Coffee is more than just caffeine – a single-center, randomized, double-blinded, placebo-controlled superiority trial (CaCo trial)

Objective

Avoidance of prolonged postoperative bowel paralysis after colorectal surgery is of major importance due to its significant clinical implications. Postoperative caffeine consumption appears to be a promising strategy. The aim of this study was to assess whether postoperative oral caffeine intake shortens bowel hypomotility after elective laparoscopic colorectal surgery.

Methods

This was a single-center, randomized, double-blinded, placebo-controlled superiority trial conducted from October 1st, 2015 to August 10th, 2020. Patients aged >=18 years with malignant or benign disease undergoing elective laparoscopic colectomy were included and assigned randomly before surgery to receive 3x daily either 100 mg caffeine or 200 mg caffeine or 250 mg corn starch (placebo) after the procedure. Substances were served in indistinguishable capsules three times daily before the meals. The primary endpoint was time to first bowel movement, measured from the time of wound closure to the patient's first defecation. Secondary endpoints included colonic transit time, time to tolerance of solid food, length of hospital stay and perioperative morbidity.

Results

A total of 60 patients were randomized, 20 to each group. Twenty-seven patients followed the protocol and were included in the per-protocol (PP) analysis. Baseline characteristics were similarly distributed among the groups. In intention-to-treat analysis, the time to first bowel movement in the caffeine 200 mg group was 67.9 h (standard deviation [SD] 19.2), in the caffeine 100 mg group 68.2 h (SD 32.2) and in the placebo group 67.3 h (SD 22.7) (p=0.887). PP analysis and measurement of colonic transit time (41.8 h [SD 21.7] in the caffeine 200 mg group, 34.2 h [SD 22.9] in the caffeine 100 mg group and 46.3 h [SD 20.6] in the placebo group, p=0.317) confirmed non-significant differences. The time to tolerance of solid food, length of hospital stay and postoperative morbidity were comparable among the three groups and no deaths or related serious adverse events were observed during the study.

Conclusion

Although caffeine intake after laparoscopic colorectal surgery is safe, its administration was not associated with a shortened time to first bowel movement in contrast to previous studies. Thus, other ingredients of coffee might be responsible for the intestinal stimulatory effect previously described.

Survival after resection of appendiceal carcinoma by hemicolectomy and less radical than hemicolectomy: a population-based propensity score matched analysis

AIM

The operative treatment for non-metastatic appendiceal carcinoma is controversial despite the recommendation of right hemicolectomy (RH) by many researchers. The aim of this population-based study was to compare outcomes after RH and less radical resection than right hemicolectomy (LRH).

METHOD

A total of 1144 patients who underwent resection with additional lymphadenectomy of Stages I-III appendiceal carcinoma from 2004 to 2012 were identified in the Surveillance, Epidemiology and End Results database. Overall survival (OS) and cancer-specific survival (CSS) after RH and LRH were assessed by unadjusted and risk-adjusted Cox regression analysis and by propensity score matched analysis.

RESULTS

A total of 855 (74.7%) patients underwent RH and 289 (25.3%) underwent LRH. In an unadjusted analysis, survival after LRH and RH did not differ in OS [hazard ratio (HR) 0.95, 95% CI 0.71-1.26, P = 0.707] and CSS (HR 0.95, 95% CI 0.69-1.32, P = 0.762). The 5-year OS and CSS in patients who underwent RH were 71.6% (95% CI 67.8-75.6%) and 76.4% (95% CI 72.8-80.3) compared with 73.8% (95% CI 67.9-80.2) and 78.7% (95% CI 73.2-84.7) in patients with LRH, respectively. No relevant difference in survival between LRH and RH could be observed in a multivariable analysis (OS, HR 0.90, 95% CI 0.65-1.25, P = 0.493; CSS, HR 0.87, 95% CI 0.60-1.26, P = 0.420) and after propensity score adjusted analysis (OS, HR 0.87, 95% CI 0.62-1.22, P = 0.442; CSS, HR 0.97, 95% CI 0.67-1.40, P = 0.883).

CONCLUSIONS

In this retrospective analysis, survival after RH for non-metastatic appendiceal carcinoma was not statistically significantly superior to LRH. Hence, LRH with lymphadenectomy might be sufficient for treatment of non-metastatic appendiceal carcinoma.

Staging of pancreatic cancer based on the number of positive lymph nodes

BACKGROUND

The International Study Group on Pancreatic Surgery has stated that at least 12 lymph nodes should be evaluated for staging of pancreatic cancer. The aim of this population-based study was to evaluate whether the number of positive lymph nodes refines staging.

METHODS

Patients who underwent pancreatectomy for stage I-II pancreatic cancer between 2004 and 2012 were identified from the Surveillance, Epidemiology, and End Results database. The predictive value of the number of positive lymph nodes for survival was assessed by generalized receiver operating characteristic (ROC) curve analysis and propensity score-adjusted Cox regression analysis.

RESULTS

Some 5036 patients were included, with a median of 18 (i.q.r. 15-24) lymph nodes examined. Positive lymph nodes were found in 3555 patients (70·6 per cent). The median duration of follow-up was 15 (i.q.r. 8-28) months. ROC curve analysis revealed that two positive lymph nodes best discriminated overall survival. Patients with one or two positive lymph nodes (pN1a) and those with three or more positive lymph nodes (pN1b) had an increased risk of overall mortality compared with patients who were node-negative (pN0): hazard ratio (HR) 1·47 (95 per cent c.i. 1·33 to 1·64) and HR 2·01 (1·82 to 2·22) respectively. These findings were confirmed by propensity score-adjusted Cox regression analysis. The 5-year overall survival rates were 39·8 (95 per cent c.i. 36·5 to 43·3) per cent for patients with pN0, 21·0 (18·6 to 23·6) per cent for those with pN1a and 11·4 (9·9 to 13·3) per cent for patients with pN1b disease.

CONCLUSION

The number of positive lymph nodes in the resection specimen is a prognostic factor in patients with pancreatic cancer.

Isolated tumor cells in stage I & II colon cancer patients are associated with significantly worse disease-free and overall survival

Background

Lymph node (LN) involvement represents the strongest prognostic factor in colon cancer patients. The objective of this prospective study was to assess the prognostic impact of isolated tumor cells (ITC, defined as cell deposits ≤ 0.2 mm) in loco-regional LN of stage I & II colon cancer patients.

Methods

Seventy-four stage I & II colon cancer patients were prospectively enrolled in the present study. LN at high risk of harboring ITC were identified via an in vivo sentinel lymph node procedure and analyzed with multilevel sectioning, conventional H&E and immunohistochemical CK-19 staining. The impact of ITC on survival was assessed using Cox regression analyses.

Results

Median follow-up was 4.6 years. ITC were detected in locoregional lymph nodes of 23 patients (31.1 %). The presence of ITC was associated with a significantly worse disease-free survival (hazard ratio = 4.73, p = 0.005). Similarly, ITC were associated with significantly worse overall survival (hazard ratio = 3.50, p = 0.043).

Conclusions

This study provides compelling evidence that ITC in stage I & II colon cancer patients are associated with significantly worse disease-free and overall survival. Based on these data, the presence of ITC should be classified as a high risk factor in stage I & II colon cancer patients who might benefit from adjuvant chemotherapy.

Meta-analysis of the predictive value of C-reactive protein for infectious complications in abdominal surgery

BACKGROUND

The aim of this analysis was to assess the predictive value of C-reactive protein (CRP) for the early detection of postoperative infectious complications after a variety of abdominal operations.

METHODS

A meta-analysis of seven cohort studies from a single institution was performed. Laparoscopic gastric bypass and colectomies, as well as open resections of cancer of the colon, rectum, pancreas, stomach and oesophagus, were included. The predictive value of CRP was assessed by the area under the curve (AUC) of the receiver operating characteristic (ROC) curve.

RESULTS

Of 1986 patients, 577 (29·1 (95 per cent c.i. 27·1 to 31·3) per cent) had at least one postoperative infectious complication. Patients undergoing laparoscopic gastric bypass (383 patients) or colectomy (285), and those having open gastric (97) or colorectal (934) resections were combined in a meta-analysis. Patients who had resection for cancer of the oesophagus (41) or pancreas (246) were analysed separately owing to heterogeneity. CRP levels 4 days after surgery had the highest diagnostic accuracy (AUC 0·76, 95 per cent c.i. 0·73 to 0·78). Sensitivity and specificity were 68·5 (60·6 to 75·5) and 71·6 (66·6 to 76·0) per cent respectively. Positive and negative predictive values were 50·4 (46·0 to 54·8) and 84·3 (80·8 to 87·3) per cent. The threshold CRP varied according to the procedure performed.

CONCLUSION

The negative predictive value of serum CRP concentration on day 4 after surgery facilitates reliable exclusion of postoperative infectious complications.

Randomized clinical trial on the effect of coffee on postoperative ileus following elective colectomy

Background

Postoperative ileus is a common problem after abdominal surgery. It was postulated that coffee intake would decrease postoperative ileus after colectomy.

Methods

This was a multicentre parallel open-label randomized trial. Patients with malignant or benign disease undergoing elective open or laparoscopic colectomy were assigned randomly before surgery to receive either coffee or water after the procedure (100 ml three times daily). The primary endpoint was time to first bowel movement; secondary endpoints were time to first flatus, time to tolerance of solid food, length of hospital stay and perioperative morbidity.

Results

A total of 80 patients were randomized, 40 to each group. One patient in the water arm was excluded owing to a change in surgical procedure. Patient characteristics were similar in both groups. In intention-to-treat analysis, the time to the first bowel movement was significantly shorter in the coffee arm than in the water arm (mean(s.d.) 60·4(21·3) versus 74·0(21·6) h; P = 0·006). The time to tolerance of solid food (49·2(21·3) versus 55·8(30·0) h; P = 0·276) and time to first flatus (40·6(16·1) versus 46·4(20·1) h; P = 0·214) showed a similar trend, but the differences were not significant. Length of hospital stay (10·8(4·4) versus 11·3(4·5) days; P = 0·497) and morbidity (8 of 40 versus 10 of 39 patients; P = 0·550) were comparable in the two groups.

Conclusion

Coffee consumption after colectomy was safe and was associated with a reduced time to first bowel action. Registration number: NCT01079442 (http://www.clinicaltrials.gov).

Long-term in vitro culture of hamster pancreatic β-cells and induction of adenocarcinoma by treatment with N-nitrosobis(2-oxopropyl)amine

OBJECTIVES

Earlier studies indicated that hamster pancreatic ductal adenocarcinoma not only derives from ductal/ductular structures but also from cells within the islet. So far unidentified cells within the islet are responsive to the carcinogenic effect of N-nitrosobis (2-oxopropyl) amine (BOP) forming poorly differentiated ductal adenocarcinoma. However, studies indicated a major role of β-cells during carcinogenesis. To find out, if β-cells are the primary target cells of BOP and if they are capable to form ductal adenocarcinoma after malignant transformation, we established a long-term culture of undifferentiated cells deriving from isolated β-cells and treated them with BOP.

METHODS

Langerhans' islets from pancreata of Syrian golden hamsters were isolated and dispersed into single cells by dispase digestion. Cells were labeled with a highly specific β-cell surface antibody (K14D10) and these K14D10+ cells were extracted from the suspension by paramagnetic Dynabeads. Cells were cultured in vitro and treated with BOP. Untreated cells served as control.

RESULTS

K14D10+ cells formed a monolayer and produced insulin over a period of 28 days in culture. However, with time in culture they became undifferentiated with a higher proliferation rate and after about 60 days in culture BOP treated cells showed anchorage independent growth. These cells autotransplanted s.c. formed a well-differentiated ductal adenocarcinoma.

CONCLUSIONS

Pancreatic β-cells are the primary target of BOP without necessarily being embedded in the compound of the Langerhans' islet. With time in culture, they give rise to undifferentiated cells and after malignant transformation they are able to form ductal adenocarcinoma.

The role of an interdisciplinary transplant team on living donation kidney transplantation program

During the last decades, the disparity between the organ supply and the demand for kidney transplantation in Europe has led to consider living donors as a more acceptable option. In the last 7 years, we have established an interdisciplinary supporting transplant team to increase the rate of living donation. After 2001, the new interdisciplinary transplant team consisted of a transplant surgeon, a nephrologist, a pediatrician, a radiologist, a psychologist, a transplant coordinator, and a transplant nurse. We performed a prospective analysis to examine the effect of implementing this team on our living donation program. Demographic data, the annual number of procedures, the duration of waiting, and the cold ischemia time were evaluated among brain-dead and living donors. From January 2002 until December 2008, the number of patients who were annually on the waiting list increased 42% (from 377 to 536 patients). Consequently, the number of the total kidney transplants increased from 81 to 120 with an annual median of 98 cases. By implementing the interdisciplinary transplant team, a significant increase of living kidney donors was observed: from 18 to 42 cases; median = 27). In the last 7 years, a total number of 796 kidney transplants have been performed: 567 from brain-dead and 229 from living donors. In 2001, the waiting list times for recipients who received grafts from brain-dead versus living donors were 1356 versus 615 days respectively. Compared with 2008, the duration on the waiting list decreased significantly for patients receiving a living donor graft, whereas there was a slight increase for the patients in the brain-dead group: brain death versus living donors: 1407 versus 305 days. The interdisciplinary approach has also reduced the cold ischemia time for the living donor recipients: 3 hours and 42 minutes in 2001 versus 2 hours and 50 minutes in 2008. During the last years, by implementing an interdisciplinary transplant team, supporting living donor procedures has produce a gradual increase in the number of kidney transplants from living donors with a remarkable decrease in waiting and cold ischemia times, the latter presumably influencing graft quality.

A single center experience of combined liver kidney transplantation

With advancements in the operative techniques, patient survival following liver transplantation (LTx) has increased substantially. This has led to the acceleration of pre-existing kidney disease because of immunosuppressive nephrotoxicity making additional kidney transplantation (KTx) inevitable. On the other hand, in a growing number of patients on the waiting list to receive liver, long waiting time has resulted in adverse effect of decompensated liver on the kidney function. During the last two decades, the transplant community has considered combined liver kidney transplantation (CLKTx) to overcome this problem. The aim of our study is to present an overview of our experience as well as a review of the literature in CLKTx and to discuss the controversy in this regard. All performed CLKTx (n = 22) at our institution as well as all available reported case series focusing on CLKTx are extracted. The references of the manuscripts were cross-checked to implement further articles into the review. The analyzed parameters include demographic data, indication for LTx and KTx, duration on the waiting list, Model for End-Stage Liver Disease (MELD) score, Child-Turcotte-Pugh (CTP) score, immunosuppressive regimen, post-transplant complications, graft and patient survival, and cause of death. From 1988 to 2009, a total of 22 CLKTx were performed at our institution. The median age of the patients at the time of CLKTx was 44.8 (range: 4.5-58.3 yr). The indications for LTx were liver cirrhosis, hyperoxaluria type 1, polycystic liver disease, primary or secondary sclerosing cholangitis, malignant hepatic epithelioid hemangioendothelioma, cystinosis, and congenital biliary fibrosis. The KTx indications were end-stage renal disease of various causes, hyperoxaluria type 1, polycystic kidney disease, and cystinosis. The mean follow-up duration for CLKTx patients were 4.6 +/- 3.5 yr (range: 0.5-12 yr). Overall, the most important encountered complications were sepsis (n = 8), liver failure leading to retransplantation (n = 4), liver rejection (n = 3), and kidney rejection (n = 1). The overall patient survival rate was 80%. Review of the literature showed that from 1984 to 2008, 3536 CLKTx cases were reported. The main indications for CLKTx were oxalosis of both organs, liver cirrhosis and chronic renal failure, polycystic liver and kidney disease, and liver cirrhosis along with hepatorenal syndrome (HRS). The most common encountered complications following CLKTx were infection, bleeding, biliary complications, retransplantation of the liver, acute hepatic artery thrombosis, and retransplantation of the kidney. From the available data regarding the need for post-operative dialysis (n = 673), a total of 175 recipients (26%) required hemodialysis. During the follow-up period, 154 episodes of liver rejection (4.3%) and 113 episodes of kidney rejection (3.2%) occurred. The cumulative 1, 2, 3, and 5 yr survival of both organs were 78.2%, 74.4%, 62.4%, and 60.9%, respectively. Additionally, the cumulative 1, 2, 3, and 5 yr patient survival were 84.9%, 52.8%, 45.4%, and 42.6%, respectively. The total number of reported deaths was 181 of 2808 cases (6.4%), from them the cause of death in 99 (55%) cases was sepsis. It can be concluded that there is still no definitive evidence of better graft and patient survival in CLKTx recipients when compared with LTx alone because of the complexity of the exact definition of irreversible kidney function in LTx candidates. Additionally, CLKTx is better to be performed earlier than isolated LTx and KTx leading to the avoidance of deterioration of clinical status, high rate of graft loss, and mortality. Shorter graft ischemia time and more effective immunosuppressive regimens can reduce the incidence of graft malfunctioning in CLKTx patients. Providing a model to reliably determine the need for CLKTx seems necessary. Such a model can be shaped based upon new and precise markers of renal function, and modification of MELD system.

Functional outcome after restorative proctocolectomy in pigs: comparing a novel transverse ileal pouch to the J-pouch and straight ileoanal anastomosis

BACKGROUND

Restorative proctocolectomy followed by an ileoanal J-pouch procedure is the therapy of choice for patients with familial adenomatous polyposis and ulcerative colitis. After low anterior rectal resection, the authors have reported on a novel, less complex pouch configuration, a transverse coloplasty pouch. The aim of the present work was to apply this new design to the ileal pouch construction, to evaluate feasibility, and to measure functional results in comparison with the J-pouch and the straight ileoanal anastomosis using the pig as an animal model.

METHODS

Twenty-three pigs underwent restorative proctocolectomy followed by reconstruction with straight ileoanal anastomosis (IAA; n = 5), J-pouch (n = 7), and a transverse ileal pouch (TIP; n = 11). Pigs were followed for 6 days postoperatively. Peristaltic function was assessed by manometry proximal to the pouch, in the reservoir, and at the level of the ileoanal anastomosis. Functional outcome was monitored by semiquantitative assessment of the general condition of the animals, postoperative feeding habits, and stool frequency and consistency. A Fourier analysis was performed in order to compare peristalsis in the ileal reservoirs. The reservoir volume was measured in situ by triple contrast computed tomography scan with 3D reconstruction.

RESULTS

Seventeen animals survived for 1 week. There was no difference in the general condition or the feeding habits of the groups. A significant number of pigs with the TIP pouch (7/10) had semisolid or formed stools as opposed to liquid stools after J-pouch (6/6) and IAA (4/5; p = 0.01). TIP animals had a lower stool frequency (3.2 +/- 1.14 per day) on day 6 after the operation than pigs with J-pouch, 5.33 +/- 1,03, and IAA, 4.6 +/- 1.82 (p = 0.0036). The in situ volume of the pouches did not differ significantly. The Fourier analysis demonstrated a disruption of peristalsis by the J-pouch and the TIP reconstruction but not after IAA.

CONCLUSION

The function of ileoanal reservoirs after proctocolectomy may result from the disruption of properistaltic waves after pouch formation. The mechanism of peristalsis disruption is independent of the in situ volume of the pouch.

Thymoglobulin and ischemia reperfusion injury in kidney and liver transplantation

Since the beginning of organ transplantation, graft preservation has been one of the most important concerns. Ischemia reperfusion injury (IRI), which plays an important role in the quality and function of the graft, is a major cause for increased length of hospitalization and decreased long term graft survival. Among numerous attempts which have been made to minimize graft damage associated with IRI, the use of Thymoglobulin (TG) seems to offer potential benefits. TG is a polyclonal antibody which blocks multiple antigens related to IRI, in addition to its better known T cell depleting effects. This review will focus on the use of TG in preventing IRI in kidney transplantation (KTx) and liver transplantation (LTx). Different studies in experimental and clinical transplantation have shown that TG protects renal and liver grafts from IRI. Improvement in early graft function and decreased delayed graft function (DGF) rates are some of the clinical benefits of TG. Additionally, it is used in patients with hepatorenal syndrome to support the recovery of kidney function after LTx, by allowing reduced exposure to nephrotoxic calcineurin inhibitors as well as improving liver graft function by minimizing IRI. TG can reduce acute rejection rates in kidney and liver transplant recipients, decrease the length of hospital stay, and hence reduce transplantation costs. TG can play an important role in expanding the donor pool in both KTx and LTx by improving long-term graft and patient survival rates which increases the possibility of using marginal donors. Although controversial, the development of post-transplant lymphoproliferative disorder is a potential side effect of TG. No single optimal immunosuppressive regimen has given consistent results in decreasing the graft damage following IRI; however, TG usage in KTx and LTx appears to have some benefits in reducing IRI.

C-reactive protein as early predictor for infectious postoperative complications in rectal surgery

BACKGROUND

This study evaluated the role of the acute phase C-reactive protein (CRP) in the postoperative course of a large series of rectal resections on the basis of a prospective database. Main focus of this study was the early identification of complications.

MATERIALS AND METHODS

Three hundred eighty-three rectal resections with primary anastomosis for rectal cancer were screened for infectious postoperative complications. Forty-eight complicated cases were identified and matched with 48 patients with an uneventful postoperative course.

RESULTS

In the postoperative setting, CRP peaked on postoperative day (POD) 2 with a median serum CRP of 140 mg/l and gradually declined thereafter in uncomplicated cases. In complicated cases, CRP elevation generally persisted after POD 2, whereas white blood cells and body temperature were within normal range in the early postoperative period. A cutoff CRP value of 140 mg/dl on PODs 3 and 4 resulted in predictive values of 85.7 and 90.5% (adjusted to the prevalence: 37.6 and 50.3%), sensitivities of 80.0 and 54.3%, and specificities of 81.0 and 92.3% for a complicated postoperative course (P<0.001), respectively.

CONCLUSION

Persistent CRP elevation and elevation of serum CRP above 140 mg/dl on PODs 3-4 are predictive of infectious postoperative complications and should prompt intense clinical search for an inflammatory process, especially for an anastomotic leak if pneumonia and wound infection are unlikely or excluded.

How to increase inflow in liver transplantation

Liver transplantation (LTx) has become the treatment of choice for selected cases of benign and malignant liver disease. Despite becoming increasingly safer in recent years this procedure still incurs several serious postoperative complications. The most significant surgical complications are related to surgical technique, particularly the reconstruction and/or anastomosis of the hepatic artery. Arterial hypoperfusion may lead to graft failure, sepsis, or ischemic biliary lesions. In this review we focus on the Achilles' heel of LTx: the hepatic artery. We provide transplant surgeons with an overview of the technical options that are available to increase arterial inflow and subsequently improve patient outcome. We exemplify some of the discussed techniques using a liver transplant case with an eventful postoperative course because of arterial complications.

Wound complications following kidney and liver transplantation

Advances in surgical techniques and immunosuppression (IS) have led to an appreciable reduction in postoperative complications following transplantation. However, wound complications as probably the most common type of post-transplantation surgical complication can still limit these improved outcomes and result in prolonged hospitalization, hospital readmission, and reoperation, consequently increasing overall transplant cost. Our aim was to review the literature to delineate the evidence-based risk factors for wound complications following kidney and liver transplantation (KTx, LTx), and to present the preventive and therapeutic modalities for this bothersome morbidity. Generally, wound complications are categorized as superficial and deep wound dehiscences, perigraft fluid collections and seroma, superficial and deep wound infections, cellulitis, lymphocele and wound drainage. The results of several studies showed that the most important risk factors for wound complications are IS and obesity. Additionally, there are surgical and/or technical factors, including type of incision, reoperation, and surgeon's expertise, as well as comorbidities such as advanced age, diabetes mellitus, malnutrition, and uremia. Preventive management of wound complications necessitates defining their etiological factors so that their detrimental effects on healing processes can be addressed and reduced. IS modalities and agents, especially sirolimus (SRL), and steroids (ST) should be adjusted according to the patient's co-existing risk factors. SRL should be administered three months after transplantation and ST should be tapered as soon as possible. A body mass index (BMI) lower than 30 kg/m2 is advisable for inclusion in a transplantation program, but higher BMIs do not exclude recipients. Surgical risk factors can be prevented by applying precise surgical techniques. Therapeutic modalities must focus on the most efficient and cost-effective medications and/or interventions to facilitate and improve wound healing.

The role and value of sirolimus administration in kidney and liver transplantation

Enormous advancements in visceral transplantation have led to significant improvements in the quality of life of patients. However, despite these developments, the average graft half-life after transplantation has remained almost unchanged and chronic rejection is still considered a major problem. In this regard, more concerns have shifted to factors influencing long-term graft survival, patient survival, and quality of life. To achieve this goal, detrimental effects of immunosuppressive (IS) agents, which have deleterious influence on the quality of life and/or patient survival, should be reduced. In the course of recent years, the transplant community has worked on reducing these side effects by developing new ISs, employing new combination regimens, or finding and adjusting optimal dosages and blood level concentrations. Among the IS agents, the antifungal, antitumoral and IS activity of mammalian target of rapamycin (mTOR) inhibitors without nephrotoxicity, have received special attention regarding this new class of IS. Sirolimus (SRL), as the first member of mTOR inhibitors, has been utilized in many clinical trials with respect to its benefit-risk assessment. In our review, the clinical evolution of SRL, as well as the evidence-based clinical benefits of SRL in kidney and liver transplantation (KTx, LTx), are summarized. Various studies of SRL in KTx and LTx have shown that combination therapy with SRL will enrich the variety of IS modalities. It also can be regarded as a safe base therapy to which other necessary drugs can be added. In addition to the enhanced acute rejection prophylaxis, and in contrast to the calcineurin inhibitors (CNI) and steroids, this drug solely does not have common side effects such as nephrotoxicity, neurotoxicity, diabetes mellitus and hypertension. Moreover, this agent might diminish vasculopathic processes that mediate chronic allograft nephropathy (CAN). Therefore, by reducing the likelihood of CAN it can decrease the rate of long-term organ failure. One possibly desirable characteristic of SRL is its antiproliferative effect, which could provoke antitumoral or antiatherogenic activity following transplantation. Despite all promising impacts of SRL in organ transplantation, there are some concerns regarding the adverse effects of this drug, for instance dyslipidemia, pneumonitis and wound healing problems. However, the majority of these side effects can be reduced or ceased by careful dose adjustments and correct timing of use. In conclusion, after a decade of both in vivo and in vitro studies on SRL, it can be advocated that SRL is a promising, potent and effective IS agent as it reduces the rate of acute rejection episodes in de novo transplants. It could improve the quality of life, graft and patient survival rate, and achieve excellent outcomes with few adverse effects when wisely used in combination with other immunosuppressants.

Precision targeting of liver lesions with a needle-based soft tissue navigation system

In this study, we assessed the targeting precision of a previously reported needle-based soft tissue navigation system. For this purpose, we implanted 10 2-ml agar nodules into three pig livers as tumor models, and two of the authors used the navigation system to target the center of gravity of each nodule. In order to obtain a realistic setting, we mounted the livers onto a respiratory liver motion simulator that models the human body. For each targeting procedure, we simulated the liver biopsy workflow, consisting of four steps: preparation, trajectory planning, registration, and navigation. The lesions were successfully hit in all 20 trials. The final distance between the applicator tip and the center of gravity of the lesion was determined from control computed tomography (CT) scans and was 3.5 +/- 1.1 mm on average. Robust targeting precision of this order of magnitude would significantly improve the clinical treatment standard for various CT-guided minimally invasive interventions in the liver.

Immunosuppressive standards in simultaneous kidney?pancreas transplantation

Simultaneous pancreas-kidney transplantation is an established procedure for patients with type I diabetes and end-stage renal disease. Continuous advances in the operation techniques with consequent reduction of perioperative morbidity and mortality and the introduction of modern immunosuppressive agents improved not only patients but also graft survival and significantly decreased rejection episodes of both kidney and pancreas grafts. Availability of a variety of new immunosuppressants in the clinical routine and increasing experience of the transplant specialists allowed further developments of therapeutic schemes with application of induction and maintenance immunosuppressive protocols. In this article, we summarize the current status of immunosuppressive regimens in simultaneous pancreas and kidney transplantation.

The human homologue of the RNA polymerase II-associated factor 1 (hPaf1), localized on the 19q13 amplicon, is associated with tumorigenesis

The 19q13 amplicon in pancreatic cancer cells contains a novel pancreatic differentiation 2 (PD2) gene (accession number AJ401156), which was identified by differential screening analysis. PD2 is the human homologue of the RNA polymerase II-associated factor 1 (hPaf1). In yeast, Paf1 is part of the transcription machinery, acting as a docking protein in between the complexes Rad6-Bre1, COMPASS-Dot1p, and the phosphorylated carboxyl terminal domain of the RNA polymerase II. As such, Paf1 is directly involved in transcription elongation via histone H2B ubiquitination and histone H3 methylation. The PD2 sequence is highly conserved from Drosophila to humans with up to 98% identity between rodent and human, suggesting the functional importance of PD2/hPaf1 to maintain cellular homeostasis. PD2 is a modular protein composed of RNA recognition motif, DEAD-boxes, an aspartic/serine (DS)-domain, a regulator of the chromosome condensation domain and myc-type helix-loop-helix domains. Our results further showed that PD2 is a nuclear 80 kDa protein, which interacts with RNA polymerase II. In addition, we have demonstrated that the overexpression of PD2 in the NIH 3T3 cells result in enhanced growth rates in vitro and tumor formation in vivo. Altogether, this paper presents strong evidence that the overexpression of PD2/hPaf1 is involved in cancer development.

MUC4 mucin expression in human pancreatic tumours is affected by organ environment: the possible role of TGFbeta2

MUC4 is highly expressed in human pancreatic tumours and pancreatic tumour cell lines, but is minimally or not expressed in normal pancreas or chronic pancreatitis. Here, we investigated the aberrant regulation of MUC4 expression in vivo using clonal human pancreatic tumour cells (CD18/HPAF) grown either orthotopically in the pancreas (OT) or ectopically in subcutaneous tissue (SC) in the nude mice. Histological examination of the OT and SC tumours showed moderately differentiated and anaplastic morphology, respectively. The OT tumour cells showed metastases to distant lymph nodes and faster tumour growth (P<0.01) compared to the SC tumours. The MUC4 transcripts in OT tumours were very high compared to the undetectable levels in SC tumours. The SC tumour cells regained their ability to express MUC4 transcripts after in vitro culture. Immunohistochemical analysis using MUC4-specific polyclonal antiserum confirmed the results obtained by Northern blot analysis. Interestingly, the OT tumours showed expression of TGFβ2 compared to no expression in SC, suggesting a possible link between MUC4 and TGFβ2. The MUC4 expression, morphology, and metastasis of human pancreatic tumour cells are regulated by a local host microenvironment. TGFβ2 may serve as an interim regulator of this function.

Abnormal differentiation of islet cells in pancreatic cancer

Pancreatic cancer in many patients is associated with altered glucose metabolism and abnormalities in pancreatic islet hormones at serum and tissue levels. Our previous studies have indicated a tendency of islet cells to differentiate toward ductal cell lineage, but the specificity of these findings for pancreatic cancer was not investigated. In the present study, we examined the immunoreactivity of pancreatic islets to antibodies against tumor-associated antigens DU-PAN-2, TAG-72 and CA19-9 in tissues from the normal pancreas, chronic pancreatitis and pancreatic cancer. Although no immunoreactive islet cells were found in the 12 normal pancreases and 20 chronic pancreatitis patients, 25 of 37 pancreatic cancer tissues showed the expression of these antigens, primarily CA19-9 and TAG-72, where the number of immunoreactive cells varied considerably from case to case. In 4 cases over 50% and in 2 of them more than 75% of the islets showed positive staining of 60-70% of islet cells within each islet. The presence of intrainsular ductular structures expressing the same antigen as the surrounding islet cells suggested transformation of antigen expressing islet cells to ductal cells. All but four islets were within or around the cancer favoring the notion that factors produced by cancer cells are responsible for the altered islet cell differentiation.

Mucin (MUC) gene expression in human pancreatic adenocarcinoma and chronic pancreatitis: a potential role of MUC4 as a tumor marker of diagnostic significance

PURPOSE

Mucins are important biomolecules that frequently display an altered expression under pathological conditions. In a search for a unique and reliable marker(s) specific for pancreatic adenocarcinoma, we investigated the expression of different MUC genes in pancreatic tumors and tumor cell lines, in chronic pancreatitis, and in the normal pancreas.

EXPERIMENTAL DESIGN

Total RNA from 16 pancreatic tumors, 10 chronic pancreatitis tissues, 7 normal pancreas tissues, and 15 pancreatic tumor cell lines were analyzed by reverse transcription-PCR with primers specific for MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC6, and MUC7 genes and by RNA slot blot analyses.

RESULTS

Our results revealed that of all of the mucins examined, only MUC4 displayed a differential expression that was specific for pancreatic adenocarcinoma. Indeed, a substantial number of tumor tissue samples (12 of 16) and tumor cell lines (11 of 15) expressed MUC4 mRNA, whereas samples from chronic pancreatitis (0 of 10) and the normal pancreas (0 of 7) tissues failed to exhibit any detectable level of this mucin. In contrast, no significant alteration was observed in the expression of the other mucins relative to that in the normal pancreas samples.

CONCLUSIONS

Overall, this work demonstrates that pancreatic mucin MUC4 is a tumor-associated mucin. Furthermore, the present study introduces a novel avenue to discriminate between pancreatic adenocarcinoma and pancreatitis. Future investigations of the role played by MUC4 in pancreatic adenocarcinoma may prove to be useful in the formulation of strategies for the diagnosis and therapeutic treatment of this malignancy.

Decreased androgen-responsive growth of human prostate cancer is associated with increased genetic alterations

Genetic mechanisms involved in prostate tumor progression from the androgen-responsive to androgen-unresponsive stage are not well understood because of the tremendous heterogeneity in the tumor as well as the lack of suitable models. Using 165 repeat microsatellite DNA markers distributed equally over all of the chromosomes, we determined an association between genetic alterations and androgen-unresponsive growth in three stages of LNCaP cell model (C33: early, androgen-responsive; C51: mid, decreased androgen-responsive; and C81: late, androgen-unresponsive and increased tumorigenicity). Furthermore, the genetic alterations were confirmed in laser microdissected normal and cancerous tissues from 15 clinical samples of human prostatic adenocarcinomas using selected markers. A stem-line karyotype analysis exhibited an identical chromosomal pattern in both C33 and C81 stage cells except for the structural rearrangements of chromosome 3 and a gain of one copy of the Y chromosome in the androgen-unresponsive C81 stage cells. Nine microsatellite DNA markers on seven different chromosomes (1, 4, 5, 11, 17, 18, and 19) showed microsatellite instability (MSI) in both C51 and C81 stage cells. Additionally, 23 markers on 15 different chromosomes revealed MSI in C81 cells. Chromosomal regions demonstrating allelic loss (AL) include 1q, 3p, 5p, 8q, 9q, and 13q in C51 and C81 cells. In clinical human specimens, MSI was observed on chromosomes 1 (20%), 5 (23%), 17 (40%), and 19 (36%), whereas ALs were found 40% on chromosomal region 1q, 20% on 3p, 26% on 5p and 8q, and 33% on 13q. In conclusion, the LNCaP cell model showed the increasing number of genetic changes including MSI and AL. These increased genetic alterations may be associated with the development of the androgen-unresponsive phenotype.

Transdifferentiation of human islet cells in a long-term culture

It has been established that ductal cells or precursor cells within the ductal tree of the pancreas can differentiate into islet cells. Although islet cells can also form exocrine cells, it is unclear whether they arise from precursor (stem) cells or from mature endocrine cells by transdifferentiation. Using a defined culture medium and technique for islet purification, for the first time we were able to maintain human islets in culture for more than a year. Multilabeling immunohistochemical and immunoelectron microscopic examination of the islets at different days of culture using islet cell markers (antibodies to hormones, neuron-specific enolase, chromogranin A) and ductal cell markers (cytokeratins 7 and 19, carbonic anhydrase II, DU-PAN2, CA 19-9, and MUC1) revealed that endocrine cells gradually transdifferentiate to ductal, acinar, and intermediary cells. Although islet hormone secretion ceased after day 28 in culture, endocrine cells were still detectable at day 60. However, later, all endocrine and exocrine cells were replaced by undifferentiated cells that expressed neuron-specific enolase, chromogranin A, laminin, vimentin, cytokeratin 7 and 19, alpha-1-antitrypsin, transforming growth factor-alpha, and epidermal growth factor receptor. Our data thus show that, under proper conditions, human islets can be maintained in vitro over a long period and that, in the culture condition, islet cells seem to transdifferentiate to exocrine cells and undifferentiated cells, which may be considered pancreatic precursor (stem) cells.

Increased expression of glutathione S-transferase-pi in the islets of patients with primary chronic pancreatitis but not secondary chronic pancreatitis

The mechanism of tissue alteration in chronic pancreatitis (CP) is still unclear. Different hypotheses have been discussed, including increasing oxidant stress in the acinar cells, often as a result of exposure to xenobiotics. To evaluate the role of oxidative stress in CP, the authors investigated the expression of the drug-metabolizing phase II enzyme, glutathione S-transferase-pi (GST-pi), in the pancreatic tissue of patients with CP and compared it with the healthy pancreatic tissue from age-matched donors. Pancreatic tissue from patients with secondary CP resulting from ductal obstruction by pancreatic cancer (PC) was also examined. The percentage of cells immunoreacting with anti-GST-pi was counted within 15 randomly selected islets in each slide of the three groups. In all specimens, ductal and ductular cells, and in PC, cancer cells, expressed GST-pi in a moderate intensity. Acinar cells did not stain. Various numbers of islet cells in each of the three groups were stained strongly. More islet cells expressed GST-pi in CP (42%) than in healthy pancreatic tissue (16%, p < 0.001) or PC (17%, p < 0.001). Our results imply an important role of islet cells in the metabolism of substances, which are the substrate for GST-pi, and lend support to the hypothesis of oxidative stress as the cause of CP.

The patterns of extrainsular endocrine cells in pancreatic cancer

Abnormal glucose tolerance and frank diabetes mellitus develop in up to 80% of pancreatic cancer patients. Islets within these tumors show a decreased number of beta cells and increased number of alpha cells. The reduced number of beta cells could induce beta cell neogenesis in extrainsular tissue to compensate for the loss of insulin in islets. On the other hand, because the beta cell depletion in pancreatic cancer seems to be the effect of substances released by cancer cells, suppression of extrainsular endocrine cells is expected. We compared the pattern of extrainsular endocrine cells in pancreatic cancer patients with normal pancreas as well as chronic pancreatitis, which is known to be associated with impaired glucose tolerance or frank diabetes. As in the normal tissue, extrainsular endocrine cells were found in chronic pancreatitis and pancreatic cancer. However, in the chronic pancreatitis specimens insulin cells were the predominant cell type, whereas in pancreatic cancer specimens more glucagon than insulin cells were found, although the differences were statistically insignificant. Thus, our results indicate that the alteration of beta cells in pancreatic cancer patients is mainly restricted to the endocrine cells within the islets and that there is no compensatory proliferation of beta cells.

[Liver resection for liver metastases--1998 Bern Symposium]

The increasing knowledge of the anatomy and function of the liver made the surgical resection of liver metastases currently to the therapy of choice. Although liver metastasis is an advanced stage in tumor-progression, surgery achieves the best long-term results due to a better understanding of the carcinogenesis (i.e. micrometastases) and the prognostic risk factors. This study summarizes the results of 109 resections of colorectal and non-colorectal liver metastases during a period of 59 months at our department. Four different surgical techniques (extended hepatectomy vs. segmental resection vs. atypical resection vs. biopsy) were investigated. For resections a tumour-free resection margin of at least 10 mm was always attempted to achieve. The accumulated morbidity of all techniques together was 23%. Although the morbidity was higher for extended resections (Encephalopathy 16% vs. 2.3% for segmental resections, Liver insufficiency 23% vs. 4.7%), compared to the limited resection procedures, the long-term survival improved. The overall mortality was 2.7%. Survival was higher in patients with resection of colorectal than non colorectal metastases. Our results indicate that liver resection, under observance of the anatomical and functional margins (i.e. an adequate resection margin), is the only potentially curative therapy for liver metastases. An extensive formal resection, although inducing a higher perioperative morbidity, is superior to the limited resection techniques and results in an increased long-term survival. One reason is the increased probability of co-resection of preoperatively undetected local micrometastases.

Combination of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and actinomycin D induces apoptosis even in TRAIL-resistant human pancreatic cancer cells

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a novel member of the tumor necrosis factor superfamily of cytokines that induces cell death by apoptosis. TRAIL has been shown to be effective in almost two-thirds of solid tumors tested thus far, but its effect on pancreatic cancer cells is unknown. We tested the effect of TRAIL on seven human pancreatic cancer cell lines (HPAF, Panc1, Miapaca2, Bxpc3, Panc89, SW979, and Aspc1) in vitro. Of these cell lines, all but Aspc1 showed a significant dose-dependent increase in apoptosis. The apoptotic rate, as detected by a terminal deoxynucleotidyl transferase-mediated nick end labeling assay, was highest in Bxpc3 (71.5%), followed by HPAF (38.0%), Miapaca2 (24.9%), Panc1 (16.1%), Panc89 (15.8%), SW979 (13.9%), and Aspc1 (5.2%). Multiple treatments were more effective than a single treatment and caused a sustained and profound cell death in all but Aspc1 cells. There was no correlation between the effect of TRAIL and the differentiation grade of the cell lines, p53 mutation, or bcl-2 or bax expression. The resistance of Aspc1 cells to TRAIL was not related to the lack of TRAIL receptors. The combination of actinomycin D and TRAIL induced an almost complete lysis of Aspc1 cells, whereas actinomycin D alone had no effect on cell survival but inhibited the expression of the Flice inhibitory protein, which is assumed to play a role in the apoptotic pathway of TRAIL. Thus, the combination of actinomycin D and TRAIL appears to be a promising approach for the therapy of pancreatic cancers resistant to TRAIL.

Maintenance of human islets in long-term culture

The long-term maintenance of human islets in culture has remained a challenge. Despite advancements in culture techniques, human islets proved to have a short life span in vitro. For the first time, we have succeeded in maintaining human islets in a defined culture medium for more than 12 months. Freshly isolated islets from a 38-year-old donor were cultured in M3:5 medium and placed on a rocker for 14 days to remove contaminated exocrine and mesenchymal cells which attached to the bottom. The floating islets were purified by daily hand-picking and transfer into fresh medium. After 14 days, purified islets were allowed to attach to the bottom of the flasks and to expand. At various time points, islets were examined immunohistochemically and electron microscopically, and the secretion of islet hormones and their mRNA were determined by radioimmunoassay and reverse transcriptase polymerase chain reaction, respectively. Within seven days of culture, ductular and acinar cells developed within the initially normal islets. With time, exocrine cell types expanded while the number of the endocrine cells and their secretion decreased. At day 60, only a few endocrine cells were identifiable, whereas most of the cells appeared undifferentiated and expressed cytokeratin 7 and 19, neuron specific enolase, tomato lectin, phaseolus leucoagglutinin, laminin, and vimentin. After 60 days, the culture consisted entirely of undifferentiated cells which could be maintained in culture for 270 days before they became senescent. This is the first report on the long-term maintenance of human islet cells in culture and allows an insight into the complex process of endocrine cell differentiation.

Establishment of human pancreatic ductal cells in a long-term culture

Cultivation and preservation of human pancreatic ductal cells have remained a challenge. With a defined culture medium and refinement of culturing techniques, we have been able to maintain human pancreatic ductal cells without any genetic manipulation in culture for more than 16 months. Freshly isolated ductal fragments were placed on a rocker in M3:5 medium free of collagen for 14 days to remove fibroblasts and endocrine cells before allowing them to attach. The cells produced an excessive amount of mucin and expressed the duct specific cytokeratins (CK) 7 and 19, DU-PAN2, CA19-9, carbonic anhydrase II (CA II), and secretin receptors. During the course of the culture, however, the cells gradually lost the expression of CA II, secretin receptors, DU-PAN2, and CA 19-9 and assumed an undifferentiated phenotype, which showed an upregulation of transforming growth factor alpha (TGFalpha) and epidermal growth factor receptor (EGFR), an increase in the expression of Ki-67, and an increased binding to Phaseolus vulgaris leucoagglutinin (PHA-L) and tomato lectin. These ductal cells present a useful source with which to study physiologic aspects of ductal cells including differentiation.

Biologic instability of pancreatic cancer xenografts in the nude mouse

Tumor transplants into nude mice (NM) may reveal abnormal biological behavior compared with the original tumor. Despite this, human tumor xenografts in NM have been widely used to study the biology of tumors and to establish diagnostic and therapeutic modalities. Clearly, precise differences in the biology of a given tumor in human and in NM cannot be assessed. We compared the growth kinetics, differentiation pattern and karyotype of an anaplastic Syrian hamster pancreatic cancer cell line in NM and in allogenic hamsters. As with the original tumor, transplants in hamsters grew fast, were anaplastic and expressed markers related to tumor malignancy like galectin 3, TGF-alpha and its receptor EGFR at high levels. However, tumors in the NM were well-differentiated adenocarcinomas, grew slower, had increased apoptotic rate and had a high expression of differentiation markers such as blood group A antigen, DU-PAN-2, carbonic anhydrase II, TGF-beta(2) and mucin. Karyotypically, the tumors in the NM acquired additional chromosomal damage. Our results demonstrate significant differences in the morphology and biology of tumors grown in NM and the allogenic host, and call for caution in extrapolating data obtained from xenografts to primary cancer.

Differentiation of islet cells in long-term culture

Our previous studies in the hamster pancreatic cancer model have shown that exocrine pancreatic cancer arises from ductal/ductular cells, as well as from within the islets, most probably from islet precursor (stem) cells. To identify and characterize these cells, we established a long-term culture from isolated hamster islets and investigated their growth, differentiation, and expression of biomarkers. Islets maintained their original form and structure within the first 14 days in culture. However, beginning at day 7, ductular structures began to form within the islets. At day 21 in culture, acinar cells, intermediary cells, oncocytes, and cells comparable to pancreatic hepatocytes also appeared between ductular and endocrine cells. The number of duct-like cells gradually increased, whereas the number of hormone-producing cells decreased. After 35 days in culture, the exocrine cells disappeared, and undifferentiated cells formed a monolayer. These cells expressed cytokeratins, alpha1-antitrypsin, transforming growth factor-alpha, epidermal growth factor receptor, carbonic anhydrase II, vimentin, laminin, and showed binding to tomato lectin and Phaseolus vulgaris leukoagglutinin. They did not express the regulatory transcriptional factors, insulin-promoting factor 1, NKx6.1, Pax6, and NeuroD. The results thus indicate that islet cells have potential to form exocrine cells. At present, it is not clear whether these cells originate from preexisting stem cells or from transdifferentiated islet cells.

In vitro induction of giant cell tumors from cultured hamster islets treated with N-Nitrosobis(2-Oxopropyl)amine

Giant cell carcinoma of the pancreas is a rare tumor. Its histogenesis is still controversial. In a Syrian hamster pancreatic cancer model, tumors similar to human giant cell carcinomas have been induced at an extremely low rate of incidence and after the use of high doses of pancreatic carcinogens. Thus far no tumors of giant cell type have been induced by the in vitro treatment of hamster pancreatic ductal cells with the potent pancreatic carcinogen N-nitrosobis(2-oxopropyl)amine (BOP). In the present study we report the induction of giant cell carcinoma from hamster islets treated with BOP in vitro. The results suggest that in hamsters some component of islet cells, probably stem cells, are the origin of giant cell carcinoma.

Alteration of the Langerhans Islets in Pancreatic Cancer Patients

An abnormal glucose metabolism occurs in up to 80% of pancreatic cancer patients shortly or a few months before the first clinical admission. Reasons for this abnormality are obscure. We investigated immunohistochemically the pattern of islets in 14 pancreatic cancer specimens and used 14 chronic pancreatitis samples and 10 normal pancreata as controls. To study the topographical relationship of these islets to the cancer, islets in four different arbitrary zones within and around the cancer were evaluated. Ten out of 14 cancer specimens showed a significant loss of beta cells (p < 0.005) and eight of them also showed a significant increase of alpha cells (p < 0.005), all of them from hyperglycemic patients. Most affected islets were found within zone 1 (intratumoral) and zone 2 (peritumoral), to a lesser extent in zone 3 (acini close to tumor) and none in zone 4 (acini remote from tumor). No comparable changes were found in chronic pancreatitis patients. The incidence of 72% with alteration of islets in our material correlates with the frequency of abnormal glucose levels in human pancreatic cancer patients. Our findings support the notion that islet cell abnormalities is likely caused by substances released from cancer cells.

In vitro pancreatic carcinogenesis

Studies in our laboratories have indicated that pancreatic cancer originates not only from pancreatic ductal/ductular cells but also from within the Langerhans' islets, probably from reserve (precursor, stem) cells. To identify, enrich and characterize these cells, we established a long-term hamster islet culture and studied their growth, differentiation and response to the pancreatic carcinogen, N-nitrosobis(2-oxopropyl)amine (BOP). One group of cultured islets was treated in vitro with BOP (KL5B group) and the other group of islets served as an untreated control (KL5N group). During the early culture days, in both groups all cultured islets showed a progressive loss of endocrine cells and replacement by ductular, acinar and intermediary cells. However, all these cells disappeared after 35 days in culture and gave room to undifferentiated cells, which we believe represent stem cells. No differences were found between KL5N and KL5B cells with regard to cell growth and differentiation until day 35, when the growth of the KL5B cells accelerated and the cells underwent increasing pleomorphism and atypia. At day 133, KL5B cells but not KL5N cells showed colony formation in soft agar and formed invasive, poorly differentiated adenocarcinomas of the ductal type when transplanted into hamsters. All of these tumors showed mutation of the K-ras gene and extensive chromosomal damage. We concluded that like ductal/ductular cells, certain cell populations within islets are responsive to the carcinogenic effect of BOP. We could not ascertain whether these cells present a preexisting (stem, reserve) cell population within the islets or transdifferentiated islet cells.

One thousand faces of Langerhans islets

Studies with different strains of Syrian hamsters and Syrian golden hamsters have revealed the remarkable potential of islet cells to undergo orthotopic and heterotopic metaplasia. The most common spontaneous change included the development of hepatocytes in aged and malnourished hamsters. Of the many other alterations that occurred during carcinogenesis, most of the metaplastic changes originated within the islet periphery and progressed inside and outside the islets. The development of ductular structures within islets and their progression either to structures identical to human serous cystadenoma or to highly invasive adenocarcinomas were the most common alterations. The remarkably greater invasive potential of cancer cells arising within the islets contrasted sharply with the slow growth of the tumors developing within ducts (intraductal tumors). Studies in human tissue also showed development of malignant cells within islets, and, in some cases, transition of islet cells to malignant cells was suggested. The overall results, along with recent findings in other studies in cultured human and hamster islets, indicate the enormous potential of islet cells to differentiate and undergo malignant transformation. Whether the metaplastic and malignant cells derive from stem cells embedded within islets or from transdifferentiated islet cells remains to be seen.