Synthesis of N3-fumaramoyl-L-2,3-diaminopropanoic acid analogues,the irreversible inhibitors of glucosamine synthetase

Several analogues of N³-fumaramoyl-L-2,3-diaminopropanoic acid were synthesized and evaluated for inhibition of glucosamine-6-phosphate synthetase activity. The syntheses were accomplished by acylation reaction of N²-tert.-butoxycarbonyl-L-2,3-diaminopropanoic acid (Boc-A₂pr) or N²-tert.-butoxy-carbonyl-L-2,4-diaminobutanoic acid (Boc-A₂-bu) with the N-succinimidoyl esters of several derivatives of α, β-unsaturated acids 2a-d followed by deprotection of the Boc groups. The obtained compounds were tested for inhibition of glucosamine synthetase isolated from Salmonella typhimurium and Saccharomyces cerevisiae. The results indicated that among the synthesized compounds, N³-4-methoxyfumaroyl-L-2,3-diaminopropanoic acid (FMDP) was the most powerful inhibitor of glucosamine synthetase.     

Ventricular Oversensing:

WERETKA, S., et al. : Ventricular Oversensing: A Study of 101 Patients Implanted with Dual Chamber Defibrillators and Two Different Lead Systems . Modern dual chamber ICD systems are able to overcome various sensing problems. However, improvement of their performance is still required. The aim of this study was to assess the sensing function in 101 consecutive patients (84 men, 17 women; mean age 63 ± 12 years; mean follow-up 24 ± 4 months) implanted with dual chamber defibrillators and integrated (IB) or dedicated bipolar (DB) lead systems. Follow-up data were analyzed for the presence of ventricular oversensing. Oversensing occurred in 25 (25%) patients, significantly more frequent in patients implanted with IB compared to DB lead systems (21/52 vs 4/49, P = 0.0002). Patients with cardiomyopathies (CMs) were more prone to sensing malfunctions than patients with no CM (12/30 vs 13/71, P = 0.04). T wave oversensing (n = 14), respirophasic ventricular oversensing (n = 4), and P wave oversensing (n = 6) were the most common pitfalls of ventricular sensing. P wave oversensing was unique to the IB lead system. CT scans performed in these patients disclosed the position of the RV coil to be proximal to the tricuspid area. Four patients received inappropriate ICD shocks due to oversensing. In all but two patients who received lead revision, oversensing was resolved by noninvasive means. In conclusion: (1) ventricular oversensing is a common problem occurring in up to 25% of patients with dual chamber ICDs; (2) P wave oversensing is a ventricular sensing problem affecting function of 11% of dual chamber devices with IB lead systems; (3) IB leads are significantly more susceptible to T wave and P wave oversensing than DB leads; and (4) patients with cardiomyopathies are more prone to oversensing than patients with other heart diseases. (PACE 2003; 26[Pt. I]:65–70)     

Far-Field R Wave Oversensing in a Dual Chamber Arrhythmia Management Device: Predisposing Factors and Practical Implications

WERETKA, S., et al. : Far-Field R Wave Oversensing in a Dual Chamber Arrhythmia Management Device: Predisposing Factors and Practical Implications. Initial experience with the Medtronic Jewel 7250, the ICD designed to detect and treat ventricular and supraventricular tachyarrhythmias, is very promising. Its effectiveness, however, depends on sensing performance, which has not yet been systematically examined. The aim of the study was to determine the incidence of, predisposing factors for, and practical implications of far-field R wave oversensing (FFRWOS) in this dual chamber ICD. During a total follow-up of 797 months in 48 patients who had the Jewel 7250, follow-up strip charts, 12-channel Holter recordings and, in particular cases, Holter recordings with intracardiac markers were analyzed for the presence of FFRWOS. FFRWOS was documented in ten (21.3%) patients. Compared to other lead locations, the right atrial appendage lead position was most frequently associated with FFRWOS (  7/27 vs 3/21, P < 0.05  ). Patients with FFRWOS had significantly more treated and nontreated atrial episodes, many of which were judged to have been detected inappropriately. In one case, inappropriate atrial antitachycardia pacing due to R wave oversensing triggered sustained ventricular tachycardia, terminated eventually with a high energy shock. In dual chamber ICDs, FFRWOS may represent a frequent phenomenon possibly leading to serious consequences. For atrial leads, a lateral atrial wall position seems to be preferable. In most cases, FFRWOS can be eliminated by optimization of atrial sensing parameters. Given the possibility of ventricular proarrhythmia with atrial pacing therapy, the capability of ventricular backup defibrillation in respective devices is at least reassuring.     

Effect of Therapeutic Ionizing Radiation on Implantable Electronic Devices: Systematic Review and Practical Guidance

Cardiac implantable electronic devices (CIEDs) have been in use for over 50 years and their therapeutic value is undisputable. With the rapidly aging population, it is estimated that the number of CIEDs will grow dramatically over the next 2 decades. Given these predictions, the topic of management of concomitant conditions associated with older age becomes more relevant than ever. In particular, the number of patients with an implanted CIED diagnosed with cancer is expected to rise by about 70%, from 14 million in 2012 to 22 million within the next 2 decades. Treatment of most of these tumors and tumor metastases requires radiation therapy. However, the necessary high doses of radiation can potentially interact with the function, longevity, and integrity of the CIEDs and/or cause harm to the patient. The impact of an absence of clear therapeutic guidelines for oncology patients with CIEDs who should undergo radiation therapy is vast; and due to the fear of possible complications related to device failure, many of these patients may not be treated adequately to their needs, which can strongly affect their prognosis. This article summarizes the available data on the management of patients with CIEDs undergoing radiotherapy. It systematically presents possible causes and consequences of direct and scattered radiation on CIEDs, highlights possible complications that may occur during this kind of treatment, and provides practical guidance for this challenging real life clinical setting.     

ANTI-LOW-DENSITY LIPOPROTEIN ANTIBODIES IN ALCOHOLICS WITHOUT AND WITH LIVER DISEASE AND IN SOCIAL DRINKERS

Antibodies directed to native and to in-vitro acetaldehyde-modified(ethylated) low-density lipoproteins (LDL) were determined in28 alcoholic subjects divided into two groups: one with do clinicalnor laboratory evidence of liver involvement and the secondwith histologically proven alcohol-related liver disease. Thecontrol group consisted of 18 individuals who drank alcoholsocially. In the individuals with alcoholic liver disease igGreactivity against both native and ethylated LDL was significantlyhigher than in alcoholic individuals without liver injury. Highlevels of IgG reactivity in individuals with alcoholic liverdisease were also observed against malondialdehyde-modified,methylated, acetylated and carbamylated LDL. A selective highanti-ethylated LDL IgG reactivity was observed in 11% of controlsubjects.     

Drug Delivery at the Aortic Valve Tissues of Healthy Domestic Pigs with a Paclitaxel-Eluting Valvuloplasty Balloon

Background: Restenosis occurs invariably within 1 year following balloon valvulopasty in aortic valve stenosis. The mechanism of restenosis seems to involve a dynamic cellular component that could be a target for drug inhibition. We investigated the feasibility of local drug delivery at the aortic valve tissues of healthy pigs with a paclitaxel-eluting balloon.
Methods: Aortic valvuloplasty was performed in eight anesthetized domestic pigs using paclitaxel-eluting balloons (3 μg/mm² balloon surface area). They were assigned to two or four times 15-second balloon inflations and were sacrificed 30 minutes after final balloon inflation.
Results: The aortic annulus to balloon diameter ratio was 1.15 ± 0.07. The mean paclitaxel concentration in the aortic valve leaflets was 0.91 ± 1.36 μg/mL (0.34 ± 0.05 μg/mL in the two-inflation group, 1.48 ± 1.86 μg/mL in the four-inflation group, P = 0.23). The percentage of the total paclitaxel dose recovered in the aortic valve leaflets was 18 ± 11⁻⁶% (13 ± 6⁻⁶% and 25 ± 14⁻⁶% in the two- and four-inflation group, P = 0.16).
Conclusion: Local drug delivery at the aortic valve leaflets of healthy pigs with a paclitaxel-eluting balloon is feasible and concentrations within the therapeutic window are detected 30 minutes after the procedure. The antirestenotic potential of this treatment should be studied.