Outcomes in Pediatric Autoimmune Hepatitis and Significance of Azathioprine Metabolites.

OBJECTIVES: Autoimmune hepatitis (AIH) is a common pediatric liver disease and long-term remission is usually maintained with azathioprine (AZA). There is no consensus on the target range for AZA active metabolite 6-thioguanine (6-TGN) levels in pediatric AIH. The aim of the present study was to characterize the outcomes of pediatric patients with AIH and determine correlations between AZA dosing or 6-TGN metabolite levels and biochemical remission. METHODS: A retrospective chart review was performed and data on presentation, laboratories including AZA metabolite levels, medication use, and outcomes were collected. RESULTS: Between 2002 and 2013, 66 children with AIH were identified (mean age at diagnosis 9.6 ±â€Š5.1 years) with a mean follow-up period of 2.9 ±â€Š3.2 years. Common presenting symptoms included jaundice, fatigue, and abdominal pain. The majority of subjects received steroids for induction and AZA for maintenance of remission. Seventy-nine percent achieved biochemical remission (mean time to remission 6.2 ±â€Š9.2 months), 14% were in the induction phase of therapy, 6% required liver transplantation, and 18% were weaned off immunosuppression and remained in remission. 6-TGN levels ranging from 50 to 250 pmol/8 × 10 red blood cell count were associated with biochemical remission (alanine aminotransferase levels of ≤50 U/L). CONCLUSIONS: The vast majority of children with AIH maintain a sustained remission with AZA monotherapy. Biochemical remission was maintained with 6-TGN levels much lower than that recommended for inflammatory bowel disease. These findings suggest that patients should be maintained at the lowest AZA dose possible that is associated with biochemical remission.

Effects of Anesthesia on Pediatric pH Impedance.

OBJECTIVES: Anesthesia can alter gastric and small intestinal motility, but its effect on gastroesophageal reflux (GER) is unclear. We set out to evaluate the effect of anesthesia on pH-multichannel intraluminal impedance (pH impedance) evaluation of GER. METHODS: Retrospective single-center analysis of 95 pH impedance probe studies performed in patients both with anesthesia exposure and esophagogastroduodenoscopy (n = 50) and without (n = 45). RESULTS: Increased acid reflux per hour, nonacid reflux per hour, and total reflux per hour were observed in the first 4 hours, both overall and in children 1 year or older and in both sedation groups. This difference remained for the older children without sedation by multiple regression analysis for nonacid reflux per hour and total reflux per hour. Patients using proton pump inhibitors had more nonacid reflux events per hour and total reflux events per hour regardless of sedation. CONCLUSIONS: Based on the results of the present study, there is no need to eliminate the data collected immediately after placement of the probe in children younger than 1 year of age, but in those who are 1 year or older without sedation, there may be a greater number of reflux events in the first 4 hours. The first 4 hours, therefore, should be carefully evaluated in patients older than 1 year of age. Further study is needed to provide normative data for the first 4 hours versus the later time period, both for those undergoing sedation and for unsedated patients, to validate the findings from the present study and to better understand the mechanism of GER.

CD4+ and CD8+ T Cell Activation in Children with Hepatitis C.

OBJECTIVES: To assess if peripheral T cell populations in children with chronic hepatitis C virus (HCV) infection would show evidence of activation/exhaustion and an attenuated functional response. STUDY DESIGN: Compared with adults, children with HCV infection have a higher rate of spontaneous viral clearance. In adults, chronic HCV has been linked to T cell exhaustion. Little is known of the immune status of children with HCV. Peripheral blood mononuclear cells were isolated from 16 children with HCV (6 males, 10 females; mean age 8.6 years, range 2-17), 16 age- and sex-matched control children without HCV infection, and 20 adults with chronic HCV. Multiparameter flow cytometry was performed to characterize T cell differences across the 3 groups. RESULTS: Controls and children with HCV had similar levels of CD4(+), CD8(+), and γδ(+) T cells. Children with HCV demonstrated a decrease in naïve T cells compared with control children and increased activation/exhaustion marker expression on both CD8(+) and CD4(+) T cells. Transcription factor analysis suggested functional activation of T cells in children with HCV; however, only the CD4(+) subset had enhanced cytokine production (interferon gamma and interleukin-2) compared with control children. CONCLUSIONS: The HCV response in children is characterized by several changes in T cell phenotype. Many of these changes, such as increased T cell expression of programmed cell death-1, are similar to responses in adults. Of note, cytokine production by CD4(+) helper T cells is increased in children with HCV compared with age- and sex-matched control children, which may influence long-term prognosis in children with HCV.

Hepatitis C Virus Sensing by Human Trophoblasts Induces Innate Immune Responses and Recruitment of Maternal NK Cells: Potential Implications for Limiting Vertical Transmission.

Hepatitis C virus (HCV) is the world's most common blood-borne viral infection for which there is no vaccine. The rates of vertical transmission range between 3 and 6% with odds 90% higher in the presence of HIV coinfection. Prevention of vertical transmission is not possible because of lack of an approved therapy for use in pregnancy or an effective vaccine. Recently, HCV has been identified as an independent risk factor for preterm delivery, perinatal mortality, and other complications. In this study, we characterized the immune responses that contribute to the control of viral infection at the maternal-fetal interface (MFI) in the early gestational stages. In this study, we show that primary human trophoblast cells and an extravillous trophoblast cell line (HTR8), from first and second trimester of pregnancy, express receptors relevant for HCV binding/entry and are permissive for HCV uptake. We found that HCV-RNA sensing by human trophoblast cells induces robust upregulation of type I/III IFNs and secretion of multiple chemokines that elicit recruitment and activation of decidual NK cells. Furthermore, we observed that HCV-RNA transfection induces a proapoptotic response within HTR8 that could affect the morphology of the placenta. To our knowledge, for the first time, we demonstrate that HCV-RNA sensing by human trophoblast cells elicits a strong antiviral response that alters the recruitment and activation of innate immune cells at the MFI. This work provides a paradigm shift in our understanding of HCV-specific immunity at the MFI as well as novel insights into mechanisms that limit vertical transmission but may paradoxically lead to virus-related pregnancy complications.

The concordance of endoscopic and histologic findings of 1000 pediatric EGDs.

BACKGROUND: Pediatric gastroenterologists frequently perform routine endoscopic biopsies despite normal-appearing mucosa during EGD. Older small studies have supported this practice. OBJECTIVE: To re-evaluate the concordance between endoscopic appearance and histology in the era of high-definition endoscopy. DESIGN: Retrospective cohort study. SETTING: Single tertiary care center. PATIENTS: A total of 1000 pediatric patients undergoing initial EGD. MAIN OUTCOME MEASUREMENTS: Endoscopic and histologic findings. RESULTS: The overall rate of an endoscopic finding was 34.7%, which was 40.4% of a histologic finding. Concordance between the presence of any endoscopic finding and any histologic finding in all locations was 69.9% (Cohen's κ coefficient=0.32). In the esophagus, the concordance between any endoscopic finding and any histologic finding was 82.6% (κ=0.45). The stomach was 73.2% concordant (κ=0.18), and the duodenum was 89.3% concordant (κ=0.42). The κ coefficient decreased when comparing specific findings in each location; it was 0.34 in the esophagus, 0.17 in the stomach, and 0.34 in the duodenum. If biopsy specimens had only been obtained when the endoscopist identified abnormal mucosa, 48.5% of the pathologic findings would have been missed. In patients with histology consistent with eosinophilic esophagitis, 30.2% had normal-appearing mucosa. For celiac disease, 43% had normal-appearing mucosa. In the stomach, an abnormal endoscopic appearance was more likely to have normal histology. LIMITATIONS: The single-center, retrospective nature and more endoscopists than pathologists. CONCLUSIONS: These data support the routine collection of biopsy specimens in the duodenum, stomach, and esophagus during EGD in pediatric patients.

Diagnostic yield of EGD in children: a retrospective single-center study of 1000 cases.

BACKGROUND: Pediatric EGD is increasingly being used, but few studies have recently evaluated the diagnostic yield. OBJECTIVE: To assess the association between presenting clinical symptoms and the likelihood of significant endoscopic and histologic abnormalities for initial diagnostic endoscopy. DESIGN: Retrospective cohort study. SETTING: Large, tertiary care children's hospital. PATIENTS: One thousand patients, ages 1 month to 18 years, who underwent initial diagnostic EGD in 2009 and 2010. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Endoscopic and histologic abnormalities. RESULTS: The most common primary indications for endoscopy were generalized abdominal pain (28.7%), gastroesophageal reflux (11.7%), and failure to thrive (9.5%). The overall prevalence of an endoscopic abnormality was 34.7% and of a histologic abnormality, 40.4%. The highest rates of endoscopic abnormalities were found in patients with strictures on upper GI radiology (100%), foreign body (88%), and GI bleeding (57%). The highest rates of histologic abnormalities were in patients with positive celiac screening (91%), foreign body (88%), dysphagia (51%), and GI bleeding (49%), and the lowest rates of histologic abnormalities were miscellaneous indications (17%), strictures on radiology (25%), and reflux (26%). Females and patients < 1 year of age had lower rates of abnormal histologic abnormalities. LIMITATIONS: Retrospective nature of the study, limitation to a single tertiary care center, and simplification of complex patient presentations to a single indication. CONCLUSIONS: Rates of endoscopic and histologic abnormalities from EGD vary based on age and indication for endoscopy, and this should be factored into the decision to proceed with initial endoscopy along with consideration of adverse event rates and effects of anesthesia.

Spatial and temporal jitter distort estimated functional properties of visual sensory neurons.

The functional properties of neural sensory cells or small neural ensembles are often characterized by analyzing response-conditioned stimulus ensembles. Many widely used analytical methods, like receptive fields (RF), Wiener kernels or spatio-temporal receptive fields (STRF), rely on simple statistics of those ensembles. They also tend to rely on simple noise models for the residuals of the conditional ensembles. However, in many cases the response-conditioned stimulus set has more complex structure. If not taken explicitly into account, it can bias the estimates of many simple statistics, and lead to erroneous conclusions about the functionality of a neural sensory system. In this article, we consider sensory noise in the visual system generated by small stimulus shifts in two dimensions (2 spatial or 1-space 1-time jitter). We model this noise as the action of a set of translations onto the stimulus that leave the response invariant. The analysis demonstrates that the spike-triggered average is a biased estimator of the model mean, and provides a de-biasing method. We apply this approach to observations from the stimulus/response characteristics of cells in the cat visual cortex and provide improved estimates of the structure of visual receptive fields. In several cases the new estimates differ substantially from the classic receptive fields, to a degree that may require re-evaluation of the functional description of the associated cells.