Zhaoping He

Pepsin, a Marker of Gastric Contents, Is Increased in Tracheal Aspirates From Preterm Infants Who Develop Bronchopulmonary Dysplasia

OBJECTIVE. The objective of this study was to study the association between pepsin in tracheal aspirate samples and the development of bronchopulmonary dysplasia in preterm infants. METHODS. Serial tracheal aspirate samples were collected during the first 28 days from mechanically ventilated preterm neonates. Bronchopulmonary dysplasia was defined as the need for supplemental oxygen at 36 weeks’ postmenstrual age. An enzymatic assay with a fluorescent substrate was used to detect pepsin. Total protein was measured by the Bradford assay to correct for the dilution during lavage. Immunohistochemistry using antibody against human pepsinogen was performed in 10 lung tissue samples from preterm infants. RESULTS. A total of 256 tracheal aspirate samples were collected from 59 preterm neonates. Pepsin was detected in 234 (91.4%) of 256 of the tracheal aspirate samples. Twelve infants had no bronchopulmonary dysplasia, 31 infants developed bronchopulmonary dysplasia, and 16 infants died before 36 weeks’ postmenstrual age. The mean pepsin concentration was significantly lower in infants with no bronchopulmonary dysplasia compared with those who developed bronchopulmonary dysplasia or developed bronchopulmonary dysplasia/died before 36 weeks’ postmenstrual age. Moreover, the mean pepsin level was significantly higher in infants with severe bronchopulmonary dysplasia compared with moderate bronchopulmonary dysplasia. The mean pepsin level in tracheal aspirate samples from the first 7 days was also lower in infants with no bronchopulmonary dysplasia compared with those who developed bronchopulmonary dysplasia or developed bronchopulmonary dysplasia/died before 36 weeks’ postmenstrual age. Pepsinogen was not localized in the lung tissues by immunohistochemistry. CONCLUSION. The concentration of pepsin was increased in the tracheal aspirate of preterm infants who developed bronchopulmonary dysplasia or died before 36 weeks’ postmenstrual age. Recovery of pepsin in tracheal aspirate samples is secondary to gastric aspiration, not by hematogenous spread or local synthesis in the lungs. Chronic aspiration of gastric contents may contribute in the pathogenesis of bronchopulmonary dysplasia.

Pepsin, a reliable marker of gastric aspiration, is frequently detected in tracheal aspirates from premature ventilated neonates: relationship with feeding and methylxanthine therapy.

Objectives: To determine the frequency of pepsin detection in tracheal aspirate (TA) samples of mechanically ventilated premature neonates and its association with feedings and methylxanthine therapy. Patients and Methods: Serial TA samples (days 1, 3, 5, 7, 14, 21, 28 and >28vdays) were collected from premature neonates receiving ventilatory support. An enzymatic assay with a fluorescent substrate was used to detect pepsin. Pepsin was also measured in 10 serum samples collected in conjunction with the TA samples from 8 neonates. Results: A total of 239 TA samples was collected from 45 premature neonates (mean birth weight, 762 ± 166 g; mean gestational age, 25.5 ± 1.5 wk). Pepsin was detectable in 222 of 239 TA samples (92.8%) and in none of the serum samples. Pepsin was significantly lower on day 1 (mean, 170 ± 216 ng/mL) when compared with all other time points (P < 0.05). Mean concentration of pepsin was significantly lower when infants were unfed (265 ± 209 ng/mL) compared with levels during feeding (390 ± 260 ng/mL, P = 0.02). The mean level of pepsin was significantly higher in infants during xanthine therapy (419 ± 370 ng/mL) compared with no xanthine therapy (295 ± 231 ng/mL, P = 0.037). Conclusion: Pepsin, a marker of gastric contents, was detected in more than 92% of TA samples from premature infants on mechanical ventilation. The level of pepsin was higher in fed infants when compared with unfed infants. Xanthine therapy was also associated with increased pepsin in TA samples. Chronic aspiration of gastric contents may worsen lung disease in premature infants.

The Role of Extraesophageal Reflux in Otitis Media in Infants and Children

Objectives/Hypothesis: Gastroesophageal reflux disease (GERD) is common in children, and extraesophageal reflux disease (EORD) has been implicated in the pathophysiology of otitis media (OM). We sought to 1) determine the incidence of pepsin/pepsinogen presence in the middle ear cleft of a large sample of pediatric patients undergoing myringotomy with tube placement for OM; 2) compare this with a control population of pediatric patients undergoing middle ear surgery (cochlear implantation) with no documented history of OM; 3) analyze potential risk factors for OM in children with EORD demonstrated by the presence of pepsin in the middle ear cleft; and 4) determine if pepsin positivity at the time of myringotomy with tube placement predisposes to posttympanostomy tube otorrhea.

Assessment of the prevalence of microaspiration by gastric pepsin in the airway of ventilated children

Aim: Mechanically ventilated patients are at risk for aspiration of gastric contents. The aim of this observational study was to determine the prevalence of micro‐aspiration in children with cuffed and uncuffed endotracheal (ET) tubes and with tracheostomies and to assess the effect of feeding status on aspiration. Micro‐aspiration was determined by measuring gastric pepsin in tracheal aspirates.

Detection of Gastric Pepsin in Middle Ear Fluid of Children with Otitis Media

OBJECTIVE: We sought to confirm the finding of pepsin/pepsinogen in the middle ear fluid of children with otitis media in a larger sample size using a sensitive and specific pepsin assay. STUDY DESIGN AND SETTING: We evaluated 152 children (225 ear samples) in a prospective study at a tertiary care childrens hospital. The presence of pepsin in middle ear aspirates was determined using enzymatic assay. RESULTS: Of the patients, 14.4 percent (22 of 152) had detectable pepsin activity in one or both of the ear samples with no pepsin activity detected in control serum. Average pepsin concentration in the samples was 96.6 ± 170.8 ng/ml, ranging from 13 to 687 ng/ml. Pepsin concentration in the middle ear of children younger than 1.0 year was significantly higher than in older age groups. CONCLUSION AND SIGNIFICANCE: Results indicate that pepsin/pepsinogen is present in the middle ears of children with otitis media, although not at the high rate previously reported. Gastric reflux may be one causative factor in the pathogenesis of otitis media.

Comparison of Fecal Elastase-1 and Pancreatic Function Testing in Children

Objectives: The fecal pancreatic elastase-1 (FE-1) test is considered a simple, noninvasive, indirect measure of pancreatic function. We aimed to evaluate the performance of the FE-1 test compared with the direct pancreatic function test (PFT) with secretin stimulation in children. Methods: Data of 70 children (6 months–17 years of age) who had both FE-1 test and PFT were analyzed. Results: The average FE-1 concentration was 403 ± 142 &mgr;g/g. Eleven children had concentrations below 200 &mgr;g/g, 23 between 201 to 500 &mgr;g/g, and 36 were above 500 &mgr;g/g. The average pancreatic elastase activity measured on direct stimulation was 49.1 ± 38.6 &mgr;mol · min−1 · ml−1 and 11 children had activity below the established cutoff (10.5 &mgr;mol · min−1 · ml−1). Among the 11 children with pathologic PFT, 7 had normal FE-1, 4 were in the intermediate range (201–500 &mgr;g/g), and none were in the low range (<200 &mgr;g/g). Among the 59 children with normal direct PFT 11 (19%) had pathologic (<200 &mgr;g/g) and 19 (32%) had intermediate FE-1 tests. Twenty-nine children had both normal FE-1 concentration and normal PFT, giving a negative predictive value of 80%. The correlation between pancreatic elastase activity and FE-1 concentration was poor (r = 0.190). The sensitivity of the FE-1 test was found to be 41.7%, whereas the specificity was 49.2%. The positive predictive value of the FE-1 test was only 14%. Conclusions: The FE-1 test is a simple, noninvasive, indirect method; however, ordering physicians should be aware of its limitations. It can give false-positive results and has low sensitivity in children with mild pancreatic insufficiency without cystic fibrosis and in those with isolated pancreatic enzyme deficiencies.

Ghrelin and obestatin levels in children with failure to thrive and obesity.

Objectives: Ghrelin and obestatin are 2 gastric hormones with opposite effects on food intake and body weight. We investigated plasma ghrelin and obestatin in children with failure to thrive (FTT) and obesity as compared with age-matched controls. Methods: A total of 63 children were included in the study: 13 with FTT, 17 with obesity, and 33 age-matched controls. Children fasted for at least 8 hours before specimen collection. Both hormones were measured using commercially available enzyme immunoassay kits. Results: Ghrelin and obestatin levels in children with FTT were not significantly different from that of the age-matched controls (P >0.05). In children with obesity, the total ghrelin levels were significantly lower (P = 0.0003) and the obestatin levels significantly higher (P = 0.029) compared with those in controls. In the control group, the fasting ghrelin level was significantly higher in the younger (<3 years) than in the older children (>3 years; P = 0.0004). Obestatin levels correlated positively with weight-for-age percentiles in the obese group (P = 0.011) and negatively in the control group >3 years (P = 0.019). Conclusions: Compared with the levels in age-matched controls, fasting ghrelin and obestatin levels did not differ significantly in children with FTT. In the children with obesity, the decreased ghrelin and increased obestatin levels suggest a possible adaptive process to positive energy balance. Ghrelin had pronounced age-related changes, and obestatin was associated with the weight status. This may suggest that these 2 hormones use different mechanisms to regulate energy balance and weight.

Detection of pepsin in mouth swab: correlation with clinical gastroesophageal reflux in preterm infants.

Abstract Objective: To study the relationship between pepsinogen/pepsin in a mouth swab and clinical gastroesophageal reflux (GER) in preterm infants. Methods: Preterm infants (birth weight ≤ 2000 g) on full enteral feeds were enrolled. Mouth swabs from cheek and below the tongue were collected one, two and three hours after feeding. An enzymatic assay with substrate fluorescein isothiocyanate-casein was used to detect pepsin A and C activities with further confirmation by western blot. Blinded investigators reviewed the infant’s medical record to clinically diagnose GER. Results: A total of 101 premature infants were enrolled. Pepsinogen/pepsin was detected in 45/101 (44.5%) infants in at least one sample. A clinical diagnosis of GER was made in 36/101 (35.6%) infants. Mouth swabs were positive in 26/36 (72%) infants with clinical GER and only 19/65 (29%) infants without GER (p < 0.001). Similarly, the levels of pepsinogen/pepsin A and C were higher in the mouth swabs of infants with clinical GER. Conclusion: The detection of pepsinogen/pepsin in a mouth swab correlates with clinical GER in premature infants.

The Role of Gastric Pepsin in the Inflammatory Cascade of Pediatric Otitis Media

IMPORTANCE Otitis media is characterized as an ongoing inflammation with accumulation of an effusion in the middle ear cleft. The molecular mechanisms underlying the pathogenesis, particularly the inflammatory response, remain largely unknown. We hypothesize that aspiration of gastric contents into the nasopharynx may be responsible for the initiation of the inflammatory process or aggravate a preexisting condition. OBJECTIVE To investigate the correlation of gastric pepsin A with inflammatory cytokines, bacterial infection, and clinical outcomes. DESIGN, SETTING, AND PARTICIPANTS Prospective study of 129 pediatric patients undergoing myringotomy with tube placement for otitis media at a tertiary care pediatric hospital. MAIN OUTCOMES AND MEASURES Ear samples were tested for pepsin A; cytokines interleukin (IL)-6, IL-8, and tumor necrosis factor; and bacterial culture inoculation. Data were analyzed by descriptive statistics and regression analysis to identify risk factors for the presence of pepsin A and to correlate pepsin A levels with cytokine levels, infection status, and clinical outcomes. RESULTS Of the 129 patients, 199 ear samples were obtained; 82 samples (41%) and 64 patients (50%) were positive for pepsin A as measured by immunoassay. Pepsin A positivity correlated with age younger than 3.0 years (mean [SD], 2.3 [2.1] years in the positive group vs 3.3 [3.0] years in the negative group) and with all 3 cytokine levels (mean [SD] tumor necrosis factor, 29.5 [45.9] pg/mL in the positive group vs 13.2 [21.6] pg/mL in the negative group; IL-6, 6791.7 [9389.1] pg/mL in the positive group vs 2849.9 [4066.3] pg/mL in the negative group; and IL-8, 6828.2 [8122.3] pg/mL in the positive group vs 2925.1 [3364.5] pg/mL in the negative group [all P < .05]); however, logistic regression analysis showed that only IL-8 (odds ratio, 3.96; 95% CI, 1.3-12.0; P = .02) and age (odds ratio, 3.83; 95% CI, 1.2-12.7; P = .03) were significant independent variables. No statistically significant association was found with other parameters. Multiple linear regressions revealed that the levels of pepsin A were correlated with IL-8 levels (R2 = 0.248; P < .001) and the need for second or third tubes 6 to 12 months after the first (R2 = 0.102; P = .006). The presence of pepsin A in the middle ear was not associated with increased bacterial infection. Interleukin 8 was independent and significantly associated with both pepsin A levels and bacterial infection (R2 = 0.144 and 0.263, respectively; P = .001 for both). CONCLUSIONS AND RELEVANCE Extraesophageal reflux as indicated by the presence of pepsin A is closely involved in the middle ear inflammatory process and may worsen the disease in some children; however, a proof of cause and effect between extraesophageal reflux and middle ear inflammation requires further investigation.

Cytokine release, pancreatic injury, and risk of acute pancreatitis after spinal fusion surgery.

Acute pancreatitis after posterior spinal fusion in children is associated with high intraoperative blood loss. Inflammation, oxidative stress, and pancreatitis markers were assessed during this period. Five of the 17 patients studied developed acute pancreatitis 3–7 days after surgery. Intraoperative blood loss (4850±2315 vs 1322±617 ml) and peak tumor necrosis factor α levels (15.29±5.3 vs 8.27±4.6 pg/ml) in the immediate postoperative period were significantly higher in these five patients than in controls, respectively. No differences were noted in serum interleukin 8, interleukin 6, pancreatis-associated protein, or urine malondialdehyde levels. Urine trypsin-associated peptide, elevated initially in all patients, was significantly higher in the acute pancreatitis group at diagnosis. Length of stay was significantly longer in the acute pancreatitis group. Greater blood loss and peak tumor necrosis factor α are associated with subsequent risk of acute pancreatitis, suggesting a role of ischemia–reperfusion injury.