Recurrent GNAS mutations define an unexpected pathway for pancreatic cyst development

More than 2% of the adult U.S. population harbors a pancreatic cyst. These often pose a difficult management problem because conventional criteria cannot always distinguish cysts with malignant potential from those that are innocuous. One of the most common cystic neoplasms of the pancreas, and a bona fide precursor to invasive adenocarcinoma, is called intraductal papillary mucinous neoplasm (IPMN). To help reveal the pathogenesis of these lesions, we purified the DNA from IPMN cyst fluids from 19 patients and searched for mutations in 169 genes commonly altered in human cancers. In addition to the expected KRAS mutations, we identified recurrent mutations at codon 201 of GNAS. A larger number (113) of additional IPMNs were then analyzed to determine the prevalence of KRAS and GNAS mutations. In total, we found that GNAS mutations were present in 66% of IPMNs and that either KRAS or GNAS mutations could be identified in 96%. In eight cases, we could investigate invasive adenocarcinomas that developed in association with IPMNs containing GNAS mutations. In seven of these eight cases, the GNAS mutations present in the IPMNs were also found in the invasive lesion. GNAS mutations were not found in other types of cystic neoplasms of the pancreas or in invasive adenocarcinomas not associated with IPMNs. In addition to defining a new pathway for pancreatic neoplasia, these data suggest that GNAS mutations can inform the diagnosis and management of patients with cystic pancreatic lesions.     

Refining the definition of perioperative mortality following hepatectomy using death within 90 days as the standard criterion

ObjectivesDefining perioperative mortality as death that occurs within 30 days of surgery may underestimate ‘true’ mortality among patients undergoing hepatic resection. To better define perioperative mortality, trends in the risk for death during the first 90 days after hepatectomy were assessed.MethodsSurveillance, Epidemiology and End Results (SEER) Medicare data were used to identify 2597 patients who underwent hepatic resection during 1991–2006. Data on their clinicopathological characteristics, surgical management and perioperative mortality were collected and survival was assessed at 30, 60 and 90 days post-surgery.ResultsOverall, 5.7% of patients died within the first 30 days. Postoperative mortality at 60 and 90 days were 8.3% and 10.1%. In-hospital mortality after hepatic resection was greater among patients with hepatocellular carcinoma (HCC) than among those with colorectal liver metastases (CRLM) (8.9% and 3.8%, respectively; P < 0.001). In CRLM patients, mortality increased from 4.3% at 30 days to 8.4% at 90 days, whereas mortality in HCC patients increased from 9.7% at 30 days to 15.0% at 90 days (both P < 0.05). Patients with HCC were twice as likely as CRLM patients to die within 30 days [odds ratio (OR) 2.03], 60 days (OR = 1.74) and 90 days (OR = 1.71) (all P < 0.001). Differences in 30- and 90-day mortality were greatest among HCC patients undergoing major hepatic resection (P < 0.05).ConclusionsReporting deaths that occur within a maximum of 30 days of surgery underestimates the mortality associated with hepatic resection. Traditional 30-day definitions of mortality are misleading and surgeons should report all perioperative outcomes that occur within 90 days of hepatic resection.     

Choledochal cyst disease in children and adults: a 30-year single-institution experience

BACKGROUND: The reported incidence of choledochal cyst (CC) disease varies greatly based on geography. Most large series on CC originate from East Asia. So our understanding of the presentation and natural history of CC disease in western societies is less well characterized. Recognition and surgical treatment are important because of the significant longterm risks of developing cholangiocarcinoma. We report here the largest single-institution western experience with CC disease. STUDY DESIGN: Ninety-two patients with CC disease who were seen at our institution between 1976 and 2006 were included in this study. Potential differences between children and adults (defined as 16 years old or older) were specifically evaluated. RESULTS: There were 19 children and 73 adults; 90% were girls/women with type I cysts. Adults were more likely to present with abdominal pain (97% versus 63%, p < 0.001), and children were more likely to present with jaundice (71% versus 25%, p=0.001). Surgical management most commonly involved cyst excision and Roux-en-Y hepaticojejunostomy reconstruction. Four adults (three with cholangiocarcinoma and one with gall bladder cancer) and one child (with embryonal rhabdomyosarcoma) had malignancies associated with their CC at the time of excision. Two patients (with type IV and type V disease) developed cholangiocarcinoma after surgical management. Another patient died of pancreatic adenocarcinoma 21 years after excision of her type I cyst. There was no operative or hospital mortality, and no patient who underwent complete cyst excision developed cholangiocarcinoma during a mean followup of 10 years. CONCLUSIONS: Western CC disease has a similar demographic profile as that seen in Asia. CCs are more frequently found in adults and girls/women and are associated with a longterm risk of developing cholangiocarcinoma. Presentation differs between adults and children. After complete cyst excision, no patients developed cholangiocarcinoma.     

Adjuvant Chemoradiation Therapy for Adenocarcinoma of the Distal Pancreas

Background

This study was designed to examine the effect of adjuvant 5-FU-based chemoradiation therapy (CRT) after distal pancreatectomy for adenocarcinoma of the distal pancreas.

Methods

All patients underwent curative resection for adenocarcinoma of the distal pancreas between December 1985 and June 2006. Patients who received adjuvant CRT were compared with those who underwent surgery alone. A Kaplan–Meier estimate of the survival curve was used to determine estimates of the median survival and proportion alive at 1 and 2 years; log-rank tests were used to make comparisons between groups.

Results

A total of 123 patients underwent distal pancreatectomy; 29 patients were excluded for distant metastases at the time of surgery (n = 12, 10%) or before adjuvant therapy (n = 11, 9%), death within 2 months of surgery (n = 2, 2%), or if CRT treatment status was unknown (n = 4, 3%). Of the remaining 94 patients, 72% received adjuvant 5-FU-based CRT and 28% underwent surgery alone. Overall median survival was 16.2 (95% confidence interval (CI), 13.1–18.9) months. The groups were similar with respect to tumor size, nodal status, and margin status. There was no significant difference in overall survival between patients treated with adjuvant CRT versus surgery alone (p = 0.23). An exploratory subgroup analysis suggested a potential survival benefit of adjuvant CRT in patients with lymph node metastases (16.7 vs. 12.1 months, p < 0.01).

Conclusions

Adjuvant CRT did not increase survival compared with surgery alone; however, patients with node-positive disease appear to benefit from adjuvant CRT.     

Impact of Obesity on Perioperative Outcomes and Survival Following Pancreaticoduodenectomy for Pancreatic Cancer: A Large Single-Institution Study

Background

To examine the effect of body mass index (BMI) on clinicopathologic factors and long-term survival in patients undergoing pancreaticoduodenectomy for pancreatic adenocarcinoma.

Methods

Data on BMI, weight loss, operative details, surgical pathology, and long-term survival were collected on 795 patients who underwent pancreaticoduodenectomy. Patients were categorized as obese (BMI?>?30 kg/m²), overweight (BMI 25 to <30 kg/m²), or normal weight (BMI?<?25 kg/m²) and compared using univariate and multivariate analyses.

Results

At the time of surgery, 14% of patients were obese, 33% overweight, and 53% normal weight. Overall, 32% of patients had preoperative weight loss of >10%. There were no differences in operative times among the groups; however, higher BMI was associated with increased risk of blood loss (P?<?0.001) and pancreatic fistula (P?=?0.01). On pathologic analysis, BMI was not associated with tumor stage or number of lymph nodes harvested (both P?>?0.05). Higher BMI patients had a lower incidence of a positive retroperitoneal/uncinate margin versus normal weight patients (P?=?0.03). Perioperative morbidity and mortality were similar among the groups. Obese and overweight patients had better 5-year survival (22% and 22%, respectively) versus normal weight patients (15%; P?=?0.02). After adjusting for other prognostic factors, as well as preoperative weight loss, higher BMI remained independently associated with improved cancer-specific survival (overweight: hazard ratio, 0.68; obese: hazard ratio, 0.72; both P?<?0.05).

Conclusion

Obese patients had similar tumor-specific characteristics, as well as perioperative outcomes, compared with normal weight patients. However, obese patients undergoing pancreaticoduodenectomy for pancreatic cancer had an improved long-term survival independent of known clinicopathologic factors.     

Loss of ATRX or DAXX expression and concomitant acquisition of the alternative lengthening of telomeres phenotype are late events in a small subset of MEN-1 syndrome pancreatic neuroendocrine tumors

Approximately 45% of sporadic well-differentiated pancreatic neuroendocrine tumors harbor mutations in either ATRX (alpha thalassemia/mental retardation X-linked) or DAXX (death domain-associated protein). These novel tumor suppressor genes encode nuclear proteins that interact with one another and function in chromatin remodeling at telomeric and peri-centromeric regions. Mutations in these genes are associated with loss of their protein expression and correlate with the alternative lengthening of telomeres phenotype. Patients with multiple endocrine neoplasia-1 (MEN-1) syndrome, genetically defined by a germ line mutation in the MEN1 gene, are predisposed to developing pancreatic neuroendocrine tumors and thus represent a unique model for studying the timing of ATRX and DAXX inactivation in pancreatic neuroendocrine tumor development. We characterized ATRX and DAXX protein expression by immunohistochemistry and telomere status by telomere-specific fluorescence in situ hybridization in 109 well-differentiated pancreatic neuroendocrine lesions from 28 MEN-1 syndrome patients. The study consisted of 47 neuroendocrine microadenomas (<0.5?cm), 50 pancreatic neuroendocrine tumors (≥0.5?cm), and 12 pancreatic neuroendocrine tumor lymph node metastases. Expression of ATRX and DAXX was intact in all 47 microadenomas, and none showed the alternative lengthening of telomeres phenotype. ATRX and/or DAXX expression was lost in 3 of 50 (6%) pancreatic neuroendocrine tumors. In all three of these, tumor size was ≥3?cm, and loss of ATRX and/or DAXX expression correlated with the alternative lengthening of telomeres phenotype. Concurrent lymph node metastases were present for two of the three tumors, and each metastasis displayed the same changes as the primary tumor. These findings establish the existence of ATRX and DAXX defects and the alternative lengthening of telomeres phenotype in pancreatic neuroendocrine tumors in the context of MEN-1 syndrome. The observation that ATRX and DAXX defects and the alternative lengthening of telomeres phenotype occurred only in pancreatic neuroendocrine tumors measuring ≥3?cm and their lymph node metastases suggests that these changes are late events in pancreatic neuroendocrine tumor development.     

重组日本血吸虫副肌球蛋白的表达与纯化

用基因重组技术 ,将日本血吸虫副肌球蛋白 (rSj97)基因亚克隆至表达载体pQE30上。在IPTG诱导下 ,重组日本血吸虫副肌球蛋白在大肠杆菌中得以高效表达。通过快速蛋白质液相色谱仪 (FPLC) ,经TALON柱和离子交换柱两步分离纯化 ,获得大量高纯度的重组日本血吸虫副肌球蛋白 ,为水牛现场试验提供了充足的抗原     

利用放射性核素示踪技术对镉及铬与毛发结合机制的研究

目的 利用放射性核素示踪方法研究内外源性镉、铬与毛发结合的机制，从分子水平探讨目前常用的头发预处理方法能否有选择地清除外源性而保留毛发中内源性镉、铬的含量。方法 提取含有内源性的放射性核素镉、铬的大白鼠鼠毛及外源性放射性核素镉、铬的人发蛋白质，利用柱层析将毛发蛋白质分组，分别测定不同蛋白组分中的放射性镉、铬的活度来确定与镉、铬相互结合的毛发蛋白组分。比较与内外源性镉、铬相结合的蛋白组分来分析核素与毛发结合机制。结果 内外源性镉、铬核素均以与毛发蛋白质相互结合的方式存在于毛发中，而且所结合的蛋白质组分的相对分子量相同。lAEA法和海鸥洗涤剂对内外源性的镉、铬有轻度地洗脱，但Ⅱ玎AN啦和稀硝酸溶液对两种核素有强力的清除效力。结论 由于内外源性镉、铬核素与毛发蛋白质结合的相似性，实验中头发样品的预处理方法在清除外源性核素的同时，在一定程度上也影响头发内源性的核素的含量。