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1.
Waste Manag ; 24(3): 277-95, 2004.
Article in English | MEDLINE | ID: mdl-15016417

ABSTRACT

The aim of this work is to present the structure and the application of a decision support system (DSS) designed to help decision makers of a municipality in the development of incineration, disposal, treatment and recycling integrated programs. Specifically, within a MSW management system, several treatment plants and facilities can generally be found: separators, plants for production of refuse derived fuel (RDF), incinerators with energy recovery, plants for treatment of organic material, and sanitary landfills. The main goal of the DSS is to plan the MSW management, defining the refuse flows that have to be sent to recycling or to different treatment or disposal plants, and suggesting the optimal number, the kinds, and the localization of the plants that have to be active. The DSS is based on a decision model that requires the solution of a constrained non-linear optimization problem, where some decision variables are binary and other ones are continuous. The objective function takes into account all possible economic costs, whereas constraints arise from technical, normative, and environmental issues. Specifically, pollution and impacts, induced by the overall solid waste management system, are considered through the formalization of constraints on incineration emissions and on negative effects produced by disposal or other particular treatments.


Subject(s)
Conservation of Natural Resources , Decision Support Techniques , Refuse Disposal , Cities , Environmental Pollution/prevention & control , Incineration
2.
J Neural Transm Suppl ; (65): 145-55, 2003.
Article in English | MEDLINE | ID: mdl-12946053

ABSTRACT

The pigmented neurons of the substantia nigra (SN) are typically lost in Parkinson's disease: however the possible relationship between neuronal vulnerability and the presence of neuromelanin (NM) has not been elucidated. Early histological studies revealed the presence of increasing amounts of NM in the SN with aging in higher mammals, showed that NM granules are surrounded by membrane, and comparatively evaluated the pigmentation of SN in different animal species. Histochemical studies showed the association of NM with lipofuscins. However, systematic investigations of NM structure, synthesis and molecular interactions have been undertaken only during the last decade. In these latter studies, NM was identified as a genuine melanin with a strong chelating ability for iron and affinity for compounds such as lipids, pesticides, and MPP+. The affinity of NM for a variety of inorganic and organic toxins is consistent with a postulated protective function for NM. Moreover, the neuronal accumulation of NM during aging, and the link between its synthesis and high cytosolic concentration of catechols suggests a protective role. However, its putative neuroprotective effects could be quenched in conditions of toxin overload.


Subject(s)
Aging/metabolism , Melanins/chemistry , Melanins/metabolism , Nerve Tissue Proteins/chemistry , Nerve Tissue Proteins/metabolism , Neurons/metabolism , Substantia Nigra/metabolism , Humans , Iron Chelating Agents/metabolism , Lipofuscin/metabolism , Melanins/biosynthesis , Nerve Tissue Proteins/biosynthesis , Neurons/pathology , Neuroprotective Agents/metabolism , Parkinson Disease/metabolism
3.
J Neurochem ; 75(6): 2583-9, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11080212

ABSTRACT

Neuromelanin (NM) is a complex polymer pigment found primarily in the dopaminergic neurons of the human substantia nigra. The structure of NM is only partially characterized, and its synthesis pathway remains unknown. We used nuclear magnetic and infrared spectroscopy to examine the structure of human NM isolated from the substantia nigra compared with synthetic dopamine melanins. Biochemical analyses were used to investigate proteinaceous and dopaminergic components in these samples. Following acid hydrolysis of NM samples, small amounts of DOPA, dopamine, and a variety of amino acids were measured. These findings suggest a peptide component in NM structure. NM also appears to contain a variety of unidentified structural components possibly derived from the oxidation of dopamine. Human NM differs structurally from synthetic dopamine melanin, but both human and synthetic NM include an aromatic backbone. It is interesting that both human NM and synthetic melanin also contain a large proportion of aliphatic structures. Our results suggest that NM is a more complex pigment than synthetic dopamine melanin formed via dopamine autoxidation alone.


Subject(s)
Dopamine/chemistry , Melanins/chemistry , Substantia Nigra/chemistry , Adult , Aged , Aged, 80 and over , Amino Acids/analysis , Dihydroxyphenylalanine/analysis , Germany , Humans , Hydrolysis , Italy , Magnetic Resonance Spectroscopy , Middle Aged , Molecular Structure
4.
J Neurochem ; 74(4): 1758-65, 2000 Apr.
Article in English | MEDLINE | ID: mdl-10737635

ABSTRACT

Neuromelanin was isolated from human substantia nigra using different procedures. In the pigment isolated by any of these procedures a peptide component covalently bound to the melanic structure was found, as shown by treatment with reagents known to eliminate noncovalently bound proteins. The amino acid content of such a peptide component was reproducible and corresponded to approximately 15% of the neuromelanin weight. Neuromelanin also showed the ability to absorb specifically lipid molecules, approximately 20% of its weight, and among these lipids cholesterol was identified, constituting approximately 5% of the total lipid mixture. A synthetic melanin, incubated with putamen homogenate, bound tissue peptides with an amino acid content quite close to that of neuromelanin. The same synthetic melanin adsorbed a lower amount of lipids from the putamen homogenate compared with neuromelanin. The sulfur content of neuromelanin was also reproducible even using different isolation procedures. A nonpigmented tissue like corpus callosum was used as a control and extracted by the method used for neuromelanin isolation; a total elimination of tissue components was found, thus demonstrating the capability of the reported procedures to isolate neuromelanin alone. The presence of a peptide component in the neuromelanin structure and the selective affinity for lipid molecules suggest new aspects of the functional role and metabolic pathway of neuromelanin.


Subject(s)
Lipid Metabolism , Melanins/metabolism , Neuropeptides/metabolism , Substantia Nigra/metabolism , Aged , Aged, 80 and over , Amino Acids/metabolism , Corpus Callosum/chemistry , Corpus Callosum/metabolism , Endopeptidase K , Humans , Magnetic Resonance Spectroscopy , Melanins/analysis , Melanins/pharmacology , Middle Aged , Parkinson Disease/metabolism , Protein Binding/drug effects , Protein Binding/physiology , Protons , Substantia Nigra/chemistry , Sulfur/analysis
5.
J Med Chem ; 42(12): 2112-24, 1999 Jun 17.
Article in English | MEDLINE | ID: mdl-10377217

ABSTRACT

A new set of phthalein derivatives stemming from the lead compound, phenolphthalein, were designed to specifically complement structural features of a bacterial form of thymidylate synthase (Lactobacillus casei, LcTS) versus the human TS (hTS) enzyme. The new compounds were screened for their activity and their specificity against TS enzymes from different species, namely, L. casei (LcTS), Pneumocystis carinii (PcTS), Cryptococcus neoformans (CnTS), and human thymidylate synthase (hTS). Apparent inhibition constants (Ki) for all the compounds against LcTS were determined, and inhibition factors (IF, ratio between the initial rates of the enzymatic reaction in the presence and absence of each inhibitor) against each of the four TS species were measured. A strong correlation was found between the two activity parameters, IF and Ki, and therefore the simpler IF was used as a screening factor in order to accelerate biological evaluation. Compounds 5b, 5c, 5ba, and 6bc showed substantial inhibition of LcTS while remaining largely inactive against hTS, illustrating for the first time remarkable species specificity among TSs. Due to sequence homology between the enzymes, several compounds also showed high activity and specificity for CnTS. In particular, 3-hydroxy-3-(3-chloro-4-hydroxyphenyl)-6-nitro-1H, 3H-naphtho[1,8-c,d]pyran-1-one (6bc) showed an IF < 0.04 for CnTS (Ki = 0.45 microM) while remaining inactive in the hTS assay at the maximum solubility concentration of the compound (200 microM). In cell culture assays most of the compounds were found to be noncytotoxic to human cell lines but were cytotoxic against several species of Gram-positive bacteria. These results are consistent with the enzymatic assays. Intriguingly, several compounds also had selective activity against Cr. neoformans in cell culture assay. In general, the most active and selective compounds against the Gram-positive bacteria were those designed and found in the enzyme assay to be specific for LcTS versus hTS. The original lead compound was least selective against most of the cell lines tested. To our knowledge these compounds are the first TS inhibitors selective for bacterial TS with respect to hTS.


Subject(s)
Anti-Infective Agents/chemical synthesis , Chlorophenols/chemical synthesis , Chromones/chemical synthesis , Enzyme Inhibitors/chemical synthesis , Thymidylate Synthase/antagonists & inhibitors , Anti-Bacterial Agents , Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Cell Line , Chlorophenols/chemistry , Chlorophenols/pharmacology , Chromones/chemistry , Chromones/pharmacology , Cryptococcus neoformans/enzymology , Crystallography, X-Ray , Drug Design , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Gram-Positive Bacteria/drug effects , Humans , Lacticaseibacillus casei/enzymology , Models, Molecular , Phenolphthalein/chemistry , Pneumocystis/enzymology , Species Specificity , Structure-Activity Relationship
6.
Pacing Clin Electrophysiol ; 21(3): 528-35, 1998 Mar.
Article in English | MEDLINE | ID: mdl-9558683

ABSTRACT

The composition of the excitable gap (EG) in common atrial flutter (AF1) was determined before and during infusion of procainamide (PA) in 9 patients (6 men and 3 women; age 70 +/- 7 years). The EG was determined by introducing a premature stimulus after every 20th AF1 complex detected using a quadripolar electrode catheter placed just above the tricuspid valve. Diastole was scanned in 2- to 4-ms decrements to the atrial effective refractory period (ERP). The relationship between the coupling interval and the return cycle length (CL) determined a reset-response curve (RRC), which described the EG. PA (15 mg/kg) was administered during AF1 over 30 minutes and RRC was repeated at maximum AF1 CL. PA prolonged AF1 CL from 227 +/- 29 to 296 +/- 62 ms (P < 0.01) but did not terminate AF1. ERP during AF1 prolonged from 169 +/- 24 to 219 +/- 41 ms (P < 0.01). Control EG was 57 +/- 16 ms or 25% +/- 6% of AF1 CL and on PA EG was 77 +/- 30 ms (P = 0.01), which was still 26% +/- 7% of the CL. Without drug, RRC was mixed in eight cases demonstrating an EG composed of fully excitable tissue (10 +/- 4 ms or 19% +/- 10% of the EG) and partially refractory tissue (48 +/- 18 ms). PA did not change the duration of the fully excitable region (13 +/- 10 ms or 19% +/- 15% of EG). Peak PA plasma concentration was 47 +/- 20 mumol/L. PA prolonged AF1 CL, ERP, and EG duration but did not change the proportion of AF1 CL occupied by the EG. The persistance of fully excitable tissue at the head of the wavefront in the presence of PA may largely explain its inefficacy in the acute termination of common AF1.


Subject(s)
Anti-Arrhythmia Agents/therapeutic use , Atrial Flutter/drug therapy , Procainamide/therapeutic use , Aged , Atrial Flutter/blood , Atrial Flutter/physiopathology , Cardiac Catheterization , Electrocardiography , Female , Follow-Up Studies , Heart Conduction System/drug effects , Heart Conduction System/physiopathology , Heart Rate/drug effects , Humans , Male , Middle Aged , Treatment Outcome
7.
Pacing Clin Electrophysiol ; 20(12 Pt 1): 2882-92, 1997 Dec.
Article in English | MEDLINE | ID: mdl-9455747

ABSTRACT

Inappropriate shocks can complicate cardioverter defibrillator therapy. Among solutions proposed to avoid oversensing are algorithms to reduce inappropriate detection of atrial fibrillation (AF) or sinus tachycardia. In patients not on antiarrythmic drugs, an interval stability criterion of 40 ms has been validated with the Medtronic PCD to discriminate ventricular tachycardia (VT) from AF. With this algorithm, VT is considered stable if no interval varies from one of the three preceding intervals by more than 40 ms. If an interval does not fulfill this criterion, the VT event counter is reset to zero. The aim of this study was to investigate the incidence of underdetection when this criterion is applied in patients treated with antiarrhythmic drugs. We studied 132 sustained monomorphic VTs induced in 42 patients during 101 electrophysiological studies (EPS). EPS were performed without treatment (group I, 24 patients, 44 VTs); on Class Ia drug (group II, 17 patients, 24 VTs); Class Ic drug (group III, 22 patients, 39 VTs); or sotalol (group IV, 17 patients, 25 VTs). The endocardial electrogram of all VT episodes was digitized and the stability algorithm was applied. The reset arrhythmias were distributed among no delay, small, moderate (< 10 s) and important (> 15 s) delay in VT detection. The relation between drug use and reset was analyzed. Reset was found in 86 (65%) of induced VTs. No difference in heart rate or induction mode was shown between reset and nonreset VTs. There was a significative association between drug use and reset probability (Chi2 significantly different, P < 0.05). In patients treated with Class Ic drugs, the probability of finding an important delay in VT detection was 12.5% versus 0% in nontreated patients or in patients treated with sotalol. We conclude that a stability criterion of 40 ms is probably safe in nontreated patients but should be used with caution in patients treated with antiarrhythmics, especially in the presence of Class Ic drugs.


Subject(s)
Anti-Arrhythmia Agents/therapeutic use , Tachycardia, Ventricular/diagnosis , Adult , Aged , Algorithms , Atrial Fibrillation/diagnosis , Cardiac Catheterization , Defibrillators, Implantable , Diagnosis, Differential , Electrophysiology , Female , Humans , Male , Middle Aged , Probability , Retrospective Studies , Sensitivity and Specificity , Tachycardia, Ventricular/drug therapy , Tachycardia, Ventricular/physiopathology
8.
Biochemistry ; 35(13): 3944-9, 1996 Apr 02.
Article in English | MEDLINE | ID: mdl-8672425

ABSTRACT

The conserved Asn 229 of thymidylate synthase (TS) forms a cyclic hydrogen bond network with the 3-NH and 4-O of the nucleotide substrate 2'-deoxyuridine 5'-monophosphate (dUMP). Asn 229 is not essential for substrate binding or catalysis [Liu, l., & Santi, D. B. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 8604-8608] but is a major determinant in substrate specificity [Liu, l., & Santi, D. V. (1993) Biochemistry 32, 9263-9267]. 3-Methyl-dUMP (3-MedUMP) is neither a substrate nor an inhibitor of wild type TS but is converted to 3-methyl 2'-deoxythymidine 5'-monophosphate by many TS Asn 229 mutants. Some of the Asn 229 mutants (N229C, -I, -M, -A, and -V) have kcat values for 3-MedUMP methylation which are up to about 20% of that for wild type TS-catalyzed methylation of dUMP, and some mutants (N229C and -A) catalyze methylation of 3-MedUMP more efficiently than that of dUMP. Mutants with hydrophobic side chains tended to be more active in catalysis of methylation of 3-MedUMP than those with hydrophilic side chains. The ability of 3-MedUMP to serve as a substrate for Asn 229 mutants shows that the active form of dUMP involves the neutral pyrimidine base and that ionization of the 3-NH group does not occur in the course of catalysis. In contrast to the negligible binding of 3-MedUMP to wild type TS, both 3-MedUMP and dUMP showed similar Km values with the Asn 229 mutants, suggesting similar binding affinities to the mutants. The X-ray crystal structure of the TS N229C--3-MedUMP complex showed that the side chain of Cys 229 was rotated away from the pyrimidine ring to allow placement of a water molecule and the 3-methyl group of 3-MedUMP in the active site. Our results suggest that the inability of 3-MedUMP to undergo methylation by wild type TS is due to its inability to bind to the enzyme, which in turn is simply a result of steric interference of the 3-methyl group with the side chain of Asn 229.


Subject(s)
Asparagine , Deoxyuracil Nucleotides/metabolism , Point Mutation , Protein Conformation , Thymidylate Synthase/chemistry , Thymidylate Synthase/metabolism , Amino Acid Sequence , Binding Sites , Chromatography, High Pressure Liquid , Conserved Sequence , Crystallization , Crystallography, X-Ray , Hydrogen Bonding , Kinetics , Lacticaseibacillus casei/enzymology , Methylation , Models, Molecular , Mutagenesis, Site-Directed , Recombinant Proteins/chemistry , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , Substrate Specificity , Thymidylate Synthase/isolation & purification
9.
Can J Cardiol ; 11(10): 891-4, 1995 Nov.
Article in English | MEDLINE | ID: mdl-7489527

ABSTRACT

OBJECTIVE: To compare the diagnostic yield of transtelephonic monitoring (TTM) with Holter monitoring in patients presenting possibly arrhythmogenic symptoms. DESIGN: A prospective comparison of Holter monitoring with TTM performed sequentially in all subjects. SETTING: Tertiary arrhythmia clinic at Hôpital du Sacré-Coeur de Montréal, Montréal, Québec. PATIENTS: One hundred consecutive patients (34 men and 66 women, mean +/- SD age 55 +/- 16 years) presenting over a two-year period for diagnosis of intermittent palpitations and/or syncope/dizziness. INTERVENTIONS: Subjects first underwent 24 h Holter monitoring and then were provided with TTM for 25 +/- 13 days, with instructions to record during symptomatic episodes and subsequently to transmit the recording at their convenience. MAIN RESULTS: Holter monitoring documented arrhythmia in 30 patients whereas TTM identified arrhythmia in 21. TTM was most useful in excluding arrhythmia during symptoms (34 patients) versus Holter (two patients). Neither method was useful in diagnosing syncope. Frequency of occurrence of palpitations did not predict which method would most likely yield a diagnosis but palpitations lasting longer than 2 mins were likely to be diagnosed by TTM. CONCLUSIONS: Holter and TTM are complementary studies whose combined use increases the diagnostic yield of arrhythmia. Further, TTM is of greatest use in excluding arrhythmia during intermittent symptoms.


Subject(s)
Arrhythmias, Cardiac/diagnosis , Electrocardiography, Ambulatory , Electrocardiography , Monitoring, Physiologic/methods , Telephone , Female , Humans , Male , Middle Aged , Prospective Studies
10.
Pharmacol Biochem Behav ; 51(1): 29-35, 1995 May.
Article in English | MEDLINE | ID: mdl-7617729

ABSTRACT

Bilateral electrolytic lesions of the red nucleus (RN) of rat decreased apomorphine-induced stereotypy, increased haloperidol-induced catalepsy, reversed apomorphine-induced hypothermy, decreased spiroperidol-induced hypomotility, and BHT-920-induced yawning and penile erection episodes. Moreover, apomorphine antagonized haloperidol-induced catalepsy in the RN-lesioned group. The lesioned animals revealed depleted levels of dopamine and its metabolites in brain areas as well as serotonin and its metabolite. The brain areas analyzed were pyriform cortex, substantia nigra, striatum, enthorinal cortex, and cerebellum. Based on these results, it is very likely that the RN has a complex role in the behavior of rats as a consequence of dopaminergic-serotoninergic changes in the central nervous system.


Subject(s)
Behavior, Animal/physiology , Brain Chemistry/physiology , Red Nucleus/physiology , Animals , Apomorphine/pharmacology , Azepines/pharmacology , Behavior, Animal/drug effects , Body Temperature/drug effects , Brain Chemistry/drug effects , Catalepsy/chemically induced , Dopamine/metabolism , Dopamine Agonists/pharmacology , Haloperidol/pharmacology , Male , Rats , Rats, Wistar , Red Nucleus/anatomy & histology , Serotonin/metabolism , Spiperone/pharmacology , Stereotyped Behavior/drug effects
11.
J Biol Chem ; 269(17): 12444-6, 1994 Apr 29.
Article in English | MEDLINE | ID: mdl-8175650

ABSTRACT

We have combined site-directed mutagenesis with the technique of reversible unfolding and subunit dissociation to construct heterodimeric thymidylate synthases that lack the C-terminal valine from only one subunit of the dimer. Removal of this residue either from both subunits of the dimer by mutagenesis (V316Am mutation) or from only one subunit by treatment with carboxypeptidase has been reported to result in an inactive enzyme (Carreras, C. W., Climie, S. C., and Santi, D. V. (1992) Biochemistry 31, 6038-6044; Aull, J.L., Loeble, R.B., and Dunlap. R.B. (1974) J. Biol. Chem. 249, 1167-1172). Arg-178 is an essential active site residue of thymidylate synthase that is donated from the opposing subunit of the dimer. The R178F-V316Am heterodimer was formed by the unfolding and refolding of a mixture of inactive R178F and V316Am mutants. This enzyme has one intact active site and was found to have half of the activity and the same Km values as wild-type thymidylate synthase that was unfolded and refolded as a control. We have also formed the V316Am-WT heterodimer and report that this heterodimeric enzyme is also active, has a kcat value that is approximately half of that of the wild-type thymidylate synthase dimer, and binds substrate and cofactor with Km values similar to those of the wild-type enzyme.


Subject(s)
Sequence Deletion , Thymidylate Synthase/metabolism , Amino Acid Sequence , Binding Sites , Lacticaseibacillus casei/enzymology , Mutagenesis, Site-Directed , Protein Folding , Thymidylate Synthase/genetics
12.
J Nucl Med ; 32(10): 1961-5, 1991 Oct.
Article in English | MEDLINE | ID: mdl-1833517

ABSTRACT

Technetium-99m-sestamibi, a new myocardial perfusion imaging agent, does not show significant or rapid myocardial redistribution following its intravenous injection at stress. The purpose of this study was to evaluate the myocardial clearance of 99mTc-sestamibi and ischemic/normal wall ratios at 1 hr and at 3 hr after injection at stress in patients with significant coronary artery disease. Twenty-five patients with ischemic defects on 201Tl scans (n = 15) and/or significant disease on coronary angiogram (n = 18) were prospectively studied. Planar images were obtained at 65 and at 190 min after an injection at stress of 20-25 mCi of 99mTc-sestamibi. A rest study was performed 1-6 days later. Ischemic/normal wall ratios were 0.73 +/- 0.10 and 0.83 +/- 0.12 (p less than 0.05) at 1 and 3 hr, respectively (0.98 +/- 0.15 at rest). Myocardial washout was 26% +/- 12% for normal walls and 15% +/- 8% for ischemic walls (p less than 0.001). Segmental analysis showed 48 and 46 ischemic segments at 1 and 3 hr, respectively. In conclusion, although only a few ischemic segments were missed at 3 hr, significantly lower ischemic/normal wall ratios were found at 1 hr. Faster myocardial washout from normal walls is responsible for the partial reduction of this ratio.


Subject(s)
Coronary Disease/diagnostic imaging , Heart/diagnostic imaging , Organotechnetium Compounds , Coronary Disease/epidemiology , Evaluation Studies as Topic , Exercise Test , Female , Humans , Male , Middle Aged , Nitriles , Prospective Studies , Radionuclide Imaging , Technetium Tc 99m Sestamibi , Time Factors
13.
J Chromatogr ; 567(2): 425-32, 1991 Jul 05.
Article in English | MEDLINE | ID: mdl-1939474

ABSTRACT

A reversed-phase high-performance liquid chromatographic method with electrochemical detection for the quantitation of diclofenac and metabolites in plasma and cerebrospinal fluid has been developed. Pirprofen is employed as internal standard. Samples are extracted with C18 solid-phase extraction columns and eluted with methanol. Oxidation potentials for detection were established by constructing voltammograms for each compound. In the concentration range found in human studies, the intra-day coefficients of variation were always less than 6%. The procedure allows the simultaneous determination of diclofenac and its four major metabolites with very low detection limits (less than 1 ng/ml), which were sufficient even for kinetic studies in cerebrospinal fluid.


Subject(s)
Diclofenac/blood , Diclofenac/cerebrospinal fluid , Biotransformation , Chromatography, High Pressure Liquid , Diclofenac/metabolism , Electrochemistry , Humans , Oxidation-Reduction , Reference Standards , Spectrophotometry, Ultraviolet
14.
Am Heart J ; 120(4): 855-63, 1990 Oct.
Article in English | MEDLINE | ID: mdl-2220538

ABSTRACT

The effects of class la antiarrhythmic drugs (procainamide, quinidine) on the right ventricular effective refractory period (VERP) and intraventricular conduction time were assessed during serial invasive electrophysiologic studies for sustained monomorphic ventricular tachycardia (VT). In 47 patients with remote myocardial infarction, sustained VT was inducible by up to two extrastimuli after the basic drive at one of two basic cycle lengths at the right ventricular apex. With oral drug administration, sustained VT was no longer inducible (group I) in 27 patients but remained inducible (group II) in 20 with the same protocol. Class la drugs prolonged the VERP in both groups, but there was greater lengthening when drugs were effective (e.g., +32 +/- 14 msec in group I vs +12 +/- 19 msec in group II; p less than 0.005, basic cycle length 600 to 700 msec). Prolongation of the VERP by greater than 30 msec had an 88% positive predictive value for prevention of sustained VT induction. In all except one patient in group I, drugs prolonged the VERP such that the coupling intervals that had resulted in sustained VT induction under control conditions were no longer attainable. In contrast, conduction time through the ventricle (surface QRS duration) in sinus rhythm and during right ventricular pacing was prolonged similarly regardless of efficacy (e.g., +33 +/- 21 msec vs +27 +/- 27 msec at a cycle length of 400 msec). The presence of similar plasma levels of drug did not imply equivalent prolongation of the VERP in the two groups. These results suggest that greater prolongation of the VERP by oral procainamide or quinidine correlates with drug efficacy against VT induction and is a better predictor of drug effect than achievement of a "therapeutic plasma level."


Subject(s)
Anti-Arrhythmia Agents/pharmacology , Tachycardia/drug therapy , Ventricular Function/drug effects , Adult , Aged , Aged, 80 and over , Anti-Arrhythmia Agents/therapeutic use , Electrocardiography , Electrophysiology , Female , Humans , Male , Middle Aged , Procainamide/pharmacology , Procainamide/therapeutic use , Quinidine/pharmacology , Quinidine/therapeutic use
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