The impact of obesity on 30-day complications in pediatric surgery

PURPOSE

To examine the effects of obesity on specialty-specific surgical outcomes in children.

MATERIALS AND METHODS

Retrospective cohort study using the National Surgical Quality Improvement Program, Pediatric, 2012-2014. Patients included those aged 2-17 years who underwent a surgical procedure in one of six specialties. Obesity was the primary patient variable of interest. Outcomes of interest were postoperative complications and operative times. Odds ratios for development of postoperative complications were calculated using stepwise multivariate regression analysis.

RESULTS

Obesity was associated with a significantly greater risk of wound complications (OR 1.24, 95% CI 1.13-1.36), but decreased risk of non-wound complications (OR 0.68, 95% CI 0.63-0.73) and morbidity (OR 0.79, 95% CI 0.75-0.84). Obesity was not a significant factor in predicting postoperative complications in patients undergoing otolaryngology or plastic surgery procedures. Anesthesia times and operative times were significantly longer for obese patients undergoing most types of pediatric surgical procedures.

CONCLUSION

Obesity confers an increased risk of wound complications in some pediatric surgical specialties and is associated with overall decreased non-wound complications and morbidity. These findings suggest that the relationship between obesity and postoperative complications is complex and may be more dependent on underlying procedure- or specialty-related factors than previously suspected.

Laparoscopic appendectomy for perforated appendicitis: a comparison with open appendectomy

BACKGROUND

The role of laparoscopic appendectomy for perforated appendicitis remains controversial. This study aimed to compare laparoscopic and open appendectomy outcomes for children with perforated appendicitis.

METHODS

Over a 36-month period, 111 children with perforated appendicitis were analyzed in a retrospective review. These children were treated with either laparoscopic (n = 59) or open appendectomy. The primary outcome measures were operative time, length of hospital stay, time to adequate oral intake, wound infection, intraabdominal abscess formation, and bowel obstruction.

RESULTS

The demographic data, presenting symptoms, preoperative laboratory values, and operative times (laparoscopic group, 61 +/- 3 min; open group, 57 +/- 3 were similar for the two groups (p = 0.3). The time to adequate oral intake was 104 +/- 7 h for the laparoscopic group and 127 +/- 12 h for the open group (p = 0.08). The hospitalization time was 189 +/- 14 h for the laparoscopic group, as compared with 210 +/- 15 h for the open group (p = 0.3). The wound infection rate was 6.8% for the laparoscopic group and 23% for the open group (p < 0.05). The wounds of another 29% of the patients were left open at the time of surgery. The postoperative intraabdominal abscess formation rate was 13.6% for the laparoscopic group and 15.4% for the open group. One patient in each group experienced bowel obstruction.

CONCLUSIONS

Laparoscopic appendectomy for the children with perforated appendicitis in this study was associated with a significant decrease in the rate of wound infection. Furthermore, on the average, the children who underwent laparoscopic appendectomy tolerated enteral feedings and were discharged from the hospital approximately 24 h earlier than those who had open appendectomy.

Laparoscopic cecostomy button placement for the management of fecal incontinence in children with Hirschsprung’s disease and anorectal anomalies

BACKGROUND

Antegrade colonic enemas offer a surgical solution for many children with chronic constipation and encopresis associated with Hirschsprung's disease and anorectal malformations. This study demonstrated the feasibility of a new laparoscopic technique for cecostomy button placement (LCBP) to allow antegrade enema treatment.

METHODS

Charts of children with encopresis who underwent LCBP between 1999 and 2001 were reviewed. The age, weight, primary diagnosis, operative time, hospital stay, associated complications, follow-up duration, and outcome of the patients were recorded. The surgical technique used a "U-stitch" method and a chait tube or a standard gastrostomy button. A follow-up telephone survey was conducted to assess parental satisfaction and overall success in continence.

RESULTS

Seven patients ages 4 to 12 years (mean, 7.3 +/- 1.3 years) and weighing 15 to 44 kg (mean, 24.5 +/- 4 kg) underwent LCBP over a 2-year period. The mean follow-up period was 15 +/- 4 months (range, 6-33 months). Four patients had anorectal malformations, and three patients had Hirschsprung's disease. For all the patients, LCBP was accomplished without any intraoperative complications. The mean operative time was 33 +/- 2 min, and the hospital stay was 2 to 5 days (mean, 3.8 +/- 0.5 days). The patients received one or two daily antegrade enemas, and none had accidental bowel movements. Episodes of soiling at night once or twice a week were observed with two children. Two patients had hypertrophic granulation tissue formation, which responded to topical therapy. The button was uneventfully changed twice in one patient because of mechanical malfunction.

CONCLUSION

To manage overflow incontinence of children with anorectal malformations and Hirschsprung's disease, LCBP is a technically straightforward, effective, and reversible method for the placement of a cecostomy button.

Comparison of the incidence of complications in open and laparoscopic pyloromyotomy: a concurrent single institution series

PURPOSE

The purpose of this study was to compare the incidence and type of technical complications seen in a concurrent series of pyloromyotomies done open and laparoscopically.

METHODS

The medical records of all patients who underwent pyloromyotomy for congenital hypertrophic pyloric stenosis over a 66-month period were reviewed (n = 457). Information obtained included age, sex, weight, operating time, and intraoperative and postoperative complications.

RESULTS

Four hundred fifty-seven pyloromyotomies were equivalently divided between the 2 techniques (232 laparoscopic, 225 open). Demographic characteristics and operating times were similar. There were no deaths in the series. The overall incidences of complications were similar in the 2 groups (open, 4.4%; laparoscopic, 5.6%). There was a greater rate of perforation with the open technique and a higher rate of postoperative problems including incomplete pyloromyotomy in the laparoscopic group.

CONCLUSIONS

The open and laparoscopic approaches have similar overall complication rates. The distribution and the type of complications differ, however.

Effect of dietary fat on fat absorption and concomitant plasma and tissue fat composition in a rat model of short bowel syndrome

The aim of this study was to investigate the effect of dietary fat on the time course of changes in fat absorption and tissue and plasma lipid composition in a rat model of short bowel syndrome (SBS). Male Sprague-Dawley rats underwent either a bowel transection with re-anastomosis (Sham rats) or 75% small bowel resection (SBS rats). Animals were randomly assigned to one of three groups: Sham rats fed normal chow (Sham-NC), SBS rats fed normal chow (SBS-NC), or SBS rats fed a high-fat diet (SBS-HFD). Rats were sacrificed on day 3 or 14. Body weight, food intake, food clearance (dry fecal mass), and fat clearance (total fecal fat) were measured twice a week. Fat and energy intakes were calculated according to the amount of ingested food. Food and fat absorbability were calculated as intake minus clearance and were expressed as percent of intake. Serum cholesterol, triglyceride, and albumin were measured. Total lipid composition of the liver, epididymal adipose tissue, and the small intestine was determined. Statistical analysis was performed by a Student's test, with p values <0.05 considered significant. Both food and fat absorbability diminished after bowel resection in rats fed NC. This was accompanied by a decrease in body weight gain, plasma triglyceride and protein levels, and total lipid content of the liver at day 3 and of a decrease in adipose tissue at day 14 following operation. SBS-HFD rats experienced a significant increase (p<0.05) in food absorbability after 7 days and fat absorbability after 3 days compared with Sham-NC and SBS-NC rats (p<0.05), as well as increases in serum cholesterol, triglycerides, and glucose compared with SBS-NC rats. On day 14, plasma lipid levels in SBS-HFD rats were not different from SBS-NC or control rats; however, albumin levels were higher. A high-fat diet increased total fat content of the liver early after operation. In conclusion, in a rat model of SBS, an early high-fat diet increased the absorptive capacity of the intestinal remnant as seen by increased food and fat absorbability. These findings suggest a benefit of a high-fat diet on intestinal adaptation in general and on lipid absorption in particular.

Pediatric laparoscopic appendectomy for acute appendicitis

BACKGROUND

The benefit of laparoscopy in the treatment of pediatric acute appendicitis continues to be controversial, particularly as it relates to operative time and costs.

METHODS

We reviewed the charts of 200 children who underwent appendectomy for acute appendicitis concurrently over 35 months at a large teaching children's hospital.

RESULTS

Laparoscopic ( n = 105) [corrected] and open ( n = 95) appendectomies were performed. The operative times and postoperative lengths of hospital stay were similar for the two groups. The mean total hospital cost for the laparoscopic group (5,572 dollars) was significantly higher than for the open group (4,472 dollars); ( p < 0.01).

CONCLUSIONS

Notably, the results show similar operative times for laparoscopic and open appendectomy. The cost of laparoscopic appendectomy for acute appendicitis is higher than for the open procedure. This study challenges health care providers to reduce costs and develop new ways to measure beneficial outcomes in a pediatric population that may reveal laparoscopic benefits.

Recent developments in our understanding of melanocortin system in the regulation of food intake

Obesity has become one of the most significant public health problems facing the world today. However, the pathogenesis of obesity is multifactorial and involves the interaction of genetic and environmental factors. There is a pressing need to better understand the biochemical pathways that control energy intake and expenditure. In the last few years, a number of important signalling molecules have been identified that play important roles in obesity. One family of these molecules is the melanocortin system, which consists of several components: (1) melanocortin peptides; (2) the five seven-transmembrane G-protein coupled melanocortin receptors (MCRs); (3) the endogenous MCR antagonists, agouti and agouti-related protein; (4) the endogenous melanocortin mediators, mahogany, and syndecan. This system plays a key role in the central nervous system control of feeding behaviour and energy expenditure. This article will provide an overview of the anatomy, physiology, and molecular biology of the melanocortin system, and recent developments in our understanding of this system in obesity.

Probiotics up-regulate MUC-2 mucin gene expression in a Caco-2 cell-culture model

Enteral probiotics such as Lactobacillus casei GG (LGG) have been used in the treatment of a variety of intestinal disorders in infants and children, including diarrhea, malabsorption, and Clostridium difficile colitis. Previous studies have identified the gene locus for mucin (MUC-2) and its expression in Caco-2 cells. Others have demonstrated that mucin, located on the surface of the intestinal epithelium, inhibits bacterial translocation (BT). We previously demonstrated that both mucin and the probiotic bacterium LGG have an inhibitory effect on BT in both an in-vitro Caco-2 cell model and a neonatal rabbit model. We hypothesized that the decline in BT by LGG is mediated by up-regulation of epithelial MUC-2. Human enterocyte Caco-2 cells were grown to confluence and incubated at 37 degrees C with either medium (control group) or 10(4) or 10(8) LGG for 180 min. Non-adherent LGG was washed away. Caco-2 cells were then lysed, purified, and quantified for MUC-2 protein and mRNA. The addition of LGG to the enterocyte monolayer surface resulted in significantly ( P < 0.05) increased MUC-2 expression compared to the untreated monolayers. Protein densities for MUC-2 significantly ( P < 0.05) increased with LGG. Density (expressed as ratio to control group) was 8.6 +/- 1.3 in the low-dose group (10(4) LGG) and 15.6 +/- 2.3 in the high-dose group (10(8) LGG). LGG may thus bind to specific receptor sites on the enterocyte and stimulate the up-regulation of MUC-2, resulting in increased inhibition of BT.

Gut expression and regulation of FAT/CD36: possible role in fatty acid transport in rat enterocytes

Fatty acid translocase (FAT)/CD36 is one of several putative plasma membrane long-chain fatty acid (LCFA) transport proteins; however, its role in intestinal absorption of LCFA is unknown. We hypothesized that FAT/CD36 would be differentially expressed along the longitudinal axis of the gut and during intestinal development, suggesting specificity of function. We found that intestinal mucosal FAT/CD36 mRNA levels varied by anatomic location along the longitudinal gut axis: stomach 45 +/- 7, duodenum 173 +/- 29, jejunum 238 +/- 17, ileum 117 +/- 14, and colon 9 +/- 1% (means +/- SE with 18S mRNA as control). FAT/CD36 protein levels were also higher in proximal compared with distal intestinal mucosa. Mucosal FAT/CD36 mRNA was also regulated during intestinal maturation, with a fourfold increase from neonatal to adult animals. In addition, FAT/CD36 mRNA levels and enterocyte LCFA uptake were rapidly downregulated by intraduodenal oleate infusion. These findings suggest that FAT/CD36 plays a role in the uptake of LCFA by small intestinal enterocytes. This may have important implications in understanding fatty acid absorption in human physiological and pathophysiological conditions.

Effect of low fat diet on lipid absorption and fatty-acid transport following bowel resection

Low-fat diets (LFD) are used extensively in many different clinical conditions. However, the effect of this diet on lipid absorption and cellular long-chain fatty-acid (LCFA) transport is unknown. Fatty-acid translocase (FAT), the rat homologue of human CD36, is one of several LCFA plasma-membrane transport proteins that may play an important role in intestinal lipid uptake. The purpose of this study was to investigate the effects of a LFD on intestinal expression of FAT/CD36, enterocyte fatty-acid transport, and in-vivo lipid absorption in rats following bowel resection. Adult male Sprague-Dawley rats were divided into five experimental groups: normal rats fed normal chow(NR-NC) (10 kcal% fat), normal rats fed a LFD (NR-LFD) (3 kcal% fat), sham rats fed normal chow (Sham-NC), short-bowel syndrome rats fed normal chow (SBS-NC), and SBS rats fed a LFD (SBS-LFD). SBS rats underwent 75% small-bowel resection, while sham animals underwent bowel transection and reanastomosis. Food intake, fecal mass, and fecal fat were measured over the last 3 days before death on day 14. Final body weight, plasma lipids and protein, and tissue total lipids in liver, adipose tissue, and intestine were determined at death. Total RNA from the mucosa of the duodenum, jejunum, and ileum was extracted for Northern blot analysis to determine fatty-acid translocase (FAT)/CD36 mRNA levels. An established cellular LCFA transport assay was used to determine isolated enterocyte [3H]-oleate uptake. Students t-test was used to determine statistical significance (P < 0.05). NR-LFD rats demonstrated a small increase in overall food absorption and no change in fat absorption compared to NR-NC animals. A significant decrease in FAT/CD36 mRNA levels was seen in the duodenum and jejunum in NF-LFD rats (vs NR-NC) and was accompanied by reduced LCFA transport by isolated enterocytes from the jejunum and ileum. SBS-LFD rats demonstrated decreased FAT/CD36 mRNA levels in all three segments and a concomitant decrease in LCFA uptake enterocytes compared to the SBS-NC group. In addition, SBS-LFD rats showed significantly lower final body weight and plasma lipids compared to SBS-NC animals.

The effect of phospholipids and fatty acids on tight-junction permeability and bacterial translocation

The activity of phospholipase A2 (PLA2) is elevated in the intestinal epithelia of patients with inflammatory bowel disease (IBD). We recently reported that PLA2 mediates hydrolysis of phosphatidylcholine (PC) to lysophosphatidylcholine (L-PC) when both are applied to the apical surface of cultured EC monolayers, resulting in increased bacterial translocation (BT) and decreased transepithelial electrical resistance (TEER). Free fatty acids (FFA) are the other products of this reaction, however, their effect on Caco-2 cell permeability has not been reported. In addition to PC, other luminal phospholipids are present at the surface of the enterocyte. PLA2 may also mediate the hydrolysis of luminal phospholipids other than PC. The aim of this study was to examine the effects of phospholipids other than PC and common FFA on intestinal epithelial permeability and BT. Human Caco-2 enterocytes were grown to confluence on porous filters in the apical chamber of a two-chamber cell-culture system. Monolayer integrity and tight-junction permeability were measured as TEER. First, common FFA released by PC hydrolysis were determined using thin-layer chromatography (TLC). In separate experiments, monolayers were treated with phosphatidylethanolamine (PE), lysophosphatidylethanolamine (L-PE), or palmitoleic acid, oleic acids, linoleic acids, and arachidonic acid solubilized in solution with PC. The magnitude of BT was determined 2 h after treatment by adding Escherichia coli C25 to the apical chamber followed by quantitatively culturing basal-chamber samples. Statistical analysis was by the Kurosaki-Wallis test. TLC of PC samples incubated with PLA2 on the apical surface of Caco-2 monolayers demonstrated the production of palmitoleic acid, oleic acids, linoleic acids, and arachidonic acid. L-PE significantly decreased TEER compared to controls, but to a lesser degree than L-PC alone. L-PE had no effects on BT. Palmitoleic acid and oleic acid likewise significantly decreased TEER compared to controls, however, less than L-PC. All FFA tested had no effect on BT. Phospholipids applied to the apical surface of enterocytes, such as those found in vivo in mucus, can be hydrolyzed by the enzyme PLA2 resulting in lysophospholipid and FFA species that can alter enterocyte monolayer permeability. However, FFA and L-PL, other than L-PC, appear to have no effect to stimulate BT. This observation may have clinical implications in the pathogenesis and treatment strategies for IBD patients in whom enterocyte PLA2 activity has been shown to be elevated.

Effect of secretory immunoglobulin A on bacterial translocation in an enterocyte-lymphocyte co-culture model

Intestinal secretory immunoglobulin A (sIgA) plays an important role in gut mucosal immunity in vivo; however, in-vitro enterocyte models for studying the mechanisms of these effects are lacking. This study utilizes a cell-culture model to investigate the effect of sIgA on bacterial translocation (BT) across human enterocytes co-cultured with human lymphoid cells (Raji cells). This model is intended to mimic in-vivo enterocyte/lymphocyte interactions found in intestinal follicle-associated epithelia. Human Caco-2 enterocytes were grown to confluence on porous filters in the apical chamber of a two-chamber cell-culture system. After differentiation, human B lymphoid cells (Raji cells) were added to the basolateral surface of Caco-2 monolayers for 3 days' co-culture, followed by washing away of unincorporated Raji cells. Transepithelial electrical resistance (TEER) was used to measure tight-junction permeability. Monolayers were treated with or without sIgA, IgG (negative control), or mannose (positive control). BT across the cell monolayer was determined 1.5 h after addition of Escherichia coli. Statistical analysis was by the Kruskal-Wallis test, P below 0.05 considered significant. In co-culture monolayers treated with sIgA, IgG, or mannose, there was no significant effect on TEER; however, the magnitude of BT across cells treated with sIgA (1.3 +/- 0.4 log10CFU/ml) and mannose (1.6 +/- 1.1 log10CFU/ml) was significantly decreased compared to PBS (3.9 +/- 0.4 log10CFU/ml) and IgG (2.9 +/- 0.6 log10CFU/ml) controls (P < 0.05). sIgA BT inhibition was dose-dependent. BT inhibition by sIgA and mannose was additive (0.5 +/- 1 log10CFU/ml). Inhibition of BT was negated when sIgA and mannose were removed by washing prior to E. Coli addition (3.6 +/- 0.5 log10CFU/ml), suggesting that both inhibitors act through bacterial binding.

Effect of probiotics on enterocyte bacterial translocation in vitro

Enteral probiotics such as Lactobacillus casei GG (LGG) have been used in the treatment of a variety of intestinal disorders in infants and children, including diarrhea, malabsorption, and Clostridium difficile colitis. We have previously demonstrated that the probiotic bacterium LGG has an inhibitory effect on bacterial translocation (BT) in a neonatal rabbit model. However, this in-vivo model is limited for investigating the cellular and molecular mechanisms responsible for probiotic inhibition of BT. The purpose of this study was to determine the efficacy of LGG in reducing the rate of Escherichia coli C25 (E. coli C25) translocation using an in-vitro enterocyte cell-culture model. Human colonic carcinoma (Caco-2) enterocytes were seeded in porous filters in the apical chamber of a two-chamber cell-culture system and grown for 14 days to confluence. The monolayers were incubated at 37 degrees C with LGG for 180 min. Non-adherent LGG was washed away prior to a 120-min incubation period with 10(5) CFU E. coli C25. E. coli that had translocated across the enterocyte monolayer were quantified by growing basal-chamber media samples on gram-negative bacteria-specific MacConkey's agar. In order to determine monolayer integrity, transepithelial electrical resistance (TEER) was measured across Caco-2 cells treated with LGG and E. coli. Statistical analysis was by ANOVA with P < 0.05 considered significant. LGG inhibited E. coli translocation at all LGG concentrations tested. The TEER ratio was not significantly altered by addition of LGG or E. coli (0.9 +/- 0.03 vs 0.8 +/- 0.05). These results demonstrate that the probiotic bacterium LGG inhibits BT of E. coli C25 in a dose-dependent manner in an in-vitro cell-culture model. This model should be valuable in investigating the cellular and molecular mechanisms involved in the inhibition of pathological enteral bacteria by probiotic agents.

Evaluation of probiotic treatment in a neonatal animal model

The clinical use of probiotic agents such as enteral Lactobacillus to enhance intestinal defense against potential luminal pathogens has been tested in vivo; however, an understanding of the mechanisms responsible for the observed protection is lacking. The purpose of this study was to evaluate the effects of Lactobacillus on bacterial translocation (BT) in a neonatal animal model. Newborn New Zealand white rabbit pups were enterally fed a 10% Formulac solution inoculated with or without a 10(8) suspension of ampicillin-resistant Escherichia coli K1 (E. coli K1A) and/or Lactobacillus casei GG (Lacto GG). Pups received either no bacteria (n = 10), Lacto GG (n = 8), E. coli K1A (n = 26), or a combination of Lacto GG and E. coli K1A (n = 33). On day 3, representative tissue specimens from the mesenteric lymph nodes (MLN), spleen (SPL), and liver (LIV) were aseptically harvested in addition to a small-bowel (SB) sample that was rinsed to remove luminal contents. The specimens were then cultured in organism-specific media. Statistical analysis was by one-way ANOVA with P values less than 0.05 considered significant. Neonatal rabbits receiving Lacto GG-supplemented formula exhibited a 25% decrease (P < 0.05) in small-bowel colonization by E. coli K1A. In addition, Lacto GG decreased the frequency of extraintestinal BT by 46% (P < 0.05), 61% (P < 0.05), and 23%, respectively, in the MLN, SPL, and LIV. We have shown that enterally-administered Lacto GG decreases the frequency of E. coli K1A translocation in a neonatal rabbit model. These results may have significant implications for the treatment of BT and sepsis in the human neonate and provide a model for further studies.

The effect of phospholipase A2 on bacterial translocation in a cell culture model

The activity of phospholipase (PL)A2 is elevated in the intestinal epithelia of patients with inflammatory bowel disease (IBD). Recently, we reported that lysophosphatidylcholine (L-PC), the PLA2 hydrolysis product of phosphatidylcholine (PC), stimulates bacterial translocation (BT) in an enterocyte cell-culture model. These two observations stimulated us to examine the effects of extracellular PLA2 on intestinal epithelial permeability. Human Caco-2 enterocytes were grown to confluence on porous filters in the apical chamber of a two-chamber cell-culture system. Monolayer integrity and tight-junction permeability were measured by dextran blue (DB) permeability and transepithelial electric resistance (TEER). Monolayers were treated with PC, L-PC, or PLA2 with and without PC. The magnitude of BT was determined 2 h after treatment by adding Escherichia coli to the apical chamber followed by quantitatively culturing basal chamber samples. Thin-layer chromatography (TLC) was utilized to verify PLA2 hydrolysis of PC to L-PC. Statistical analysis was performed by one-way analysis of variance. The magnitude of BT across monolayers pretreated with PLA2 + PC significantly increased compared to either PC or PLA2 (6.83 +/- 0.069, 2.41 +/- 0.46, and 3.06 +/- 1.14 log10 colony forming units/ml, respectively, P < 0.05). Absence of DB-permeability in any group confirmed monolayer integrity. TLC of PL samples harvested from the apical monolayer surface confirmed PC hydrolysis. PLA2 mediates hydrolysis of PC to L-PC when both are applied to the apical surface of cultured enterocyte monolayers, resulting in increased BT and increased TEER with no damage to monolayer integrity. These observations may have implications in the pathogenesis and treatment strategies for IBD.

Confirmation of translocated gastrointestinal bacteria in a neonatal model

PURPOSE

The hypothesis that enteric bacteria translocate from the gastrointestinal (GI) tract to extraintestinal sites has been extensively studied. However, definitive evidence that spontaneous bacterial translocation and dissemination from the GI tract to extraintestinal sites occur in a neonatal model has been lacking. The aim of this study was to confirm this phenomenon by tracking enterally administered, plasmid-labeled bacteria to extraintestinal sites.

MATERIALS AND METHODS

Escherichia coli 07:K1 (E. coli K1) with and without a nontransferable, ampicillin resistance plasmid (pGEM-7) were used in this study. Newborn New Zealand white rabbit pups were separated into three treatment groups: transformed E. coli K1 (E. coli K1 + pGEM-7, n = 20), nontransformed E. coli K1 (n = 12), and control pups (no bacteria, n = 7). Pups were enterally fed 10% Formulac solution supplemented with a suspension of bacteria respective to their group. After the pups fed twice daily for 2 days, representative tissue specimens from the small bowel (SB), mesenteric lymph nodes (MLNs), spleen (SPL), and liver (LIV) were aseptically harvested and tested for culture growth in ampicillin-supplemented medium.

RESULTS

Positive growths of plasmid-induced ampicillin-resistant bacteria were detected in tissue specimens harvested from rabbits fed transformed E. coli K1, but were not detected in the other groups.

CONCLUSION

This experiment demonstrated conclusively that transformed E. coli K1 fed to healthy rabbit pups spontaneously translocated from the intestinal lumen and subsequently disseminated to the mesenteric lymph nodes, spleen, and liver.

Specialty networking in pediatric surgery: a paradigm for the future of academic surgery

OBJECTIVE

To review retrospectively a 4-year experience with pediatric surgical networking at a major academic medical center in the Midwest.

BACKGROUND

The growth of managed care in the United States during the past decade has had a major impact on the practice of medicine in general, but especially on academic medicine. In some academic medical centers, the loss of market share has not only affected clinical activity but has also compromised the educational and research missions of these institutions.

METHODS

At the authors' institution, a networking strategy in pediatric surgery was established in 1993 and implemented on July 1, 1994. In 1994, one new satellite practice was established; over the next 4 years, four additional practices were added, including one in another state. To assess the impact on financial status, clinical activity, education, and academic productivity, the following parameters were analyzed: gross and net revenue, surgical cases, clinic visits, ranking of the pediatric surgery residency, publications, grant support, and development and endowment funds.

RESULTS

Gross and net revenue increased from $3,273,000 and $302,000 in 1993 to $10,087,000 and $2,826,000, respectively, in 1998. Surgical cases and clinic visits increased from 1240 and 3751 in 1993 to 5872 and 11,604, respectively, in 1998. At the medical center's children's hospital, surgical cases and clinic visits increased from 1240 and 3751 to 2592 and 4729 during the same time period. During this 4-year period, the faculty increased from 4 to 11. Since 1997, the National Resident Matching Program has provided data on how pediatric surgery residency candidates ranked a training program. In 1997, this program received the second-most one to five rankings; in 1998, it tied for first. This exceeds the faculty's perception of previous years' rankings. Publications increased from 26 in 1993 to a peak number of 62 in 1996; in 1997 and 1998 the publications were 48 and 37, respectively. External grant support increased from $139,882 in 1993 to a total of $6,109,971 in 1998. Development and endowment funds increased from $103,559 in 1993 to $2,702,2777 in 1998.

CONCLUSIONS

Pediatric surgical networking at the authors' institution has had a markedly positive impact on finances, clinical activity, education, and academic productivity during a 4-year period. The residency training program appears to have improved in popularity among candidates, probably because of the increased referral of complex cases to the medical center from the various networking satellites. External grant support and basic laboratory research significantly increased, most likely because of the greater number of faculty with protected time for research recruited. Development and endowment funds dramatically grew because of the excellent fiscal health of the pediatric surgical program. This experience may serve as a model for other academic surgical specialties.

The effect of mucin on bacterial translocation in I-407 fetal and Caco-2 adult enterocyte cultured cell lines

Although the intestinal mucosa forms a crucial barrier between the host and the environment, bacterial translocation (BT) occurs frequently in neonates and may be a source of sepsis. The intestinal mucous gel layer is thought to be a vital component of the gut barrier and is composed, in part, of a family of glycoproteins known as mucins. Our aim was to study the effects of mucin on BT in an enterocyte cell-culture model using a fetal (I-407) and an adult (Caco-2) intestinal cell line. I-407 and Caco-2 cells were grown to confluence on porous filters in a two-chamber Transwell system. The integrity of the monolayers was confirmed by transepithelial electrical resistance (TEER) and permeability using the macromolecule dextran blue. Cells were treated with mucin (40 mg/ml) prior to inoculation of 1 x 10(6) Escherichia coli C25. The magnitude of BT was determined quantitatively by culturing the samples from the basal chamber of the wells and was expressed as log 10 [Colony Forming Units (CFU)/ml]. Statistical analysis was performed by the Mann-Whitney U test with statistical significance at P < 0.05. Mucin inhibited BT across both fetal and adult cultured enterocyte monolayers; however, the inhibitory effect was less on the fetal cells compared to the adult cells. Dextran-blue studies showed that monolayers were intact throughout the experiments. Despite 98% inhibition of BT, mucin had a statistically significant effect on post-bacterial inoculation TEER in Caco-2 cells and no effect in I-407 cells. The ability of mucin, a mucous-barrier glycoprotein, to inhibit BT across immature intestinal enterocytes, as in the neonate, may be diminished compared to mature adult enterocytes.

The effect of phospholipids and mucin on bacterial internalization in an enterocyte-cell culture model

A primary component of the intestinal mucous layer that functions as a barrier to luminal bacteria is mucin, a high-molecular-weight glucoprotein. In addition, the mucous layer also contains other important elements such as phospholipids (PLs), which may effect bacterial translocation (BTL). It has been reported that mucin inhibits Escherichia coli translocation; however, the effect of PLs on intestinal permeability is still controversial. We have recently reported that the concentration of mucous PLs is higher in neonatal as compared to adult rabbits. The functional significance of these biochemical differences on BTL remains to be determined. The aim of this study was to evaluate the effect of PL and mucin composition on BTL in a human enterocyte-cell culture model. Human enterocyte Caco-2 cells were seeded in 24-well tissue-culture plates and grown for 14 days to confluence. The monolayers were pretreated with phosphate buffered saline as control, 10 mg/ml or 20 mg/ml mucin, 0. 5 mM or 1.0 mM PL mixture based on neonatal (NPL) and adult (APL) composition, and 10 mg/ml mucin with 0.5 mM either APL or NPL mixtures 30 min before a 120-min incubation period at 37 degrees C with 10(8) colony forming units (CFU) of E. coli C25. Non-internalized bacteria were killed by the addition of gentamicin. Internalized bacteria were quantified by counting CFU from enterocyte-cell lysates grown on MacConkey's agar. Mucin inhibited bacterial internalization, while both compositions of PLs promoted it. Mucin added to the PL solution also diminished the stimulatory effect of PLs on bacterial internalization. These results indicate that the increased concentration of PLs found in the intestinal mucous layer of neonates, and/or the alteration in the balance between PLs and mucin, may play a role in the increased BTL seen in neonates.

Latex sensitization in general pediatric surgical patients: a call for increased screening of patients

BACKGROUND/PURPOSE

Latex sensitization is a well-documented occurrence in children with myelodysplastic and urologic anomalies. The incidence of latex allergy in general pediatric surgical patients, however, has not been previously addressed. The purpose of this study was to examine the risk of perioperative latex reactions in a general pediatric surgical practice over a 1-year period.

METHODS

This study examined the occurrence of latex sensitization using two methods. First, the preoperative anesthesia records of patients that have undergone surgery from October 1995 through September 1996 at Mott Children's Hospital were reviewed retrospectively. Second, all patients who had intraoperative anaphylaxis attributable to latex sensitization, including those from three additional hospitals, were evaluated.

RESULTS

During a 12-month period, 1,523 pediatric general surgical operations were performed at the C.S. Mott Children's Hospital. Of these, only 11 operations on five patients were performed under latex precautions. All of these patients had a preoperative diagnosis of latex sensitivity. During the same period, intraoperative anaphylactic reactions caused by latex allergy occurred in two of the general surgical patients (0.13%) at the C.S. Mott Hospital. Four additional cases are also reported from other study hospitals. None of these patients were suspected, based on current screening methods, of having a latex allergy before their surgery.

CONCLUSIONS

Latex allergy is a potentially life-threatening condition in the pediatric general surgical population. Further study is needed to develop criteria to preoperatively identify patients at risk for latex sensitization.

The lateral approach for open splenectomy

BACKGROUND

Laparoscopic splenectomy (LS) has been used increasingly to treat children with hematologic disorders and has been reported to have advantages over open splenectomy performed through a standard vertical or subcostal incision. The authors perform open splenectomy (OS) through a lateral, muscle-splitting approach, and believe their approach is more reasonable in comparison with LS.

METHODS

Thirty-nine consecutive open splenectomies performed between 1991 and 1995 were reviewed retrospectively and compared with recent reports of LS. The series included 24 boys and 15 girls with an average age of 9 years and average weight of 37.5 kg. Indications included immune thrombocytopenic purpura (n = 20), hereditary spherocytosis (n = 18), and sickle cell anemia (n = 1). The operation was performed with the child in the lateral decubitus position through a left upper abdominal muscle-splitting incision (off the 11th rib), sparing the rectus muscle.

RESULTS

All 39 cases were completed without intraoperative complications with an average surgical time of 98.0 minutes (range, 30 to 302). The average surgical blood loss was 89 mL (range, 10 to 300). The children started feeding an average of 1.2 days (range, 0 to 4) postoperatively, were on a regular diet at an average of 2.0 days (range, 1 to 6) postoperatively, and had an average length of stay of 2.7 days (range, 1 to 6). There was no mortality or morbidity.

CONCLUSIONS

Open lateral splenectomy is performed with shorter surgical times, less blood loss, an excellent cosmetic result, no complications, and a length of stay comparable to any of the published series on laparoscopic splenectomy in children. This approach provides a reasonable basis for comparison with laparoscopic splenectomy.

Immediate and long-term results of surgical management of low imperforate anus in girls

BACKGROUND

The majority of girls with imperforate anus are reported to have a malformation of the low variety. Despite this, much of the literature has focused on the more complex, high lesions.

METHODS

This study reviews our experience with 44 girls with low imperforate anus from a 22-year period.

RESULTS

The incidence of associated anomalies was 61%, which is higher than generally reported. All patients in the study had anal fistulae. Fifty-seven percent had perineal fistulae, 23% had fourchette fistulae, and 20% had vestibular fistulae. Cutback anoplasty was performed in 55%, Potts transfer anoplasty was used in 27%, and 18% of patients were treated with either limited posterior sagittal anorectoplasty or anterior sagittal anorectoplasty. Surgical complications were uncommon. Long-term follow-up was carried out by telephone survey. This showed 89% of the girls to be successfully toilet trained. However, 47% of patients experience at least occasional soilage or episodic fecal incontinence.

CONCLUSIONS

Low imperforate anus can be successfully treated using a variety of procedures without colostomy. Most girls with low imperforate anus are successfully toilet trained, but problems with continence persist in a significant number of these patients.

Changes, with age, in the phospholipid content of the intestinal mucus layer of the newborn rabbit

BACKGROUND/PURPOSE

The high incidence of bacterial translocation in newborns is thought to be caused, in part, by the immaturity of the intestinal mucosal barrier. Recently, intestinal mucus phospholipids (PL) have been reported to be important factors in the function of this mucosal barrier. The aim of this study was to quantify changes, with age, in the intestinal mucus PL of the newborn rabbit.

METHODS

Mucus was gently scraped from the small intestinal mucosal surface of rabbits of different ages (0, 7, 14, and 28 days old and adult; n = 6 for all groups). PL was extracted from the mucus and was separated by two-dimensional thin-layer chromatography. The isolated phospholipid spots were quantified for their phosphorus content.

RESULTS

Total PL content of the mucus decreased significantly with age (day 0, 21+/-2; day 7, 16+/-4; day 14, 9+/-3; day 28, 2+/-1; adult, 1+/-1 micromol/g wet mucus; P = .0001). Phosphatidylcholine and phosphatidylethanolamine levels in the adult rabbits were significantly lower in comparison with the 0-, 7-, and 14-day-old pups (P < .05). In contrast, lysophosphatidylcholine and lysophosphatidylethanolamine were significantly higher in the 28-day-old and adult rabbits in comparison with the 0-, 7-, and 14-day-old pups (P < .05). Phosphatidylinositol + phosphatidylserine levels in 7-day-old rabbits was significantly higher compared with adult rabbits. There was no significant difference in the composition of sphingomyeline between groups.

CONCLUSION

Significant changes in the content and composition of the intestinal mucus phospholipids were observed during the first month of life in rabbits.

Conservative management of mesenchymal hamartoma of the liver

The natural history of mesenchymal hamartoma of the liver is poorly understood. This case demonstrates the course of a biopsy-proven mesenchymal hamartoma using sequential computed tomography (CT) examinations. These CT scans show initial expansion of the lesion with subsequent involution. The spontaneous resolution in this patient suggests the possibility of conservative management of asymptomatic mesenchymal hamartomas. The case is presented, and the literature on mesenchymal hamartoma is reviewed.

Acute pancreatitis

The etiology of acute pancreatitis in children is widely varied and includes idiopathic, drug-related, congenital, and posttraumatic causes. Most children have abdominal pain and tenderness without evidence of peritonitis, and most patients will have elevated serum amylase levels initially or after a delay of about 12 hours. If the diagnosis remains equivocal or in the setting of trauma, an abdominal CT scan should be obtained. Initial treatment for all forms of acute pancreatitis includes bowel rest and support with intravenous fluids. A nasogastric tube should only be placed for symptomatic relief and prophylactic broad-spectrum antibiotics should be given only in the setting of necrotizing pancreatitis, especially if patients are receiving pharmacologic immunosuppression. Fever or decline in clinical status should prompt CT scan with intravenous contrast and possible fine needle aspiration to detect the presence of sterile or infected necrotizing pancreatitis. Positive cultures or severely worsening clinical status are indications for necrosectomy and debridement with sequential packing and explorations. All patients who have had an episode of gallstone pancreatitis should have a cholecystectomy after resolution of pancreatic inflammation but before discharge from the hospital.

Effect of very delayed repair of congenital diaphragmatic hernia on survival and extracorporeal life support use

BACKGROUND

Since November 1992, operative repair in neonates with congenital diaphragmatic hernia (CDH) at this institution was delayed until respiratory insufficiency had resolved.

METHODS

A retrospective analysis was performed (n = 33) comparing delayed repair with our previously reported institutional experience with immediate repair from January 1988 to October 1992 (n = 66). Infants with severe genetic defects or moribund conditions or who were premature were not considered candidates for repair or extracorporeal life support (ECLS), but they were included in the survival analysis. Survival was defined as hospital discharge. Data were compared with an independent t test or Pearson chi-squared test.

RESULTS

Mean age at repair was 8.9 +/- 4.5 days (range, 3 to 20 days). Eleven infants in the study group were placed on ECLS (33% versus 68% in the comparison group; p = 0.001). Six of these infants survived (55% versus 58% in the comparison group; p = 0.846). Of these survivors, one patient was repaired while on ECLS, and the remainder underwent repair after decannulation from ECLS. All 20 of the remaining candidates for repair survived without need for ECLS. Overall survival was 79% versus 56% in the comparison group (p = 0.027).

CONCLUSIONS

Our current data suggest that very delayed repair of newborns with CDHs is associated with an increase in the overall survival and a decrease in the use of ECLS when compared with previous experience at this institution.

Ovarian torsion: clinical and imaging presentation in children

Ovarian torsion is uncommon and has a nonspecific clinical presentation. To determine the impact of imaging on clinical management, the authors reviewed their recent experience with 12 children who had a total of 13 episodes of ovarian torsion. Three children presented as neonates, six were premenarchal, and three were postmenarchal. Ultrasound was the imaging study of choice. In all three neonates, ultrasonography showed complex abdominopelvic cysts indicating the need for surgery. In five of 10 episodes in older patients, ultrasonography showed a solid mass with an appearance strongly suggestive of torsion. Same-day surgery was performed in three patients, and the involved ovary was salvaged in one. Another patient had a small piece of normal-appearing ovary left in situ. This low rate of ovarian salvage is attributable to the combination of delay in patient presentation and surgical delay owing to the often nonspecific clinical and imaging presentation of ovarian torsion. A high level of clinical suspicion, expeditious imaging, and familiarity with the varied clinical and imaging presentations of ovarian torsion should decrease the surgical delay and improve the likelihood of ovarian salvage.

Midaortic syndrome and hypertension in childhood

Midaortic syndrome is a form of fibromuscular hyperplasia that involves the abdominal aorta including the renal and visceral branches. Symptomatology depends on the degree and location of vessel narrowing. This report updates the authors' experience and details 17 operative cases, the largest reported series. Seventeen of the 45 patients who have been operated on for severe renovascular hypertension have had this syndrome. Ages have ranged from 5 months to 15 years (average, 9.7 years). Signs and symptoms have included various manifestations of malignant hypertension, congestive heart failure, oliguric renal failure, and claudication. Intestinal angina has not been noted despite celiac and/or superior mesenteric arterial involvement. Although balloon angioplasty was performed in two patients, lasting results were not achieved. One primary nephrectomy was performed. The other 16 patients had vascular reconstructions including aortoaortic bypass grafting (n = 12), with bilateral renal artery bypasses (n = 9) or unilateral renal bypass (n = 3) or bilateral renal bypass alone (n = 4). The majority had associated visceral artery narrowing, but excellent collaterals have been present so no visceral reconstructions have been required. All renal artery bypasses have been with reinforced saphenous vein.

RESULTS

In the average follow-up period of 48 months, 12 of the 17 patients have been cured of hypertension, and the other five have improved. Claudication, congestive failure, and renal failure have been alleviated. Thus far, reinforcement of the saphenous vein grafts has prevented aneurysmal degeneration and graft loss.

CONCLUSION

These results indicate that aggressive single-stage reconstruction is the best approach for these children.

Thoracic trauma in children

Thoracic trauma in children is an infrequent but potentially lethal injury often associated with coexisting significant injury to other systems. Most reports suggest that the incidence of chest trauma in the injured child is approximately 10%. The most frequently associated trauma is, unfortunately, to the central nervous system and is an unusually deadly combination of injuries. As such, the thoracic injuries serve as a reliable marker for injury severity in children, mandating meticulous evaluation of the child presenting with thoracic trauma. The diagnosis of the thoracic injury may be difficult on cursory clinical examination and supine chest radiograph, and a thorough and focused evaluation of the child's thoracic injuries is required to discover the extent and severity of these injuries. This is particularly important because most of the thoracic injuries that may be immediately life threatening may be expediently and easily treated in the emergency department during the primary survey phase of Advanced Trauma Life Support. But when the injuries are not suspected, diagnosed, and treated, the child's morbidity and mortality risk rises exponentially and approaches 50%. Many current published reports have concentrated on the overall epidemiology of childhood thoracic trauma in order to focus medical attention on the importance of thoracic trauma to medical planning. Much of the remaining pertinent clinical literature on thoracic trauma during the last several years has looked at particular markers of injury severity and on the recognition and management of the rare but morbid cardiovascular and tracheobronchial injuries. Each of these topics is reviewed, with particular attention to the recent literature over the past 12 months.

Binding of sulfosuccinimidyl fatty acids to adipocyte membrane proteins: isolation and amino-terminal sequence of an 88-kD protein implicated in transport of long-chain fatty acids

We recently reported (Harmon et al., J. Membrane Biol. 124:261-268, 1991) that sulfo-N-succinimidyl derivatives of long-chain fatty acids (SS-FA) specifically inhibited transport of oleate by rat adipocytes. These compounds bound to an 85-90 kD membrane protein which was also labeled by another inhibitor of FA transport [3H]DIDS (4,4'-diisothiocyanostilbene-2-2'-sulfonate). These results indicated that the protein was a strong candidate as the transporter for long-chain fatty acids. In this report we determined that the apparent size of the protein is 88 kD and its isoelectric point is 6.9. We used [3H]SS-oleate (SSO), which specifically labels the 88-kD protein, to isolate it from rat adipocyte plasma membranes. Identification of 15 amino acids at the N-terminus region revealed strong sequence homology with two previously described membrane glycoproteins: CD36, a ubiquitous protein originally identified in platelets and PAS IV, a protein that is enriched in the apical membranes of lipid-secreting mammary cells during lactation. Antibody against PAS IV cross-reacted with the adipocyte protein. This, together with the N-terminal sequence homology, suggested that the adipocyte protein belongs to a family of related intrinsic membrane proteins which include CD36 and PAS IV.

Labeling of adipocyte membranes by sulfo-N-succinimidyl derivatives of long-chain fatty acids: inhibition of fatty acid transport

Sulfo-N-succinimidyl derivatives of the long-chain fatty acids, oleic and myristic, were synthesized and covalently reacted with isolated rat adipocytes. The plasma membrane proteins labeled by these compounds and the effect of labeling on the transport of long-chain fatty acids were investigated. Sulfo-N-succinimidyl oleate (SSO) and myristate (SSM) inhibited the transport of fatty acids (by about 70%). Inhibition of fatty acid transport was not a result of alterations in cell integrity, as intracellular water volume was not changed. It did not reflect effects on fatty acid metabolism, since it was observed under conditions where greater than 90% of the fatty acid taken up was recovered in the free form. The inhibitory effect was specific to the fatty acid transport system, as the transport of glucose and the permeation of retinoic acid, a substance with structural similarities to long-chain fatty acids, were unaffected. Sulfosuccinimidyl oleate reacted exclusively with a plasma membrane protein with an apparent size of 85 kDa while sulfosuccinimidyl myristate also labeled a 75-kDa protein. These proteins were among the ones labeled by diisothiocyanodisulfonic acid (DIDS) which also inhibits fatty acid transport irreversibly. The data suggest that the 85-kDa protein, which is the only one labeled by all three inhibitors is involved in facilitating membrane permeation of long-chain fatty acids.

Insulin antagonism of catecholamine stimulation of fatty acid transport in the adipocyte. Studies on its mechanism of action

Insulin at physiological concentrations can suppress catecholamine activation of the membrane transport of long chain fatty acids in the adipocyte. We have previously shown that the stimulatory effect of catecholamines was mediated by a beta-receptor interaction and cAMP (Abumrad, N.A., Park, C.R., and Whitesell, R. R. (1986) J. Biol. Chem. 261, 13082-13086). In this study we have investigated the mechanism of insulin action to antagonize transport activation. Fatty acid transport was stimulated using different cAMP derivatives with varying susceptibilities to hydrolysis by the cAMP-degrading enzyme phosphodiesterase. Insulin was effective in antagonizing the effect of cAMP analogs which were good substrates for the phosphodiesterase and failed to suppress the effect of those which were poorly hydrolyzed by the enzyme. Addition of increasing concentrations (1-100 microM) of the phosphodiesterase inhibitor methylisobutylxanthine (MIX) to norepinephrine (0.1 microgram/ml) gradually abolished insulin's antagonism. Insulin was completely ineffective in inhibiting stimulation by norepinephrine and 20 microM methylisobutylxanthine. Also consistent with involvement of cAMP lowering in insulin action was the finding that adenosine removal greatly diminished insulin's responsiveness. Treatment of cells with adenosine deaminase (1 unit/ml) enhanced the effect of norepinephrine by about 30%. A 10-fold higher range of insulin concentrations was then required to produce inhibition of fatty acid transport. The effect of adenosine removal was reversed by addition of phenylisopropyladenosine (500 nM), which is resistant to hydrolysis by the deaminase. Finally, exposure of insulin-treated cells (1 nM for 5 min) to dinitrophenol (1 mM for 5 min) reversed insulin action, consistent with reports of reversal of insulin's activation of the phosphodiesterase. In conclusion, our studies support the involvement of cAMP lowering in insulin's antagonism of fatty acid transport stimulation in the adipocyte.

Management of children with hypertension from reflux or obstructive nephropathy

During a ten-year period, 35 children presenting with vesicoureteral reflux, ureteropelvic junction obstruction, or a "small kidney" were found to be hypertensive. Of these, 15 subsequently underwent surgical procedures for relief of hypertension. Seven were "cured," six were "improved," and two were "unchanged." The severity of hypertension could not be correlated with the degree of reflux nor with the degree of obstructive uropathy. However, all children with reflux in our study who were hypertensive had some degree of calicectasis noted preoperatively on intravenous pyelogram. Also it was noted that hypertension may occur several years after successful anti-reflux surgery. Children with vesicoureteral reflux, ureteropelvic junction obstruction, or a small kidney need to have blood pressure determinations at regular intervals, even if all previous readings had been in the normotensive range and whether or not they were followed up medically or post surgically. We suggest that blood pressure determinations be made every three months for the first year after diagnosis of reflux or ureteropelvic junction obstruction, and at least once a year thereafter.