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Biomedical subjects

J L Anderson

Publications and source records attributed to J L Anderson.

At least 163 records · Page 9Linked to original sources
PubMed1992

Correlation of symptoms with occurrence of paroxysmal supraventricular tachycardia or atrial fibrillation: a transtelephonic monitoring study. The Flecainide Supraventricular Tachycardia Study Group.

The purpose of this study was to determine whether symptoms recorded at the time of transtelephonic ECG monitoring (TTEM) correlate with attacks of paroxysmal supraventricular tachycardia (PSVT) or paroxysmal atrial fibrillation (PAF). We studied 113 patients with these arrhythmias who made a total of 3319 TTEM calls during their participation in double-blind, placebo-controlled, crossover, multicenter trials of flecainide therapy. Among 49 patients with PSVT, 62.7% of symptomatic calls were associated with ECG-documented PSVT as compared with 6.8% of asymptomatic calls (p less than 0.001). Similarly, among 69 patients with PAF, 69% of symptomatic calls were associated with ECG-documented PAF compared with 10.6% of asymptomatic calls (p less than 0.001). Both in patients with PSVT and PAF, an attack of PSVT or PAF could be documented by ECG in more than 70% of the calls when patients complained of tachycardia, increased sweating, or dyspnea. The sensitivity of a symptomatic call was 91% for PSVT and 89% for PAF, and it was not influenced by flecainide therapy. However, flecainide therapy was associated with a decrease in the positive predictive value of symptomatic TTEM calls and an increase in false positive TTEM transmissions. We conclude that in patients with symptomatic PSVT or PAF, there is a temporal relationship between symptoms and the occurrence of ECG-documented attacks of PSVT or PAF. However, sole reliance should not be placed on the presence or absence of symptoms as a measure of drug failure or efficacy, and it is important to document the cardiac rhythm by TTEM at the time symptoms are recorded.

Atrial Fibrillation↗
PubMed1992

A model of pulsatile flow in a uniform deformable vessel.

Simulations of blood flow in natural and artificial conduits usually require large computers for numerical solution of the Navier-Stokes equations. Often, physical insight into the fluid dynamics is lost when the solution is purely numerical. An alternative to solving the most general form of the Navier-Stokes equations is described here, wherein a functional form of the solution is assumed in order to simplify the required computations. The assumed forms for the axial pressure gradient and velocity profile are chosen such that conservation of mass is satisfied for fully established pulsatile flow in a straight, deformable vessel. The resulting equations are cast in finite-difference form and solved explicitly. Results for the limiting cases of rigid wall and zero applied pressure are found to be in good agreement with analytical solutions. Comparison with the experimental results of Klanchar et al. [Circ. Res. 66, 1624-1635 (1990]) also shows good agreement. Application of the model to realistic physiological parameter values provides insight as to the influence of the pulsatile nature of the flow field on wall shear development in the presence of a moving wall boundary. Specifically, the model illustrates the dependence of flow rate and shear rate on the amplitude of the vessel wall motion and the phase difference between the applied pressure difference and the oscillations of the vessel radius. The present model can serve as a useful tool for experimentalists interested in quantifying the magnitude and character of velocity profiles and shearing forces in natural and artificial biologic conduits.

Animals↗
PubMed1992

Does thrombolysis in myocardial infarction (TIMI) perfusion grade 2 represent a mostly patent artery or a mostly occluded artery? Enzymatic and electrocardiographic evidence from the TEAM-2 study. Second Multicenter Thrombolysis Trial of Eminase in Acute Myocardial Infarction.

One measure of the success of thrombolysis is the early patency status of the infarct-related coronary artery. The Thrombolysis in Myocardial Infarction (TIMI) study group designated patency grades 0 (occluded) or 1 (minimal perfusion) as thrombolysis failure and grade 2 (partial perfusion) or 3 (complete perfusion) as success. To evaluate their true functional significance, perfusion grades were compared with enzymatic and electrocardiographic (ECG) indexes of myocardial infarction in 359 patients treated within 4 h with anistreplase (APSAC) or streptokinase. Serum enzymes and ECGs were assessed serially. Patency was determined at 90 to 240 min (median 2.1 h) and graded by an observer who had no knowledge of patient data. Results for the two drug arms were similar and combined. Distribution of patency was grade 0 = 20%, n = 72; grade 1 = 8% n = 27; grade 2 = 16%, n = 58 and grade 3 = 56%, n = 202. Interventions were performed after angiography but within 24 h in 51% (n = 37), 70% (n = 19), 41% (n = 24) and 14% (n = 28) of patients with grades 0, 1, 2 and 3, respectively. Outcomes were compared among the four patency groups by the orthogonal contrast method. Patients with perfusion grade 2 did not differ significantly from those with grade 0 or 1 in enzymatic peaks, time to peak activity and evolution of summed ST segments, Q waves and R waves (contrast 2). Conversely, comparisons of patients with grade 3 perfusion with those with grades 0 to 2 yielded significant differences for enzymatic peaks and time to peak activity for three of the four enzymes (p = 0.02 to 0.0001) and ECG indexes of myocardial infarction (p = 0.02 to 0.0001) (contrast 3). Thus, patients with grade 2 flow have indexes of myocardial infarction similar to those in patients with an occluded artery (grades 0 and 1 flow). Only early grade 3 flow results in a significantly better outcome than that of the other grades. Because early achievement of grade 2 flow does not appear to lead to optimal myocardial salvage, the frequency of achieving grade 3 perfusion alone may best measure the reperfusion success of thrombolytic therapy.

Anistreplase↗
PubMed1992

Anistreplase versus alteplase in acute myocardial infarction: comparative effects on left ventricular function, morbidity and 1-day coronary artery patency. The TEAM-3 Investigators.

OBJECTIVES: This double-blind, randomized, multicenter trial was designed to compare the effects of treatment with anistreplase (APSAC) and alteplase (rt-PA) on convalescent left ventricular function, morbidity and coronary artery patency at 1 day in patients with acute myocardial infarction. BACKGROUND: Anistreplase (APSAC) is a new, easily administered thrombolytic agent recently approved for treatment of acute myocardial infarction. Alteplase (rt-PA) is a rapidly acting, relatively fibrin-specific thrombolytic agent that is currently the most widely used agent in the United States. METHODS: Study entry requirements were age less than or equal to 75 years, symptom duration less than or equal to 4 h, ST segment elevation and no contraindications. The two study drugs, APSAC, 30 U/2 to 5 min, and rt-PA, 100 mg/3 h, were each given with aspirin (160 mg/day) and intravenous heparin. Prespecified end points were convalescent left ventricular function (rest/exercise), clinical morbidity and coronary artery patency at 1 day. A total of 325 patients were entered, stratified into groups with anterior (37%) or inferior or other (63%) acute myocardial infarction, randomized to receive APSAC or rt-PA and followed up for 1 month. RESULTS: At entry, patient characteristics in the two groups were balanced. Convalescent ejection fraction at the predischarge study averaged 51.3% in the APSAC group and 54.2% in the rt-PA group (p less than 0.05); at 1 month, ejection fraction averaged 50.2% versus 54.8%, respectively (p less than 0.01). In contrast, ejection fraction showed similar augmentation with exercise at 1 month after APSAC (+4.3% points) and rt-PA (+4.6% points), and exercise times were comparable. Coronary artery patency at 1 day was high and similar in both groups (APSAC 89%, rt-PA 86%). Mortality (APSAC 6.2%, rt-PA 7.9%) and the incidence of other serious clinical events, including stroke, ventricular tachycardia, ventricular fibrillation, heart failure within 1 month, recurrent ischemia and reinfarction were comparable in the two groups; and mechanical interventions were applied with equal frequency. A combined clinical morbidity index was determined and showed a comparable overall outcome for the two treatments. CONCLUSIONS: Convalescent rest ejection fraction was high after both therapies but higher after rt-PA; other clinical outcomes, including exercise function, morbidity index, and 1-day coronary artery patency, were favorable and comparable after APSAC and rt-PA.

Anistreplase↗
PubMed1992

Coffee consumption and cause-specific mortality. Association with age at death and compression of mortality.

The relationship between reported coffee consumption and specific causes of death was examined in 9484 males enrolled in the Adventist Mortality Study in 1960 and followed through 1985. Coffee consumption was divided into three levels: less than 1 cup per day, 1-2 cups per day, and greater than or equal to 3 cups per day. Approximately one third of the subjects did not drink coffee. Cause-specific mortality rates were compared using survival analysis including Cox's proportional hazard model, and controlling for potential confounders such as body mass index, heart disease and hypertension at baseline, race, physical activity, marital status, educational level, smoking history, and dietary pattern. Inclusion of interaction terms between coffee consumption and attained age as time-dependent covariates allowed the hazard ratio to vary with age. Univariate analyses showed a statistically significant association (p less than 0.05) for coffee consumption and mortality for most endpoints. Multivariate analyses showed a small but statistically significant association between coffee consumption and mortality from ischemic heart disease, other cardiovascular diseases, all cardiovascular diseases, and all causes of death. For the major causes of death, the hazard ratios decreased from about 2.5 at 30 years of age to 1.0 around 95 years of age. These results indicate that abstinence from coffee leads to compression of mortality rather than an increase in lifespan.

Adult↗
PubMed1992

Inhibition of benzo[a]pyrene-induced bone marrow micronuclei formation by diallyl thioethers in mice.

Diallyl thioethers (DATEs), naturally occurring compounds present in garlic, were investigated for their putative ability to inhibit benzo[a]pyrene-induced genotoxicity in ICR and C3H strains of mice. The mouse bone marrow micronucleus assay was used as an indicator of in vivo genotoxicity. A dose of 0.67 mmol total DATEs/kg body weight inhibited formation of micronucleated polychromatic erythrocytes (MPCEs) by 24%, and 0.33 mmol DATEs inhibited formation of MPCEs by 45%. Possibly the toxicity of DATEs accounted for less inhibition with the higher dose. Formation of MPCEs were inhibited only slightly by DATEs in C3H mice. These results indicate that the mouse bone marrow micronucleus assay can be used to identify organosulfur components of garlic that inhibit genotoxicity.

Allyl Compounds↗
PubMed1992

Pattern-reversal electroretinographic acuity in untreated eyes with subfoveal neovascular membranes.

To define further the natural history of visual loss in eyes with age-related macular degeneration (ARMD) complicated by a subfoveal neovascular membrane, pattern-reversal electroretinograms (ERGs) were obtained from patients randomized to no treatment at the Dallas center of the Macular Photocoagulation Study (Texas Retina Associates). Study eyes (n = 20) were tested during the initial visit and at 3-, 6-, and 12-month follow-up visits. Responses were obtained to phase-alternating checkerboards of varying check size. Extrapolation of the best-fit regression line relating the logarithm of the check size to amplitude was used to determine "retinal" acuity (log MAR). The pattern-reversal ERG acuity rating (100 - [50 x log MAR]) was derived for each visit. Pattern-reversal ERG acuity ratings for all patients across visits were correlated significantly with visual acuity ratings derived from the Bailey-Lovie chart (r = 0.61, P less than 0.001) and inversely related to neovascular membrane area (r = -0.55, P less than 0.001). During 1 yr of follow-up, pattern-reversal acuity ratings dropped from 53 to 12, corresponding to an average decrease of approximately 0.2 octaves/month. These results suggest that the pattern-reversal ERG, which samples the resolving power of the central 20 degrees, is a sensitive index of visual loss in age-related macular degeneration.

Aged↗
PubMed1991

Overview of patency as an end point of thrombolytic therapy.

Underlying the use of thrombolytic therapy is the hypothesis that reestablishment and maintenance of coronary blood flow (coronary patency) are the primary mechanisms of therapeutic benefit in patients with acute myocardial infarction. Early achievement and maintenance of adequate coronary blood flow (patency) in the infarct-related artery are the primary goals of thrombolytic therapy. One third of patients may achieve spontaneous patency within a few days following acute myocardial infarction. When antithrombotic therapy (i.e., heparin) is administered, this rate increases to greater than 50%, but patency is achieved only gradually and mortality reductions comparable to thrombolytic therapy are not achieved. After administration of a thrombolytic agent, early (90-minute) patency rates are greater with alteplase or anistreplase than with streptokinase. However, patency rates for alteplase decline by 10-30% if intravenous heparin is not given concurrently. When patency is assessed greater than 24 hours following thrombolytic therapy, no significant difference exists among the agents. A single angiographic observation of the artery at 90 minutes, although useful, may be inadequate to distinguish among the beneficial clinical effects of different thrombolytic regimens. The overall reperfusion or patency profile is probably a better basis for assessing relative benefits. Intravenous thrombolytic regimens that are increasingly effective in rapidly achieving and maintaining coronary patency are now available and in further development.

Coronary Vessels↗
PubMed1991

Effects of early thrombolytic therapy (anistreplase versus streptokinase) on enzymatic and electrocardiographic infarct size in acute myocardial infarction. TEAM-2 Investigators.

The effects of thrombolytic therapy on enzymatic and electrocardiographic indexes of myocardial infarction were examined in 370 patients who were enrolled within 4 hours of onset of symptoms and were randomized to blinded therapy with intravenous anistreplase (30 U/5 min, n = 188) or streptokinase (1.5 million IU/1 hour, n = 182). Creatine kinase and its MB isoenzyme were initially measured every 4 to 6 hours, and lactic dehydrogenase (LDH) and its cardiac isoenzyme (LDH-1) every 8 to 12 hours. Electrocardiograms were obtained before, and at 90 minutes and 8 hours after starting thrombolysis, and on discharge. Enzymatic and electrocardiographic measures of infarction were compared between drug treatment and patency groups. Early patency was associated with significant reductions in peak values for each of 4 cardiac enzymes (averaging 21 to 25%, p less than 0.01 to 0.001), even though later rescue procedures were often used in the nonpatient group; times to peaks were also reduced for 3 of the enzymes. Treatment with anistreplase was associated with enzymatic peaks that tended to be lower than with streptokinase (6 to 16%), approaching or reaching significance for LDH (p less than or equal to 0.07) and LDH-1 (p less than or equal to 0.04); times to peaks were similar. Early patency favorably affected electrocardiographic indexes. Summed ST-segment elevations resolved more rapidly (p less than or equal to 0.04), summed Q-wave amplitude was reduced by 32% (p less than or equal to 0.01), and total QRS infarct score on discharge was 22% less (p less than or equal to 0.006) in those achieving early patency. Small differences in electrocardiographic indexes between the 2 drug treatment groups were not significant. These results support use of early reperfusion to reduce infarct size in acute myocardial infarction with administration of streptokinase and anistreplase.

Anistreplase↗
PubMed1991

Older age and elevated blood pressure are risk factors for intracerebral hemorrhage after thrombolysis.

Intracerebral hemorrhage is an important concern after thrombolytic therapy for acute myocardial infarction, but risk factors are controversial. Accordingly, we assessed risk factors in 107 treated patients of whom 4 had intracerebral hemorrhage. Intracerebral hemorrhage occurred at a mean of 25 hours (range 3.5 to 48) after therapy and was fatal in 2 patients. Significant differences were found between patients with and without intracerebral hemorrhage for age (77 +/- 7 vs 62 +/- 11 years, p less than or equal to 0.01), and initial (161 +/- 23 vs 135 +/- 23 mm Hg, p less than or equal to 0.03) and maximal (171 +/- 30 vs 146 +/- 20, p less than or equal to 0.02) systolic blood pressures. Initial and maximal diastolic blood pressures also tended to be higher (101 +/- 25 vs 86 +/- 16, p less than or equal to 0.07; 104 +/- 24 vs 90 +/- 13, p less than or equal to 0.06). Differences did not achieve significance for comparisons of gender, height, weight, site of infarction, time to therapy, specific thrombolytic agent used, concomitant therapy, interventions and partial thromboplastin time. It is concluded that age (greater than or equal to 70 years) and elevated blood pressure (greater than or equal to 150/95 mm Hg) are important risk factors for intracerebral hemorrhage. The overall balance of benefit and risk of thrombolysis should continue to be assessed by large mortality trials.

Age Factors↗
PubMed1991

Usefulness of d, I sotalol for suppression of chronic ventricular arrhythmias.

Sotalol is a unique beta-blocking drug, possessing significant class III antiarrhythmic activity. The efficacy and safety of 2 doses of sotalol (320 and 640 mg/day, divided in 2 doses) were compared to placebo in a 6-week randomized, double-blind, multicenter study of 114 patients with chronic ventricular premature complexes (VPCs) at frequencies of greater than or equal to 30/hour. Sotalol significantly reduced VPCs in patients receiving both low (n = 38) and high (n = 39) doses, compared with patients (n = 37) receiving placebo (by 75 and 88%, respectively, vs 10%; p less than 0.001, sotalol vs placebo; p less than 0.05, high vs low dose). The individual efficacy criterion (greater than or equal to 75% VPC reduction) was achieved in 34% of low-dose and 71% of high-dose sotalol versus 6% of placebo-treated patients (p less than 0.003, sotalol vs placebo; p = 0.007, high vs low dose). Repetitive beats were suppressed 25% by placebo (difference not significant), 80% by low-dose (p less than 0.003) and 78% by high-dose sotalol (p less than 0.005). Sotalol decreased heart rate (by 24 to 25%, p less than 0.001) and increased PR (by 4 to 6%, p less than 0.001) and corrected JT intervals (by 12 to 13%, p less than 0.001), but did not change ejection fraction. Proarrhythmia (nonfatal) occurred in 3 sotalol and in 2 placebo patients. Nine discontinued therapy because of adverse effects (1 low dose and 8 high dose, p less than 0.02). In summary, sotalol is an efficacious antiarrhythmic drug for VPC suppression; in lower doses, it is somewhat less effective but better tolerated.

Adult↗
PubMed1991

Longitudinal measures in children receiving ENCAD for hereditary retinal degeneration.

A hydrolysate of yeast RNA (ENCAD) is used in the Soviet Union for the treatment of hereditary retinal degenerations. We report longitudinal data from three young patients who have made at least two visits to the Soviet Union over a five-year period to receive treatment with ENCAD. Two children were diagnosed with cone-rod degeneration and the third has an isolated (simplex) form of retinitis pigmentosa. Visual function measurements were obtained before and after each visit to Moscow. In the comparison of previsit and postvisit visual acuity, 30 Hz flicker amplitude, and visual fields, ENCAD treatment had no significant short-term effect. Despite treatment with ENCAD, each patient has shown a significant decrease in visual function over the 5-year period. The rate of progression in these patients appears similar to previously published data on the natural history of their retinal degenerative disorders.

Adjuvants, Immunologic↗
PubMed1991

Quantification of rate of coronary artery disease progression by a new method of angiographic analysis.

To assess the rate and variability of atherostenosis progression in patients with coronary artery disease at baseline angiography, we used a simplified quantitative method of analysis to study single angiograms in 54 patients and paired angiograms in 29 patients. All discrete lesions were identified, then traced and digitized to determine lumen diameter (LD), and summed to give the total LD; the differences in LD for paired angiograms were summed to give total stenosis change (TSC). The following results were obtained: Correlation between LD measured by our method and LD determined by the Brown/Dodge method was excellent (r = 0.99, N = 54). There also was a high correlation between interobserver (r = 0.98, N = 54) and intraobserver (r = 0.99, N = 54) findings. Short-term TSC (N = 9, angiograms paired at less than 1 week) was negligible (0.03 +/- 0.38 mm). Long-term (N = 20, angiograms paired at 0.6 to 4.3 years) total LD differed significantly from baseline total LD (4.1 +/- 2.5 mm vs 6.0 +/- 3 mm; p less than 0.001), and TSC (2.0 +/- 1.3 mm) in long-term patients differed significantly from TSC in short-term patients (p less than 0.001). These results show that true coronary disease progression occurring over 1 to 4 years can be distinguished from intraobserver, interobserver, and interstudy variability by means of a simplified method and provide approximate rates and variability of progression. These results will be useful for power calculations in therapeutic trials aimed at slowing progression. Further prospective studies with the use of this method appear indicated.

Adult↗
PubMed1991

Hemodynamic and clinical benefits with intravenous milrinone in severe chronic heart failure: results of a multicenter study in the United States.

The response of patients with chronic severe heart failure to extended infusions (greater than or equal to 48 hours) of milrinone was evaluated in a multicenter, baseline-controlled, phase III efficacy and safety trial in 189 patients in the United States. Milrinone was given as loading and maintenance infusions according to one of four dose regimens. An effective response was defined as greater than or equal to 20% increases in cardiac index or decreases in pulmonary wedge pressure. All loading doses (range, 37.5 to 75 micrograms/kg/10 min) were effective short term, and maximum response occurred at 15 minutes. For the three effective regimens, cardiac index increased initially (at 15 minutes) by 24% to 42%, and pulmonary wedge pressure decreased by 24% to 33%. Systemic vascular resistance was reduced by 15% to 31%. The maximal acute response was effective in 99% of individual patients. During maintenance therapy, effective responses were seen at infusion doses of 0.375, 0.50, and 0.75 micrograms/kg/min, whereas an infusion of 0.25 micrograms/kg/min was ineffective. During 2 days of maintenance therapy, cardiac index remained augmented by 34% to 39% for the low and intermediate doses and by 44% to 73% for the high-dose infusion regimen. Pulmonary wedge pressure decreased an average of 18% on day 1 and 30% on day 2. Systemic vascular resistance was reduced by 20% to 25%, and stroke work index was augmented by 21% to 58%. Symptomatic improvement was common during intravenous milrinone therapy for symptoms of dyspnea (61% response), orthopnea (63%), edema (62%), and fatigue (40%). Improvement occurred more frequently in those with worse baseline functional indexes and in those with greater hemodynamic responses to therapy. Safety and tolerance were exceptionally good for these patients with advanced heart failure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Contrasts between symptoms of summer depression and winter depression.

Epidemiological studies and studies of clinical populations suggest that there are primarily two opposite patterns of seasonally recurring depressions: summer depression and winter depression. In addition, there is preliminary evidence that the two seasonal types of depression may have opposite types of vegetative symptoms. In the present study, we prospectively monitored symptoms of depression in 30 patients with recurrent summer depression and 30 sex-matched patients with recurrent winter depression and compared the symptom profiles of the two groups. Consistent with predictions based on the earlier reports, we found that winter depressives were more likely to have atypical vegetative symptoms, with increased appetite, carbohydrate craving, weight gain and hypersomnia, and that summer depressives were more likely to have endogenous vegetative symptoms, with decreased appetite and insomnia. A cluster analysis performed on the patients' symptom profiles without reference to season of occurrence of their episodes separated 78% of the summer depressives and winter depressives from each other on the basis of their symptoms (chi 2 = 19.29, P less than 0.001).

Adult↗
PubMed1991

Inhibition by wine of tumorigenesis induced by ethyl carbamate (urethane) in mice.

Groups of 18-21 male weanling C3H mice were given, as drinking fluid, tap-water, 12% ethanol solution, one of two commercial white wines, or red wine, ad lib. for 41 wk. Ethyl carbamate was added to each of the drinking liquids at levels adjusted to provide average daily ethyl carbamate intakes of 0, 10 or 20 mg/kg body weight. After 41 wk the cumulative survival of the mice given 20 mg ethyl carbamate/kg in water was depressed compared with the mice drinking wines or ethanol solution with this ethyl carbamate level. Both ethanol and wine treatments reduced the incidence of lung Clara-cell adenomas in mice given 10 mg ethyl carbamate/kg and reduced the frequency (number of specific tumours/number of tumour-bearing mice) of both Clara-cell adenomas in mice given 10 mg ethyl carbamate/kg and of alveolar adenomas in mice given 20 mg ethyl carbamate/kg. Wine treatments also reduced the frequency of hepatocellular adenomas compared with those of other treatment groups, and no hepatocellular carcinomas developed in any of the groups given wine, even with the 20-mg/kg ethyl carbamate dose. The incidence of hepatocellular adenomas in the groups given 10 mg ethyl carbamate/kg was, as shown by chi-square analysis, significantly reduced by the ethanol and wine treatments. The mean weight gains of mice on all the wine treatments were lower than those of water-treated mice and this may have been a factor in tumour inhibition; however, it is also possible that wine components other than ethanol may play a role in the inhibition of tumour development.

Adenoma↗