Accuracy of dobutamine echocardiography for detection of myocardial viability in patients with an occluded left anterior descending coronary artery

Objectives.We studied the accuracy of dobutamine echocardiography for the detection of myocardial viability in patients with an occluded left anterior descending coronary artery and regional ventricular dysfunction.Background.Contractile reserve during dobutamine echocardiography is an accurate marker of myocardial viability in patients with coronary stenoses and ventricular dysfunction. However, its accuracy in patients with an occluded vessel has not been evaluated.Methods.We studied 41 patients with >50% stenosis of the left anterior descending coronary artery and regional ventricular dysfunction who underwent dobutamine echocardiography for detection of viable myocardium. Contractile reserve was defined as improvement in wall motion score of two or more contiguous septal or anterior segments during dobutamine echocardiography. Recovery of function was defined as improvement in rest wall motion score of two or more contiguous segments after revascularization.Results.Patients were classified into two groups according to the presence (n = 20) or absence (n = 21) of left anterior descending coronary artery occlusion. Contractile reserve was detected in 40% of patients with an occluded and 43% with a nonoccluded artery (p = 0.8). Of 41 patients, 27 underwent revascularization, 12 with and 15 without an occluded vessel. Recovery of function occurred in 6 (50%) of 12 patients in the occluded artery group and in 5 (33%) of 15 in the nonoccluded artery group (p = 0.4). Among patients with an occluded artery, the positive and negative predictive values of dobutamine echocardiography for recovery of function were 100% (95% confidence interval [CI] 48% to 100%) and 86% (95% CI 42% to 100%), respectively.Conclusions.Our results indicate that contractile reserve during dobutamine echocardiography can be detected in patients with an occluded vessel and may be useful for predicting recovery of function after revascularization

Combined assessment of microvascular integrity and contractile reserve improves differentiation of stunning and necrosis after acute anterior wall myocardial infarction

AbstractObjectivesWe sought to determine the relative accuracy of myocardial contrast echocardiography (MCE) and low-dose dobutamine echocardiography (LDDE) in predicting recovery of left ventricular (LV) function in patients with a recent anterior wall myocardial infarction (MI).BackgroundLeft ventricular dysfunction after acute MI may be secondary to myocardial stunning or necrosis. Myocardial contrast echocardiography allows real-time echocardiographic perfusion assessment from a venous injection of a fluorocarbon-based contrast agent. Although this technique is promising, it has not been compared with LDDE.MethodsForty-six patients underwent baseline wall motion assessment, MCE, and LDDE two days after admission, as well as follow-up echocardiography after a mean period of 53 days.ResultsPerfusion by MCE predicted recovery of segmental function with a sensitivity of 69%, specificity of 85%, positive predictive value of 74%, negative predictive value of 81%, and overall accuracy of 78%. Contractile reserve by LDDE predicted recovery of segmental function with a sensitivity of 50%, specificity of 88%, positive predictive value of 72%, negative predictive value of 73%, and overall accuracy of 73%. Concordant test results occurred in 74% of segments and further increased the overall accuracy to 85%. The mean wall motion score at follow-up was significantly better in perfused versus nonperfused segments (1.9 vs. 2.6, p < 0.0001) and in segments with contractile reserve, compared with segments lacking contractile reserve (1.9 vs. 2.5, p < 0.0001).ConclusionsMyocardial contrast echocardiography compares favorably with LDDE in predicting recovery of regional LV dysfunction after acute anterior wall MI. Concordant contractile reserve and myocardial perfusion results further enhance the diagnostic accuracy

Effects of weaning age on pig performance in three-site production

Two trials (n = 5,728 weaned pigs) were conducted to determine the effects of weaning age (12 to 21.5 days) on pig performance in a three-site production system. The second trial also examined the effects of modifying nursery feed budgets according to weaning age. In both studies, wean-to-finish ADG, mortality rate, average pig gain per days postweaning, and pounds sold per pig weaned improved linearly as weaning age increased. The improvements in growth rate and mortality largely occurred in the initial 42- days post-weaning, with some ongoing growth improvement to slaughter. Modifying nursery feed budgets did not affect wean-to-finish growth performance. These studies indicate increasing weaning age up to 21.5 days predictably improves grow-finish throughput within a three-site production system

Effects of weaning age on pig performance in three-site production

Two trials (n = 5,728 weaned pigs) were conducted to determine the effects of weaning age (12 to 21.5 days) on pig performance in a three-site production system. The second trial also examined the effects of modifying nursery feed budgets according to weaning age. In both studies, wean-to-finish ADG, mortality rate, average pig gain per days postweaning, and pounds sold per pig weaned improved linearly as weaning age increased. The improvements in growth rate and mortality largely occurred in the initial 42- days post-weaning, with some ongoing growth improvement to slaughter. Modifying nursery feed budgets did not affect wean-to-finish growth performance. These studies indicate increasing weaning age up to 21.5 days predictably improves grow-finish throughput within a three-site production system.; Swine Day, Manhattan, KS, November 14, 200

Effects of increasing crystalline lysine and dietary fat on finishing pig growth performance

A total of 1,024 barrows (each initially 157 lb, PIC L337 x C22) were used in a 28-d study to evaluate the effects of increased crystalline amino acids (none versus 4.5 lb/ton of L-lysine HCl plus L-threonine to maintain the proper ratio relative to lysine) and added dietary fat (none, 3 or 6% choice white grease) on finishing pig growth performance. All experimental diets were formulated with a constant true ileal digestible lysine:ME ratio based on NRC, (1998) ingredient values for ME. A minimum true ileal digestible threonine:lysine ratio of 68% and a minimum true ileal digestible methionine + cystine:lysine ratio of 55% were used in diet formulation. There was no synthetic amino acid by added fat interactions. Increasing added fat increased (linear, P<0.01) ADG and improved F/G. Replacing soybean meal with crystalline amino acids had no affect on growth performance. This indicates that the increased amounts of L-lysine HCl and added L-threonine were used as efficiently as amino acids provided from soybean meal. Neither adding fat nor crystalline lysine affected feed cost/lb of gain using current ingredient prices. However, margin over feed cost (profit) increased as added fat increased because of the increased pig weight due to improved ADG. In summary, these results confirm the improved ADG and F/G when adding fat to finishing pig diets. Furthermore, 4.5 lb/ton of Llysine HCl and L-threonine can effectively replace soybean meal without negatively affecting growth performance of pigs from 157 to 217 lb

Effects of increasing crystalline lysine with other amino acids on growth performance of 85- to 135-lb gilts

A total of 1,134 gilts (each initially 85 lb, PIC L337 x C22) was used in a 28-d experiment to evaluate the effects of replacing soybean meal with up to 8 lb/ton of crystalline Llysine HCl with other crystalline amino acids on growth performance. Gilts were randomly allotted to one of six experimental diets. Diets were corn-soybean meal-based with 3% added fat. Diets included a negative control containing 3 lb/ton of L-lysine HCl and formulated to 0.90% true ileal digestible lysine. Two additional diets were formulated with 3 lb/ton Llysine to 1.0% true ileal digestible lysine but with or without crystalline threonine and methionine to compare threonine to lysine ratios of 60 versus 65% and methionine & cystine (TSAA) ratios of 55 vs. 60%. The three remaining diets contained 6, 7, or 8 lb/ton of Llysine HCl with crystalline threonine and methionine to provide the same ratios relative to lysine of 65 and 60%, respectively. Pigs fed the negative control diet (0.90 true ileal digestible lysine) had decreased ADG, poorer F/G, and were lighter at then end of the trial than pigs fed the diet containing 3 lb/ton L-lysine with added L-threonine and DL methionine (P<0.05). This indicates that diets containing 1.0% true ileal digestible lysine were not over the pigs’ lysine requirement. Pigs fed 1.0% true ileal digestible lysine with high threonine and TSAA ratios (65 and 60% relative to lysine, respectively) had similar ADG but tended to have better (P<0.08) F/G than those fed the lower threonine and TSAA ratios. Using 6, 7, or 8 lb/ton of Llysine HCl with added threonine and methionine in diets formulated to 1.0% true ileal digestible lysine had no effect on ADG or F/G, but did tend to decrease ADFI (linear, P<0.04; quadratic P<0.07). These results suggest that the use of up to 8 lb/ton of L-lysine HCl in conjunction with L-threonine and DL methionine to maintain proper amino acid to lysine ratios will not negatively affect pig performance. In addition, increasing the true ileal digestible threonine:lysine (60 to 65%) and TSAA:lysine ratios (55 to 60%) improved F/G in this experiment

Comparison of three methods of feeding sows in gestation and the subsequent effects on lactation performance

A total of 684 sows from breeding groups over six weeks were used to compare three methods of feeding during gestation and to assess the subsequent effects on lactation performance. Control gilts and sows were fed according to body condition based on a scale of 1 to 5, (1=thin, 5=fat). Sows were visually assessed for body condition at breeding and were assigned a daily feed allowance to achieve a body condition score of 3 at farrowing. Sow body condition was evaluated every two weeks throughout gestation, and feed allowance was adjusted as required. Treatment two used feeding levels based on backfat thickness (measured between d 0 and 5 after breeding) and weight at weaning for sows or weight at service for gilts. Feed allowance was calculated to achieve a target backfat of 19 mm at farrowing. Sow feeding level remained constant from d 0 to 101 of gestation. Feed allowances were based on modeled calculations of energy and nutrient requirements to achieve target sow maternal weight and backfat gain. Treatment three was identical to treatment two except that feeding pattern was altered for thin sows and gilts (\u3c15 mm at service) in an attempt to reach 19 mm by d 36 of gestation. Sows were weighed at the previous weaning and gilts at-service and again between d 112 and 114 of gestation. Backfat was measured between d 0 and 5 and again between d 108 and 113 of gestation. Sows on treatments two and three achieved backfat of 19 and 19.1 mm at farrowing, respectively, while control sows numerically tended to have greater backfat at farrowing (20 mm). On average, sows targeted to gain large amounts (6 to 9 mm) of backfat in gestation failed to achieve target gains regardless of feeding method. Feeding sows in gestation based on backfat (treatments two and three) resulted in a higher proportion of sows in the target backfat range of 17 to 21 mm at farrowing and a lower percentage of fat sows (\u3e21 mm) but no difference in the percentage of thin sows (\u3c17 mm) compared to the standard method of feeding based on body condition. Gestation feeding method had no effect on performance during lactation. Feed intake in lactation was lower for high backfat sows (\u3e21 mm) at farrowing compared to sows with \u3c21 mm. The high proportion of sows in the optimum backfat category demonstrates that feeding based on backfat and body weight has potential for facilitating more precise gestation feeding.; Swine Day, 2003, Kansas State University, Manhattan, KS, 200

Effects of Nitrogen and Planting Seed Size on Cotton Growth, Development, and Yield

A standardized experiment was conducted during 2009 and 2010 at 20 location-years across U.S. cotton (Gossypium hirsutum L.)-producing states to compare the N use requirement of contemporary cotton cultivars based on their planting seed size. Treatments consisted of three cotton varieties with planting seed of different numbers of seed per kg and N rates of 0, 45, 90, and 134 kg ha⁻¹. Soil at each trial location was sampled and tested for nitrate presence. High levels of soil nitrate (>91 N-NO₃⁻kg ha⁻¹) were found in Arizona and western Texas, and soil nitrate in the range of 45 to 73 kg N-NO₃⁻ ha⁻¹ was found at locations in the central United States. Cotton lint yield responded to applied N at 11 of 20 locations. Considering only sites that responded to applied N, highest lint yields were achieved with 112 to 224 kg ha⁻¹of applied plus pre-plant residual soil NO₃—translating to an optimal N requirement of 23 kg ha⁻¹ per 218 kg bale of lint produced. Among the varieties tested those with medium-sized seed produced higher yields in response to N than did larger and smaller seeded varieties. Varieties with larger seed had longer and stronger fibers, higher fiber length uniformity than small seeded varieties and decreased micronaire. Seed protein and oil increased and decreased slightly in response to increasing amounts of soil nitrate plus applied N, respectively

Low-cost electronic sensors for environmental research: pitfalls and opportunities

Repeat observations underpin our understanding of environmental processes, but financial constraints often limit scientists’ ability to deploy dense networks of conventional commercial instrumentation. Rapid growth in the Internet-Of-Things (IoT) and the maker movement is paving the way for low-cost electronic sensors to transform global environmental monitoring. Accessible and inexpensive sensor construction is also fostering exciting opportunities for citizen science and participatory research. Drawing on 6 years of developmental work with Arduino-based open-source hardware and software, extensive laboratory and field testing, and incor- poration of such technology into active research programmes, we outline a series of successes, failures and lessons learned in designing and deploying environmental sensors. Six case studies are presented: a water table depth probe, air and water quality sensors, multi-parameter weather stations, a time-sequencing lake sediment trap, and a sonic anemometer for monitoring sand transport. Schematics, code and purchasing guidance to reproduce our sensors are described in the paper, with detailed build instructions hosted on our King’s College London Geography Environmental Sensors Github repository and the FreeStation project website. We show in each case study that manual design and construction can produce research-grade scientific instrumentation (mean bias error for calibrated sensors –0.04 to 23%) for a fraction of the conventional cost, provided rigorous, sensor-specific calibration and field testing is conducted. In sharing our collective experiences with build-it- yourself environmental monitoring, we intend for this paper to act as a catalyst for physical geographers and the wider environmental science community to begin incorporating low-cost sensor development into their research activities. The capacity to deploy denser sensor networks should ultimately lead to superior envi- ronmental monitoring at the local to global scales