Henning Schrader

Functional Assessment of Pancreatic β-Cell Area in Humans

OBJECTIVE β-Cell mass declines progressively during the course of diabetes, and various antidiabetic treatment regimens have been suggested to modulate β-cell mass. However, imaging methods allowing the monitoring of changes in β-cell mass in vivo have not yet become available. We address whether pancreatic β-cell area can be assessed by functional test of insulin secretion in humans. RESEARCH DESIGN AND METHODS A total of 33 patients with chronic pancreatitis (n = 17), benign pancreatic adenomas (n = 13), and tumors of the ampulla of Vater (n = 3) at various stages of glucose tolerance were examined with an oral glucose load before undergoing pancreatic surgery. Indexes of insulin secretion were calculated and compared with the fractional β-cell area of the pancreas. RESULTS β-Cell area was related to fasting glucose concentrations in an inverse linear fashion (r = −0.53, P = 0.0014) and to 120-min postchallenge glycemia in an inverse exponential fashion (r = −0.89). β-Cell area was best predicted by a C-peptide–to–glucose ratio determined 15 min after the glucose drink (r = 0.72, P < 0.0001). However, a fasting C-peptide–to–glucose ratio already yielded a reasonably close correlation (r = 0.63, P < 0.0001). Homeostasis model assessment (HOMA) β-cell function was unrelated to β-cell area. CONCLUSIONS Glucose control is closely related to pancreatic β-cell area in humans. A C-peptide–to–glucose ratio after oral glucose ingestion appears to better predict β-cell area than fasting measures, such as the HOMA index.

Increased Expression of RelA/Nuclear Factor-κB Protein Correlates with Colorectal Tumorigenesis

Objective: To identify the role of RelA/nuclear factor-ĸB, an important inhibitor of apoptosis in colorectal tumorigenesis, we examined the expression of RelA in normal colorectal mucosa (n = 10), colorectal adenomas (n = 30) and colorectal adenocarcinomas (n = 30). Furthermore, the association of RelA expression with tumor cell apoptosis, proliferation, and expression of Bcl-2/Bcl-xL was also studied. Methods: Paraffin sections were stained with monoclonal antibodies directed against RelA, Bcl-2, Bcl-xL, and Ki-67 to assess protein expression patterns in normal, adenomatous and colon cancer tissue. Apoptotic cells were detected by terminal deoxynucleotidyl-transferase-mediated dUTP-biotin nick end labeling (TUNEL) using an in situ detection kit. Results: The results of immunohistochemical staining revealed that expression of RelA, Bcl-2, Bcl-xL, and Ki-67 labeling index (LI) significantly increased in the transition from adenoma with low dysplasia to adenocarcinoma. This transition was associated with a significant decrease in the apoptotic index (AI) and a significant increase in the Ki-67 LI. The expression of RelA correlated inversely with the AI and correlated positively with the expression of Bcl-2, Bcl-xL, and Ki-67 LI in the transition from low-grade dysplasia to adenocarcinoma. Conclusion: Our results suggest that increased expression of RelA/nuclear factor-ĸB plays an important role in the transition from colorectal adenoma with low-grade dysplasia to adenocarcinoma in the pathogenesis of colon cancer in humans.

Selective amino acid deficiency in patients with impaired glucose tolerance and type 2 diabetes

INTRODUCTION Amino acids are important modulators of glucose metabolism, insulin secretion and insulin sensitivity. However, little is known about the changes in amino acid metabolism in patients with diabetes. PATIENTS AND METHODS The circulating amino acid levels were determined in 17 patients with type 2 diabetes, 17 individuals with impaired glucose tolerance (IGT), and 14 control subjects. RESULTS Total amino acid concentrations were 2850+/-57micromol/l in patients with type 2 diabetes, 2980+/-77micromol/l in individuals with IGT, and 2886+/-74micromol/l in control subjects (p=0.38). Patients with type 2 diabetes exhibited significant reductions in the concentrations of gamma-aminobutyric acid (GABA), arginine, glutamine and phosphoethanolamine (p<0.05), whereas valine levels were higher than in controls (p=0.008). In IGT subjects, GABA levels were reduced, while tyrosine concentrations were increased (p<0.05). The plasma levels of essential amino acids were positively related to fasting and post-challenge glucose levels, fasting C-peptide, HOMA insulin resistance and fasting glucagon levels (p<0.05). CONCLUSIONS Total amino acid levels are similar in patients with diabetes, IGT subjects and controls, but the individual levels of several amino acids differ significantly between these groups. These alterations may contribute to the disturbances in insulin secretion and action in diabetic patients and may provide a rationale for offering specific amino acid supplementations to diabetic patients.

The effects of acetylsalicylic acid on proliferation, apoptosis, and invasion of cyclooxygenase-2 negative colon cancer cells

Background Acetylsalicylic acid (ASA, aspirin), the most common nonsteroidal anti‐inflammatory drug (NSAID), has been shown to have a protective effect against the incidence and mortality of colorectal cancer. However, the mechanism of its anticancer function remains unclear. The aim of this study was to determine the effects of acetylsalicylic acid on proliferation, apoptosis, and invasion in human cyclooxygenase‐2 (COX‐2) negative colorectal cancer cell lines.

Cellular expression of CCK-A and CCK-B/gastrin receptors in human gastric mucosa

Gastrin stimulates gastric acid secretion in various species, but the role of the structurally related CCK for the peripheral regulation of acid secretion in humans remains controversial. Moreover, species differences in CCK receptor function and expression have been reported. We therefore sought to identify the cellular targets of CCK and gastrin within the human gastric mucosa in situ. Gastric biopsies were collected from 15 patients without gastric disease. Expression of CCK receptor subtypes was detected in individual cells of the gastric mucosa by reverse transcription (RT)-PCR in situ, immunohistochemistry and confocal laser scanning microscopy, using antisera against the CCK-A or CCK-B/gastrin receptor subtype. Both CCK-A and CCK-B receptors were detected in antral and oxyntic mucosa at the mRNA and protein level. In fundic mucosa, CCK-A receptor mRNA and protein mapped to D cells (37.4+/-7.7). Besides, individual chief cells, mucous neck cells and parietal cells (12.3+/-4.7%) expressed CCK-A receptors. CCK-B/gastrin receptor mRNA and protein were detected in parietal cells (57.4+/-11.1%) and in neuroendocrine cells (33.2+/-4.4%) expressing chromogranin A. Furthermore, epithelial cells within the neck of the gastric gland were found to express the CCK-B/gastrin receptor. We conclude that (i) identification of CCK-A receptors on somatostatin producing D cells in humans provide the anatomical basis for a receptor-mediated mode of action of CCK on somatostatin release and (ii) detection of either CCK receptor subtype in the putative stem cell compartment implies a role of CCK in the maintenance of tissue homeostasis in human gastric mucosa.

Reduced Pancreatic Volume and β-Cell Area in Patients With Chronic Pancreatitis

BACKGROUND & AIMS Chronic pancreatitis (CP) often leads to the development of diabetes. To understand better this pathogenic mechanism, we investigated whether islet cell area and pancreatic volume are reduced in CP patients, islet cell turnover increases in CP patients, and islet cells are less vulnerable to apoptosis than acinar cells. METHODS Pancreatic tissues from 43 patients with CP and 27 controls were examined by immunohistochemistry and quantitative morphometry. Pancreas volume was determined using abdominal computed tomography data. RESULTS The pancreatic volumes were 64.9 +/- 4.3 cm(3) in CP patients and 82.3 +/- 6.7 cm(3) in controls (P = .035). beta-cell areas were 0.69% +/- 0.08% in CP patients and 0.97% +/- 0.08% in controls (P = .017), whereas alpha-cell areas did not differ between the groups (P = .47). There were no differences in the frequencies of replication among groups of alpha-cells, beta-cells, duct cells, or acinar cells nor were there differences in numbers of apoptotic alpha-cells or beta-cells between CP patients and controls. However, CP patients had an approximately 10-fold increase in numbers of apoptotic acinar cells compared with controls (P < .0001). CONCLUSIONS Pancreatic volume was reduced by 21%, and the area comprising beta-cells was reduced by 29% in patients with CP. The lack of increased beta-cells turnover in CP patients, despite an approximately 10-fold increase in the number of apoptotic acinar cells, suggests that the damage to the pancreas is highly specific for the exocrine compartment and affects the endocrine islets to a lesser extent.

Increased abundance of cyclooxygenase-2 correlates with vascular endothelial growth factor-A abundance and tumor angiogenesis in gastric cancer

To understand the role of cyclooxygenase-2 (COX-2) in gastric cancer, we examined the abundance of COX-2, vascular endothelial growth factor-A (VEGF-A), and CD34 in 45 surgically resected human gastric cancers and paired normal gastric mucosa by immunohistochemical analysis. In addition, the message RNA (mRNA) expression of COX-2 and VEGF-A was evaluated in ten fresh surgically resected human gastric cancers and paired normal gastric mucosas using semi-quantitative reverse transcriptional polymerase chain reaction analysis. Our results confirmed an increased abundance of COX-2 and VEGF-A, and the microvessel density, which was assessed by CD34 abundance, in gastric cancer tissues compared with normal paired mucosa. Abundance of COX-2 and VEGF-A was significantly associated with tumor-node-metastasis (TNM) stage (P<0.05) and lymph node metastasis (P<0.001). In addition, abundance of VEGF-A associates with distance metastasis. A significant correlation was found between COX-2 and VEGF-A abundances (P<0.001). Both abundance of COX-2 and VEGF-A were significantly correlated with microvessel density (P<0.001, respectively). In six of ten cancerous tissues and in one of ten paired normal mucosas, the mRNA expression of COX-2 and VEGF-A was detected in the same specimen. In one other cancerous tissue, only COX-2 mRNA was detected. This study indicates that COX-2 is related to tumor angiogenesis in gastric cancer. VEGF-A might play a main role in the COX-2 angiogenic pathway.

Amino acid malnutrition in patients with chronic pancreatitis and pancreatic carcinoma.

Objectives: Chronic pancreatitis (CP) and pancreatic cancer (CA) have been associated with intestinal malabsorption and inflammation. However, little is known about the changes in amino acid metabolism in such patients. Methods: The circulating amino acid levels were determined in 12 patients with CP, 12 CA patients, and 12 controls. Results: Total amino acid concentrations were 2850 ± 71 &mgr;mol/L in controls, 2640 ± 96 &mgr;mol/L in CP patients, and 2210 ± 123 &mgr;mol/L in CA patients (P < 0.001). In CP patients, significant reductions in the concentrations of citrulline, &ggr;-aminobutyric acid, taurine, and aspartic acid were found (P < 0.05), whereas in CA patients, the levels of phosphoethanolamine, &ggr;-aminobutyric acid, aspartic acid, taurine, arginine, threonine, alanine, citrulline, and tryptophan were reduced. There was a significant inverse relationship between the total amino acid levels and the white blood cell counts (r = −0.44, P = 0.008). Conclusions: Both patients with CP and with CA exhibit alterations in amino acid levels. The mechanisms underlying these defects may involve intestinal malabsorption as well as systemic inflammation. Providing selective amino acid supplementation to such patients may minimize the excess morbidity and mortality associated with protein malnutrition.

Bacteribilia after preoperative bile duct stenting: a prospective study.

Study Design A prospective analysis of intraoperative bile duct cultures in patients undergoing surgery for both, malignant or benign periampullary diseases at the Department of Surgery, St Josef Hospital, Bochum, Germany, during a period of 18 months, between January 2004 and June 2005. Goals The goals of the presented study were to investigate the effects of preoperative bile duct stenting on intraoperative bile duct cultures and postoperative outcome in patients undergoing pancreatic surgery. Background In pancreatic surgery, bile duct stenting is often aimed at improving postoperative outcome. As implantation of xenograft material in the main bile duct facilitates bacterial contamination and cholangitis, a critical evaluation of stenting is mandatory. Study In all patients with a hepaticojejunostomy (n=80), a bile duct culture was collected during the operation. All patients received antibiotic prophylaxis perioperatively and a retrograde flushing of bile ducts with warm saline after bile duct resection. Fifty-one percent (41/80) patients had biliary drainage before surgery, whereas 49% (39/80) were operated without preoperative draining procedures. Results After bile duct stenting, 98% of patients had a positive bile culture, whereas only 21% of infected bile was seen in patients without drainage (P<0.001). Despite infected bile, only 2% stented patients developed acute cholangitis postoperatively, versus 13% patients in the group without stent (P=0.231). After stenting, major complications occurred in 12%, versus 8% in patients without stent (P=0.817). Conclusions Preoperative biliary drainage leads to an almost 100% bacterial contamination of bile ducts. With hospital-adjusted antibiotic prophylaxis and retrograde flushing of bile ducts, the postoperative rate of acute cholangitis and morbidity is not elevated. A critical evaluation of benefits from preoperative biliary drainage for each patient is necessary.

Increased expression of nuclear factor-κB/RelA is correlated with tumor angiogenesis in human colorectal cancer

Background and aimsRecent studies have shown that nuclear factor-κ B/RelA (NF-κ B/RelA) is involved in tumor angiogenesis. This study examined whether NF-κ B/RelA expression is associated with vascular endothelial growth factor (VEGF) expression and microvessel density in human colorectal cancer.Materials and methodsTen specimens from normal colorectal mucosa and 52 colorectal adenocarcinomas were obtained by surgery or endoscopy. Immunohistochemical expression of NF-κ B/RelA, VEGF, and CD34 was detected on paraffin-embedded tissue sections.ResultsNF-κ B/RelA and VEGF were significantly overexpressed and associated with microvessel density in colorectal cancer. A significant association was found between NF-κ B/RelA and VEGF expression. Clinicopathological features were not correlated with NF-κ B/RelA, VEGF expression, or microvessel density.ConclusionOur results suggest that increased expression of NF-κ B/RelA contributes to tumor angiogenesis in colorectal cancer. VEGF may play an important role in mediating the NF-κ B/RelA angiogenic pathway.