Zachary J. Kastenberg

Alternative sources of pluripotency: science, ethics, and stem cells

Despite many advances in human embryonic stem cell (hESC) technology the ethical dilemma involving the destruction of a human embryo is one factor that has limited the development of hESC based clinical therapies. Two recent reports describing the production of pluripotent stem cells following the in vitro reprogramming of human somatic cells with certain defined factors illustrate one potential method of bypassing the ethical debate surrounding hESCs (Yu J, Vodyanik MA, Smuga-Otto K, et al. Induced pluripotent stem cell lines derived from human somatic cells. Science. 2007 Dec;318(5858):1917-1920; Takahashi K, Tanabe K, Ohnuki M, et al. Induction of pluripotent stem cells from adult human fibroblasts by defined factors. Cell. 2007 Nov;131(5): 861-872.). Other alternative methods include nuclear transfer, altered nuclear transfer, and parthenogenesis; each with its own set of advantages and disadvantages. This review discusses recent advances in these technologies with specific focus on the issues of embryo destruction, oocyte recovery, and the potential of each technology to produce large scale, patient specific cell transplantation therapies that would require little or no immunosuppression.

Urine Protein Biomarkers for the Diagnosis and Prognosis of Necrotizing Enterocolitis in Infants

OBJECTIVES To test the hypothesis that an exploratory proteomics analysis of urine proteins with subsequent development of validated urine biomarker panels would produce molecular classifiers for both the diagnosis and prognosis of infants with necrotizing enterocolitis (NEC). STUDY DESIGN Urine samples were collected from 119 premature infants (85 NEC, 17 sepsis, 17 control) at the time of initial clinical concern for disease. The urine from 59 infants was used for candidate biomarker discovery by liquid chromatography/mass spectrometry. The remaining 60 samples were subject to enzyme-linked immunosorbent assay for quantitative biomarker validation. RESULTS A panel of 7 biomarkers (alpha-2-macroglobulin-like protein 1, cluster of differentiation protein 14, cystatin 3, fibrinogen alpha chain, pigment epithelium-derived factor, retinol binding protein 4, and vasolin) was identified by liquid chromatography/mass spectrometry and subsequently validated by enzyme-linked immunosorbent assay. These proteins were consistently found to be either up- or down-regulated depending on the presence, absence, or severity of disease. Biomarker panel validation resulted in a receiver-operator characteristic area under the curve of 98.2% for NEC vs sepsis and an area under the curve of 98.4% for medical NEC vs surgical NEC. CONCLUSIONS We identified 7 urine proteins capable of providing highly accurate diagnostic and prognostic information for infants with suspected NEC. This work represents a novel approach to improving the efficiency with which we diagnose early NEC and identify those at risk for developing severe, or surgical, disease.

The Surgical Management of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC), a common cause of neonatal morbidity and mortality, is strongly associated with prematurity and typically occurs following initiation of enteral feeds. Mild NEC is adequately treated by cessation of enteral feeding, empiric antibiotics, and supportive care. Approximately 50% of affected infants will develop progressive intestinal necrosis requiring urgent operation. Several surgical techniques have been described, but there is no clear survival benefit for any single operative approach. While debate continues regarding the optimal surgical management for infants with severe NEC, future progress will likely depend on the development of improved diagnostic tools and preventive therapies.

Effect of deregionalized care on mortality in very low-birth-weight infants with necrotizing enterocolitis.

IMPORTANCE There has been a significant expansion in the number of low-level and midlevel neonatal intensive care units (NICUs) in recent decades. Infants with necrotizing enterocolitis represent a high-risk subgroup of the very low-birth-weight (VLBW) (<1500 g) population that would benefit from focused regionalization. OBJECTIVES To describe the current trend toward deregionalization and to test the hypothesis that infants with necrotizing enterocolitis represent a particularly high-risk subgroup of the VLBW population that would benefit from early identification, increased intensity of early management, and possible targeted triage to tertiary hospitals. DESIGN, SETTING, AND PARTICIPANTS A retrospective cohort study was conducted of NICUs in California. We used data collected by the California Perinatal Quality Care Collaborative from 2005 to 2011 to assess mortality rates among a population-based sample of 30 566 VLBW infants, 1879 with necrotizing enterocolitis, according to the level of care and VLBW case volume at the hospital of birth. EXPOSURES Level and volume of neonatal intensive care at the hospital of birth. MAIN OUTCOMES AND MEASURES In-hospital mortality. RESULTS There was a persistent trend toward deregionalization during the study period and mortality rates varied according to the level of care. High-level, high-volume (level IIIB with >100 VLBW cases per year and level IIIC) hospitals achieved the lowest risk-adjusted mortality. Infants with necrotizing enterocolitis born into midlevel hospitals (low-volume level IIIB and level IIIA NICUs) had odds of death ranging from 1.42 (95% CI, 1.08-1.87) to 1.51 (95% CI, 1.05-2.15, respectively). In the final year of the study, just 28.6% of the infants with necrotizing enterocolitis were born into high-level, high-volume hospitals. For infants born into lower level centers, transfer to a higher level of care frequently occurred well into the third week of life. CONCLUSIONS AND RELEVANCE These findings represent an immediate opportunity for local quality improvement initiatives and potential impetus for the regionalization of important NICU resources.

Hospital readmission after a pancreaticoduodenectomy: an emerging quality metric?

BACKGROUND Hospital readmission has attracted attention from policymakers as a measure of quality and a target for cost reduction. The aim of the study was to evaluate the frequency and patterns of rehospitalization after a pancreaticoduodenectomy (PD). METHODS The records of all patients undergoing a PD at an academic medical centre for malignant or benign diagnoses between January 2006 and September 2011 were retrospectively reviewed. The incidence, aetiology and predictors of subsequent readmission(s) were analysed. RESULTS Of 257 consecutive patients who underwent a PD, 50 (19.7%) were readmitted within 30 days from discharge. Both the presence of any post-operative complication (P = 0.049) and discharge to a nursing/rehabilitation facility or to home with health care services (P = 0.018) were associated with readmission. The most common reasons for readmission were diet intolerance (36.0%), pancreatic fistula/abscess (26.0%) and superficial wound infection (8.0%). Nine (18.0%) readmissions had lengths of stay of 2 days or less and in four of those (8.0%) diagnostic evaluation was eventually negative. CONCLUSION Approximately one-fifth of patients require hospital readmission within 30 days of discharge after a PD. A small fraction of these readmissions are short (2 days or less) and may be preventable or manageable in the outpatient setting.

A novel urine peptide biomarker-based algorithm for the prognosis of necrotising enterocolitis in human infants.

Objective Necrotising enterocolitis (NEC) is a major source of neonatal morbidity and mortality. The management of infants with NEC is currently complicated by our inability to accurately identify those at risk for progression of disease prior to the development of irreversible intestinal necrosis. We hypothesised that integrated analysis of clinical parameters in combination with urine peptide biomarkers would lead to improved prognostic accuracy in the NEC population. Design Infants under suspicion of having NEC (n=550) were prospectively enrolled from a consortium consisting of eight university-based paediatric teaching hospitals. Twenty-seven clinical parameters were used to construct a multivariate predictor of NEC progression. Liquid chromatography/mass spectrometry was used to profile the urine peptidomes from a subset of this population (n=65) to discover novel biomarkers of NEC progression. An ensemble model for the prediction of disease progression was then created using clinical and biomarker data. Results The use of clinical parameters alone resulted in a receiver-operator characteristic curve with an area under the curve of 0.817 and left 40.1% of all patients in an ‘indeterminate’ risk group. Three validated urine peptide biomarkers (fibrinogen peptides: FGA1826, FGA1883 and FGA2659) produced a receiver-operator characteristic area under the curve of 0.856. The integration of clinical parameters with urine biomarkers in an ensemble model resulted in the correct prediction of NEC outcomes in all cases tested. Conclusions Ensemble modelling combining clinical parameters with biomarker analysis dramatically improves our ability to identify the population at risk for developing progressive NEC.

Chest wall reconstruction using implantable cross-linked porcine dermal collagen matrix (Permacol) ☆

BACKGROUND/PURPOSE Chest wall reconstruction in children is typically accomplished with either primary tissue repair or synthetic mesh prostheses. Primary tissue repair has been associated with high rates of scoliosis, whereas synthetic prostheses necessitate the placement of a permanent foreign body in growing children. This report describes the use of biologic mesh (Permacol; Covidien, Mansfield, MA) as an alternative to both tissue repair and synthetic prostheses in pediatric chest wall reconstruction. METHODS A retrospective chart review was performed identifying patients undergoing chest wall reconstruction with biologic mesh at our tertiary referral childrens hospital between 2007 and 2011. Data collection included patient demographics, indication for chest wall resection, number of ribs resected, the administration of postoperative radiation, length of follow-up, postoperative complications, and the degree of spinal angulation (preoperatively and at most recent follow-up). RESULTS Five patients (age, 9.0-21.7 years; mean, 15.4 years) underwent resection for primary chest wall malignancy followed by reconstruction with biologic mesh (Permacol) during the study period. There were no postoperative mesh-related complications, and none of the patients developed clinically significant scoliosis (follow-up, 1.1-2.6 years; mean 1.9 years). CONCLUSION Biologic mesh offers a safe and dependable alternative to both primary tissue repair and synthetic mesh in pediatric patients undergoing chest wall reconstruction.

A Data-Driven Algorithm Integrating Clinical and Laboratory Features for the Diagnosis and Prognosis of Necrotizing Enterocolitis

Background Necrotizing enterocolitis (NEC) is a major source of neonatal morbidity and mortality. Since there is no specific diagnostic test or risk of progression model available for NEC, the diagnosis and outcome prediction of NEC is made on clinical grounds. The objective in this study was to develop and validate new NEC scoring systems for automated staging and prognostic forecasting. Study design A six-center consortium of university based pediatric teaching hospitals prospectively collected data on infants under suspicion of having NEC over a 7-year period. A database comprised of 520 infants was utilized to develop the NEC diagnostic and prognostic models by dividing the entire dataset into training and testing cohorts of demographically matched subjects. Developed on the training cohort and validated on the blind testing cohort, our multivariate analyses led to NEC scoring metrics integrating clinical data. Results Machine learning using clinical and laboratory results at the time of clinical presentation led to two NEC models: (1) an automated diagnostic classification scheme; (2) a dynamic prognostic method for risk-stratifying patients into low, intermediate and high NEC scores to determine the risk for disease progression. We submit that dynamic risk stratification of infants with NEC will assist clinicians in determining the need for additional diagnostic testing and guide potential therapies in a dynamic manner. Algorithm availability http://translationalmedicine.stanford.edu/cgi-bin/NEC/index.pl and smartphone application upon request.

Cost-effectiveness of preoperative imaging for appendicitis after indeterminate ultrasonography in the second or third trimester of pregnancy.

OBJECTIVE: To assess the cost-effectiveness of diagnostic laparoscopy, computed tomography (CT), and magnetic resonance imaging (MRI) after indeterminate ultrasonography in pregnant women with suspected appendicitis. METHODS: A decision-analytic model was developed to simulate appendicitis during pregnancy taking into consideration the health outcomes for both the pregnant women and developing fetuses. Strategies included diagnostic laparoscopy, CT, and MRI. Outcomes included positive appendectomy, negative appendectomy, maternal perioperative complications, preterm delivery, fetal loss, childhood cancer, lifetime costs, discounted life expectancy, and incremental cost-effectiveness ratios. RESULTS: Magnetic resonance imaging is the most cost-effective strategy, costing

A modification of the laparoscopic transcutaneous inguinal hernia repair to achieve transfixation ligature of the hernia sac.

6,767 per quality-adjusted life-year gained relative to CT, well below the generally accepted