of lisinopril, an angiotensin-converting enzyme inhibitor, in reducing the echocardiographic signs of MR severity over a one-year period. Severe coronary disease was excluded by stress echocardiography. Treatment effectiveness was estimated to be proportional to the reduction in MR fraction and cardiac chamber dimensions, compared with baseline, according to intention-to-treat analysis. A final patient population of 23 asymptomatic adults aged 53.3 +/- 2.4 years (mean +/- SEM), with moderate, organic MR and normal left ventricular function was selected from the echocardiographic database. All baseline patient characteristics were comparable in the two treatment groups, including the MR fraction (55 +/- 3%). Twelve patients received lisinopril (18 +/- 1 mg) and 11 received placebo. After one year of treatment, a statistically significant difference in the MR fraction was observed between the two groups. For the lisinopril group the MR fraction dropped by 6.4 +/- 3.5% and for the placebo group it increased by 3.7 +/- 3.2% versus baseline (P < 0.05). No differences in left atrial or ventricular dimensions were observed. The study drug was stopped in four patients after one patient presented with rapid atrial fibrillation and angina while three patients were intolerant to lisinopril. Only one patient receiving placebo was taken off therapy. In conclusion, treatment with lisinopril indicates some reduction in the severity of chronic moderate MR in asymptomatic patients with normal left ventricular function. This approach appears to be safe, but side effects are not uncommon, warranting regular follow-up.

An assessment of the physiological significance of cimetidine interactions with copper and zinc in biofluids as based on the computer-simulated distribution of the involved complexes at therapeutic levels of the drug.

The hypothesis was formerly put forward that the main therapeutic action of cimetidine (the histamine H2-receptor antagonist marketed as Tagamet) as well as some of its side effects might be mediated by its interactions with essential metal ions. The present paper reports the potentiometric study of the coordination of the drug with copper(II) and zinc(II) in NaCl 0.15 mol dm-3 at 37 degrees C. Special attention was paid to copper complexes, due to (i) the involvement of cimetidine in rheumatoid arthritis evolution which could be related to the well-established role of copper against this disease, (ii) the anti-ulcer and anti-inflammatory properties of copper. In particular, the copper-cimetidine-histamine and copper-cimetidine-histidine ternary systems were investigated. Computer simulations of the distribution of cimetidine, zinc and copper in blood plasma were performed at therapeutic levels of the drug. No influence can be expected from cimetidine on the bioavailability of these metal ions, the opposite being also true. The mediation of copper in the action of cimetidine on rheumatoid arthritis should thus be ruled out, the influence of the drug being rather interpretable in terms of reduction of histamine release. Similarly, the sexual dysfunctions due to cimetidine administration are unlikely to arise from the interactions of drug with zinc in blood plasma. The possible involvement of copper and zinc in cimetidine gastrointestinal absorption is also discussed.

Trace metal requirements in total parenteral nutrition (TPN). 5. Formation constants for the copper(II)--histidine ternary complexes with threonine, lysine, glycine, phenylalanine, valine, and cystine, and discussion of their implications regarding the copper distribution in blood plasma during TPN and the evaluation of the daily dose of copper.

Specific metal deficiencies have been reported to affect patients receiving total parenteral nutrition (TPN). Our previous studies on the topic were devoted to the computer-based interpretation of the extra urinary excretion of zinc; a theoretical approach was also proposed, with a view to compensating for the extra losses of this metal. Similarly, the present work deals with the problem of TPN-induced copper deficiency and its remedy. As is the case for zinc, the TPN-induced excretion of copper clearly stems from the relative mobilization of the plasma protein-bound pool of this metal into its diffusable low-molecular-weight fraction; this phenomenon being due to the competitive complexation of copper by the amino acids of the nutritive solution. The computer simulation of this effect thus required that first the equilibrium constants be experimentally determined for the main complexes of copper that might form in the solution as well as in plasma during the infusion. Accordingly, complex formation in the copper-histidine ternary systems with threonine, lysine, glycine, phenylalanine, valine, and cystine was investigated by potentiometry at 37 degrees C in NaCIO4 0.15 mol X dm-3. The implications of the results obtained are discussed with regard to the interpretation of the copper excretion and the estimation of the desirable daily dose of this metal for the TPN mixture under consideration.