High expression of thymidylate synthase is associated with the drug resistance of gastric carcinoma to high dose 5-fluorouracil-based systemic chemotherapy

BACKGROUND

In the past 4 years, the weekly 24-hour infusion of high dose 5-fluorouracil (5-FU) and leucovorin in the treatment of patients with advanced gastric carcinoma has been prospectively studied at the authors' institution. This has enabled them to explore the possibility that the level of expression of thymidylate synthase (TS), the target enzyme of 5-FU, is related to the drug sensitivity of gastric carcinoma to 5-FU-based chemotherapy.

METHODS

To be eligible for this study, patients were required to have received high dose 5-FU and leucovorin chemotherapy (weekly 24-hour infusions of 5-FU, 2,600 mg/m2, and leucovorin, 300 mg/m2) and to have had adequate prechemotherapy gastric carcinoma tissues for immunohistochemical study. TS106 monoclonal antibody was used to detect the expression of TS. A visual scoring system, which ranged from 0 to 3+, was adopted by 2 independent pathologists to semiquantitate the intensity of TS expression.

RESULTS

Between 1993 and 1996, a total of 30 patients, 18 men and 12 women, with a median age of 61.5 years, were enrolled. Of these patients, 16 (53.3%) and 14 (46.7%) had high and low expression of TS, respectively. Two of the 16 patients (12.5%) with high expression of TS and 13 of the 14 patients (92.9%) with low expression of TS responded to chemotherapy (P < 0.001, chi-square test). The median overall survival was 10 months for patients with low TS expression and 4 months for patients with high TS expression (P < 0.01, log rank test).

CONCLUSIONS

The data from this study suggest that the expression of TS, as determined by immunohistochemistry, is a relatively reliable indicator of whether 5-FU should be used in the treatment of patients with gastric carcinoma.

High expression of thymidylate synthase is associated with the drug resistance of gastric carcinoma to high dose 5-fluorouracil-based systemic chemotherapy

BACKGROUND

In the past 4 years, the weekly 24-hour infusion of high dose 5-fluorouracil (5-FU) and leucovorin in the treatment of patients with advanced gastric carcinoma has been prospectively studied at the authors' institution. This has enabled them to explore the possibility that the level of expression of thymidylate synthase (TS), the target enzyme of 5-FU, is related to the drug sensitivity of gastric carcinoma to 5-FU-based chemotherapy.

METHODS

To be eligible for this study, patients were required to have received high dose 5-FU and leucovorin chemotherapy (weekly 24-hour infusions of 5-FU, 2,600 mg/m2, and leucovorin, 300 mg/m2) and to have had adequate prechemotherapy gastric carcinoma tissues for immunohistochemical study. TS106 monoclonal antibody was used to detect the expression of TS. A visual scoring system, which ranged from 0 to 3+, was adopted by 2 independent pathologists to semiquantitate the intensity of TS expression.

RESULTS

Between 1993 and 1996, a total of 30 patients, 18 men and 12 women, with a median age of 61.5 years, were enrolled. Of these patients, 16 (53.3%) and 14 (46.7%) had high and low expression of TS, respectively. Two of the 16 patients (12.5%) with high expression of TS and 13 of the 14 patients (92.9%) with low expression of TS responded to chemotherapy (P < 0.001, chi-square test). The median overall survival was 10 months for patients with low TS expression and 4 months for patients with high TS expression (P < 0.01, log rank test).

CONCLUSIONS

The data from this study suggest that the expression of TS, as determined by immunohistochemistry, is a relatively reliable indicator of whether 5-FU should be used in the treatment of patients with gastric carcinoma.

Pancreas divisum coexistent with gallbladder carcinoma--report of a Chinese patient

The coexistence of pancreas divisum and gallbladder carcinoma is uncommon and, to the best of our knowledge, has never been reported in English literatures. We have encountered a 62-year-old patient with symptom of intermittent right upper quadrant abdominal pain. Abdominal ultrasonography and computed tomography showed a gallbladder tumor. Endoscopic retrograde cholangiopancreatography revealed existence of complete pancreas divisum but no anomalous union of pancreaticobiliary duct. He underwent cholecystectomy and histologic analysis revealed tubulovillous adenoma with focal malignant change in the gallbladder.

ATP-Dependent human erythrocyte glutathione-conjugate transporter. II. Functional reconstitution of transport activity

Purified dinitrophenyl S-glutathione (DNP-SG) ATPase was reconstituted into artificial liposomes prepared from soybean asolectin. Electron micrography confirmed the formation of unilamellar vesicles with an average radius of 0.25 micron. Intravesicular volume estimated by incorporation of radiolabled inulin into the vesicles was found to be 19.7 +/- 1.3 microL/mL reconstitution solution. Accumulation of the glutathione-conjugate of CDNB, DNP-SG, and of doxorubicin (DOX) in the proteoliposomes was increased in the presence of ATP as compared to equimolar ADP or adenosine 5'-[beta,gamma-methylene]triphosphate tetralithium. ATP-dependent transmembrane movement of DOX and DNP-SG into DNP-SG ATPase-reconstituted vesicles was saturable with respect to time, sensitive to the osmolarity of the assay medium, and temperature dependent. The energy of activation was found to be 12 and 15 kcal/mol for DNP-SG and DOX, respectively. Optimal temperature for transport was 37 degrees C. Saturable transport was demonstrated for DNP-SG (Vmax of 433 +/- 20 nmol/min/mg of protein, KmATP = 2.4 +/- 0. 3 mM and KmDNP-SG = 36 +/- 5 microM) as well as DOX (Vmax = 194 +/- 19 nmol/min/mg of protein, KmATP = 2.5 +/- 0.6 mM and KmDOX = 2.4 +/- 0.7 microM). The kinetic data for both DNP-SG and DOX transport were consistent with a random bi-bi sequential reaction mechanism. DOX was found to be a competitive inhibitor of DNP-SG transport with Kis of 1.2 +/- 0.2 microM and DNP-SG was found to be a competitive inhibitor of DOX transport with Kis of 13.3 +/- 2.6 microM.

Radiographic and computed tomographic findings of gastric mucosa-associated lymphoid tissue lymphomas

The purpose of this retrospective study was to evaluate the detection of gastric mucosa-associated lymphoid tissue (MALT) lymphoma lesions by upper gastrointestinal (UGI) radiography and computed tomography (CT). Fifteen patients with endoscopic biopsy-proven MALT lymphoma were included. Fourteen of these patients underwent double-contrast UGI radiography and 14 were examined with CT of the upper abdomen; 13 underwent both procedures. UGI radiography identified 88% (30/34) of lesions detected by endoscopy, including 12 of 13 enlarged rugal folds and 15 of the 17 multinodular lesions, but failed to identify two of the three ulcerative lesions. UGI radiography identified the only submucosal lesion demonstrated by endoscopy, as well as one at the gastric antrum that had been missed by endoscopy. CT demonstrated nine of 30 endoscopically proven MALT lymphoma lesions, three with focal thickening of the gastric wall and six with a lobulated inner gastric wall. CT failed to demonstrate two fundal and 19 antral or gastric body lesions. Our findings suggest that the predominant UGI features of gastric MALT lymphoma are enlarged folds and multinodular lesions. Although UGI radiography does not reveal all MALT lymphoma lesions, it may find lesions that are not detected by endoscopy. Mucosal lesions of gastric MALT lymphoma are usually not detected by CT.

Clinicopathological significance of altered loci of replication error and microsatellite instability-associated mutations in gastric cancer

Replication errors (RERs) judged by microsatellite instability and its associated mutations have been recognized as an important mechanism in tumorigenesis of gastric cancers (GCs). To gain a deeper insight into its significance, we examined the frequency of RERs using nine microsatellite markers and screened mutations in the polydeoxyadenine tract of the transforming growth factor beta type II receptor gene (TGF-betaRII) and polydeoxyguanine tracts of insulin-like growth factor II receptor and BAX genes. Twenty-four (30%) of 80 patients with GC had RERs, of which 3, 8, and 13 had one, two, and three or more loci, respectively. In 13 tumors with RERs in three or more loci, frameshift mutations of TGF-betaRII, insulin-like growth factor II receptor, and BAX were identified in 12, 3, and 2, respectively. Compared with GC with none, one or two RER-positive loci as a group, GC with RERs in three or more loci showed a significantly higher frequency of antral location (12 of 13 versus 35 of 67; P = 0.01), intestinal subtype (11 of 13 versus 30 of 67; P = 0.01), and previous Helicobacter pylori infection (12 of 13 versus 41 of 67; P = 0.05) and a lower incidence of lymph node metastasis (5 of 13 versus 49 of 67; P = 0.02) and tended to be in an advanced stage (12 of 13 versus 54 of 67; P = 0.28). These data indicate that GC with multiple RERs manifest distinct clinicopathological characteristics, and that a high frequency of frameshift mutations involving the TGF-betaRII gene may be causatively linked with tumorigenesis and progression.

Antibody to a Helicobacter pylori species specific antigen in patients with adenocarcinoma of the stomach

This study attempted to identify a possible antibody response to Helicobacter pylori, which is associated with patients with adeno-carcinoma of the stomach. By using proteins of H. pylori as the antigen, pooled sera from gastric cancer and non-cancer patients were used as the first antibody for Western blot analysis. Antibody responses to a 26 kD secreted protein were observed in pooled cancer sera, but not in pooled sera from non-cancer patients. The protein was purified, while amino acid sequences revealed that it was a H. pylori species specific protein. The gene of this protein was cloned and a recombinant protein was expressed in E. coli. In addition, an antibody to the recombinant protein was tested in each individual patient using Western blot analysis. None of the forty non-gastric cancer patients were positive for the antibody to the recombinantly expressed 26 kD species specific protein. Meanwhile, six of the twenty four cancer patients tested positive (0/40 vs 6/24, p < 0.01). Results presented herein demonstrate that the species specific protein of H. pylori can be useful in detecting H. pylori associated with adenocarcinoma of the stomach.

Detection of circulating cancer cells by nested reverse transcription-polymerase chain reaction of cytokeratin-19 (K19)--possible clinical significance in advanced gastric cancer

Intermediate filament cytokeratin-19 (K19) protein is expressed in normal and malignant gastrointestinal epithelial cells, but not in peripheral blood (PB). Small amount of circulating gastric cancer cells can be detected by a sensitive nested reverse transcription-polymerase chain reaction (RTPCR) with primers specific for K19 mRNA. Thirty-four PB samples obtained from patients with inoperable/metastatic gastric cancer were examined. The mononuclear cell (MNC) fraction was collected by Ficoll centrifugation, and followed by total RNA extraction by acid guanidinium thiocyanate-phenol-chloroform method. RNA from 8 gastric cancer cell lines and the mononuclear cells of 33 healthy adults were used as positive and negative controls, respectively. DNA fragment of 774 bp amplified by the internal primers was found to be a highly reliable marker for K19 mRNA expression. The sensitivity of detection was between 1 and 10 cells/10(6) normal MNCs. The K19 transcripts were detected in 20.6% (7/34; 8-37%, 95% C.I.) of PB samples. None of the other pertinent clinicopathological features, including the disease extent and the histopathologic types of the tumors, were related to the expression of K19 in PB. All 34 patients had been treated by systemic chemotherapy. Among the 17 non-responders to chemotherapy, the survival of the 4 patients with detectable K19 was significantly shorter than that of 13 patients without detectable K19 in their circulating blood (p = 0.014). However, the survival impact of K19 was less significant in the other 17 patients whose tumors had responded to systemic chemotherapy. Of the whole group of patients, the median survival of the 7 and 27 patients with and without detectable K19 in their circulating blood was 1 and 3.5 months, respectively (p = 0.368). We concluded that detecting circulating cancer cells by K19 nested RT-PCR is associated with poor prognosis of gastric cancer, particularly in those patients who are not responsive to systemic chemotherapy.

Loss of pS2 protein expression is an early event of intestinal-type gastric cancer

To investigate the prevalence of pS2 expression in gastric cancer with respect to tumor histopathology, intestinal metaplasia and Helicobacter pylori (H. pylori) infection, pathologic specimens of 91 patients with gastric cancer were immunostained for pS2. Such immunoreactivity was correlated with the status of H. pylori infection, tumor staging, histology, subtyping, and associated intestinal metaplasia. Positive pS2 staining was seen throughout all non-neoplastic epithelia, and in all 9 patients with the complete type of intestinal metaplasia. In contrast, 21 of 45 incomplete type of intestinal metaplasia had negative pS2 staining (P < 0.001), and 54 out of 91 tumors (59.3%) showed loss of pS2 expression in the cancer tissues proper. There was no correlation of pS2 expression with age, gender, depth of invasion, duodenal involvement, lymph node metastasis, venous invasion or H. pylori infection. Negative pS2 staining was significantly higher in the intestinal (74.5%) and Borrmann type I, II, III (64.2%) tumors than the diffuse (43.2%, P < 0.005) and Borrmann type IV (20%, P < 0.05) tumors. Our results indicate that loss of pS2 expression may occur as an early event in the malignant transformation process of intestinal-type tumors.

Cisplatin, etoposide, and weekly high-dose 5-fluorouracil and leucovorin infusion (PE-HDFL)--a very effective regimen with good patients' compliance for advanced gastric cancer

We have previously shown that weekly 24-hour infusion of high-dose 5-fluorouracil and leucovorin (HDFL), a regimen initially designed for the treatment of advanced colorectal cancer, is also effective in the treatment of gastric cancer. This HDFL regimen is unique in that it is virtually non-myelosuppressive, and thus provides a comerstone on which ideal protocols may be developed. In this prospective phase II study, we examined the efficacy and toxicity of PE (cisplatin, etoposide)-HDFL, a HDFL-based combination chemotherapy, in the treatment of advanced-gastric cancer. This regimen consisted of cisplatin 60 mg/m2, i.v., D1; etoposide 65 mg/m2, i.v., D1-3; and 5-fluorouracil 2600 mg/m2 plus leucovorin 300 mg/m2, 24-hour i.v. infusion by an ambulatory infusion pump, D2,9,16; repeated every 4 weeks. The major eligibility criteria of the patients included: a) a histologically confirmed, objectively measurable, recurrent or primary inoperable gastric adenocarcinoma; b) age > or = 75 years; c) a Karnofsky performance status > or = 50%; d) an absolute granulocyte count (AGC) > or = 2000/mm3, and a platelet count > or = 100,000/mm3; e) a serum bilirubin concentration < or = 2.0 mg/dl; f) a serum creatinine concentration < or = 1.5 mg/dl; and g) a signed informed consent. Between March 1992 and June 1996, a total of 42 patients were enrolled onto the study. There were 31 men and 11 women with a median age of 54 (24-75) years; these included 16 primary metastatic, 3 locally advanced and inoperable, and 23 postgastrectomy recurrent gastric cancer patients. ECOG (Eastern Cooperative Oncology Group) grade III/IV leukopenia and thrombocytopenia developed in 34.0% and 11.0% of a total of 229 courses given, respectively. There was no treatment-related death. Four patients developed a reversible neurotoxicity; and two of them refused further chemotherapy. Among the 40 patients evaluable for responses, 9 [22.5%; 12-38%, 95% confidence interval (C.I.)] patients achieved complete remission, and 20 [50.0%; 33-67%, 95% C.I.] patients achieved partial remission. The overall response rate was 72.5% [56-86%, 95% C.I.]. The overall median survival and median time to progression of the responders were 10 and 7 months, respectively. The overall median survival of the whole group was 9 months. We concluded that PE-HDFL is a highly effective treatment for advanced gastric cancer. The treatment-related toxicity was mild and the patients' compliance was satisfactory.

Overexpression of mutant p53 and c-erbB-2 proteins and mutations of the p15 and p16 genes in human gastric carcinoma: with respect to histological subtypes and stages

Although the mechanism remains obscure, two histological subtypes of gastric carcinoma (GC), the diffuse and intestinal types, differ drastically in epidemiological, clinical, pathological and biological characteristics. We investigated whether the genetic alterations of several oncogenes and tumour suppressor genes could be correlated with the two histological subtypes. In 60 patients with GC, the overexpression of mutant p53 and c-erbB-2 oncoproteins was studied using immunohistochemical stains. Mutations of the p15 and p16 tumour suppressor genes were assessed by polymerase chain reaction, Southern blotting, and direct DNA sequencing. Overexpression of c-erbB-2 and p53 was found in 21 (35.0%) and 27 (45.0%) patients, respectively. Overexpression of the c-erbB-2 oncoprotein was more common in the intestinal type (15/32, 46.9%) and the advanced stage (19/45, 42.2%) than in the diffuse type (6/28, 21.4%) and the early stage (2/15, 13.3%) of GC (P<0.05). Similarly, p53 overexpression was more frequently found in the intestinal type (19/32, 59.4%) and the advanced stage (24/45, 53.3%) than in the diffuse type (8/28, 28.6%) and the early stage (3/15, 20.0%) of GC (P<0.05). Homozygous deletions of p16 in exon 1 were found in six (10.0%) patients. Five of them had the intestinal-type advanced GC. Neither point mutations of p16 nor alterations of p15 were detected. The frequency of alterations of p53, c-erbB-2, and p16 was not related to sex and Helicobacter pylori infection. No correlation of genetic changes between any two genes was observed. Our preliminary results indicate alterations in the p15 gene were not important in gastric tumorigenesis, while infrequent homozygous deletions in the p16 gene play a limited role in tumour progression of intestinal-type GC. Moreover, overexpression of c-erbB-2 and p53 is frequently encountered in the intestinal-type advanced GC. Alterations of p53, c-erbB-2 and p16 genes may function independently of each other in gastric carcinogenesis. The association between genetic alterations and histological subtypes supports the notion that a distinct pathogenesis may exist in different histological subtypes.

Biosynthesis of triacylglycerols containing ricinoleate in castor microsomes using 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine as the substrate of oleoyl-12-hydroxylase

We have examined the biosynthetic pathway of triacylglycerols containing ricinoleate to determine the steps in the pathway that lead to the high levels of ricinoleate incorporation in castor oil. The biosynthetic pathway was studied by analysis of products resulting from castor microsomal incubation of 1-palmitoyl-2-[14C]oleoyl-sn-glycero-3-phosphocholine, the substrate of oleoyl-12-hydroxylase, using high-performance liquid chromatography, gas chromatography, mass spectrometry, and/or thin-layer chromatography. In addition to formation of the immediate and major metabolite, 1-palmitoyl-2-[14C]ricinoleoyl-sn-glycero-3-phosphocholine, 14C-labeled 2-linoleoyl-phosphatidylcholine (PC), and 14C-labeled phosphatidylethanolamine were also identified as the metabolites. In addition, the four triacylglycerols that constitute castor oil, triricinolein, 1,2-diricinoleoyl-3-oleoyl-sn-glycerol, 1,2-diricinoleoyl-3-linoleoyl-sn-glycerol, 1,2-diricinoleoyl-3-linolenoyl-sn-glycerol, were also identified as labeled metabolites in the incubation along with labeled fatty acids: ricinoleate, oleate, and linoleate. The conversion of PC to free fatty acids by phospholipase A2 strongly favored ricinoleate among the fatty acids on the sn-2 position of PC. A major metabolite, 1-palmitoyl-2-oleoyl-sn-glycerol, was identified as the phospholipase C hydrolyte of the substrate; however, its conversion to triacylglycerols was blocked. In the separate incubations of 2-[14C]ricinoleoyl-PC and [14C]ricinoleate plus CoA, the metabolites were free ricinoleate and the same triacylglycerols that result from incubation with 2-oleoyl-PC. Our results demonstrate the proposed pathway: 2-oleoyl-PC-->2-ricinoleoyl-PC-->ricinoleate-->triacylglycerols. The first two steps as well as the step of diacylglycerol acyltransferase show preference for producing ricinoleate and incorporating it in triacylglycerols over oleate and linoleate. Thus, the productions of these triacylglycerols in this relatively short incubation (30 min), as well as the availability of 2-oleoyl-PC in vivo, reflect the in vivo drive to produce triricinolein in castor bean.

Distinct clinicopathologic characteristics of diffuse- and intestinal-type gastric cancer in Taiwan

The clinicopathologic features of 221 patients with intestinal-type (IT) gastric cancer were compared retrospectively with those of 290 diffuse type (DT). Intestinal type was characterized by an older mean age (65.0 +/- 10.8 years vs. 56.2 +/- 13 years), a higher male-female ratio (2.56 vs. 1.06), predominance of blood group O (46.2% vs. 31.1%), and frequent habitual smoking (50.7% vs. 31.4%) and drinking (28.5% vs. 17.6%) than did DT. In contrast, DT had a higher frequency of positive history of parent or sibling with gastric cancer (9.3% vs. 4.1%) and blood group A (40.3% vs. 27.6%) than did IT. The distinguishing histologic features of DT included more Borrmann type IV (13.1% vs. 1.3%) but less Borrmann type I (1% vs. 7.2%), more frequent involvement of middle third (26.9% vs. 15.9%) and whole stomach (4.1% vs. 0%), and more peritoneal seeding (15.5% vs. 9%), lymph node metastasis (67.2% vs. 51%), and nerve permeation (34.1% vs. 24.4%), but less Helicobacter pylori infection (55.9% vs. 69.2%) when compared with those of IT. There was no difference in depth of tumor invasion, venous permeation, duodenal involvement, and postoperative survival between IT and DT. These distinct clinicopathologic features between IT and DT in Taiwan suggest the presence of a different pathogenic process for these two histologic subtypes of gastric cancer.

Loss of imprinting and overexpression of IGF2 gene in gastric adenocarcinoma

Both insulin-like growth factor II (IGF2) and H19 gene are located on chromosome 11p15.5 in close vicinity to each other, and are imprinted on different parental alleles. Although the exact mechanism remains unclear, loss of imprinting (LOI) leading to the biallelic expression of IGF2 and H19 genes has recently been reported in a variety of tumors. To study the role of IGF2 and H19 genes in gastric carcinogenesis, the LOI and loss of heterozygosity (LOH) status of these two genes were determined in 70 patients with gastric cancer. Among them, 30 patients were heterozygous for IGF2, 28 patients were heterozygous for H19, and 42 patients were heterozygous for either IGF2 or H19 gene. Among the 30 patients who were heterozygous for IGF2, one exhibited LOH (1/30, 3.3%) and 10 exhibited LOI (10/29, 34.5%). None of the 28 patients heterozygous for H19 gene had either LOH or LOI. LOI of IGF2 was more frequently found in the diffuse type (8/15, 53.3%) than the intestinal type (2/14, 14.3%, P < 0.05) gastric cancer. Five out of the six tumors with LOI of IGF2 exhibited overexpression of mRNA, but no obvious alterations of expression of H19 were noted by Northern hybridization. These data suggest that LOI leading to overexpression of IGF2 plays an important role in carcinogenesis of diffuse type gastric cancer.

Nitrate assimilation by bacteria

Nitrate is a significant nitrogen source for plants and microorganisms. Recent molecular genetic analyses of representative bacterial species have revealed structural and regulatory genes responsible for the nitrate-assimilation phenotype. Together with results from physiological and biochemical studies, this information has unveiled fundamental aspects of bacterial nitrate assimilation and provides the foundation for further investigations. Well-studied genera are: the cyanobacteria, including the unicellular Synechococcus and the filamentous Anabaena; the gamma-proteobacteria Klebsiella and Azotobacter; and a Gram-positive bacterium, Bacillus. Nitrate uptake in most of these groups seems to involve a periplasmic binding protein-dependent system that presumably is energized by ATP hydrolysis (ATP-binding cassette transporters). However, Bacillus may, like fungi and plants, utilize electrogenic uptake through a representative of the major facilitator superfamily of transport proteins. Nitrate reductase contains both molybdenum cofactor and an iron-sulfur cluster. Electron donors for the enzymes from cyanobacteria and Azotobacter are ferredoxin and flavodoxin, respectively, whereas the Klebsiella and Bacillus enzymes apparently accept electrons from a specific NAD(P)H-reducing subunit. These subunits share sequence similarity with the reductase components of bacterial aromatic ring-hydroxylating dehydrogenases such as toluene dioxygenase. Nitrite reductase contains sirohaem and an iron-sulfur cluster. The enzymes from cyanobacteria and plants use ferredoxin as the electron donor, whereas the larger enzymes from other bacteria and fungi contain FAD and NAD(P)H binding sites. Nevertheless, the two forms of nitrite reductase share recognizable sequence and structural similarity. Synthesis of nitrate assimilation enzymes and uptake systems is controlled by nitrogen limitation in all bacteria examined, but the relevant regulatory proteins exhibit considerable structural and mechanistic diversity in different bacterial groups. A second level of control, pathway-specific induction by nitrate and nitrite in Klebsiella, involves transcription antitermination. Several issues await further experimentation, including the mechanism and energetics of nitrate uptake, the pathway(s) for nitrite uptake, the nature of electron flow during nitrate reduction, and the action of transcriptional regulatory circuits. Fundamental knowledge of nitrate assimilation physiology should also enhance the study of nitrate metabolism in soil, water and other natural environments, a challenging topic of considerable interest and importance.

Acute pancreatitis complicated by infarction of the spleen and spinal cord

Complications of acute pancreatitis may include local pancreatic necrosis with pseudocyst or abscess formation, and extrapancreatic manifestations such as pulmonary renal, hepatic, endocrine, and coagulation abnormalities. Coagulation abnormalities associated with acute pancreatitis usually present as thrombophlebitis or widespread microthrombi; most occur in the venous or capillary circulation. We report a rare case of acute pancreatitis complicated by pseudocyst formation, splenic vein thrombosis, splenic infarction, and spinal cord infarction, which resulted in paraplegia. An association between acute pancreatitis and spinal cord infarction has not been reported before.

Weekly 24-hour infusion of high-dose 5-fluorouracil and leucovorin in the treatment of advanced gastric cancers. An effective and low-toxic regimen for patients with poor general condition

Systemic chemotherapy for advanced gastric cancer is frequently associated with significant treatment-related toxicity, which is particularly serve in patients presenting with a poor general condition. A search for effective and low-toxic regimens for this group of patients is mandatory. A weekly 24-hour infusion of high-dose 5-fluorouracil (5-FU) and leucovorin (HDFL) has previously been demonstrated to be an effective treatment for advanced colorectal cancer with minimal toxicity. In the past 3 years, this regimen has been tested at our institutes in patients with advanced gastric cancer, the general condition of whom had made the use of intensive combination chemotherapy impossible. The regimen consisted of a weekly 24-hour infusion of 2,600 mg/m2 of 5-FU and 300 mg/m2 of leucovorin. From August 1992 to December 1995, 34 patients had been treated with this regimen for a total of 488 courses (average: 14.4 per patient). Hematological toxicity of this regimen was minimal, with grade 3 or 4 leukopenia developing in only 1 (2.9%) patient. Other nonhematological toxicities were also negligible except a reversible neurotoxicity which developed in 2 patients. Twenty-five patients were eligible for response analysis. One complete response, 11 partial responses, 5 stable diseases, and 8 progressive diseases were observed. The response rate was 48% (32-72%, 95% CI). The median overall survival (OS) of the whole group was 7 months (range: 1-18+). The median OS and time to progression of the responders were 8.5 months (range: 2-18) and 5 months (range: 2-10+), respectively. The palliative effect was satisfactory with the Karnofsky performance status of the responders improving from a median of 50% (range: 20-90%) to 70% (range: 50-100%). Our retrospective data suggested that HDFL is an effective and low-toxic palliative treatment even in patients with a very poor general condition. We advocated that this regimen should be further tested in ordinary patients with advanced gastric cancer.

Visual sensitivities of nur77 (NGFI-B) and zif268 (NGFI-A) induction in the suprachiasmatic nucleus are dissociated from c-fos induction and behavioral phase-shifting responses

Mammalian circadian rhythms are regulated by a pacemaker in the suprachiasmatic nucleus of the hypothalamus. Recent work from several laboratories has shown that light induces the IEGs, c-fos and jun-B, in the rodent suprachiasmatic nucleus. In hamsters, there is a strong correlation between circadian entrainment and the induction of c-fos and jun-B in the suprachiasmatic nucleus by light. Previous work has shown that the IEGs, nur77 and zif268, both of which encode transcription factors, are also light-inducible in the rat suprachiasmatic nucleus [Rusak, B., McNaughton, L., Robertson, H.A. and Hunt, S.P., Circadian variation in photic regulation of IEG mRNAs in rat suprachiasmatic nucleus cells, Mol. Brain Res., 14 (1992) 124-130.; Sutin, E.L. and Kilduff, T.S., Circadian and light-induced expression of IEG mRNAs in the rat suprachiasmatic nucleus, Mol. Brain Res., 15 (1992) 281-290.]. To characterize the photic-regulation of these genes in the suprachiasmatic nucleus of golden hamsters, we used in situ hybridization to measure nur77 and zif268 mRNA levels with 33P-labeled complementary RNA probes. 5-min monochromatic light pulses at CT19 induced a dramatic increase in both nur77 and zif268 mRNA levels. Peak mRNA levels occurred 45-60 min after light onset for both nur77 and zif268. In addition, the induction of both nur77 and zif268 mRNA levels was gated by the circadian pacemaker. Light pulses during subjective day (CT3 and CT9), which do not cause behavioral phase-shifts, did not significantly alter mRNA levels of either nur77 or zif268; whereas light pulses during the subjective night (CT14 and CT19), which induce phase-shifts, dramatically increased both nur77 and zif268 mRNA levels. In contrast to c-fos induction, which has a photic threshold indistinguishable from that of the behavioral phase-shifting response, nur77 and zif268 mRNA induction were found to have visual sensitivities greater than the phase-shifting response by 1-2 log units (10-100-fold). Although light and circadian phase regulate nur77 and zif268 expression in the SCN, these results demonstrate that their induction is not rate-limiting for photic entrainment of the hamster circadian system.

Increased prevalence of Helicobacter pylori infection among patients affected with intestinal-type gastric cancer at non-cardiac locations

Previous data on the association of Helicobacter pylori infection with gastric cancer by demographic or histological features are inconsistent due to a univariate analysis of limited case numbers. The aim of the present study was to determine such an association by the use of a large series of patients and multiple variables analysis. The serum IgG antibodies against H. pylori were measured in 397 patients with histologically verified gastric cancer. A multiple logistic regression analysis was used to define the association between seropositivity and demographic or tumour characteristics of gastric cancer. The overall seropositivity of H. pylori was 63%. In univariate analysis, the prevalence was significantly lower among patients with cardia (50%) or diffuse-type (56.6%) cancers than those with non-cardia (64.8%) or intestinal-type (70.3%) cancer (P < 0.05 and P < 0.01, respectively). There was no statistical difference between H. pylori infection rate and gender, age or tumour stage. A multiple logistic regression analysis showed tumour location and histology remained significant factors associated with seropositivity of H. pylori with an odds ratio of approximately 2.0. Analysis of combined histology and location revealed that patients with intestinal-type cancer at non-cardia locations had the highest odds ratio of 3.93 (95% confidence interval (CI): 1.55-10.0) compared with the lowest odds ratio of 0.69 (95% CI: 0.30-1.62) in diffuse cardia cancer (P < 0.005). Our data indicate H. pylori infection in gastric cancer is independently affected by the histological subtype and by tumour location.

Seroprevalences of hepatitis B and C viruses and Helicobacter pylori infection in a small, isolated population at high risk of gastric and liver cancer

The objective of this study was to examine the seroprevalences of chronic infection with hepatitis B and C viruses and Helicobacter pylori in Matzu, a group of small islets with 5,566 civilian residents who have extremely high mortality from cancers of the stomach and liver. The standardized mortality ratios (SMR) of all cancer sites combined, liver cancer and stomach cancer in 1984-1993 were calculated using the general population in Taiwan as the referent (SMR = 100). The SMRs (95% confidence interval) for all cancer sites combined, liver cancer and stomach cancer were 160 (131-195), 252 (170-360) and 351 (229-516), respectively, in Matzu. A health survey was carried out with 1,485 civilian residents aged 30 years or more, giving a response rate of 69% among those who were eligible. Serum samples were tested for antibodies against Helicobacter pylori (anti-HP) by enzyme-linked immunosorbent assay and hepatitis B surface antigen (HBsAg) and antibodies against hepatitis C virus (anti-HCV) by enzyme immunoassay. The seroprevalence was 61% for anti-HP, 24.7% for HBsAg and 1.8% for anti-HCV in Matzu. While mortality rates of liver and stomach cancers were significantly higher in Matzu than in Taiwan, the seroprevalences of anti-HP, HBsAg and anti-HCV in Matzu were similar to or even lower than those in Taiwan. These findings suggest the existence of risk factors other than microbial agents involved in the development of stomach and liver cancers.

Genetic alterations in gastric cancer: relation to histological subtypes, tumor stage, and Helicobacter pylori infection

BACKGROUND & AIMS

A different spectrum of genetic changes including p53, c-erbB-2, c-met, adenomatous polyposis coli (APC), and deleted in colorectal cancer (DCC) is involved in gastric cancer (GC). The aim of this study was to correlate these alterations with histological subtypes, tumor stages, and Helicobacter pylori infection.

METHODS

Specimens of 163 patients with GC were immunostained for p53, c-erbB-2, and c-met, and polymerase chain reaction was performed in them to determine loss of heterozygosity (LOH) of APC and DCC.

RESULTS

Overexpression of p53 was more frequent in early intestinal than early diffuse GC and was noted in the stage progression of diffuse but not intestinal GC. Overexpression of c-erbB-2 occurred more commonly in intestinal GC and advanced GC of both types. Overexpression of c-met was greater in diffuse GC, particularly at advanced stage. LOH of APC was more common in intestinal GC irrespective of the stage but rarely in diffuse GC. LOH of DCC occurred primarily in advanced intestinal GC and infrequently in early GC or advanced diffuse GC. Alterations of these five genes were not correlated with H. pylori infection.

CONCLUSIONS

A distinct genetic pathway exists in gastric carcinogenesis of different histological subtypes and their tumor progression, in which H. pylori infection may play an equal role or no role.

Chronic calcifying pancreatitis in Taiwan: a multicentric study and comparison with western countries

BACKGROUND/AIMS

This study investigates the clinical features of chronic calcifying pancreatitis (CCP) in Taiwan and also the comparative differences in the disorder as it affects orientals and occidentals.

MATERIALS AND METHODS

Medical records at seven tertiary hospitals relating to patients diagnosed with CCP between 1976 and 1996 are reviewed and analyzed. Ninety patients were enrolled. Defining the calcification of the pancreas is achieved by plain film, ultrasonography, computed tomography, or histology.

RESULTS

CCP afflicts men more frequently than it does women, by a ratio of 3.5:1 (70 men and 20 women). The mean age is 45 years (male: 46 female: 41.4). For fifty-two patients (57.8%), alcohol is the major cause of the condition, while in others, the causes are non-alcoholic (idiopathic: 31; biliary: 4; hereditary: 3). Alcoholism is mainly associated with males and younger sufferers. The major complications are diabetes mellitus (53.3%), cysts or pseudocysts (21.1%), and biliary stricture or stones (20%). Pancreatic adenocarcinoma and splenic vein thrombosis were found in six and five patients, respectively. Three patients died from cancers of other than pancreatic origin (lung: 1;liver: 1;bile duct: 1). Thirty-three patients were treated surgically of which thirteen (39.4%), including one with pancreatic auto transplantation, improved. Fifty-seven patients received medical treatment but only eleven (19.3%) improved.

CONCLUSIONS

The clinical features of CCP in Taiwan are notably similar to those manifesting in western countries and in Japan. With the changes in life style and increased alcoholic consumption in Taiwan, the prevalence of CCP may increase and its demographic features may alter in the future.