Prevascular hernias of the abdominal wall: a difficult problem, a difficult repair.

INTRODUCTION: Secondary prevascular hernias occurring anterior to the iliofemoral vessels and involving the lower abdominal wall are rare. These hernias can be difficult to repair because of loss of the inguinal ligament and the musculofascial elements of the inguinal region. MATERIALS AND METHODS: We describe a new technique of repair using an intraperitoneal sling of prosthetic material. The sling is sewn posteriorly to the anterior surface of the sacrum, and is then draped caudally to be sewn to the pubis and Cooper's ligaments before being reflected anterior to be sewn to the posterior surface of the anterior abdominal wall. This sling "patches" the hernia defect as a form of intraperitoneal sublay. CONCLUSIONS: We describe three such patients with satisfactory results at follow-ups of 8-16 months. Potential problems and considerations are discussed.

Long-term outcomes (>5-year follow-up) with porcine acellular dermal matrix (Permacol) in incisional hernias at risk for infection.

PURPOSE: We reviewed retrospectively all patients undergoing abdominal wall reconstruction using porcine acellular dermal matrix (PADM) from 2004 to 2008 with follow-up assessment in 2012. Technique, short-term (infection, seroma, wound dehiscence), and long-term (mesh infection, recurrence) complications, and hernia recurrences were evaluated by physician examination ≥5 years postoperatively. RESULTS: 56 patients at high risk for infection had elective operation; nine had non-elective operation for complications of prior incisional hernia/hernia repair. Operations were clean, clean-contaminated, contaminated, or grossly infected in 49, 32, 12, and 6%, respectively. Techniques of repair included 10 onlay (six reinforced primary closures, four bridging patches), 47 sublay (20 reinforced primary closures, 27 bridging patches), six inlay, and two sandwich (sublay and onlay). Early complications (≤30 days postoperatively) occurred in 19 of the 65 patients (29%), including two prosthetic dehiscences from fascial attachment, 13 wound infections, and 4 seromas. After a mean follow-up of ≥5 years in 59 of 65 patients, physician-reported incidences of infection requiring removal of mesh or hernia recurrence were 25 and 66%, respectively. Hernia recurrence occurred in 12 of 26 (46%) patients with a reinforced repair and 27 of 33 (82%) with patched repairs. Mesh infection occurred in 7 of 24 patients with sublay patch and in 4 of 19 sublay reinforcement. The greatest recurrence rate was in contaminated (71%) and grossly infected wounds (100%), while recurrence rate was 63% in clean and 63% in clean-contaminated wounds. CONCLUSIONS: At ≥5 years of follow-up, use of PADM as a bioprosthesis in ventral hernia in high-risk patients is unreliable as a definitive repair in the majority of patients, but may provide satisfactory outcomes in some patients.

Distribution of TMEM100 in the mouse and human gastrointestinal tract--a novel marker of enteric nerves.

Identification of markers of enteric neurons has contributed substantially to our understanding of the development, normal physiology, and pathology of the gut. Previously identified markers of the enteric nervous system can be used to label all or most neuronal structures or for examining individual cells by labeling just the nucleus or cell body. Most of these markers are excellent but have some limitations. Transmembrane protein 100 (TMEM100) is a gene at locus 17q32 encoding a 134-amino acid protein with two hypothetical transmembrane domains. TMEM100 expression has not been reported in adult mammalian tissues but does appear in the ventral neural tube of embryonic mice and plays a role in signaling pathways associated with development of the enteric nervous system. We showed that TMEM100 messenger RNA is expressed in the gastrointestinal tract and demonstrated that TMEM100 is a membrane-associated protein. Furthermore TMEM100 immunoreactivity was restricted to enteric neurons and vascular tissue in the muscularis propria of all regions of the mouse and human gastrointestinal tract. TMEM100 immunoreactivity colocalized with labeling for the pan-neuronal marker protein gene product 9.5 (PGP9.5) but not with the glial marker S100ß or Kit, a marker of interstitial cells of Cajal. The signaling molecule, bone morphogenetic protein (BMP) 4, was also expressed in enteric neurons of the human colon and co-localized with TMEM100. TMEM100 is also expressed in neuronal cell bodies and fibers in the mouse brain and dorsal root ganglia. We conclude that TMEM100 is a novel, membrane-associated marker for enteric nerves and is as effective as PGP9.5 for identifying neuronal structures in the gastrointestinal tract. The expression of TMEM100 in the enteric nervous system may reflect a role in the development and differentiation of cells through a transforming growth factor ß, BMP or related signaling pathway.

Obstructive sleep apnoea and perioperative complications in bariatric patients.

BACKGROUND: The objective of this study was to determine the relationship between perioperative complications and the severity of obstructive sleep apnoea (OSA) in patients undergoing bariatric surgery who had undergone preoperative polysomnography (PSG). METHODS: The records of 797 patients, age >18 yr, who underwent bariatric operations (442 open and 355 laparoscopic procedures) at Mayo Clinic and were assessed before operation by PSG, were reviewed retrospectively. OSA was quantified using the apnoea-hypopnoea index (AHI) as none (≤ 4), mild (5-15), moderate (16-30), and severe (≥ 31). Pulmonary, surgical, and 'other' complications within the first 30 postoperative days were analysed according to OSA severity. Logistic regression was used to assess the multivariable association of OSA, age, sex, BMI, and surgical approach with postoperative complications. RESULTS: Most patients with OSA (93%) received perioperative positive airway pressure therapy, and all patients were closely monitored after operation with pulse oximetry on either regular nursing floors or in intensive or intermediate care units. At least one postoperative complication occurred in 259 patients (33%). In a multivariable model, the overall complication rate was increased with open procedures compared with laparoscopic. In addition, increased BMI and age were associated with increased likelihood of pulmonary and other complications. Complication rates were not associated with OSA severity. CONCLUSIONS: In obese patients evaluated before operation by PSG before bariatric surgery and managed accordingly, the severity of OSA, as assessed by the AHI, was not associated with the rate of perioperative complications. These results cannot determine whether unrecognized and untreated OSA increases risk.

Changes in interstitial cells of cajal with age in the human stomach and colon.

BACKGROUND: Aging produces inevitable changes in the function of most organs including the gastrointestinal tract. Together with enteric nerves and smooth muscle cells, interstitial cells of Cajal (ICC) play a key role in the control of gastrointestinal motility, yet little is known about the effect of aging on ICC. The aim of this study was to determine the effect of aging on ICC number and volume in the human stomach and colon. METHODS: Gastric and colonic tissues from patients aged 25-70 and 36-92 years old, respectively, and with no co-existent motility disorders were immunolabeled with an anti-Kit antibody and ICC were counted in the circular muscle and myenteric regions. Network volumes were measured using 3D reconstructions of confocal stacks. The effects of aging were determined by testing for linear trends using regression analysis. KEY RESULTS: In both stomach and colon, the number of ICC bodies and volume significantly decreased with age at a rate of 13% per decade. ICC size was only affected in the myenteric plexus in the colon. The changes associated with age were not differentially affected by sex or colonic region. CONCLUSIONS & INFERENCES: The number and volume of ICC networks in the normal human stomach and colon decline with age. This decrease in ICC likely reduces the functional capacity of the gastrointestinal motor apparatus, may contribute to changes in gastrointestinal motility with aging and may influence intestinal responses to insults such as disease, operative interventions and medications in older patients. Tissue specimens must be carefully age-matched when studying ICC in disease.

Mechanisms of ileal adaptation for glucose absorption after proximal-based small bowel resection.

INTRODUCTION: The hexose transmembrane transporters SGLT1 and GLUT2 are present in low quantities in ileum where little glucose absorption occurs normally; however, glucose uptake in ileum is highly adaptable after small bowel resection. HYPOTHESIS: Ileal adaptability for glucose absorption after jejunal resection is mediated predominately by upregulation of GLUT2. METHODS: Rats underwent 70% proximal-based jejunoileal resection. Transporter-mediated glucose uptake was measured in proximal and distal remnant ileum 1 and 4 wk postoperatively (n = 6 rats, each) and in corresponding ileal segments in control and 1 wk sham laparotomy rats (n = 6, each) without and with selective inhibitors of SGLT1 and GLUT2. In separate groups of rats (n = 6, each), protein (Western blots), mRNA (reverse transcriptase polymerase chain reaction [RT-PCR]), and villus height (histomorphology) were measured. RESULTS: After 70% proximal intestinal resection, there was no dramatic change in protein or mRNA expression per cell of either SGLT1 or GLUT2, but median glucose uptake (nmol/cm/min) increased markedly from 52 (range 28-63) in controls to 118 (range 80-171) at 1 wk, and 203 (range 93-248) at 4 wk (p < or = 0.04 each) correlating with change in villus height (p < or = 0.03). CONCLUSIONS: Ileal adaptation for glucose transport occurs through cellular proliferation (hyperplasia) and not through cellular upregulation of glucose transporters.

Effects of extrinsic denervation on innervation with VIP and substance P in circular muscle of rat jejunum.

Extrinsic denervation contributes to enteric motor dysfunction after small bowel transplantation (SBT). Our aim was to determine changes in nonadrenergic, noncholinergic innervation with vasoactive intestinal polypeptide (VIP) and substance P (Sub P) in rat jejunal circular muscle after SBT. Muscle strips were studied in tissue chambers from six groups of rats (n > or = 6 per group): naïve controls (NC), animals 1 week after anaesthesia/sham celiotomy (SC-1), and 1 and 8 weeks after jejunal and ileal transection/reanastomosis (TA-1, TA-8) and after syngeneic, orthotopic SBT (SBT-1, SBT-8). Response to exogenous VIP and Sub P and their endogenous release during electrical field stimulation (EFS) were studied. Exogenous VIP and Sub P caused a dose-dependent inhibition and stimulation of mechanical activity in all groups respectively (P < 0.05). The responses to VIP and Sub P were decreased (compared to NC) in all groups at 1 and 8 weeks postoperatively. The VIP antagonist ([D-p-Cl-Phe(6),Leu(17)]-VIP) did not prevent the inhibition by exogenous VIP in any group, while the Sub P antagonist ([D-Pro(2),D-Trp(7,9)]-Sub P) prevented the effect of exogenous Sub P in NC, TA-8 and SBT-8 (P < 0.05). Responses to exogenous VIP were unaffected by the nitric oxide synthase inhibitor l-N(G)-nitro arginine and precontraction of muscle strips with Sub P. Endogenous release of VIP and Sub P during EFS was preserved after SBT. In circular muscle of rat jejunum, changes in neuromuscular transmission with VIP and Sub P during the first 8 weeks after SBT are not mediated by extrinsic denervation.

Effect of chronic, extrinsic denervation on functional NANC innervation with vasoactive intestinal polypeptide and substance P in longitudinal muscle of rat jejunum.

Intestinal denervation contributes to enteric motor dysfunction after intestinal transplantation [small bowel transplantation (SBT)]. Our aim was to determine long-term effects of extrinsic denervation on functional non-adrenergic, non-cholinergic innervation with vasoactive intestinal polypeptide (VIP) and substance P. Contractile activity of jejunal longitudinal muscle from six age-matched, naïve control rats (NC) and eight rats 1 year after syngeneic SBT were studied in tissue chambers. Spontaneous contractile activity did not differ between groups. Exogenous VIP inhibited contractile activity dose-dependently in both groups, greater in NC than in SBT. The VIP antagonist ([D-p-Cl-Phe(6),Leu(17)]-VIP) and the nitric oxide synthase inhibitor l-N(G)-nitro arginine prevented inhibition by exogenous VIP and electrical field stimulation (EFS) in both groups. Exogenous substance P increased contractile activity dose-dependently, greater in NC than in SBT. The substance P antagonist ([D-Pro(2),D-Trp(7,9)]-substance P) inhibited effects of exogenous substance P and increased the EFS-induced inhibitory response. Immunohistofluorescence showed staining for tyrosine hydroxylase in the jejunoileum 1 year after SBT suggesting sympathetic reinnervation. In rat jejunal longitudinal muscle after chronic denervation, response to exogenous VIP and substance P is decreased, while endogenous release of both neurotransmitters is preserved. These alterations in excitatory and inhibitory pathways occur despite extrinsic reinnervation and might contribute to enteric motor dysfunction after SBT.

Hyperoxaluric nephrolithiasis is a complication of Roux-en-Y gastric bypass surgery.

Roux-en-Y bypass surgery is the most common bariatric procedure currently performed in the United States for medically complicated obesity. Although this leads to a marked and sustained weight loss, we have identified an increasing number of patients with episodes of nephrolithiasis afterwards. We describe a case series of 60 patients seen at Mayo Clinic-Rochester that developed nephrolithiasis after Roux-en-Y gastric bypass (RYGB), including a subset of 31 patients who had undergone metabolic evaluation in the Mayo Stone Clinic. The mean body mass index of the patients before procedure was 57 kg/m(2) with a mean decrease of 20 kg/m(2) at the time of the stone event, which averaged 2.2 years post-procedure. When analyzed, calcium oxalate stones were found in 19 and mixed calcium oxalate/uric acid stones in two patients. Hyperoxaluria was a prevalent factor even in patients without a prior history of nephrolithiasis, and usually presented more than 6 months after the procedure. Calcium oxalate supersaturation, however, was equally high in patients less than 6 months post-procedure due to lower urine volumes. In a small random sampling of patients undergoing this bypass procedure, hyperoxaluria was rare preoperatively but common 12 months after surgery. We conclude that hyperoxaluria is a potential complicating factor of RYGB surgery manifested as a risk for calcium oxalate stones.

Species dependent expression of intestinal smooth muscle mechanosensitive sodium channels.

A mechanosensitive Na(+) current carried by Na(v)1.5 is present in human intestinal circular smooth muscle and contributes to regulation of intestinal motor function. Expression of this channel in different species is unknown. Our aim was to determine if Na(+) currents and message for the alpha subunit of the Na(+) channel (SCN5A) are found in circular smooth muscle cells of human, dog, pig, mouse and guinea pig jejunum. Currents were recorded using patch clamp techniques. Message for SCN5A was investigated using laser capture microdissection and reverse transcription polymerase chain reaction (RT-PCR). Na(+) currents were identified consistently in human and dog smooth muscle cells; however, Na(+) current was not found in pig (0/20) or guinea pig smooth muscle cells (0/21) and found only one mouse cell (1/21). SCN5A mRNA was found in circular muscle of human, dog, and mouse, but not in pig or guinea pig, and not in mouse longitudinal or mucosal layers. In summary, SCN5A message is expressed in, and Na(+) current recorded from, circular muscle layer of human and dog but not from pig and guinea pig. These data show that there are species differences in expression of the SCN5A-encoded Na(v)1.5 channel, suggesting species-specific differences in the electrophysiological response to mechanical and depolarizing stimuli.

Bariatric surgery at the extremes of age.

The safety and efficacy of bariatric surgery in adolescents and especially in Medicare population have been challenged. Our aim was to determine short-term (30-day) and long-term outcomes of bariatric surgery in patients>or=60 years and or=60 years and 12 patientsor=60 years and all 12 adolescents returned the questionnaire (92%) at a mean of 5 years (range 1-19 years). For patients>or=60 years, 30-day mortality was 0.7%, serious morbidity delaying discharge was 14%, and 5-year mortality was 5%. At a mean of 5 years, body mass index (BMI in kg/m2) decreased from a mean (+/-SEM) of 46+/-1 to 33+/-1 with a 51% resolution of weight-related comorbidities and an 89% subjective overall satisfaction rate. In patients

Malignant potential of solid pseudopapillary neoplasm of the pancreas.

BACKGROUND: Solid pseudopapillary neoplasms of the pancreas are rare malignant lesions of the pancreas that typically occur in young women. Large series from any one centre are notably absent in the literature. The aim of this study was to determine long-term outcomes of operative therapy. METHODS: The records of all 14 patients diagnosed with pseudopapillary neoplasms of the pancreas over 17 years were reviewed. RESULTS: Thirteen of the 14 patients were female and the mean age at diagnosis was 30 years. Solid pseudopapillary neoplasm was suspected in only half of these patients before operation. On computed tomography, ultrasonography and/or magnetic resonance imaging, three lesions were solid, three were largely cystic, and five had solid and cystic components. All 14 patients underwent surgical exploration and curative resections were possible in 13, including distal pancreatectomy in nine, pancreaticoduodenectomy in three and resection of a local intraperitoneal recurrence in one patient. After follow-up ranging from 3 months to 20 years, 12 patients were alive, including one who had undergone re-exploration and resection of local and subcutaneous recurrences 9 years previously. CONCLUSION: Solid pseudopapillary neoplasm of the pancreas should be considered in the differential diagnosis of any solid or partly cystic pancreatic mass in women aged less than 35 years. An attempt at en bloc resection without formal lymphadenectomy should be undertaken, including resection of synchronous or metachronous distant metastases.

Pyloroplasty for benign gastric outlet obstruction--indications and techniques.

The understanding of peptic ulcer disease (PUD) etiology, and improvements in treatment during the last two decades, has dramatically decreased the once so frequently performed procedures for PUD and its complications. Benign gastric outlet obstruction may, however, still require operative intervention when non-operative treatment fails. Today, surgeons in training, and even practicing surgeons, may have limited operative experience with procedures required to alleviate an obstructed pylorus. Our aim of this paper is to review the techniques (the Heineke-Mikulicz and Finney pyloroplasties, and modifications) and indications for pyloroplasty in the modern surgical era.

A controlled study of peripheral neuropathy after bariatric surgery.

BACKGROUND: Although peripheral neuropathy (PN) occurs after bariatric surgery (BS), a causal association has not been established. OBJECTIVES: To ascertain whether PN occurs more frequently following BS vs another abdominal surgery, to characterize the clinical patterns of PN, to identify risk factors for PN, and to assess if nerve biopsy provides pathophysiologic insight. METHODS: Retrospective review identified patients with PN after BS. The frequency of PN was compared with that of an age- and gender-matched, retrospectively evaluated cohort of obese patients undergoing cholecystectomy. RESULTS: Of 435 patients who had BS, 71 (16%) developed PN. Patients developed PN more often after BS than after cholecystectomy (4/126; 3%) (p < 0.001). The clinical patterns of PN were polyneuropathy (n = 27), mononeuropathy (n = 39), and radiculoplexus neuropathy (n = 5). Risk factors included rate and absolute amount of weight loss, prolonged gastrointestinal symptoms, not attending a nutritional clinic after BS, reduced serum albumin and transferrin after BS, postoperative surgical complications requiring hospitalization, and having jejunoileal bypass. Most risk factors were associated with the polyneuropathy group. Sural nerve biopsies showed prominent axonal degeneration and perivascular inflammation. CONCLUSIONS: Peripheral neuropathy (PN) occurs more frequently after bariatric surgery (BS) than after another abdominal surgery. The three clinical patterns of PN after BS are sensory-predominant polyneuropathy, mononeuropathy, and radiculoplexus neuropathy. Malnutrition may be the most important risk factor, and patients should attend nutritional clinics. Inflammation and altered immunity may play a role in the pathogenesis, but further study is needed.