Associations between hospital-level socioeconomic patient mix and rates of central line-associated bloodstream infections in short bowel syndrome: A retrospective cohort study.

BACKGROUND: Low neighborhood income is linked with increased hospitalizations for central line-associated bloodstream infections (CLABSIs) in pediatric short bowel syndrome (SBS). We assessed whether this relationship varies by hospital center. METHODS: We performed a retrospective cohort study using the Pediatric Health Information System (2018-2023) database for patients <18 years old with SBS (N = 1210) at 24 hospitals in the United States. Using 2015 US Census data, we determined the estimated median household income of each patient's zip code. Hospital-level neighborhood income was defined as the median of the estimated median household income among patients at each hospital. We applied an extension of Cox regression to assess risk for CLABSI hospitalization. RESULTS: Among 1210 children with 5255 hospitalizations, most were <1 year on initial admission (53%), male (58%), and publicly insured (69%). Hospitals serving low-income neighborhoods served more female (46% vs 39%), Black (29% vs 22%), and Hispanic (22% vs 16%) patients with public insurance (72% vs 65%) residing in the southern United States (47% vs 21%). In univariate analysis, low hospital-level neighborhood income was associated with increased risk of CLABSI hospitalization (rate ratio [RR], 1.48; 95% CI, 1.21-1.83; P < 0.001). These findings persisted in multivariate analysis (RR, 1.43; 95% CI, 1.10-1.84; P < 0.01) after adjusting for race, ethnicity, insurance, region, and patient-level neighborhood income. CONCLUSION: Hospitals serving predominantly low-income neighborhoods bear a heavier burden of CLABSI hospitalizations for all their patients across the socioeconomic spectrum. Hospital initiatives focused on CLABSI prevention may be pivotal in addressing this disparity.

The influence of neighborhood income on healthcare utilization in pediatric liver transplant.

OBJECTIVES: Neighborhood contextual factors are associated with liver transplant outcomes. We analyzed associations between neighborhood-level socioeconomic status and healthcare utilization for pediatric liver transplant recipients. METHODS: We merged the Pediatric Health Information System and Scientific Registry of Transplant Recipients databases and included liver transplant recipients ≤21 years hospitalized between January 2004 and May 2022. Outcomes were annual inpatient bed-days, risk of hospitalizations, and risk of liver biopsies. The primary exposure was zip code-based neighborhood income at transplant. We applied causal inference for variable selection in multivariable analysis. We modeled annual inpatient bed-days with mixed-effect zero-inflated Poisson regression, and rates of hospitalization and liver biopsy with a Cox-type proportional rate model. RESULTS: We included 1006 participants from 29 institutions. Children from low-income neighborhoods were more likely to be publicly insured (67% vs. 46%), Black (20% vs. 12%), Hispanic (30% vs. 17%), and have higher model for end-stage liver disease/pediatric end-stage liver disease model scores at transplant (17 vs. 13) than the remaining cohort. We found no differences in inpatient bed-days or rates of hospitalization across neighborhood groups. In univariable analysis, low-income neighborhoods were associated with increased rates of liver biopsy (rate ratio [RR]: 1.57, 95% confidence interval [CI]: 1.04-2.34, p = 0.03). These findings persisted after adjusting for insurance, race, and ethnicity (RR: 1.86, 95% CI: 1.23-2.83, p < 0.01). CONCLUSIONS: Children from low-income neighborhoods undergo more liver biopsies than other children. These procedures are invasive and potentially preventable. In addition to improving outcomes, interventions to mitigate health inequities among liver transplant recipients may reduce resource utilization.

Control of the signaling role of PtdIns(4)P at the plasma membrane through H2O2-dependent inactivation of synaptojanin 2 during endocytosis.

Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] is implicated in various processes, including hormone-induced signal transduction, endocytosis, and exocytosis in the plasma membrane. However, how H2O2 accumulation regulates the levels of PtdIns(4,5)P2 in the plasma membrane in cells stimulated with epidermal growth factors (EGFs) is not known. We show that a plasma membrane PtdIns(4,5)P2-degrading enzyme, synaptojanin (Synj) phosphatase, is inactivated through oxidation by H2O2. Intriguingly, H2O2 inhibits the 4-phosphatase activity of Synj but not the 5-phosphatase activity. In EGF-activated cells, the oxidation of Synj dual phosphatase is required for the transient increase in the plasma membrane levels of phosphatidylinositol 4-phosphate [PtdIns(4)P], which can control EGF receptor-mediated endocytosis. These results indicate that intracellular H2O2 molecules act as signaling mediators to fine-tune endocytosis by controlling the stability of plasma membrane PtdIns(4)P, an intermediate product of Synj phosphoinositide dual phosphatase.

Neighborhood Income Is Associated with Health Care Use in Pediatric Short Bowel Syndrome.

OBJECTIVE: To evaluate associations between neighborhood income and burden of hospitalizations for children with short bowel syndrome (SBS). STUDY DESIGN: We used the Pediatric Health Information System (PHIS) database to evaluate associations between neighborhood income and hospital readmissions, readmissions for central line-associated bloodstream infections (CLABSI), and hospital length of stay (LOS) for patients <18 years with SBS hospitalized between January 1, 2006, and October 1, 2015. We analyzed readmissions with recurrent event analysis and analyzed LOS with linear mixed effects modeling. We used a conceptual model to guide our multivariable analyses, adjusting for race, ethnicity, and insurance status. RESULTS: We included 4289 children with 16 347 hospitalizations from 43 institutions. Fifty-seven percent of the children were male, 21% were Black, 19% were Hispanic, and 67% had public insurance. In univariable analysis, children from low-income neighborhoods had a 38% increased risk for all-cause hospitalizations (rate ratio [RR] 1.38, 95% CI 1.10-1.72, P = .01), an 83% increased risk for CLABSI hospitalizations (RR 1.83, 95% CI 1.37-2.44, P < .001), and increased hospital LOS (ß 0.15, 95% CI 0.01-0.29, P = .04). In multivariable analysis, the association between low-income neighborhoods and elevated risk for CLABSI hospitalizations persisted (RR 1.70, 95% CI 1.23-2.35, P < .01, respectively). CONCLUSIONS: Children with SBS from low-income neighborhoods are at increased risk for hospitalizations due to CLABSI. Examination of specific household- and neighborhood-level factors contributing to this disparity may inform equity-based interventions.

Caregiver perspectives on the everyday medical and social needs of long-term pediatric liver transplant patients.

Using in-depth interviews, we sought to characterize the everyday medical and social needs of pediatric liver transplant caregivers to inform the future design of solutions to improve care processes. Participants (parents/caregivers of pediatric liver transplant recipients) completed a survey (assessing socioeconomic status, economic hardship, health literacy, and social isolation). We then asked participants to undergo a 60-min virtual, semistructured qualitative interview to understand the everyday medical and social needs of the caregiver and their household. We intentionally oversampled caregivers who reported a social or economic hardship on the survey. Transcripts were analyzed using thematic analysis and organized around the Capability, Opportunity, Motivation-Behavior model. A total of 18 caregivers participated. Of the participants, 50% reported some form of financial strain, and about half had less than 4 years of college education. Caregivers had high motivation and capability in executing transplant-related tasks but identified several opportunities for improving care. Caregivers perceived the health system to lack capability in identifying and intervening on specific family social needs. Caregiver interviews revealed multiple areas in which family supports could be strengthened, including (1) managing indirect costs of prolonged hospitalizations (e.g., food, parking), (2) communicating with employers to support families' needs, (3) coordinating care across hospital departments, and (4) clarifying care team roles in helping families reduce both medical and social barriers. This study highlights the caregiver perspective on barriers and facilitators to posttransplant care. Future work should identify whether these themes are present across transplant centers. Caregiver perspectives should help inform future interventions aimed at improving long-term outcomes for children after liver transplantation.

Peroxiredoxin 3 deficiency induces cardiac hypertrophy and dysfunction by impaired mitochondrial quality control.

Mitochondrial quality control (MQC) consists of multiple processes: the prevention of mitochondrial oxidative damage, the elimination of damaged mitochondria via mitophagy and mitochondrial fusion and fission. Several studies proved that MQC impairment causes a plethora of pathological conditions including cardiovascular diseases. However, the precise molecular mechanism by which MQC reverses mitochondrial dysfunction, especially in the heart, is unclear. The mitochondria-specific peroxidase Peroxiredoxin 3 (Prdx3) plays a protective role against mitochondrial dysfunction by removing mitochondrial reactive oxygen species. Therefore, we investigated whether Prdx3-deficiency directly leads to heart failure via mitochondrial dysfunction. Fifty-two-week-old Prdx3-deficient mice exhibited cardiac hypertrophy and dysfunction with giant and damaged mitochondria. Mitophagy was markedly suppressed in the hearts of Prdx3-deficient mice compared to the findings in wild-type and Pink1-deficient mice despite the increased mitochondrial damage induced by Prdx3 deficiency. Under conditions inducing mitophagy, we identified that the damaged mitochondrial accumulation of PINK1 was completely inhibited by the ablation of Prdx3. We propose that Prdx3 interacts with the N-terminus of PINK1, thereby protecting PINK1 from proteolytic cleavage in damaged mitochondria undergoing mitophagy. Our results provide evidence of a direct association between MQC dysfunction and cardiac function. The dual function of Prdx3 in mitophagy regulation and mitochondrial oxidative stress elimination further clarifies the mechanism of MQC in vivo and thereby provides new insights into developing a therapeutic strategy for mitochondria-related cardiovascular diseases such as heart failure.

Mitochondrial Peroxiredoxin III Protects against Non-Alcoholic Fatty Liver Disease Caused by a Methionine-Choline Deficient Diet.

Non-alcoholic fatty liver disease (NAFLD) is emerging as the most common chronic liver disease worldwide. In addition, NAFLD may increase the risk of cardiovascular and liver-related diseases, and displays features of metabolic syndrome. In NAFLD, oxidative stress is primarily caused by excessive free fatty acids. The oxidation of fatty acids is usually caused by ß-oxidation of mitochondria under normal conditions, resulting in the production of energy. However, when the inflow of fatty acids in NAFLD becomes excessive, the ß-oxidation of mitochondria becomes saturated and the oxidation process increases at sites including peroxisomes and microsomes, thereby increasing production of reactive oxygen species (ROS). Thus, hepatic mitochondrial ROS play an important role in the pathogenesis of NAFLD. Eliminating mitochondrial ROS may improve NAFLD, but the underlying mechanism remains unclear. We examined the effect of mitochondrial ROS on NAFLD by focusing on peroxiredoxin (Prx), an antioxidant protein that can remove hydrogen peroxide. The protective effect and pathological phenomenon of mitochondrial peroxiredoxin in methionine-choline deficient diet (MCD)-induced liver injury was assessed in a mouse model of NAFLD. In these mice, mitochondrial peroxiredoxin deficiency significantly increased hepatic steatosis and fibrosis. In addition, ablation of Prx III enhances susceptibility to MCD diet-induced oxidative stress and exacerbates NAFLD progression by promoting inflammation. The binding assay results also showed that Prx III-deficient mice had more severe liver damage than Prx III-abundant mice in MCD diet liver injury models. The present data suggest that mitochondrial peroxiredoxin III could be a therapeutic target for preventing and suppressing diet-induced NAFLD.

Non-operative management of biliary complications after Liver Transplantation in pediatric patients: A 30-year experience.

BACKGROUND: To evaluate the efficacy of percutaneous and endoscopic therapeutic interventions for biliary strictures and leaks following LT in children. METHODS: Retrospective analysis of 49 consecutive pediatric liver transplant recipients (27 girls, 22 boys, mean age at transplant 3.9 years) treated at our institution from 1989 to 2019 for biliary leak and/or biliary stricture was performed. Minimally invasive approach was considered clinically successful if it resulted in patency of the narrowed biliary segment and/or correction of the biliary leak. RESULTS: Forty-two patients had a stricture at the biliary anastomosis; seven had a biliary leak. After an average 13.8 years of follow-up, long-term clinical success with minimally invasive treatment (no surgery or re-transplant) was achieved for 24 children (57%) with biliary stricture and 4 (57%) with biliary leaks. Eight patients required re-transplant; however, only one was due to failure of both percutaneous and surgical management. For biliary strictures, failure of non-surgical management was associated with younger age at stricture diagnosis (p < .02). CONCLUSIONS: Percutaneous and endoscopic management of biliary strictures and leaks after LT in children is associated with a durable result in >50% of children.

Maturation of Mitochondrially Targeted Prx V Involves a Second Cleavage by Mitochondrial Intermediate Peptidase That Is Sensitive to Inhibition by H2O2.

Prx V mRNA contains two in-frame AUG codons, producing a long (L-Prx V) and short form of Prx V (S-Prx V), and mouse L-Prx V is expressed as a precursor protein containing a 49-amino acid N-terminal mitochondria targeting sequence. Here, we show that the N-terminal 41-residue sequence of L-Prx V is cleaved by mitochondrial processing peptidase (MPP) in the mitochondrial matrix to produce an intermediate Prx V (I-Prx V) with a destabilizing phenylalanine at its N-terminus, and further, that the next 8-residue sequence is cleaved by mitochondrial intermediate peptidase (MIP) to convert I-Prx V to a stabilized mature form that is identical to S-Prx V. Further, we show that when mitochondrial H2O2 levels are increased in HeLa cells using rotenone, in several mouse tissues by deleting Prx III, and in the adrenal gland by deleting Srx or by exposing mice to immobilized stress, I-Prx V accumulates transiently and mature S-Prx V levels decrease in mitochondria over time. These findings support the view that MIP is inhibited by H2O2, resulting in the accumulation and subsequent degradation of I-Prx V, identifying a role for redox mediated regulation of Prx V proteolytic maturation and expression in mitochondria.

Peroxiredoxin 3 Has Important Roles on Arsenic Trioxide Induced Apoptosis in Human Acute Promyelocytic Leukemia Cell Line via Hyperoxidation of Mitochondrial Specific Reactive Oxygen Species.

NB4 cell, the human acute promyelocytic leukemia (APL) cell line, was treated with various concentrations of arsenic trioxide (ATO) to induce apoptosis, measured by staining with 7-amino-actinomycin D (7-AAD) by flow cytometry. 2', 7'-dichlorodihydro-fluorescein-diacetate (DCF-DA) and MitoSOXTM Red mitochondrial superoxide indicator were used to detect intracellular and mitochondrial reactive oxygen species (ROS). The steady-state level of SO2 (Cysteine sulfinic acid, Cys-SO2H) form for peroxiredoxin 3 (PRX3) was measured by a western blot. To evaluate the effect of sulfiredoxin 1 depletion, NB4 cells were transfected with small interfering RNA and analyzed for their influence on ROS, redox enzymes, and apoptosis. The mitochondrial ROS of NB4 cells significantly increased after ATO treatment. NB4 cell apoptosis after ATO treatment increased in a time-dependent manner. Increased SO2 form and dimeric PRX3 were observed as a hyperoxidation reaction in NB4 cells post-ATO treatment, in concordance with mitochondrial ROS accumulation. Sulfiredoxin 1 expression is downregulated by small interfering RNA transfection, which potentiated mitochondrial ROS generation and cell growth arrest in ATO-treated NB4 cells. Our results indicate that ATO-induced ROS generation in APL cell mitochondria is attributable to PRX3 hyperoxidation as well as dimerized PRX3 accumulation, subsequently triggering apoptosis. The downregulation of sulfiredoxin 1 could amplify apoptosis in ATO-treated APL cells.

Ablation of Peroxiredoxin V Exacerbates Ischemia/Reperfusion-Induced Kidney Injury in Mice.

Ischemia/reperfusion (I/R) is one of the major causes of acute kidney injury (AKI) and associated with increased mortality and progression to chronic kidney injury (CKI). Molecular mechanisms underlying I/R injury involve the production and excessive accumulation of reactive oxygen species (ROS). Peroxiredoxin (Prx) V, a cysteine-dependent peroxidase, is located in the cytosol, mitochondria, and peroxisome and has an intensive ROS scavenging activity. Therefore, we focused on the role of Prx V during I/R-induced AKI using Prx V knockout (KO) mice. Ablation of Prx V augmented tubular damage, apoptosis, and declined renal function. Prx V deletion also showed higher susceptibility to I/R injury with increased markers for oxidative stress, ER stress, and inflammation in the kidney. Overall, these results demonstrate that Prx V protects the kidneys against I/R-induced injury.

Multiple functions of 2-Cys peroxiredoxins, I and II, and their regulations via post-translational modifications.

Peroxiredoxins (Prxs) are an unusual family of thiol-specific peroxidases that possess a binding site for H2O2 and rely on a conserved cysteine residue for rapid reaction with H2O2. Among 6 mammalian isoforms (Prx I to VI), Prx I and Prx II are mainly found in the cytosol and nucleus. Prx I and Prx II function as antioxidant enzymes and protein chaperone under oxidative distress conditions. Under oxidative eustress conditions, Prx I and Prx II regulate the levels of H2O2 at specific area of the cells as well as sense and transduce H2O2 signaling to target proteins. Prx I and Prx II are known to be covalently modified on multiple sites: Prx I is hyperoxidized on Cys52; phosphorylated on Ser32, Thr90, and Tyr194; acetylated on Lys7, Lys16, Lys27, Lys35, and Lys197; glutathionylated on Cys52, Cys83, and Cys173; and nitrosylated on Cys52 and Cys83, whereas Prx II is hyperoxidized on Cys51; phosphorylated on Thr89, Ser112, and Thr182; acetylated on Ala2 and Lys196; glutathionylated on Cys51 and Cys172; and nitrosylated on Cys51 and Cys172. In this review, we describe how these post-translational modifications affect various functions of Prx I and Prx II.

Factors Associated With Frequent Opioid Use in Children With Acute Recurrent and Chronic Pancreatitis.

OBJECTIVES: The aim of the study was to understand the association of frequent opioid use with disease phenotype and pain pattern and burden in children and adolescents with acute recurrent (ARP) or chronic pancreatitis (CP). METHODS: Cross-sectional study of children <19 years with ARP or CP, at enrollment into the INSPPIRE cohort. We categorized patients as opioid "frequent use" (daily/weekly) or "nonfrequent use" (monthly or less, or no opioids), based on patient and parent self-report. RESULTS: Of 427 children with ARP or CP, 17% reported frequent opioid use. More children with CP (65%) reported frequent opioid use than with ARP (41%, P = 0.0002). In multivariate analysis, frequent opioid use was associated with older age at diagnosis (odds ratio [OR] 1.67 per 5 years, 95% confidence interval [CI] 1.13-2.47, P = 0.01), exocrine insufficiency (OR 2.44, 95% CI 1.13-5.24, P = 0.02), constant/severe pain (OR 4.14, 95% CI 2.06-8.34, P < 0.0001), and higher average pain impact score across all 6 functional domains (OR 1.62 per 1-point increase, 95% CI 1.28-2.06, P < 0.0001). Children with frequent opioid use also reported more missed school days, hospitalizations, and emergency room visits in the past year than children with no frequent use (P < 0.0002 for each). Participants in the US West and Midwest accounted for 83% of frequent opioid users but only 56% of the total cohort. CONCLUSIONS: In children with CP or ARP, frequent opioid use is associated with constant pain, more healthcare use, and higher levels of pain interference with functioning. Longitudinal and prospective research is needed to identify risk factors for frequent opioid use and to evaluate nonopioid interventions for reducing pain and disability in these children.

Impact of the Pediatric End-Stage Liver Disease (PELD) growth failure thresholds on mortality among pediatric liver transplant candidates.

The Pediatric End-Stage Liver Disease (PELD) score is intended to determine priority for children awaiting liver transplantation. This study examines the impact of PELD's incorporation of "growth failure" as a threshold variable, defined as having weight or height <2 standard deviations below the age and gender norm (z-score <2). First, we demonstrate the "growth failure gap" created by PELD's current calculation methods, in which children have z-scores <2 but do not meet PELD's growth failure criteria and thus lose 6-7 PELD points. Second, we utilized United Network for Organ Sharing (UNOS) data to investigate the impact of this "growth failure gap." Among 3291 pediatric liver transplant candidates, 26% met PELD-defined growth failure, and 17% fell in the growth failure gap. Children in the growth failure gap had a higher risk of waitlist mortality than those without growth failure (adjusted subhazard ratio [SHR] 1.78, 95% confidence interval [95% CI] 1.05-3.02, P = .03). They also had a higher risk of posttransplant mortality (adjusted HR 1.55, 95% CI 1.03-2.32, P = .03). For children without PELD exception points (n = 1291), waitlist mortality risk nearly tripled for those in the gap (SHR 2.89, 95% CI 1.39-6.01, P = .005). Current methods for determining growth failure in PELD disadvantage candidates arbitrarily and increase their waitlist mortality risk. PELD should be revised to correct this disparity.

Risk Factors for Rapid Progression From Acute Recurrent to Chronic Pancreatitis in Children: Report From INSPPIRE.

OBJECTIVE: The aim of the study was to determine the rate of progression from acute recurrent pancreatitis (ARP) to chronic pancreatitis (CP) in children and assess risk factors. STUDY DESIGN: Data were collected from the INternational Study group of Pediatric Pancreatitis: In search for a cuRE (INSPPIRE) cohort. Kaplan-Meier curves were constructed to calculate duration of progression from initial attack of acute pancreatitis (AP) to CP. Log-rank test was used to compare survival (nonprogression) probability distribution between groups. Cox proportional hazard regression models were fitted to obtain hazard ratio (with 95% confidence interval [CI]) of progression for each risk variable. RESULTS: Of 442 children, 251 had ARP and 191 had CP. The median time of progression from initial attack of AP to CP was 3.79 years. The progression was faster in those ages 6 years or older at the first episode of AP compared to those younger than 6 years (median time to CP: 2.91 vs 4.92 years; P = 0.01). Children with pathogenic PRSS1 variants progressed more rapidly to CP compared to children without PRSS1 variants (median time to CP: 2.52 vs 4.48 years; P = 0.003). Within 6 years after the initial AP attack, cumulative proportion with exocrine pancreatic insufficiency was 18.0% (95% CI: 12.4%, 25.6%); diabetes mellitus was 7.7% (95% CI: 4.2%, 14.1%). CONCLUSIONS: Children with ARP rapidly progress to CP, exocrine pancreatic insufficiency, and diabetes. The progression to CP is faster in children who were 6 years or older at the first episode of AP or with pathogenic PRSS1 variants. The factors that affect the aggressive disease course in childhood warrant further investigation.

Peroxiredoxin-mediated disulfide bond formation is required for nucleocytoplasmic translocation and secretion of HMGB1 in response to inflammatory stimuli.

The nuclear protein HMGB1 (high mobility group box 1) is secreted by monocytes-macrophages in response to inflammatory stimuli and serves as a danger-associated molecular pattern. Acetylation and phosphorylation of HMGB1 are implicated in the regulation of its nucleocytoplasmic translocation for secretion, although inflammatory stimuli are known to induce H2O2 production. Here we show that H2O2-induced oxidation of HMGB1, which results in the formation of an intramolecular disulfide bond between Cys23 and Cys45, is necessary and sufficient for its nucleocytoplasmic translocation and secretion. The oxidation is catalyzed by peroxiredoxin I (PrxI) and PrxII, which are first oxidized by H2O2 and then transfer their disulfide oxidation state to HMGB1. The disulfide form of HMGB1 showed higher affinity for nuclear exportin CRM1 compared with the reduced form. Lipopolysaccharide (LPS)-induced HMGB1 secretion was greatly attenuated in macrophages derived from PrxI or PrxII knockout mice, as was the LPS-induced increase in serum HMGB1 levels.

Chronic Pancreatitis: Pediatric and Adult Cohorts Show Similarities in Disease Progress Despite Different Risk Factors.

OBJECTIVES: The aim of the present study was to investigate the natural history of chronic pancreatitis (CP); patients in the North American Pancreatitis Study2 (NAPS2, adults) and INternational Study group of Pediatric Pancreatitis: In search for a cuRE (INSPPIRE, pediatric) were compared. METHODS: Demographics, risk factors, disease duration, management and outcomes of 224 children and 1063 adults were compared using appropriate statistical tests for categorical and continuous variables. RESULTS: Alcohol was a risk in 53% of adults and 1% of children (P < 0.0001); tobacco in 50% of adults and 7% of children (P < 0.0001). Obstructive factors were more common in children (29% vs 19% in adults, P = 0.001). Genetic risk factors were found more often in children. Exocrine pancreatic insufficiency was similar (children 26% vs adult 33%, P = 0.107). Diabetes was more common in adults than children (36% vs 4% respectively, P < 0.0001). Median emergency room visits, hospitalizations, and missed days of work/school were similar across the cohorts. As a secondary analysis, NAPS2 subjects with childhood onset (NAPS2-CO) were compared with INSPPIRE subjects. These 2 cohorts were more similar than the total INSPPIRE and NAPS2 cohorts, including for genetic risk factors. The only risk factor significantly more common in the NAPS2-CO cohort compared with the INSPPIRE cohort was alcohol (9% NAPS2-CO vs 1% INSPPIRE cohorts, P = 0.011). CONCLUSIONS: Despite disparity in age of onset, children and adults with CP exhibit similarity in demographics, CP treatment, and pain. Differences between groups in radiographic findings and diabetes prevalence may be related to differences in risk factors associated with disease and length of time of CP.

A catalytic career: Studies spanning glutamine synthetase, phospholipase C, peroxiredoxin, and the intracellular messenger role of hydrogen peroxide.

I learned biochemistry from P. Boon Chock and Earl Stadtman while working on the regulation of Escherichia coli glutamine synthetase as a postdoctoral fellow at the National Institutes of Health. After becoming a tenured scientist at the same institute, my group discovered, purified, and cloned the first three prototypical members of the phospholipase C family and uncovered the mechanisms by which various cell-surface receptors activate these enzymes to generate diacylglycerol and inositol 1,4,5-trisphosphate. We also discovered the family of peroxiredoxin (Prx) enzymes that catalyze the reduction of H2O2, and we established that mammalian cells express six Prx isoforms that not only protect against oxidative damage but also mediate cell signaling by modulating intracellular H2O2 levels. To validate the signaling role of H2O2, we showed that epidermal growth factor induces a transient increase in intracellular H2O2 levels, and the essential cysteine residue of protein-tyrosine phosphatases is a target for specific and reversible oxidation by the H2O2 produced in such cells. These observations led to a new paradigm in receptor signaling, in which protein tyrosine phosphorylation is achieved not via activation of receptor tyrosine kinases alone but also through concurrent inhibition of protein-tyrosine phosphatases by H2O2 Our studies revealed that Prx isozymes are extensively regulated via phosphorylation as well as by hyperoxidation of the active-site cysteine to cysteine sulfinic acid, with the reverse reaction being catalyzed by sulfiredoxin. This reversible hyperoxidation of Prx was further shown to constitute a universal marker for circadian rhythms in all domains of life.