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PubMed2006

Combined food and predator effects on songbird nest survival and annual reproductive success: results from a bi-factorial experiment.

Food and predators have traditionally been viewed as mutually exclusive alternatives when considering factors affecting animal populations. This has led to long controversies such as whether annual reproductive success in songbirds is primarily a function of food-restricted production or predator-induced loss. Recent studies on both birds and mammals suggest many of these controversies may be resolved by considering the combined effects of food and predators. We conducted a 2x2 manipulative food addition plus natural predator reduction experiment on song sparrows (Melospiza melodia) over three consecutive breeding seasons. Food and predators together affected partial clutch or brood loss, nest survival (total clutch or brood loss) and annual reproductive success. When combined, our two treatments reduced partial losses by more than expected if the effects of food and predators were independent and additive. Food and predators also interacted in their effects on nest survival since food addition significantly reduced the rate of nest predation. While annual reproductive success was highly correlated with nest predation (r2=0.71) the strength of this relationship was reinforced by the indirect effects of food addition on nest predation. A stepwise multiple regression showed that the residual variation in annual reproductive success was explained by food effects on the total number of eggs laid over the season and the combined effects of food and predators on partial losses noted above. We conclude that annual reproductive success in song sparrows is a function of both food-restricted production and predator-induced loss and indirect food and predator effects on both clutch and brood loss. We highlight the parallels between our results and those from a comparable bi-factorial experiment on mammals because we suspect combined food and predator effects are likely the norm in both birds and mammals.

Animals↗

PubMed2006

Experimental investigation of the effect of spatial aggregation on reproductive success in a rewardless orchid.

Plant reproductive success within a patch may depend on plant aggregation through pollinator attraction. For rewardless plants that lack rewards for pollinators, reproductive success may rely strongly on the learning abilities of pollinators. These abilities depend on relative co-flowering rewarding and rewardless plant species spatial distributions. We investigated the effect of aggregation on the reproductive success of a rewardless orchid by setting up 16 arrays in a factorial design with two levels of intraspecific aggregation for both a rewardless orchid and a rewarding co-flowering species. Our results show that increasing aggregation of both species negatively influenced the reproductive success of the rewardless plants. To our knowledge, this is the first experimental study demonstrating negative effects of aggregation on reproductive success of a rewardless species due both to its own spatial aggregation and that of a co-flowering rewarding species. We argue that pollinator learning behaviour is the key driver behind this result.

Analysis of Variance↗

PubMed2004

Successive reversal of concurrent discriminations by macaques (Macaca mulatta): proactive interference effects.

Rhesus monkeys received concurrent within-session training on eight, two-choice object pairs and then underwent successive reversals of these problems. Initially, reversals required about six times more training than acquisition with no improvement over seven successive reversals. Surprisingly, performance on these eight problems was unimpaired if they were embedded in different eight-problem tasks, thereby indicating a release from proactive interference. When the original eight problems again underwent successive reversal, no improvement was seen over seven reversals, although there was significantly less error-per-reversal than in the initial test. Subsequently, monkeys appeared to be developing a learning set for successive reversal because performance on successive reversal of eight novel problems was not different from that seen with the old familiar task. Set acquisition was confirmed when proficient reversal was eventually achieved on both old and new concurrent tasks. Thus, "concurrent reversal set" did develop, but it required arduous training to overcome proactive interference effects on memory. The ubiquitous influence of measurement context on organization of monkey memory was noted.

Animals↗

PubMed1995

Electrophysiologic effects of antiarrhythmic drug therapy in the prediction of successful suppression of induced ventricular tachycardia.

Predictors of a successful outcome of serial electrophysiologic (EP) and drug studies have been identified from among baseline patient characteristics but not from among measures of baseline and drug-related EP effects. Identifying such predictors would be useful in explaining the mechanism of successful drug therapy and in guiding drug development and selection. We prospectively studied EP characteristics in 159 trials in 62 patients with ventricular tachycardia or ventricular fibrillation during antiarrhythmic therapy and compared EP measures between successful (n = 30) and failed trials (n = 129). The average age of the patients was 64 years (range 27 to 78 years); 82% were men and 18% women; and 87% had coronary artery disease. Measurements included R-R, QRS, and QT intervals during intrinsic rhythm and during pacing at cycle lengths of 600 of 400 msec; ventricular effective refractory periods (ERP) during pacing at cycle lengths of 600 and 400 msec; and changes in these measures, comparing treatment with drug-free baseline. Univariate predictors of success (in order of significance) included ERP600/QRS600, sotalol versus other drugs, ERP400/QRS400, delta ERP600, delta R-R, ERP600, QRS400 (negative association), delta ERP400, QRS600 (negative association), ERP400 (all p < 0.1). In two separate multivariate models, one for each drive cycle length, only the ratio ERP600/QRS600 (p = 0.01) in the first model and ERP400/QRS400 (p = 0.01) in the second model were significantly and independently associated with achieving noninducibility with drug therapy. Therefore measures of greater refractoriness and lesser delays in conduction velocity (ie, greater "wavelength") relate to drug success.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

Reliability of Q-wave formation and QRS score in predicting regional and global left ventricular performance in acute myocardial infarction with successful reperfusion.

The frequency of electrocardiographic Q-wave formation and the relation of Q wave and QRS score to regional and global left ventricular (LV) performance were determined in 131 patients with acute myocardial infarction (AMI) receiving thrombolytic therapy. Thrombolytic therapy was successful in reperfusing the occluded infarct artery in 100 patients and was unsuccessful in 31. The number of patients who had 1 or more Q waves (88 vs 87%) and 2 or more Q waves (70 vs 74%) was similar. In contrast, normal wall motion was significantly more common in the infarct area in patients in whom reperfusion was successful (42 vs 15%, p less than 0.05). Total QRS scores were similar in patients in whom reperfusion was successful and in those in whom it was not (6.0 +/- 3.2 vs 6.4 +/- 4.2). Despite similar QRS scores, successfully treated patients had significantly higher LV ejection fraction (53 +/- 13% vs 46 +/- 15%, p less than 0.05). Thus, Q-wave formation after successful thrombolytic therapy for AMI is common but does not faithfully reflect regional or global LV performance. Electrocardiographic analysis alone is not a reliable method to assess efficacy of reperfusion therapy.

Aged↗

PubMed1990

Magnesium tocolysis: serum levels versus success.

The relationship between maternal serum magnesium levels and tocolytic success is poorly established. We performed a retrospective analysis of 101 episodes of preterm labor treated with magnesium sulfate and compared the initial, average, and maximum serum magnesium levels with tocolytic success at 48 hours and 7 days. There was no difference in the proportions of tocolytic success when serum levels were less than 6 mg/dl compared with levels of greater than or equal to 6 mg/dl. Similar analyses on either side of 5 mg/dl also revealed no significant relationship. Mean serum magnesium levels in patients with successful tocolysis were statistically similar to those of patients in whom tocolysis failed. Multiple logistic regression analysis also failed to establish a positive relationship between serum magnesium levels and tocolytic success. We conclude that serum magnesium levels alone should not serve as an end point of therapy.

Adult↗

PubMed1983

Methods to determine success of attempts to terminate early gestation pregnancies with prostaglandin vaginal suppositories.

One-hundred subjects received vaginal suppositories containing prostaglandin analogues in order to terminate their pregnancies of 49 days gestation or less. This non-surgical method was successful in 61 subjects, failed in 35 subjects and four subjects were lost to follow-up. Success of prostaglandin therapy cannot be predicted using pretreatment clinical parameters, pretreatment serum beta-hCG levels, or the passage of tissue from the vagina based upon history obtained from the subject. The passage of tissue histologically identified as of fetal origin is a definitive way to determine the success of pregnancy termination but the passage of tissue obtained by history is not. Of the 61 subjects in whom the prostaglandin suppositories were a success, 56 (92%) had a beta-hCG level day 7 +/- 2 following treatment which was 15% or less than the pretreatment value and 5 had beta-hCG levels which were more than 15% of the pretreatment value. All subjects with beta-hCG levels 5 to 9 days after the abortion that were less than 15% of the pretreatment concentrations had a successful termination. Of 35 subjects in whom the prostaglandin suppositories were unsuccessful, 26 had a beta-hCC level 7 +/- 2 days following treatment which was greater than the pretreatment level and 9 had beta-hCG levels less than the pretreatment value. The results of this study indicate that when prostaglandin vaginal suppositories are used to terminate early gestations, if there is no decline in beta-hCG levels 7 +/- 2 days following treatment, the pregnancy should be terminated by another method.

Abortion, Induced↗

PubMed1991

Regulation of sexual succession in the protogynous black sea bass, Centropristis striatus (Osteichthyes: Serranidae)

Serum levels of 17 beta-hydroxy-4-androstene-3,11-dione (11-KT) and testosterone in the protogynous black sea bass, Centropristis striatus fluctuate annually, correlated with the breeding season. Although serum 11-KT levels in both males and females exhibit seasonality, serum estradiol-17 beta concentrations cycle annually only in the females. Throughout the year, serum estradiol levels in males (127 +/- 56 pg/ml, mean +/- SD) were significantly (P less than 0.05) less than levels in breeding (3,930 +/- 1,390 pg/ml), or nonbreeding females (261 +/- 62 pg/ml). In all female sea bass not undergoing sexual succession, histological examination of the ovary revealed only spermatogonia or ongoing spermatogenesis restricted to the posterior male lamellae; a duct system was nonexistent. In female fish undergoing sexual succession, ovarian tissue was always nonvitellogenic and regressing. Breeding females were not observed to undergo gender change. During sexual succession in the postspawning period, male tissue spread into neighboring female lamellae containing oocytes, gradually replacing them and other female tissue. A male duct system developed on the surface. At any time of year, black sea bass undergoing sexual succession had serum estradiol levels (79 +/- 19 pg/ml) which were significantly less (P less than 0.05) than concurrent female serum estradiol levels. A chi-square test demonstrated that serum estradiol levels in these intersex animals were not significantly different from those of males. The possibility is discussed that sexual succession results from inhibition of ovarian tissue response to steroidogenic gonadotropin.

Aging↗

PubMed1983

Urodynamic analysis of successful and failed incontinence surgery.

Seventy-nine patients were investigated by simultaneous urethrocystometry before and, on average, 15 months after vaginal and/or suprapubic operations for stress urinary incontinence. Subjective and objective success rates were 78% and 60%, respectively, with no significant differences between operation types. Patients with a low (less than 0.6) index of urethral relaxation at stress preoperatively indicating excessive loss of basal urethral pressure at stress, had objective success rates of 39% whereas a higher index was associated with a success rate of 70%. Maximal urethral closure pressure and functional urethral length did not correlate with the operative result and were virtually unchanged postoperatively. Successful operations increased the index of urethral relaxation at stress and urethral pressure peaks at stress especially in the distal functional urethra. No significant quantitative differences except for sling operations producing higher urethral closure pressure at stress in the proximal and lower in the distal functional urethra compared to the other operations were found. The results indicate, that successful operations eliminate the failure to maintain adequate basal urethral pressure at stress and emphasizes the importance of reflex activity of pelvic floor musculature at stress for continence.

Adult↗

PubMed1992

Comparative analysis of successful and unsuccessful candidates for the pediatric surgical matching program.

Only one third of the applicants for training in pediatric surgery obtain a position through the pediatric surgery matching program. In order to identify factors that contribute to a successful outcome, we conducted a retrospective survey of all participants in the matching process for positions during the years 1983 to 1991. This survey was designed to identify characteristics associated with success in the match through comparison of successful and unsuccessful applicants. Significant factors associated with a successful match included: a greater incidence of residency-supported research (P = .012) with a greater number of publications (P = .003) and national presentations (P = .014), specifically at the annual meetings of the American Pediatric Surgical Association (P = .05) and the American Academy of Pediatrics (P = .05). In addition, successful candidates had more contact with (P = .004) and letters of recommendation from (P = .015) well-known pediatric surgeons involved in the general surgical residency program. This information should be invaluable to those counseling medical students and residents interested in a career in pediatric surgery.

Adult↗

PubMed1993

Apomorphine and amphetamine produce differential effects on the speed and success of reaction time responding in the rat.

Apomorphine, a nonselective, direct-acting dopamine agonist, and amphetamine, a nonselective indirect-acting dopamine agonist, were compared for their effects on the reaction time response in rats. Animals were shaped to release a lever in response to an auditory/visual stimulus to avoid mild foot shock. The characteristics of the reaction time response of primary interest were percent successful avoidance and response latency. Apomorphine (0, 1, and 5 mg/kg, IP) significantly decreased successful avoidance, but had no effect on response latencies. Thus, the decrease in successful avoidance was not a direct result of longer latencies. Amphetamine (0, 0.5, and 1 mg/kg, IP) produced a different pattern of effects on the reaction time response. Successful avoidance was not affected by amphetamine treatment. However, response latencies were dose-dependently decreased in response to amphetamine. These results demonstrate that dopamine receptor stimulation by different dopamine agonists produces a different pattern of effects on the characteristics of the reaction time response. In addition, these results demonstrate that successful avoidance can be modulated independently of response latencies.

Amphetamine↗

PubMed1989

The television, school and family smoking prevention/cessation project. IV. Controlling for program success expectancies across experimental and control conditions.

A major issue in smoking prevention research is that no study has tried to equate program success expectancies across experimental and placebo control conditions. Equivalent overall program success expectancies should be established to help rule out the effects of extra-theoretical variables which influence program outcomes. The present study tested whether an attention-placebo (information based) smoking prevention program would produce equivalent expectancies about the likelihood of program success in comparison to an experimental social influences program. To try to equate program success expectancies, the design of the two programs differed in content but was similar in procedure. Fourteen middle schools were randomly assigned to the two conditions. As hypothesized, baseline expectancies were found to predict outcome measures, even after controlling for baseline smoking intentions, ethnic group, and gender. Second, the equivalence of program expectancies at posttest was tested. Youths held equivalent overall expectancies for success across conditions. This study suggested the need to control for program expectancies in prevention research, and showed that program expectancies could be controlled for by equating process of program delivery.

Adolescent↗

PubMed1990

Success and failure of exercise training after myocardial infarction: is the outcome predictable?

One hundred fifty-six patients underwent a 5 week daily exercise training program after recovery from acute myocardial infarction. Outcome was assessed on the basis of exercise testing, integrating the measurements into a single outcome measure consisting of three categories (positive, n = 79; negative, n = 42; no change, n = 35). This composite criterion served as the end point for determining the predictability of a positive (training success) and negative (training failure) outcome. With use of logistic regression analysis, the baseline variables of clinical information, exercise data and psychosocial variables were able to identify patients with training success, as well as patients with failure (correct classification rates 81% and 85%, respectively). The characteristics of patients for whom training was beneficial differed from those of patients with a negative outcome. Work status before infarction was the single most important predictor of success, but it did not determine failure. Psychologic variables (type A behavior, well-being, depression) were important for predicting failure, but not for predicting success. Cardiac state and physical fitness largely determined training success. It is concluded that the physical benefit of exercise training in patients after myocardial infarction is highly predictable. Validation will make it possible to optimally apply exercise training as a therapeutic modality in these patients.

Aged↗

PubMed1992

Characteristics of local electrogram predicting successful transcatheter radiofrequency ablation of left-sided accessory pathways.

OBJECTIVES: The purpose of this study was to analyze and compare the local electrograms recorded at successful and unsuccessful sites of ablation to identify the criteria that may predict successful sites and minimize unnecessary radiofrequency delivery. BACKGROUND: Transcatheter ablation of accessory pathways using radiofrequency energy requires extremely precise localization of an accessory pathway. METHODS: Local electrograms from 50 consecutive patients with left-sided accessory pathways who underwent transcatheter radiofrequency ablation were analyzed. During catheter ablation, localization of accessory pathways was performed in 39 pathways during pre-excited sinus rhythm and in 14 pathways during orthodromic tachycardia. A total of 429 local electrograms at target sites obtained before delivery of radiofrequency current was analyzed. A prospective study was performed in another 20 patients using the criteria derived from the retrospective study. RESULTS: Accessory pathway conduction block was achieved in 36 (92%) of 39 pathways in which mapping was performed during pre-excited sinus rhythm and in 9 (64%) of 14 pathways in which mapping was performed during orthodromic tachycardia (p less than 0.05). When mapping was performed during pre-excited sinus rhythm, a combination of four variables (that is, an accessory pathway potential, stability of local electrograms, atrial activation greater than 1 mV and ventricular activation preceding the onset of the delta wave) showed a 62% probability of success. In contrast, excluding these variables resulted in a 95% probability of failure (noneffective or transiently effective). The prospective study shows that the use of these criteria can significantly reduce the number of current applications. When mapping was performed during orthodromic tachycardia, recording the earliest atrial activation was the most powerful predictor of success. A stable local electrogram with a small notch on the ventricular potential, presumed to be an accessory pathway potential, may add predictive value. CONCLUSIONS: Transcatheter radiofrequency ablation is highly effective in the treatment of patients with left-sided accessory pathways. Specific characteristics of local electrograms can be important predictors of success or failure. Mapping during pre-excited rhythm renders ablation more effective than does mapping during orthodromic tachycardia.

Adolescent↗

PubMed1992

Recurrence of conduction in accessory atrioventricular connections after initially successful radiofrequency catheter ablation.

The purpose of this study was to characterize the incidence and clinical features of accessory pathway recurrence after initially successful radiofrequency catheter ablation and to identify variables correlated with recurrence. Radiofrequency ablation was performed with a 7F deflectable tip catheter with a large (4 mm in length) distal electrode. Left-sided accessory pathways were approached through the left ventricle and right-sided pathways by way of the right atrium. Patients were included in the study if 1) they had an initially successful procedure, defined as the absence of accessory pathway conduction immediately after ablation, and 2) had undergone a 3-month follow-up electrophysiologic test or had documented recurrence of accessory pathway conduction. Accessory pathway conduction recurred after initially successful ablation in 16 (12%) of 130 patients. Almost half (7 of 16) of these recurrences were in the 1st 12 h after ablation, and the last occurred after 106 days. Return of delta waves on the electrocardiogram (ECG) or spontaneous paroxysmal supraventricular tachycardia was the initial indication of recurrence in 15 of the 16 patients. Two patients with manifest accessory pathways exhibited recurrence with exclusively concealed accessory pathway conduction. Accessory pathways ablated from the tricuspid anulus (right free wall or septal accessory pathways) had a much higher recurrence rate (24%) than did those on the mitral anulus (6%). Fourteen of 15 patients have had successful repeat accessory pathway ablation after the initial recurrence. After a mean follow-up period of 4 +/- 3 months, there have been no repeat recurrences of any of these accessory pathways. It is concluded that accessory pathway recurrence is infrequent after successful radiofrequency catheter ablation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Determinants of successful nonthoracotomy cardioverter-defibrillator implantation: experience in 101 patients using two different lead systems.

OBJECTIVES: This study was conducted to identify the determinants of successful nonthoracotomy cardioverter-defibrillator implantation. BACKGROUND: Until recently, either median sternotomy or thoracotomy was necessary to implant the electrodes used for internal cardioverter-defibrillator systems. A number of manufacturers have developed nonthoracotomy lead systems comprising two transvenous coil electrodes and a subcutaneous patch electrode. At present, the factors associated with the success or failure of a nonthoracotomy approach are unknown. METHODS: A total of 101 consecutive patients requiring a cardioverter-defibrillator underwent an initial nonthoracotomy approach. Factors associated with successful nonthoracotomy implantation were prospectively determined. RESULTS: A nonthoracotomy system was implanted in 72 (71%) of 101 patients. Twenty-nine patients (29%) required thoracotomy. Univariate predictors of successful nonthoracotomy implantation included smaller cardiac size (p < 0.0001), smaller cardiothoracic ratio (p < 0.0002), QRS duration < 120 ms (p = 0.003), female gender (p = 0.006), ventricular fibrillation as the presenting arrhythmia (p = 0.03) and smaller echocardiographic left ventricular size (p = 0.04). Multivariate predictors included smaller cardiac size (p < 0.002) and female gender (p < 0.007). Total actuarial survival over a mean (+/- SD) follow-up interval of 12 +/- 7 months was 91 +/- 0.03% and was not different in the thoracotomy and nonthoracotomy groups. CONCLUSIONS: A nonthoracotomy cardioverter-defibrillator system can be implanted in a majority of patients. Smaller cardiac size and female gender are associated with a high probability of successful implantation.

Actuarial Analysis↗

PubMed1995

Clinical and lesion morphologic determinants of coronary angioplasty success and complications: current experience.

OBJECTIVES: This study evaluated the validity of the American College of Cardiology/American Heart Association ABC lesion classification scheme and its modifications. BACKGROUND: With the continued refinement in angioplasty technique and equipment evolution, the lesion morphologic determinants of immediate angioplasty outcome have changed significantly. Hence, the validity of the classification scheme has been questioned. METHODS: We assessed the lesion morphologic determinants of immediate angioplasty outcome in 729 consecutive patients who underwent coronary angioplasty of 994 vessels and 1,248 lesions. RESULTS: Angioplasty success was achieved in 91% of lesions, and abrupt closure occurred in 3%. Success was achieved in 96%, 93% and 80% of type A, B and C lesions, respectively (A vs. B, p = NS; B vs. C, p < 0.001; A vs. C, p < 0.001; A vs. B1, p = NS; A vs. B2, p = 0.03; B1 vs. B2, p = 0.02; B2 vs. C, p < 0.001; C1 vs. C2, p = NS). Abrupt closure occurred in 2.1%, 2.6% and 5% of type A, B and C lesions, respectively (A vs. B, B vs. C, A vs. C and A vs. B1, all p = NS; B1 vs. B2, p = 0.01; B2 vs. C1, p = NS; C1 vs. C2, p = 0.04). Type B characteristics had a success rate ranging from 74% to 95% and an abrupt closure rate ranging from 2.2% to 14%. Type C characteristics had a success rate ranging from 57% to 88% and an abrupt closure rate ranging from 0% to 16%. Longer lesions, calcified lesions, diameter stenosis of 80% to 99% and presence of thrombus were predictive of a lower success rate. Longer lesions, angulated lesions, diameter stenosis of 80% to 99% and calcified lesions were predictive of an abrupt closure. CONCLUSIONS: The previously proposed classification schemes are outdated and need to be changed for application in current angioplasty practice. Analyzing specific lesion morphologic characteristics rather than applying a simple lesion classification score when evaluating angioplasty outcome may be more useful because it provides a more precise profile of the lesion and allows better patient stratification and selection.

Adult↗

PubMed1996

"Pseudodisappearance" of atrial electrogram during orthodromic tachycardia: new criteria for successful ablation of concealed left-sided accessory pathways.

OBJECTIVES: This study sought to analyze two new criteria along with other known predictors of success of radiofrequency ablation. Background. Although the overall success rate of radiofrequency ablation of accessory pathways is high, the individual predictive value of each of the established criteria is low. METHODS: We prospectively studied the local electrograms obtained before the application of radiofrequency energy in 33 patients with a left-sided concealed accessory pathway successfully ablated. Two new criteria ("pseudodisappearance" during tachycardia of a bipolar atrial electrogram visible during sinus rhythm and the presence of an "atrial notch" in the ascending limb of the unipolar ventricular electrogram during tachycardia) were studied along with other known predictors. Electrograms recorded at a total of 157 sites were analyzed (33 successful applications, 124 failures). RESULTS: Electrogram characteristics that were predictive of success during ablation on the basis of univariate analyses were a pseudodisappearance criterion (p<0.001), the presence of a Kent potential (p<0.005) and the presence of an "atrial notch" (p<0.005). After adjustment for between-patient differences, logistic regression analysis showed that only the "pseudodisappearance" criterion (odds ratio [OR] 7.2, 95% confidence interval [CI] 1.2 to 42.5, p<0.03) and the presence of a Kent potential (OR 2.4, 95% CI 1.01 to 5.79, p<0.05) had independent predictive value. CONCLUSIONS: The pseudodisappearance during tachycardia or ventricular pacing of a bipolar atrial electrogram present during sinus rhythm is associated with a good outcome during radiofrequency ablation of concealed accessory pathways. These observations may help to ablate accessory pathways and to avoid missing appropriate sites for ablation when the atrial activation is not clearly visible at the local electrogram.

Adolescent↗