Not just vegetations: focal myocardial changes in patients with fungal infections.

BACKGROUND: Fungal endocarditis classically involves dense heterogenous vegetations. However, several patients with fungal infections were noted to have myocardial changes ranging from focal brightening to nodular thickening of chordae or papillary muscles. This study evaluates whether these findings are associated with fungal infections. METHODS: In a retrospective case-control study, paediatric inpatients with fungal infections (positive blood, urine, or catheter tip culture) in a 5-year period were matched 1:1 to inpatients without positive fungal cultures. Echocardiograms were scored on a 5-point scale by two independent readers for presence of myocardial brightenings, nodular thickenings, and vegetations. Clinical data were compared. RESULTS: Of 67 fungal cases, positive culture sites included blood (n = 44), vascular catheter tip (n = 7), and urine (n = 29); several had multiple positive sites. "Positive" echo findings (score ≥ 2+) were more frequent in the Fungal Group (33 versus 18%, p = 0.04). Fungal Group patients with "positive" versus "negative" echo findings had similar proportion of bacterial infections. Among fungal cases, those with "positive" echo findings had longer hospital length of stay than cases with "negative" echos (median 58 versus 40 days, p = 0.03) but no difference in intensive care unit admission, extracorporeal membranous oxygenation support, or mortality. CONCLUSIONS: Myocardial and papillary muscle brightening with nodular thickening on echocardiogram appear to be associated with fungal infections. There may be prognostic implications of these findings as patients with "positive" echo have longer length of stay. Further studies are needed to better understand the mechanism and temporal progression of these changes and determine the prognostic value of this scoring system.

Predicting and Surviving Prolonged Critical Illness After Congenital Heart Surgery.

OBJECTIVES: Prolonged critical illness after congenital heart surgery disproportionately harms patients and the healthcare system, yet much remains unknown. We aimed to define prolonged critical illness, delineate between nonmodifiable and potentially preventable predictors of prolonged critical illness and prolonged critical illness mortality, and understand the interhospital variation in prolonged critical illness. DESIGN: Observational analysis. SETTING: Pediatric Cardiac Critical Care Consortium clinical registry. PATIENTS: All patients, stratified into neonates (≤28 d) and nonneonates (29 d to 18 yr), admitted to the pediatric cardiac ICU after congenital heart surgery at Pediatric Cardiac Critical Care Consortium hospitals. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: There were 2,419 neonates and 10,687 nonneonates from 22 hospitals. The prolonged critical illness cutoff (90th percentile length of stay) was greater than or equal to 35 and greater than or equal to 10 days for neonates and nonneonates, respectively. Cardiac ICU prolonged critical illness mortality was 24% in neonates and 8% in nonneonates (vs 5% and 0.4%, respectively, in nonprolonged critical illness patients). Multivariable logistic regression identified 10 neonatal and 19 nonneonatal prolonged critical illness predictors within strata and eight predictors of mortality. Only mechanical ventilation days and acute renal failure requiring renal replacement therapy predicted prolonged critical illness and prolonged critical illness mortality in both strata. Approximately 40% of the prolonged critical illness predictors were nonmodifiable (preoperative/patient and operative factors), whereas only one of eight prolonged critical illness mortality predictors was nonmodifiable. The remainders were potentially preventable (postoperative critical care delivery variables and complications). Case-mix-adjusted prolonged critical illness rates were compared across hospitals; six hospitals each had lower- and higher-than-expected prolonged critical illness frequency. CONCLUSIONS: Although many prolonged critical illness predictors are nonmodifiable, we identified several predictors to target for improvement. Furthermore, we observed that complications and prolonged critical care therapy drive prolonged critical illness mortality. Wide variation of prolonged critical illness frequency suggests that identifying practices at hospitals with lower-than-expected prolonged critical illness could lead to broader quality improvement initiatives.

Atrioventricular block after congenital heart surgery: Analysis from the Pediatric Cardiac Critical Care Consortium.

OBJECTIVES: Our primary aims were to describe the contemporary epidemiology of postoperative high-grade atrioventricular block (AVB), the timing of recovery and permanent pacemaker (PPM) placement, and to determine predictors for development of and recovery from AVB. METHODS: Patients who underwent congenital heart surgery from August 2014 to June 2017 were analyzed for AVB using the Pediatric Cardiac Critical Care Consortium registry. Predictors of AVB with or without PPM were identified using multinomial logistic regression. We used these predictors to model the probability of PPM for the subgroup of patients with intraoperative complete AVB. RESULTS: We analyzed 15,901 surgical hospitalizations; 422 (2.7%) were complicated by AVB and 162 (1.0%) patients underwent PPM placement. In patients with transient AVB, 50% resolved by 2 days, and 94% resolved by 10 days. In patients who received a PPM, 50% were placed by 8 days and 62% were placed by 10 days. Independent risk factors associated with PPM compared with resolution of AVB were longer duration of cardiopulmonary bypass (relative risk ratio, 1.04; P = .023) and a high-risk operation (relative risk ratio, 2.59; P < .001). Among patients with complete AVB originating in the operating room, those with the highest predicted probability of PPM had a PPM placed only 77% of the time. CONCLUSIONS: In this cohort, postoperative AVB complicated almost 3% of congenital heart surgery cases and 1% of patients underwent PPM placement. Because almost all patients (94%) with transient AVB had resolution by 10 days, our results suggest there is limited benefit to delaying PPM placement beyond that time frame.

Variation in Adjusted Mortality for Medical Admissions to Pediatric Cardiac ICUs.

OBJECTIVES: Pediatric cardiac ICUs should be adept at treating both critical medical and surgical conditions for patients with cardiac disease. There are no case-mix adjusted quality metrics specific to medical cardiac ICU admissions. We aimed to measure case-mix adjusted cardiac ICU medical mortality rates and assess variation across cardiac ICUs in the Pediatric Cardiac Critical Care Consortium. DESIGN: Observational analysis. SETTING: Pediatric Cardiac Critical Care Consortium clinical registry. PATIENTS: All cardiac ICU admissions that did not include cardiac surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary endpoint was cardiac ICU mortality. Based on multivariable logistic regression accounting for clustering, we created a case-mix adjusted model using variables present at cardiac ICU admission. Bootstrap resampling (1,000 samples) was used for model validation. We calculated a standardized mortality ratio for each cardiac ICU based on observed-to-expected mortality from the fitted model. A cardiac ICU was considered a statistically significant outlier if the 95% CI around the standardized mortality ratio did not cross 1. Of 11,042 consecutive medical admissions from 25 cardiac ICUs (August 2014 to May 2017), the observed mortality rate was 4.3% (n = 479). Final model covariates included age, underweight, prior surgery, time of and reason for cardiac ICU admission, high-risk medical diagnosis or comorbidity, mechanical ventilation or extracorporeal membrane oxygenation at admission, and pupillary reflex. The C-statistic for the validated model was 0.87, and it was well calibrated. Expected mortality ranged from 2.6% to 8.3%, reflecting important case-mix variation. Standardized mortality ratios ranged from 0.5 to 1.7 across cardiac ICUs. Three cardiac ICUs were outliers; two had lower-than-expected (standardized mortality ratio <1) and one had higher-than-expected (standardized mortality ratio >1) mortality. CONCLUSIONS: We measured case-mix adjusted mortality for cardiac ICU patients with critical medical conditions, and provide the first report of variation in this quality metric within this patient population across Pediatric Cardiac Critical Care Consortium cardiac ICUs. This metric will be used by Pediatric Cardiac Critical Care Consortium cardiac ICUs to assess and improve outcomes by identifying high-performing (low-mortality) centers and engaging in collaborative learning.

Similar Interstage Outcomes for Single Ventricle Infants Palliated With an Aortopulmonary Shunt Compared to the Norwood Procedure.

BACKGROUND: Interstage outcomes for single ventricle infants following Norwood operation have been well studied, showing significant mortality. Other single ventricle infants require only an aortopulmonary shunt. The aim of the study was to describe the interstage outcomes of this group compared to Norwood patients and identify risk factors for mortality. METHODS: A single-center retrospective cohort review was performed in patients who underwent a Norwood operation (Norwood) or aortopulmonary shunt (Shunt) during 2000 to 2011 and survived to discharge. Hybrid or pulmonary artery banding patients were excluded. Univariate comparison was made between Norwood and Shunt patients as well as a Shunt subgroup analysis. RESULTS: A total of 486 patients (368 Norwood and 118 Shunt) were included. Norwood and Shunt patients were similar in terms of preterm birth, surgery weight, and stage 1 complications. Shunt patients were more likely to be female, have an extracardiac or genetic anomaly, and have a shorter hospital length of stay compared to the Norwood patients (all P < .0001). No significant difference in interstage mortality was seen between the Shunt and Norwood patients (6.8% vs 11.1%, respectively; P = .17). Stage 2 mortality was also similar (Shunt 4.6% vs Norwood 7.8%; P = .25). In the Shunt patients, those who died during interstage weighed less at surgery (2.7 [0.7] kg vs 3.3 [0.7] kg, P = .03) and were more likely to have arrhythmias (50% vs 12%, P = .01), compared to survivors. CONCLUSIONS: Shunt patients have an interstage mortality that is not significantly less than Norwood patients. Lower weight at surgery and arrhythmias are risk factors for interstage death in Shunt patients.

Characteristics, Risk Factors, and Outcomes of Extracorporeal Membrane Oxygenation Use in Pediatric Cardiac ICUs: A Report From the Pediatric Cardiac Critical Care Consortium Registry.

OBJECTIVES: Cardiopulmonary failure in children with cardiac disease differs from the general pediatric critical care population, yet the epidemiology of extracorporeal membrane oxygenation support in cardiac ICUs has not been described. We aimed to characterize extracorporeal membrane oxygenation utilization and outcomes across surgical and medical patients in pediatric cardiac ICUs. DESIGN: Retrospective analysis of the Pediatric Cardiac Critical Care Consortium registry to describe extracorporeal membrane oxygenation frequency and outcomes. Within strata of medical and surgical hospitalizations, we identified risk factors associated with extracorporeal membrane oxygenation use through multivariate logistic regression. SETTING: Tertiary-care children's hospitals. PATIENTS: Neonates through adults with cardiac disease. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: There were 14,526 eligible hospitalizations from August 1, 2014, to June 30, 2016; 449 (3.1%) included at least one extracorporeal membrane oxygenation run. Extracorporeal membrane oxygenation was used in 329 surgical (3.5%) and 120 medical (2.4%) hospitalizations. Systemic circulatory failure and extracorporeal cardiopulmonary resuscitation were the most common extracorporeal membrane oxygenation indications. In the surgical group, risk factors associated with postoperative extracorporeal membrane oxygenation use included younger age, extracardiac anomalies, preoperative comorbidity, higher Society of Thoracic Surgeons-European Association for Cardiothoracic Surgery category, bypass time, postoperative mechanical ventilation, and arrhythmias (all p < 0.05). Bleeding requiring reoperation (25%) was the most common extracorporeal membrane oxygenation complication in the surgical group. In the medical group, risk factors associated with extracorporeal membrane oxygenation use included acute heart failure and higher Vasoactive Inotropic Score at cardiac ICU admission (both p < 0.0001). Stroke (15%) and renal failure (15%) were the most common extracorporeal membrane oxygenation complications in the medical group. Hospital mortality was 49% in the surgical group and 63% in the medical group; mortality rates for hospitalizations including extracorporeal cardiopulmonary resuscitation were 50% and 83%, respectively. CONCLUSIONS: This is the first multicenter study describing extracorporeal membrane oxygenation use and outcomes specific to the cardiac ICU and inclusive of surgical and medical cardiac disease. Mortality remains high, highlighting the importance of identifying levers to improve care. These data provide benchmarks for hospitals to assess their outcomes in extracorporeal membrane oxygenation patients and identify unique high-risk subgroups to target for quality initiatives.

Early Childhood Stress and Child Age Predict Longitudinal Increases in Obesogenic Eating Among Low-Income Children.

OBJECTIVE: To identify whether psychosocial stress exposure during early childhood predicts subsequent increased eating in the absence of hunger (EAH), emotional overeating, food responsiveness, and enjoyment of food. METHODS: This was an observational longitudinal study. Among 207 low-income children (54.6% non-Hispanic white, 46.9% girls), early childhood stress exposure was measured by parent report and a stress exposure index calculated, with higher scores indicating more stress exposure. Eating behaviors were measured in early (mean, 4.3; standard deviation, 0.5 years) and middle (mean, 7.9; standard deviation, 0.7 years) childhood. Observed EAH was assessed by measuring kilocalories of palatable food the child consumed after a meal. Parents reported on child eating behaviors on the Child Eating Behavior Questionnaire. Child weight and height were measured and body mass index z score (BMIz) calculated. Multivariable linear regression, adjusting for child sex, race/ethnicity, and BMIz, was used to examine the association of stress exposure with rate of change per year in each child eating behavior. RESULTS: Early childhood stress exposure predicted yearly increases in EAH (ß = 0.14; 95% confidence interval, 0.002, 0.27) and Emotional Overeating (ß = 0.14; 95% confidence interval, 0.008, 0.27). Stress exposure was not associated with Food Responsiveness (trend for decreased Enjoyment of Food; ß = -0.13; 95% confidence interval, 0.002, -0.26). All child obesogenic eating behaviors increased with age (P < .05). CONCLUSIONS: Early stress exposure predicted increases in child eating behaviors known to associate with overweight/obesity. Psychosocial stress may confer overweight/obesity risk through eating behavior pathways. Targeting eating behaviors may be an important prevention strategy for children exposed to stress.

The Epidemiology of Healthcare-associated Infections in Pediatric Cardiac Intensive Care Units.

BACKGROUND: Healthcare-associated infections (HAIs) represent serious complications for patients within pediatric cardiac intensive care units (CICU). HAIs are associated with increased morbidity, mortality and resource utilization. There are few studies describing the epidemiology of HAIs across the entire spectrum of patients (surgical and nonsurgical) receiving care in dedicated pediatric CICUs. METHODS: Retrospective analyses of 22,839 CICU encounters from October 2013 to September 2016 across 22 North American CICUs contributing data to the Pediatric Cardiac Critical Care Consortium clinical registry. RESULTS: HAIs occurred in 2.4% of CICU encounters at a rate of 3.3 HAIs/1000 CICU days, with 73% of HAIs occurring in children <1 year. Eighty encounters (14%) had ≥2 HAIs. Aggregate rates for the 4 primary HAIs are as follows: central line-associated blood stream infection, 1.1/1000 line days; catheter-associated urinary tract infections, 1.5/1000 catheter days; ventilator-associated pneumonia, 1.9/1000 ventilator days; surgical site infections, 0.81/100 operations. Surgical and nonsurgical patients had similar HAIs rates/1000 CICU days. Incidence was twice as high in surgical encounters and increased with surgical complexity; postoperative infection occurred in 2.8% of encounters. Prematurity, younger age, presence of congenital anomaly, Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Mortality Categories (STAT) 4-5 surgery, admission with an active medical condition, open sternum and extracorporeal membrane oxygenation were independently associated with HAIs. In univariable analysis, HAI was associated with longer hospital length of stay and durations of urinary catheter, central venous catheter and ventilation. Mortality was 24.4% in patients with HAIs versus 3.4% in those without, P < 0.0001. CONCLUSIONS: We provide comprehensive multicenter benchmark data regarding rates of HAIs within dedicated pediatric CICUs. We confirm that although rare, HAIs of all types are associated with significant resource utilization and mortality.

Family food talk, child eating behavior, and maternal feeding practices.

Families discuss food and eating in many ways that may shape child eating habits. Researchers studying how families talk about food have examined this process during meals. Little work has examined parent-child food-related interactions outside of mealtime. We assessed family food talk at home outside of mealtime and tested whether food talk was associated with obesogenic child eating behaviors, maternal feeding practices, or child weight. Preschool and school-aged mother-child dyads (n = 61) participated in naturalistic voice recording using a LENA (Language ENvironment Analysis) recorder. A coding scheme was developed to reliably characterize different types of food talk from LENA transcripts. Mothers completed the Children's Eating Behavior Questionnaire (CEBQ) and Child Feeding Questionnaire (CFQ) to assess child eating behaviors and maternal feeding practices. Child weight and height were measured and body mass index z-score (BMIz) calculated. Bivariate associations among food talk types, as a proportion of total speech, were examined and multivariate regression models used to test associations between food talk and child eating behaviors, maternal feeding practices, and child BMIz. Proportion of child Overall Food Talk and Food Explanations were positively associated with CEBQ Food Responsiveness and Enjoyment of Food (p's < 0.05). Child food Desire/Need and child Prep/Planning talk were positively associated with CEBQ Enjoyment of Food (p < 0.05). Child Food Enjoyment talk and mother Overt Restriction talk were positively associated with CEBQ Emotional Over-Eating (p < 0.05). Mother Monitoring talk was positively associated with CFQ Restriction (p < 0.05). Mother Prep/Planning talk was negatively associated with child BMIz. Food talk outside of mealtimes related to child obesogenic eating behaviors and feeding practices in expected ways; examining food talk outside of meals is a novel way to consider feeding practices and child eating behavior.

Associations between stress biology indicators and overweight across toddlerhood.

Biological stress responses are proposed as a pathway through which stress exposure can "get under the skin" and lead to health problems, specifically obesity. Yet, it is not clear when such associations may emerge or whether they are bidirectional. Cortisol and salivary alpha amylase (sAA) were considered indicators of the biological stress response. We tested the longitudinal association between cortisol and sAA and weight in 215 low-income children at ages 21, 27, and 33 months (52% male; 46% non-Hispanic white). sAA and cortisol intercept and slope (representing morning level and rate of change across the day) were calculated for each age point using random effect models. Children were weighed and length measured and categorized as overweight versus normal weight (overweight defined as weight-for-length z-score ≥85th percentile for age and sex). Cross-lagged models stratified by sex and controlling for birthweight z-score tested the concurrent and cross-lagged associations between each of 4 indices of stress biology individually (cortisol and sAA intercept and slope) and overweight. Overweight status was correlated across time. Cortisol and sAA were correlated across occasions of measurement, though somewhat less strongly in boys. There were no concurrent associations between stress indicators and overweight. sAA at 27 months predicted greater risk of overweight at 33 months in girls, such that both lower sAA intercept and more rapidly increasing sAA at 27 months predicted greater risk of overweight at 33 months (ß=-0.64, p<0.05 and ß=1.09, p<0.05, respectively). For boys only, overweight at 21 months predicted lower sAA intercept at 27 months (ß=-0.35, p<0.05). Findings suggest that longitudinal associations of stress biology and weight status may be present only on a limited basis very early in the lifespan.

Longitudinal associations between maternal feeding and overweight in low-income toddlers.

Maternal feeding is a frequent intervention target for the prevention of early childhood obesity but longitudinal associations between feeding and child overweight are poorly understood. This observational cohort study sought to examine the cross-lagged associations between maternal feeding and overweight across ages 21, 27, and 33 months. Feeding was measured by maternal self-report (n = 222) at each age. Child weight and length were measured. Cross-lagged analysis was used to evaluate longitudinal associations between feeding and overweight, adjusting for infant birth weight, maternal body mass index, maternal education, and maternal depressive symptoms. The sample was 50.5% white, 52.3% male and 37.8% of mothers had a high school education or less. A total of 30.6%, 29.2%, and 26.3% of the sample was overweight at each age, respectively. Pressuring to Finish, Restrictive with regard to Amount, Restrictive with regard to Diet Quality, Laissez-Faire with regard to Diet Quality, Responsiveness to Satiety, Indulgent Permissive, Indulgent Coaxing, Indulgent Soothing, and Indulgent Pampering each tracked strongly across toddlerhood. There were no significant associations between maternal feeding and child overweight either in cross-sectional or cross-lagged associations. Our results do not support a strong causal role for feeding in childhood overweight. Future work longitudinal work should consider alternative approaches to conceptualizing feeding and alternative measurement approaches.

Observed self-regulation is associated with weight in low-income toddlers.

Obesity emerges in early childhood and tracks across development. Self-regulation develops rapidly during the toddler years, yet few studies have examined toddlers' self-regulation in relation to concurrent child weight. Further, few studies compare child responses in food and non-food-related tasks. Our goal was to examine toddlers' observed behavioral and emotional self-regulation in food and non-food tasks in relation to their body mass index z-score (BMIz) and weight status (overweight/obese vs. not). Observational measures were used to assess self-regulation (SR) in four standardized tasks in 133 low-income children (M age = 33.1 months; SD = 0.6). Behavioral SR was measured by assessing how well the child could delay gratification for a snack (food-related task) and a gift (non-food-related task). Emotional SR was measured by assessing child intensity of negative affect in two tasks designed to elicit frustration: being shown, then denied a cookie (food-related) or a toy (non-food-related). Task order was counterbalanced. BMIz was measured. Bivariate correlations and regression analyses adjusting for child sex, child race/ethnicity, and maternal education were conducted to examine associations of SR with weight. Results were that better behavioral SR in the snack delay task associated with lower BMIz (ß = -0.27, p < 0.05) and lower odds of overweight/obesity (OR = 0.66, 95% CI 0.45, 0.96), but behavioral SR in the gift task did not associate with BMIz or weight status. Better emotional SR in the non-food task associated with lower BMIz (ß = -0.27, p < 0.05), and better emotional SR in food and non-food tasks associated with lower odds of overweight/obesity (OR = 0.65, 95% CI 0.45, 0.96 and OR = 0.56, 95% CI 0.37, 0.87, respectively). Results are discussed regarding how behavioral SR for food and overall emotional SR relate to weight during toddlerhood, and regarding early childhood obesity prevention implications.

Eating in the Absence of Hunger and Weight Gain in Low-income Toddlers.

OBJECTIVE: To identify predictors of eating in the absence of hunger (EAH) in low-income toddlers, describe affect during EAH, test EAH as a predictor of body mass index (BMI), and examine the type of food eaten as a predictor of BMI. METHODS: EAH, indexed as kilocalories (sweet, salty, and total) of palatable foods consumed after a satiating meal, was measured (n = 209) at ages 21, 27, and 33 months. Child gender, age, race/ethnicity, and previous exposure to the foods; maternal education and depressive symptoms; and family chaos, food insecurity, and structure were obtained via questionnaire. Child and mother BMI were measured. Child affect was coded from videotape. Linear regression was used to examine predictors of EAH and the association of kilocalories consumed and affect with 33 month BMI z-score (BMIz). RESULTS: Predictors of greater total kilocalories included the child being a boy (P < .01), being older (P < .001), and greater maternal education (P < .01). Being in the the top quartile of sweet kilocalories consumed at 27 months and showing negative affect at food removal had higher BMIz (ß = 0.29 [95% confidence interval 0.10 to 0.48] and ß = 0.34 [95% confidence interval, 0.12 to 0.56], respectively).There was no association of salty kilocalories consumed or positive affect with BMIz. CONCLUSIONS: There was little evidence that maternal or family characteristics contribute to EAH. EAH for sweet food predicts higher BMIz in toddlerhood. Studies investigating the etiology of EAH and interventions to reduce EAH in early childhood are needed.

Design and initial results of a programme for routine standardised longitudinal follow-up after congenital heart surgery.

BACKGROUND: With improvements in early survival following congenital heart surgery, it has become increasingly important to understand longer-term outcomes; however, routine collection of these data is challenging and remains very limited. We describe the development and initial results of a collaborative programme incorporating standardised longitudinal follow-up into usual care at the Children's Hospital of Philadelphia (CHOP) and University of Michigan (UM). METHODS: We included children undergoing benchmark operations of the Society of Thoracic Surgeons. Considerations regarding personnel, patient/parent engagement, funding, regulatory issues, and annual data collection are described, and initial follow-up rates are reported. RESULTS: The present analysis included 1737 eligible patients undergoing surgery at CHOP from January 2007 to December 2014 and 887 UM patients from January 2010 to December 2014. Overall, follow-up data, of any type, were obtained from 90.8% of patients at CHOP (median follow-up 4.3 years, 92.2% survival) and 98.3% at UM (median follow-up 2.8 years, 92.7% survival), with similar rates across operations and institutions. Most patients lost to follow-up at CHOP had undergone surgery before 2010. Standardised questionnaires assessing burden of disease/quality of life were completed by 80.2% (CHOP) and 78.4% (UM) via phone follow-up. In subsequent pilot testing of an automated e-mail system, 53.4% of eligible patients completed the follow-up questionnaire through this system. CONCLUSIONS: Standardised follow-up data can be obtained on the majority of children undergoing benchmark operations. Ongoing efforts to support automated electronic systems and integration with registry data may reduce resource needs, facilitate expansion across centres, and support multi-centre efforts to understand and improve long-term outcomes in this population.

Evaluation of [99mTc-(CO)3-X-Y-Bombesin(7-14)NH2] conjugates for targeting gastrin-releasing peptide receptors overexpressed on breast carcinoma.

BACKGROUND: Gastrin-releasing peptide (GRP) receptors are overexpressed on a variety of human carcinomas, including those of the breast. These receptors may be targeted with bombesin (BBN), which binds to GRP receptors with high affinity and specificity. The aim of this study was to develop a (99m)Tc(I)-BBN analog with favorable pharmacokinetic properties in order to improve the visualization of breast cancer tissue. MATERIALS AND METHODS: Solid-phase peptide synthesis was used to produce a series of X-Y-BBN-NH2 conjugates, where X is pyrazolyl (PZ1) or 2,3-diaminopropionic acid (DPR) and Y is a spacer sequence. Their metallated counterparts were prepared by reacting [(99m)Tc-(H(2)O)(3)(CO)(3)](+) with the corresponding ligand. RESULTS: While the PZ1 conjugates exhibited higher GRP receptor binding affinities in vitro, the DPR analogs demonstrated superior target tissue accumulation and pharmacokinetic properties in vivo. CONCLUSION: These results demonstrate the ability of the DPR derivatives (Y=glycylserylglycine, triserine) to clearly identify the T47-D tumor tissue in xenografted SCID mice.

Radiolabeled regulatory peptides for imaging and therapy.

PURPOSE OF REVIEW: The purpose of the present review is to describe new, innovative strategies of diagnosing and treating specific human cancers using a cadre of radiolabeled regulatory peptides. RECENT FINDINGS: Peptide receptor-targeted radionuclide therapy is a method of site-directed radiotherapy that specifically targets human cancers expressing a cognate receptor-subtype in very high numbers. Ideally, the procedure targets only the primary or metastatic disease and is minimally invasive, with little radiation damage to normal, collateral tissues. For treatment strategies of this type to be effective, it is critical to evaluate the toxicity of the treatment protocol, the radiation dosimetry of the therapeutic regimen, and the biological profile of the radiopharmaceutical, including biodistribution and pharmacokinetics of the drug. Site-directed molecular imaging procedures via gamma-scintigraphy can address many of the critical issues associated with peptide receptor-targeted radionuclide therapy and it is, therefore, necessary to describe the effective balance between the clinical benefits and risks of this treatment strategy. SUMMARY: Continued development in the design or chemical structure of radiolabeled, biologically active peptides could do much to improve the targeting ability of these drugs, thereby creating new and innovative strategies for diagnosis or treatment of human cancers.

In vitro and in vivo analysis of [(64)Cu-NO2A-8-Aoc-BBN(7-14)NH(2)]: a site-directed radiopharmaceutical for positron-emission tomography imaging of T-47D human breast cancer tumors.

INTRODUCTION: Human breast cancer, from which the T-47D cell line was derived, is known to overexpress the gastrin-releasing peptide receptor (GRPR) in some cases. Bombesin (BBN), an agonist for the GRPR, has been appended with a radionuclide capable of positron-emission tomography (PET) imaging and therapy. (64)Cu-NO2A-8-Aoc-BBN(7-14)NH(2) (NO2A=1,4,7-triazacyclononane-1,4-diacetate) has produced high-quality microPET images of GRPR-positive breast cancer xenografted tumors in mice. METHODS: The imaging probe was synthesized by solid-phase peptide synthesis followed by manual conjugation of the 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) bifunctional chelator and radiolabeling in aqueous solution. The radiolabeled conjugate was subjected to in vitro and in vivo studies to determine its specificity for the GRPR and its pharmacokinetic profile. A T-47D tumor-bearing mouse was imaged with microPET/CT and microMRI imaging. RESULTS: The (64)Cu-NO2A-8-Aoc-BBN(7-14)NH(2) targeting vector was determined to specifically localize in GRPR-positive tissue. Accumulation was observed in the tumor in sufficient quantities to allow for identification of tumors in microPET imaging procedures. For example, uptake and retention in T-47D xenografts at 1, 4 and 24 h were determined to be 2.27+/-0.08, 1.35+/-0.14 and 0.28+/-0.07 % ID/g, respectively. CONCLUSIONS: The (64)Cu-NO2A-8-Aoc-BBN(7-14)NH(2) produced high-quality microPET images. The pharmacokinetic profile justifies investigation of this bioconjugate as a potentially useful diagnostic/therapeutic agent. Additionally, the bioconjugate would serve as a good starting point for modification and optimization of similar agents to maximize tumor uptake and minimize nontarget accumulation.

In vitro and in vivo evaluation of Alexa Fluor 680-bombesin[7-14]NH2 peptide conjugate, a high-affinity fluorescent probe with high selectivity for the gastrin-releasing peptide receptor.

Gastrin-releasing peptide (GRP) receptors are overexpressed on several types of human cancer cells, including breast, prostate, small cell lung, and pancreatic cancers. Bombesin (BBN), a 14-amino acid peptide that is an analogue of human GRP, binds to GRP receptors with very high affinity and specificity. The aim of this study was to develop a new fluorescent probe based on BBN having high tumor uptake and optimal pharmacokinetics for specific targeting and optical imaging of human breast cancer tissue. In this study, solid-phase peptide synthesis was used to produce H(2)N-glycylglycylglycine-BBN[7-14]NH(2) peptide with the following general sequence: H(2)N-G-G-G-Q-W-A-V-G-H-L-M-(NH(2)). This conjugate was purified by reversed-phase high-performance liquid chromatography and characterized by electrospray-ionization mass spectra. The fluorescent probe Alexa Fluor 680-G-G-G-BBN[7-14]NH(2) conjugate was prepared by reaction of Alexa Fluor 680 succinimidyl ester to H(2)N-G-G-G-BBN[7-14]NH(2) in dimethylformamide (DMF). In vitro competitive binding assays, using (125)I-Tyr(4)-BBN as the radiolabeling gold standard, demonstrated an inhibitory concentration 50% value of 7.7 +/- 1.4 nM in human T-47D breast cancer cells. Confocal fluorescence microscopy images of Alexa Fluor 680-G-G-G-BBN[7-14]NH(2) in human T-47D breast cancer cells indicated specific uptake, internalization, and receptor blocking of the fluorescent bioprobe in vitro. In vivo investigations in SCID mice bearing xenografted T-47D breast cancer lesions demonstrated the ability of this new conjugate to specifically target tumor tissue with high selectivity and affinity.

Pyrazolyl conjugates of bombesin: a new tridentate ligand framework for the stabilization of fac-[M(CO)3]+ moiety.

We have described the synthesis of tridentate pyrazolyl ligand frameworks for coordination to the fac-[*M(CO)(3)](+) metal fragment (*M=(186/188)Re or (99m)Tc). These ligands impart a degree of kinetic inertness on the metal center, warranting their study in biological systems. We herein report in vitro/in vivo radiolabeling investigations of a new series of pyrazolyl bombesin (BBN) conjugates radiolabeled via the Isolink kit. These new conjugates are based on the general structure [(99m)Tc-pyrazolyl-X-BBN[7-14]NH(2)], where X=beta-alanine, serylserylserine or glycylglycylglycine. The pyrazolyl ligand is a tridentate ligand framework that coordinates the metal center through nitrogen donor atoms. The results of these investigations demonstrate the ability of these new conjugates to specifically target the gastrin-releasing peptide receptor subtype 2, which is overexpressed on human prostate PC-3 cancerous tissues. Therefore, these studies suggest the tridentate pyrazolyl ligand framework to be an ideal candidate for the design and development of low-valent (99m)Tc-based diagnostic radiopharmaceuticals based on BBN or other targeting vectors.