Recurrence after laparoscopic and open Nissen fundoplication: a comparison of the mechanisms of failure

BACKGROUND

Laparoscopic Nissen fundoplication as treatment for gastroesophageal reflux disease (GERD) in adults has a reported recurrence rate of 2-17%. We investigated the rates and mechanisms of failure after laparoscopic Nissen fundoplication in children.

METHODS

All patients who underwent a laparoscopic Nissen fundoplication for GERD and who subsequently required a redo Nissen were reviewed (n = 15). The control group consisted of the most recent 15 patients who developed recurrent GER after an open Nissen, fundoplication.

RESULTS

Between 1994 and 2000, laparoscopic Nissen fundoplication was performed in 179 patients. Fifteen patients (8.7%) underwent revision. The mechanisms of failure were herniation in four patients, wrap dehiscence in four, a too-short wrap in three, a loosened wrap in two, and other reasons in two. The reoperation was performed laparoscopically in five patients (33%). The failure mechanisms were different in the open patients: eight were due to slipped wraps; three to dehiscences; and two to herniations.

CONCLUSION

The failure rate after laparoscopic Nissen is acceptably low. A redo laparoscopic Nissen can be performed safely after an initial laparoscopic approach.

The market for pediatric surgeons: an updated survey of recent graduates

PURPOSE

The aim of this study was to identify the demand for pediatric surgeons as perceived by recent graduates of North American pediatric surgery training programs.

METHODS

A survey was mailed to every pediatric surgeon who completed a certified training program in North America between 1998 and 2000; 81% of 83 responded. Data from the previous survey of 1992 through 1997 graduates provided longitudinal comparisons. The data were analyzed using univariate and bivariate statistical analysis.

RESULTS

The number of graduates was 28, 31, and 24 for 1998, 1999, and 2000, respectively, down from 35 graduates in 1997. All found positions in pediatric surgery, and first-year incomes continue to rise. Fewer graduates (54%) desired an academic position coupled with research compared with previous survey respondents (64%), and 69% were able to find such a position. A practice at a university children's hospital remained the most desired by over 80%, but only 38% obtained positions in this type of practice. However, 55% were able to find a position in a children's hospital (university or community), which had declined gradually to a low of 32% in 1997. The 1998 to 2000 graduates perceive a much stronger demand for pediatric surgeons compared with previous survey respondents (46% v 14%), and greater than 50% felt that too few pediatric surgeons were being trained.

CONCLUSIONS

The market demand for pediatric surgeons remains strong as measured by employment and income. The perception of the market by the 1998 through 2000 graduates is positive, which contrasts with the 1992 through 1997 graduates. However, there continues to be significant market changes including a proliferation of positions at community Children's hospitals.

MUC-2 mucin production in Hirschsprung's disease: possible association with enterocolitis development

BACKGROUND/PURPOSE

The etiology of Hirschsprung's-associated enterocolitis (HAEC) is unknown. Previous investigations have suggested that abnormal production of mucins may have an etiologic role. Recently, a series of mucin genes have been identified. MUC-2 is the predominant mucin expressed in humans. The authors have shown previously in vitro that use of MUC-2 can prevent bacterial translocation. Based on this, it was hypothesized that those patients with Hirschsprung's disease (HD) would have an abnormal production of MUC-2 compared with normal patients.

METHODS

Fresh stool specimens were collected from children with a diagnosis of HD (with or without HAEC) and from age-matched control patients. Protein was extracted, and MUC-2 was detected with Western blot analysis. MUC-2 protein expression was quantified by densitometry measurements. Results are expressed as mean density +/- SD. Statistical comparison was done with unpaired t tests, with P less than.05 being considered significant.

RESULTS

MUC-2 expression was detected in all control patients (mean density, 121 +/- 47). MUC-2 level was lowest in one child with a viral-induced diarrhea (density = 71). In those patients with HD, levels of MUC-2 protein expression were significantly lower (P <.05) than controls (12 +/- 15 for all HD patients). Levels of MUC-2 were lowest (nondetectable) in 2 HD patients who had clinical evidence of HAEC.

CONCLUSIONS

MUC-2 production is markedly depressed in patients with Hirschsprung's disease and is absent with enterocolitis. This decline in protein expression may result in a decrease in epithelial barrier function and be a predisposing factor in the development of HAEC.

Effect of transforming growth factor-alpha on intestinal adaptation in a rat model of short bowel syndrome

OBJECTIVE

TGF-alpha has recently been shown to stimulate enterocyte proliferation. In the present study we investigated the effect of TGF-alpha on enterocyte proliferation and loss via apoptosis and its effects on intestinal adaptation in a rat following massive bowel resection.

METHODS

Male Sprague-Dawley rats underwent bowel transection and reanastomosis (sham group) or 75% small bowel resection and anastomosis (SBS group) and were treated with intraperitoneal TGF-alpha (75 microg/kg) from the ninth postoperative day (SBS-TGF-alpha group). Parameters of intestinal adaptation (overall bowel and mucosal weight, mucosal DNA and protein, villus height, and crypt depth), enterocyte proliferation, and apoptosis were determined on day 15. Statistical significance was determined by ANOVA with a P < 0.05 considered significant.

RESULTS

SBS-TGF-alpha rats demonstrated a significant increase (vs SBS) in duodenal, jejunal, and ileal overall bowel and mucosal weights; ileal mucosal DNA and protein; and jejunal and ileal villus height. SBS-TGF-alpha rats also showed an increased cell proliferation index in jejunum (704 +/- 43 vs 499 +/- 63 BrdU-positive cells/10 crypts, P < 0.05) and ileum (715 +/- 84 vs 529 +/- 40 BrdU-positive cells/10 crypts, P < 0.05) and decreased apoptotic index in ileum (8.7 +/- 1.1 vs 21.8 +/- 3.2 apoptotic cells/1,000 villus cells, P < 0.05) compared to SBS animals.

CONCLUSIONS

In a rat model of SBS, TGF-alpha enhances intestinal adaptation. Possible mechanisms may include increased cell proliferation and decreased enterocyte loss via apoptosis.

Lysophosphatidylcholine alters enterocyte monolayer permeability via a protein kinase C/Ca2+ mechanism

The activity of phospholipase A(2) (PLA(2)) is elevated in the intestinal epithelia of patients with inflammatory bowel disease. We recently reported that PLA(2) mediates the hydrolysis of phosphatidylcholine (PC) to lysophosphatidylcholine (L-PC) when both are applied to the apical surface of cultures enterocyte monolayers, resulting in increased bacterial translocation (BT) and decreased transepithelial electrical resistance (TEER). However, the mechanism by which the converted L-PC affects tight-junction permeability (TJP) as reflected by decreased TEER is unknown. There are some reports that protein kinase C (PKC) or Ca(2+) mediate TJP in enterocyte monolayer models. To investigate whether the observed change in TJP was mediated via PKC or Ca(2+) in our Caco-2 monolayer model, human Caco-2 enterocytes were grown to confluence on porous filters in the apical chamber of a two-chamber cell culture system. The filters were then transferred to an Ussing chamber for precise, real-time resistance measurements. After 30 min equilibration, PC (0.1 or 1 mM) and L-PC (0.01, 0.1 or 1 mM), PMA 200 or 300 nM (phorbol 12-myristate 13-acetate, PCK activator), or staurosporine 12 nM (PKC inhibitor) were added to the apical chamber and TEER was measured every 20 s for 2 h. The concentration of intracellular free Ca(2+) in the monolayers before and after treatment with L-PC (1 mM) was measured by fluorometry of whole monolayers using the fluorescent calcium indicator fura-2. Neither PC at any dose nor the 0.01-mM L-PC dose had an effect on TEER. The 0.1-mM dose of L-PC had its greatest effect (47% +/- 3.5% reduction in TEER vs control) within 6 min following its addition, with TEER recovery to control levels (100%) at 2 h ( P < 0.05). The 1-mM dose of L-PC had its greatest effect (6% +/- 0.5% reduction in TEER vs control) within 3 min after its addition, but the TEER did not recover to control levels after 2 h of incubation ( P < 0.05). The addition of 200 or 300 nM PMA inhibited the observed recovery of TEER by L-PC. Conversely, the addition of 12 nM staurosporine enhanced TEER recovery to control levels. The 1-mM dose of L-PC increased the concentration of intracellular free Ca(2+) immediately after the addition of L-PC. These results suggest that L-PC alters TJP via a PKC/Ca(2+) interaction in our Caco-2 monolayer model.

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.

Gastric transposition for esophageal replacement in children: experience with 41 consecutive cases with special emphasis on esophageal atresia

OBJECTIVE

To evaluate the authors' experience with gastric transposition as a method of esophageal replacement in children with congenital or acquired abnormalities of the esophagus.

SUMMARY BACKGROUND DATA

Esophageal replacement in children is almost always done for benign disease and thus requires a conduit that will last more than 70 years. The organ most commonly used in the past has been colon; however, most series have been fraught with major complications and conduit loss. For these reasons, in 1985 the authors switched from using colon interpositions to gastric transpositions for esophageal replacement in infants and children.

METHODS

The authors retrospectively reviewed the records of 41 patients with the diagnoses of esophageal atresia (n = 26), corrosive injury (n = 8), leiomyomatosis (n = 5), and refractory gastroesophageal reflux (n = 2) who underwent gastric transposition for esophageal replacement.

RESULTS

Mean +/- SE age at the time of gastric transposition was 3.3 +/- 0.6 years. All but two transpositions were performed through the posterior mediastinum without mortality or loss of the gastric conduit despite previous surgery on the gastric fundus in 8 (20%), previous esophageal operations in 15 (37%), and previous esophageal perforations in 6 (15%) patients. Complications included esophagogastric anastomotic leak (n = 15, 36%), which uniformly resolved without intervention; stricture formation (n = 20, 49%), all of which no longer require dilation; and feeding intolerance necessitating jejunal feeding (n = 8, 20%) due to delayed gastric emptying (n = 3), feeding aversion related to the underlying anomaly (n = 1), or severe neurological impairment (n = 4). No redo anastomoses were required.

CONCLUSIONS

Gastric transposition reestablishes effective gastrointestinal continuity with few complications. Oral feeding and appropriate weight gain are achieved in most children. Therefore, gastric transposition is an appropriate alternative for esophageal replacement in infants and children.

Effect of bowel resection and high-fat diet on heart CD36/fatty-acid translocase expression in a rat model of short-bowel syndrome

Long-chain fatty acids (LCFA) are the major energy substrates for the heart. In short-bowel syndrome (SBS), LCFA delivery to the myocardium decreases due to fat malabsorption. Fatty-acid translocase (FAT)/CD36 has recently been identified as a LCFA-binding protein in heart tissue. To determine the effects of bowel resection and a high-fat diet (HFD) on myocardial CD36 expression, male Sprague-Dawley rats were randomly assigned to one of three groups: sham rats fed normal chow (Sham-NC); SBS rats fed NC (SBS-NC), and SBS rats fed a HFD (SBS-HFD). Control rats underwent transection and anastomosis; SBS animals underwent 75% small-bowel resection. Rats were killed at 3 or 14 days. Total body weight, heart weight, heart-tissue total lipid, serum cholesterol, and triglycerides were determined at death. Total RNA from the myocardium was extracted using TRIZOL reagent. Northern-blot analysis was used to determine FAT/CD36 mRNA. Statistical significance was determined by Student's t-test with P values below 0.05 considered significant. SBS-NC and SBS-HFD rats had significantly lower body weights compared with Sham-NC animals. The heart weights and myocardial total lipid did not vary among experimental groups. Decreases in plasma triglycerides (38.2 +/- 3.8 vs 58.8 +/- 5.5 mg/dl, P < 0.05) and cholesterol (38.2 +/- 6.9 vs 55.3 +/- 8.2 mg/dl, P < 0.05) in SBS-NC compared to Sham-NC rats on day 3 was accompanied by a twofold increase ( P < 0.05) in myocardial CD36/FAT mRNA levels. Early exposure to HFD led to increased (vs SBS-NC) plasma cholesterol (82.9 +/- 5.7 vs 38.2 +/- 6.9 mg/dl, P < 0.05) and triglycerides (62.5 +/- 15.6 vs 38.2 +/- 3.8 mg/dl, P < 0.05), and a concomitant decrease in CD36/FAT mRNA levels (45.1 +/- 17.8 vs 86.6 +/- 15%, respectively, P < 0.05). Plasma lipid concentration and myocardial CD36/FAT mRNA levels on day 14 were not significantly different among the experimental groups. In this rat model of SBS, the heart thus reacts to decreased LCFA delivery by increased tissue CD36/FAT mRNA levels and, consequently, active LCFA uptake. A HFD increased plasma lipid concentrations and decreased CD36/FAT levels.

Lipopolysaccharide endotoxemia reduces cell proliferation and decreases enterocyte apopotosis during intestinal adaptation in a rat model of short-bowel syndrome

Sepsis is frequently associated with or complicates short-bowel syndrome (SBS). To investigate the effects of lipopolysaccharide (LPS) endotoxemia on enterocyte proliferation and death via apoptosis in a rat model of SBS, adult male Sprague-Dawley rats were divided into three experimental groups: sham rats underwent bowel transection and reanastomosis; SBS rats underwent 75% small-bowel resection; and SBS-LPS rats underwent 75% bowel resection and were given intraperitoneal injections of LPS 10 mg/kg. Parameters of intestinal adaptation (bowel and mucosal weights, mucosal DNA and protein, villus height, and crypt depth), enterocyte proliferation, and death via apoptosis were determined on day 15 after the operation. Statistical analysis was determined by Student's and ANOVA tests with a P less than 0.05 considered significant. SBS-LPS animals demonstrated a significant decrease (vs SBS rats) in duodenal (20%), jejunal (30%), and ileal (15%) overall weight, duodenal (20%), jejunal (27%), and ileal (18%) mucosal weight, jejunal (20%) and ileal (30%) mucosal DNA, jejunal (29%) and ileal (31%) villus height, and jejunal (14%) and ileal (29%) crypt depth. LPS endotoxemia led to reduced cell proliferation and enterocyte apoptosis compared to untreated SBS animals. Thus, in a rat model of SBS, LPS endotoxemia inhibits intestinal adaptation. A possible mechanism may be decreased cell proliferation. Decreased enterocyte loss via apoptosis may reflect a reduced number of enterocytes. Other mechanisms (necrosis) may be mainly responsible for cell death following LPS injection.

Stooling and manometric findings after primary pull-throughs in Hirschsprung's disease: Perineal versus abdominal approaches

BACKGROUND/PURPOSE

Primary pull-through via a perineal approach (PA) has recently been reported for Hirschsprung's disease. One criticism of this approach is that it requires a large amount of retraction on the anal sphincters. Additionally, because the procedure is new, most patients undergoing a PA are too young to assess long-term continence rates. This study examined early stooling patterns, anal sphincteric pressures, and number of enterocolitic episodes in infants who underwent a PA. Results were compared with a conventional combined transabdominal and perineal approach (TA).

METHODS

Over 2 years, 26 pull-through procedures were performed. Nine of those were PA, and 17 were TA. Twelve of the 26 patients had formal manometric studies postoperatively. Results are expressed as mean +/- SD; unpaired t test and Chi;(2) were used for statistical analysis.

RESULTS

Mean follow-up post-pull-through was 23 +/- 2.3 months for the TA and 14 +/- 1.9 months for the PA. Manometric resting sphincter pressure in the TA group averaged 79 +/- 17 mm Hg compared with 76 +/- 21 mm Hg in the PA group (P =.78). Number of stools per day was 3.3 +/- 0.6 in the TA group compared with 2.2 +/- 0.3 in the PA group (P =.17). Post-pull-through enterocolitis was experienced by 53% of the TA group (mean, 1.5 +/- 0.6 episodes) and 56% of the PA group (mean 0.9 +/- 0.4 episodes) for a P =.08 by Chi;(2) analysis.

CONCLUSIONS

Manometric sphincter pressure and enterocolitic episodes after a PA for Hirschsprung's disease appear to be similar to results obtained with a conventional TA. Evaluation of early stooling frequency shows a comparable frequency after a PA. This suggests that both methods are safe, and the PA does not appear to compromise sphincter integrity.

Sandostatin impairs postresection intestinal adaptation in a rat model of short bowel syndrome

Because of its antisecretory properties, sandostatin has been advocated for the treatment of patients with short bowel syndrome (SBS). This study was conducted to determine the effect of sandostatin on structural intestinal adaptation, cell proliferation and apoptosis in a rat model of SBS. Sprague-Dawley rats were divided into three experimental groups: Sham rats underwent bowel transection, SBS rats underwent 75% small bowel resection, and SBS-sandostatin rats underwent bowel resection and were treated with sandostatin (SBS-SND). Parameters of intestinal adaptation, enterocyte proliferation, and enterocyte apoptosis were determined on day 14 following operation. We have demonstrated that SBS-SND animals demonstrated lower (vs SBS rats) duodenal and jejunal bowel weights, jejunal and ileal mucosal weight, jejunal and ileal mucosal DNA and protein, jejunal and ileal villus height, cell proliferation index in the ileum, and enterocyte apoptosis in jejunum and ileum. We conclude that in a rat model of SBS sandostatin decreases cell proliferation and inhibits structural intestinal adaptation.

Sporadic aplasia cutis congenita

Aplasia cutis congenita (ACC) is a rare group of disorders characterized by the focal absence of skin at birth. The majority of cases affect the scalp, but involvement of the trunk and extremities has been described. Proposed etiologies for ACC include infection, vascular malformations, amniogenesis, and teratogens, but no unifying theory has been identified. We present the case of a 1-day-old female with large, bilateral posterolateral trunk skin defects noted at birth. The prenatal history was significant for maternal diabetes, fetal papyraceus at 12 weeks' gestation, and a family history of limb defects. The infant was treated non-surgically with local wound care and antibiotics, as well as frequent dressing changes. The areas of absent skin developed a granulation-tissue layer followed by re-epithelialization and mild wound contracture. With early identification of the etiology of the lesions and appropriate investigation and treatment, including conservative wound management, aplastic lesions can heal successfully without affecting growth, but may require cosmetic repair at a later stage.

Vaginal reconstruction for ambiguous genitalia and congenital absence of the vagina: a 27-year experience

BACKGROUND/PURPOSE

Gender assignment to a neonate with ambiguous genitalia is crucial. Patients with an absent vagina require the construction of an artificial vagina. In an effort to improve care, the authors have categorized their experience with this group of children.

METHODS

Since 1974, we cared for 114 patients with anomalies of the genitalia. There were 53 genotypic girls with congenital adrenal hyperplasia (CAH), 16 genotypic boys with testicular feminization syndrome (TFS), 13 with mixed gonadal dysgenesis (MGD), 9 with Mayer-Rokitansky syndrome, and 4 true hermaphrodites. The remaining 19 had other genital abnormalities.

RESULTS

After 1980, patients with CAH underwent clitoral recession and vaginoplasty. All patients with TFS were raised as girls and underwent orchidectomy. Eleven of the MGD patients were given a female sex assignment and underwent gonadectomy. Twenty-eight patients underwent intestinal vaginoplasty including 8 of the TFS patients, 9 with Mayer-Rokitansky syndrome, 8 patients with cloacal anomalies, 2 patients for rhabdomyosarcoma, and 1 of the MGD patients.

CONCLUSIONS

(1) This review emphasizes the range of diagnoses the surgeon must be prepared to address in patients with ambiguous genitalia. (2) Colovaginoplasty is an excellent procedure for replacement of a completely absent vagina. (3) Continued evaluation of this group will delineate appropriate timing and choice of procedure.

Lung resection in infants and children with pulmonary infections refractory to medical therapy

BACKGROUND/PURPOSE

Pulmonary infections in children are common and often resolve with antibiotics and supportive therapy. When these infections become refractory to medical therapy or develop into an abscess, operative intervention may become necessary. This study was undertaken to review the experience with these pulmonary infections at the authors' institution.

METHODS

Charts of patients who underwent pulmonary resection for infectious causes were reviewed and their presentation, operative course, and long-term outcome analyzed.

RESULTS

Between 1975 and 1999, 21 children underwent operative resection of lung parenchyma for infection. Sixty-six percent of children previously had required hospitalization for pneumonia, and 91% had been treated previously, either as an inpatient or as an outpatient, for pneumonia. Seventy-one percent of children had an identifiable underlying comorbidity. Eighteen lobectomies were performed on 17 children with the remaining children requiring either segmentectomy or wedge resection. The median length of stay was 6 days. There were 3 minor complications and 3 deaths. At follow-up (median, 8.25 months), all surviving children had improvement of the chest x-ray, and this was paralleled by clinical improvement.

CONCLUSIONS

In children with pulmonary infection refractory to conservative medical therapy, operative resection can provide significant clinical improvement. When resection is performed, formal lobectomy often is required and yields a good outcome.

Efficacy and durability of autogenous saphenous vein conduits for lower extremity arterial reconstructions in preadolescent children

OBJECTIVE

Limb length discrepancies (LLDs) in growing children may accompany extremity arterial occlusions. Revascularization with vein grafts has been questioned because of degenerative graft changes observed at other sites. This study was undertaken to define vein graft durability and efficacy in lower extremity revascularizations in preadolescent children.

STUDY DESIGN

Fourteen children (10 boys, 4 girls) with a mean age of 7.3 years (range, 2-11 years) who underwent 16 lower extremity revascularizations with greater saphenous vein grafts were subjected to follow-up with graft ultrasonography, ankle/brachial indices (ABIs) with and without exercise, and limb length determinations. A mean of 5.7 years elapsed between the onset of ischemia and operation. Arterial occlusions resulted from cardiac catheterizations (11), arteritis (1), dialysis cannulation (1), and penetrating trauma (1). Indications for operation included LLD (6), claudication (4), both LLD and claudication (3), markedly diminished ABIs with a potential for LLD (2), and a traumatic transection with hemorrhage (1). The reconstructions with 15 reversed and one in situ vein grafts included iliofemoral (11), femorofemoral (1), aortofemoral (1), femoropopliteal (1), popliteal-popliteal (1), and popliteal-posterior tibial (1) arterial bypass grafts.

RESULTS

Among patent grafts available for follow-up, 36% (5 of 14) remained unchanged, 50% (7 of 14) developed nonaneurysmal dilatation, and 14% (2 of 14) exhibited nonprogressive aneurysmal expansion. One graft became occluded, and one graft was lost to follow-up. Collectively, the grafts manifest an 11.2% expansion at an average of 10.7 years postoperatively. ABIs increased from 0.75 preoperatively to 0.97, at an average of 11.0 years postoperatively. LLDs were reduced from 1.66 to 1.24 cm, at an average of 11.4 years postoperatively.

CONCLUSION

Vein graft reconstructions of lower extremity arteries in preadolescent children are durable. They provide an efficacious means of restoring normal blood flow, and in 70% of children their preexisting LLDs were reduced.

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.

Recent advances in the management of Hirschsprung's disease

BACKGROUND

Major advances have occurred in the management of Hirschsprung's disease since Swenson described his definitive operation in 1948. These advances have occurred in the following areas: genetics, neurophysiology, definitive management in the newborn, total colonic aganglionosis (TCA), Hirschsprung's-associated enterocolitis (HAEC), intestinal neuronal dysplasia (IND), and laparoscopic and perineal approaches for definitive pull-through and redo pull-through operations.

METHODS

This paper will focus on the definitive management of the newborn, TCA, and HAEC, areas in which we have had considerable experience at our institution.

RESULTS

We have treated almost 90 newborns with the definitive pull-through with minimum morbidity. We have managed 25 patients with TCA, of whom 5 had total intestinal involvement and died. The remaining 20 have undergone a total colectomy and endorectal pull-through (ERPT), with zero mortality and a very acceptable stooling pattern and continence rate. Our experience with more than 350 patients with Hirschsprung's disease over the past 25 years has demonstrated an incidence of HAEC of between 20% and 30%. During this period, we have performed 19 redo pull-through operations, the majority of which were ERPTs, with results comparable with those seen with a primary pull-through operation.

CONCLUSIONS

The major advances that have occurred in the management of Hirschsprung's disease include the definitive management of the newborn, our understanding of Hirschsprung's-associated enterocolitis and the treatment of this entity, and the recent successful management of the very complex form of this disease, total colonic aganglionosis.

A decade of experience with the primary pull-through for hirschsprung disease in the newborn period: a multicenter analysis of outcomes

OBJECTIVE

To determine whether use of a primary pull-through would result in equivalent perioperative and long-term complications compared with the two-stage approach.

SUMMARY BACKGROUND DATA

During the past decade, the authors have advanced the use of a primary pull-through for Hirschsprung disease in the newborn, and preliminary results have suggested excellent outcomes.

METHODS

From May 1989 through September 1999, 78 infants underwent a primary endorectal pull-through (ERPT) procedure at four pediatric surgical sites. Data were collected from medical records and a parental telephone interview (if the child was older than 3 years) to assess stooling patterns. A similar group of patients treated in a two-stage fashion served as a historical control.

RESULTS

Mean age at the time of ERPT was 17.8 days of life. Comparing primary ERPT with a two-stage approach showed a trend toward a higher incidence of enterocolitis in the primary ERPT group compared with those with a two-stage approach (42.0% vs. 22.0%). Other complications were either lower in the primary ERPT group or similar, including rate of soiling and development of a bowel obstruction. Median number of stools per day was two at a mean follow-up of 4.1 +/- 2.5 years, with 83% having three or fewer stools per day.

CONCLUSIONS

Performance of a primary ERPT for Hirschsprung disease in the newborn is an excellent option. Results were comparable to those of the two-stage procedure. The greater incidence of enterocolitis appears to be due to a lower threshold in diagnosing enterocolitis in more recent years.

Long-term follow-up of redo pull-through procedures for Hirschsprung's disease: efficacy of the endorectal pull-through

BACKGROUND/PURPOSE

The purpose of this study was to review the authors' 25-year experience with redo pull-through procedures for Hirschsprung's disease including surgical technique and long-term outcome.

METHODS

From 1974 to now, over 325 patients with Hirschsprung's disease have been treated at C.S. Mott Children's Hospital. This includes 30 patients referred after an unsuccessful pull-through at another hospital and 2 patients with an unsuccessful pull-through from C.S. Mott. All redo pull-throughs (n = 19) were performed in these patients, and their clinical courses are reviewed.

RESULTS

Twelve patients required reoperation secondary to a mechanical problem with their first pull-through. The other 7 patients had evidence of residual segments of dilated colon leading to functional failure of their initial operation including 5 patients with documented aganglionic bowel present at the second pull-through. Ten of the patients requiring reoperation initially had an endorectal pull-through (ERPT), 5 had a Duhamel procedure, 3 had a Swenson procedure, and 1 had a Rehbein procedure. Choice of revision was an ERPT in 8 patients in whom an adequate rectal cuff could be developed. Additional redo procedures included a Duhamel in 8 patients and a Swenson in 3 patients. Follow-up ranges from 3 months to 23 years (mean, 13.8 years). There were no deaths in the series, and 1 patient required a third pull-through. All patients who are not neurologically impaired and are over age 3 are continent except one (94%). Stools per day range from 1 to 10 (mean, 3.2).

CONCLUSIONS

Redo pull-through operations for Hirschsprung's disease appear to be as effective as primary procedures in terms of continence and stooling frequency. Distinct from other series, we found an ERPT to be the procedure of choice if an adequate rectal cuff was present.

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.