Mutation of the MENIN gene in sporadic pancreatic endocrine tumors.

Pancreatic endocrine tumors occur both sporadically and as part of the multiple endocrine neoplasia type 1 (MEN1) syndrome. MEN1 is an autosomal dominant disease characterized by parathyroid hyperplasia, pancreatic endocrine tumors, and pituitary adenomas. The MEN1 gene called MENIN maps to chromosome 11q13 and is thought to function as a tumor suppressor gene. We previously demonstrated loss of heterozygosity (LOH) at 11q13 in approximately 40% of sporadic pancreatic endocrine tumors and hypothesize that MENIN is involved in the development of these tumors. Thirty-one sporadic pancreatic endocrine tumors were analyzed for mutation of MENIN by nonradioactive single-stranded conformation polymorphism. Twelve mutations were detected in 31 sporadic pancreatic endocrine tumors (34%). Twelve of these 31 tumors previously demonstrated loss of heterozygosity at 11q13. Of the tumors with LOH, seven contained mutations of the MENIN gene (58%). The majority of the MENIN mutations occurred within exon 2. Two independent mutations in MENIN were detected in a gastrinoma that also revealed LOH, leading to the possibility of another tumor suppressor gene locus at 11q13. Mutations were present in both benign and malignant pancreatic endocrine tumors, suggesting that a MENIN gene mutation is a frequent and early event in the tumorigenesis. The high incidence of truncating mutations in tumors with LOH at 11q13 support the hypothesis that MENIN is a tumor suppressor gene.

Deletion of chromosome 1 predicts prognosis in pancreatic endocrine tumors.

Endocrine tumors, such as parathyroid adenomas and pheochromocytomas, frequently have deletions of chromosome 1, suggesting that inactivation of a tumor suppressor gene from chromosome 1 is important in their tumorigenesis. We hypothesized that deletion of chromosome 1 may contribute to pancreatic endocrine tumor formation. Twenty-nine sporadic and MEN1 pancreatic endocrine tumors were studied for loss of heterozygosity (LOH) with 12 chromosome 1 microsatellite markers. LOH on chromosome 1 was identified in 10 of 29 (34%) tumors studied. Allele loss occurred more frequently in tumors with hepatic metastases (7 of 8) than tumors without metastases (3 of 21) (P = 0.004). Tumors in patients with lymph node involvement and patients with multiple endocrine neoplasia type 1 did not demonstrate LOH for chromosome 1 markers. These data suggest that loss of chromosome 1 is associated specifically with the development of hepatic metastases in patients with sporadic pancreatic endocrine tumors.

Bypass enteropathy: an inflammatory process in the excluded segment with systemic complications.

Evidence is presented that many of the enteric and systemic manifestations after jejunoileal bypass can be related to an inflammatory process within the bypassed small bowel rather than to the surgically induced sequelae of a short bowel syndrome with malabsorption. Invasion of the excluded segment by fecal flora was associated with a histologically demonstrable inflammatory response of the mucosa. The disorder was of variable severity and duration and occurred in the majority of 28 bypass patients. Progression to a clinical syndrome resembling an acute abdomen occurred in about 15% of the patients. Small bowel ileus and, in some patients, obstruction of the colon were suggested by physical signs and x-ray findings. Surgical exploration in such instances demonstrated an inflammaotry process of the excluded small bowel loops with severe distention of this segment and of the colon, but not organic obstruction. Pneumatosis cystoides intestinalis was a sequal in two patients. Exudative protein loss was documented in the severe cases. Most of the systemic sequelae are comparable to those seen with inflammatory diseases of the bowel such as Crohn's disease. Fever, excessive weight and lean tissue loss, and the involvement of skin, blood vessels, joints and possibly, the liver suggest an immune response as a common factor in the pathogenesis. The clinical improvement with antibiotics such as metronidazole or with restitution of normal bowel continuity indicates that the bacterial flora in the excluded small bowel segment or its byproducts are causally related to the systemic complications. Hyperoxaluria may be primarily the sequela of steatorrhea and not of the inflammatory process.

Sleep deprivation does not affect seizure frequency during inpatient video-EEG monitoring.

OBJECTIVE: To determine whether acute sleep deprivation facilitates seizures during inpatient monitoring in a controlled protocol. METHODS: Eighty-four patients with medically refractory partial epilepsy undergoing inpatient monitoring were assigned in consecutive blocks to either sleep deprivation every other night or to normal sleep. In both groups, subjects were requested to stay awake during the day, from 6 AM to 10 PM. In the sleep deprivation group, patients also stayed awake between 10 PM and 6 AM every other night beginning with Day 2. Patients were removed from sleep deprivation if they had two or more secondarily generalized seizures within 24 hours. Patients were removed from the normal sleep group and were sleep deprived if they did not have a complex partial or secondarily generalized seizure by Day 6 of monitoring. In these patients removed from sleep deprivation or from normal sleep, data were analyzed up to and including the day of removal from the protocol. RESULTS: The sleep deprivation and normal sleep subjects did not differ in age, sex, seizure localization, or percent dosage reduction in antiepileptic drugs from baseline at days 1 to 3 of monitoring. Protocol duration was 6.5 +/- 2.4 days (mean +/- SD) for the sleep deprivation group and 5.8 +/- 2.0 days for the normal sleep group. Seizures per day for complex partial, secondarily generalized, and combined complex partial and secondarily generalized, calculated from admission until end of protocol, did not differ significantly between the two groups. CONCLUSION: Acute sleep deprivation did not affect seizure frequency during inpatient monitoring in our patients with intractable complex partial seizures with secondary generalization.

Cholecystokinin acts through catecholaminergic mechanisms in the hypothalamus to influence ingestive behaviour in the rat.

Administration of cholecystokinin (CCK) (0.2 - 0.6 micrograms in a volume of 2 microliter) into the lateral cerebral ventricle caused a decrease in intake of food but a relative increase in intake of water (or water-to-food ratio) in rats. To determine whether the anorexic actions of CCK were mediated through the hypothalamic nuclei, rats were infused with CCK (0.02 - 0.12 microgram in a volume of 0.5 microliter) through previously implanted hypothalamic cannulae. Administration of CCK into the lateral hypothalamus, but not the anterior hypothalamus or ventromedial hypothalamus, caused decreased intake of food and a relative increased intake of water. In addition, the responses induced by injection of CCK into the hypothalamus were completely abolished by selective depletion of catecholamines in the hypothalamus (eg. noradrenaline and dopamine) with intra-hypothalamic injection of 6-hydroxydopamine. Intraperitoneal administration of 0.12 microgram of CCK had no effect on the intake of food and water in rats. The data indicate that CCK acts through catecholaminergic mechanisms in the hypothalamus to influence feeding behaviour.

Human islet isolation in 104 consecutive cases. Factors affecting isolation success.

One of the major steps toward successful islet transplantation for the treatment of type diabetes is to obtain islets of sufficient number and viability. Using a standardized method of isolating islets, the goal of this study was to analyze the factors influencing the outcome of islet isolation. A total of 104 cadaveric human pancreata were processed for islets by the same team. Data from the islet-processing charts were reviewed retrospectively. The two endpoints were the recovery of islets, viable after 2 days of culture (group V = viable, group NV = nonviable) and the islet yield. Viable islets were recovered in 61% of cases (n = 63). Minimal blood glucose recorded during hospitalization was very significantly lower in group V (124 +/- 5 vs. 148 +/- 9, P = 0.01). Lack of significant medical history in the donor was associated with better viability as compared with various donor predispositions (chi-2 4.21, P = 0.04). Cold ischemia time (8.1 +/- 0.5 hr in group V vs. 9.8 +/- 0.9 hr in group NV, P = 0.07) and collagenase lot (5 lots tested, chi-2 13.1, P = 0.01) also affected the recovery of viable islets. Hospital time was shorter in group V (65.3 +/- 6.8 vs. 80.9 +/- 17.9 hr, P = 0.35). Multivariate logistic regression analyses of viable islet recovery identified minimal blood glucose (P = 0.03) and collagenase lot (P = 0.06) as the most significant risk factors. However, the best multivariate predictive model--which includes blood glucose, collagenase lot, donor age and surgical procurement team--correctly predicted 66.2% of cases only. Multivariate analysis of final islet yield designed hospitalization length, cardiorespiratory arrest, surgical procurement team, and collagenase lot as the best predictors. These data obtained in a large series of pancreata emphasized several donor and technical factors that should target the attention of islet transplant researchers in order to improve islet yield and viability.

Vasoactive intestinal polypeptide receptor binding sites in the human gastrointestinal tract: localization by autoradiography.

Vasoactive intestinal polypeptide (VIP) is a putative neurotransmitter in both the brain and peripheral tissues. To define possible target tissues of VIP we have used quantitative receptor autoradiography to localize and quantify the distribution of [125I]VIP receptor binding sites in histologically normal human surgical specimens. While the distribution of VIP binding sites was different for each gastrointestinal segment examined, specific vasoactive intestinal polypeptide binding sites were localized to the mucosa, the muscularis mucosa, the smooth muscle of submucosal arterioles, the circular and longitudinal smooth muscle of the muscularis externa, the myenteric plexus, and lymph nodules. In most segments, the mucosal layer expressed the highest concentration of VIP binding sites, with the duodenal and jejunal mucosa showing the highest density of receptors. These results identify putative VIP target tissues in the human gastrointestinal tract. In correlation with physiological data, VIP binding sites appear to be involved in the regulation of a variety of gastrointestinal functions including mucosal ion transport, gastric secretion, hemodynamic regulation, gastric and intestinal motility, neuronal excitability, and modulation of the immune system.

The use of somatostatin and its analogs in the treatment of surgical disorders.

Somatostatin is a naturally occurring peptide with a wide spectrum of biologic actions, most of which are inhibitory in nature. It has wide distribution, and within the gastrointestinal tract is is found in the pancreas, the stomach, intestinal mucosa, and myenteric neurons. It appears to function as a classic circulating hormone, as well as both a paracrine or locally acting agent and a neurocrine agent. Because of its inhibitory actions on gut endocrine, secretory, and motor functions, it has potential applicability in the treatment of a variety of disorders of interest to the surgeon. Indeed, it has been used successfully in the management of upper gastrointestinal hemorrhage, secretory diarrhea, short bowel syndrome, pancreatitis, gastrointestinal fistulas, and peptide-secreting tumors of the gut (apudomas). This review discusses physiology, pathophysiology, and therapeutic applications of somatostatin that may be important in surgical practice.

Evidence for vagus-dependent pancreatic polypeptide-releasing factor in the antrum: studies with the autotransplanted dog pancreas.

Pancreatic polypeptide (PP) response to food is suppressed by truncal vagotomy, antral vagotomy, and antrectomy. The inhibitory effect of antral vagotomy and of antrectomy may be due to inadvertent vagal denervation of the pancreas, disruption of antropyloric neural reflexes, or inhibition of release of a PP-releasing factor from the antrum. In this study we examined the latter hypothesis by achieving total extrinsic pancreatic denervation by orthotopic autotransplantation of the entire pancreas in four dogs. Total extrinsic pancreatic denervation, which abolished the pancreatic juice protein response to insulin, did not significantly alter plasma PP response to a meal (peak 30-minute PP of 696 +/- 192 pg/ml before transplantation versus 961 +/- 80 pg/ml after transplantation). Therefore, postprandial release of PP is, to a large extent, not mediated either by direct vagal innervation of the pancreas or by neural communications between the pancreas and antrum or the pancreas and the small intestine. In two of the dogs with pancreatic transplants, subsequent antral vagotomy resulted in greater than 80% inhibition of postprandial PP response. These findings are consistent with the hypothesis that a PP-releasing factor is present in the antrum and that the release of this factor is dependent on intact antral vagal innervation.

An Internet multicast symposium concerning the microcirculation of the islets of Langerhans.

The Internet Globally-linked Computer System was used to conduct an international scientific symposium. The symposium was held at the VAMC-Long Beach and consisted of prepared lectures that were multicast over the Internet. The basic unit of hardware used for the Internet Multicast was the Silicon Graphics Indy Unix Workstation, which was equipped with a color video camera. The multicast required four additional pieces of software from the file transfer protocol. The multicast backbone protocol allowed for simultaneous audio and video signals (the presenter, the slides, and the videotape images of islet microcirculation studies) to be transmitted over the computer network. The faculty included 12 experts in microcirculation, who gave 15-min lectures that included a question and answer period. All lectures were received at 14 computer stations in six countries. Eleven of the faculty gave their lectures at the VAMC-Long Beach, and one gave her lecture at the Massachusetts Institute of Technology in Boston, MA. The presenter from Boston was able to receive and answer questions from the faculty at the VAMC-Long Beach. An estimated $12,000 was saved in travel, hotel, and food costs and an estimated 180 travel hours were saved by viewers who did not have to travel to the symposium. We have demonstrated that a scientific symposium can be conducted using the Internet. We propose that many of our future meeting will be organized over the computer network. This format of multiimage projections allows us to effectively communicate in a personal way with a reduction in expensive and time-consuming travel.

The fasciovascular flap: a new vehicle for islet transplantation.

In order to determine whether pancreatic islets could be neovascularized by a fasciovascular flap (FVP), islet transplant studies were conducted in Lewis rats. Islets from two donors were isolated by collagenase digestion and discontinuous gradient centrifugation on Ficoll. These islets were injected in syngeneic recipients either into random groin SC fat as a control, or into a flap composed of fascia and fat elevated from the groin based on the superficial inferior epigastric vessels. After two wk, islet viability was assessed by histological analysis. The degree of neovascularization of the islet tissue was evaluated with India ink injection through the vascular pedicle. Whereas control islets degenerated and did not show clear signs of neovascularization, FVP-islets showed rich neovascularization and viability as a large sheet of islet clusters. These results have demonstrated that the FVP-flap is a novel recipient site which can support a large quantity of islet tissue. This model constitutes a unique neo-endocrine pancreas flap, which can be subsequently transplanted at will to transfer the established neo-endocrine pancreas to a desired site using microvascular surgical technique.

Transplant rejection. Mechanisms and treatment.

In this review, we summarize the cellular and molecular events in the rejection of transplanted allografts, as well as the rationale for the evolving techniques to suppress such rejection. Allogenic major histocompatibility complex antigens expressed on the allograft and/or on the "passenger leukocytes" within the graft are the major antigenic stimuli recognized as being foreign by receptors of CD4+/T helper cells of the host. Host macrophages provide a second signal, interleukin (IL) 1, essential to the activation of T helper cells. Subsequent production of IL-2 by T helper cells leads to activation and proliferation of cytotoxic T cells and lymphokine-activated killer cells and the release of IL-4 and IL-6. In addition, IL-2 promotes release of interferon gamma as well as tumor necrosis factor and other proinflammatory cytokines. Therapeutic options to "downregulate" this cascade have gradually evolved from global nonspecific immunosuppressive techniques (total body irradiation, antilymphocyte serum) to increasingly specific modalities currently being studied, including monoclonal antibodies against the IL-2 receptor (thus targeting only vigorously proliferating T cells), antibodies against specific cytokines (interferon gamma, tumor necrosis factor), and now "designer" antibody-toxin conjugate molecules that deliver toxins to selected receptor targets. Finally, work continues toward inducing preoperative antigen-specific (graft) tolerance, including utilization of gene transfection techniques to transfect donor major histocompatibility complex antigens to recipients before surgery, which has been shown to prolong murine cardiac allografts, perhaps by priming specific suppressor cells. Further understanding of the initiation of, and subsequent events in, transplantation rejection will lead to increasingly effective prolongation of graft survival while minimizing adverse effects on the host.

Heterotopic tissue in lymph nodes. An unrecognized problem.

Heterotopic tissue in lymph nodes is both unknown to clinicians and a potential source of confusion with metastatic disease. We reviewed the English literature and found 289 cases of heterotopic tissue in lymph nodes. The majority (84%) of these patients were operated on for malignant neoplasms. The most frequent sites of occurrence was the pelvis (67%), followed by the axilla (14%), neck (14%), groin (3%), abdomen (2%), and mediastinum (less than 1%). The tissue seen is site-specific and frequently resembles a neighboring organ. Three cases have been reported in which heterotopic tissue was mistaken for metastatic disease. These cases illustrate the importance of being familiar with heterotopic tissue in lymph nodes and identifying it when it does occur, to avoid inappropriate therapy.

Serum gastrin and human chorionic gonadotropin in the Zollinger-Ellison syndrome.

Prior to total gastrectomy, serum levels of gastrin and human chorionic gonadotropin (HCG) and its alpha- and beta-subunits (alpha-HCG and beta-HCG) were determined by radioimmunoassays in 40 patients with the Zollinger-Ellison syndrome. Basal serum gastrin levels greater than 1,500 pg/mL were found only in patients with metastases to lymph nodes or liver, while levels greater than 8,000 indicated massive liver replacement by tumor. Gastrin levels less than 1,500 pg/mL had no correlation with malignant behavior. Neither the calcium-infusion nor secretin-injection test was useful in identifying tumors as benign or malignant. Basal serum levels of alpha-HCG were elevated (> 7 ng/mL) in four of 20 patients with metastatic gastrinoma and were normal in all 16 patients with benign disease. There was a significant correlation between basal gastrin and alpha-HCG levels in patients with malignant gastrinoma but not for those with benign tumors. The results suggest that serum gastrin and alpha-HCG levels can be useful in assessing the biologic behavior of gastrinomas and in planning appropriate surgical and nonsurgical treatment.

'Kissing' duodenal ulcers.

Among 70 cases of perforated duodenal ulcers treated by plication, eight were complicated by massive postoperative hemorrhage from a syncronous posterior "kissing" duodenal ulcer. Critical analysis revealed that only signs of gastrointestinal (GI) bleeding preoperatively had predictive value for postoperative hemorrhage. Twenty-four patients had one or more predictive signs, and eight actually bled postoperatively. There was a 50% mortality and 75% additional complication rate for the bleeders. In contrast, the nonbleeders had a mortality and a complication rate of only 18% and 35%, respectively. There was no observed superiority of either surgical or medical treatment for postoperative hemorrhage. In perforated duodenal ulcer with evidence of GI blood loss, an intraoperative search for a posterior kissing ulcer is recommended. If a kissing ulcer is found, an acid-reducing operation and suture ligation of the ulcer is indicated.

Elevated serum prolactin level in the Zollinger-Ellison syndrome.

To estimate the prevalence of prolactinoma in the Zollinger-Ellison syndrome (ZES), serum prolactin (PRL) levels were measured by radioimmunoassay in 36 patients with ZES. Eight patients had elevated PRL levels; however, in one patient the finding was attributed to primary hypothyroidism rather than a prolactinoma. The seven other patients were believed to have previously undiagnosed prolactinomas on the basis of elevated serum PRL levels; the presence of pituitary tumors were confirmed in four by demonstration of sella turcica erosions or enlargement. Serial determinations over three to six years showed a tendency for serum PRL levels to increase modestly in four of six patients. Thus far, two patients have undergone transsphenoidal tumor resections with good results. This study suggests that the prevalence of prolactinoma in patients with ZES is substantial (10% for those with isolated ZES and 54% for those with ZES with multiple endocrine neoplasia, type 1, syndrome), and that early diagnosis is possible with measurement of serum PRL levels. Since levels of PRL tend to increase and clinically significant pituitary tumors can develop, determinations of serial serum PRL levels are recommended for all patients with ZES.

Intestinal blood flow. An evaluation by clearance of xenon Xe 133 from the canine jejunum.

Clearance of a parenchymal injection of xenon Xe 133 from the jejunum was used to asses changes in tissue perfusion produced by variations in superiorr mesenteric artery flow resulting from partial aortic occlusion. Disappearance of xenon from submucosa and muscularis was similar and reproducible. The biexponential function of the isotope clearanc exhibited a rapid initial component representing mean flow. Calculated xenon clearance rates, expressed as half-times for isotope disappearance and plotted as a function of decreasing superior mesenteric artery flow, were characteristically rapid for a broad range of superio mesenteric artery flows (90 to 600 ml/min). With reduction of superior mesenteric artery flow beyond 80 plus or minus 10 ml/min, tissue clearance of xenon was markedly prolonged. Adequate perfusion of the vascular compartments of the small bowel as measured by xenon clearance was maintained until 80% reduction of superior mesenteric artery flow.

Massive lower gastrointestinal bleeding from intestinal varices.

Lower gastrointestinal bleeding from intestinal varices cannot readily be detected at operation; hence, preoperative identification is important. Our experience with six patients having sudden, massive bleeding per rectum from intestinal varices suggests a group of common findings. These patients had cirrhosis, no blood in the stomach or duodenum, characteristic mucosal imprints on barium enema, or direct visualization of varices on sigmoidscopy or colonoscopy. Only two had demonstrable esophageal varices. The diagnosis was confirmed and the site of the varices localized on the venous phase of selective mesenteric angiography in five patients. Varices were located in the duodenojejunum in two, in the cecum and ascending colon in two, and in the rectum and sigmoid colon in two patients. Three patients were treated nonoperatively with transfusion and intraarterial infusion of vasopressin into the superior mesenteric artery; one died. One patient with cecal varices had a right hemicolectomy that controlled the bleeding, but progressive hepatic failure resulted in postoperative death. The remaining two patients had successful decompression of left colonic varices by portasystemic shunt.

Cirsoid aneurysms of the jejunum. An unrecognized cause of massive gastrointestinal bleeding.

Cirsoid aneurysms (exulceratio simplex Dieulafoy) as a cause of massive gastrointestinal hemorrhage have been known to occur in the stomach. Endoscopy plays an important role in the diagnosis of and therapy for these lesions. We report two cases of a cirsoid aneurysm in the proximal jejunum; two cases have been previously reported in the literature. These lesions have the same pathologic features as gastric cirsoid lesions and cause massive gastrointestinal hemorrhage. Because these lesions are beyond the reach of current endoscopy, surgery was necessary to diagnose and treat the lesions in three of four patients. The fourth patient died after unsuccessful surgical exploration, and the lesion was found post mortem. Jejunal cirsoid aneurysms may be an unrecognized rather than a rare cause of gastrointestinal bleeding. They should be considered in the patient with massive proximal gastrointestinal bleeding in whom the source is not known, especially if angiography suggests a small-bowel site. With the advent of newer forms of endoscopy that can examine the small bowel, the management of these lesions may change; at present, surgery is lifesaving.

Common duct stricture from chronic pancreatitis.

Common bile duct stricture secondary to chronic pancreatitis is difficult to detect clinically. Surgical bypass is necessary if complications from biliary obstruction develop. In 21 patients operated on between 1968 and 1979, the earliest typical biochemical finding was a persistently elevated serum alkaline phosphatase level. The SGOT level was minimally elevated in seven patients, but did not correlate with changes in the stricture. An increased bilirubin level was noted either during an acute exacerbation of pancreatitis or late in the course of the stricture development, when obstruction was almost complete. Operative cholangiograms taken in 12 of these patients and transhepatic cholangiograms taken in nine demonstrated a stricture of the intrapancreatic bile duct more than 2 cm long. Operations were performed for treatment of obstructive jaundice (11), ascending cholangitis (three), suspected pancreatic cancer (three), and progressive biliary cirrhosis (two). Sphincteroplasty, initially attempted in four patients, uniformly failed to relieve the obstruction due to the length of strictured duct. Satisfactory drainage was obtained for up to ten years with choledochoduodenostomy (12), choledochojejunostomy (three), and cholecystojejunostomy (six).