Endoscopic imaging modalities for diagnosing the invasion depth of superficial esophageal squamous cell carcinoma: a systematic review

Esophagus - Endoscopic diagnosis of the invasion depth of superficial esophageal squamous cell carcinoma (ESCC) is an important determinant of the treatment strategy. The three endoscopic imaging...     

Repeated talaporfin sodium photodynamic therapy for esophageal cancer: safety and efficacy

Esophagus - Talaporfin sodium photodynamic therapy (tPDT) is an effective salvage treatment for local failure after chemoradiotherapy for esophageal cancer. Repeated tPDT could also be indicated...     

CGG: an unassigned or nonsense codon in Mycoplasma capricolum.

CGG is an arginine codon in the universal genetic code. We previously reported that in Mycoplasma capricolum, a relative of Gram-positive eubacteria, codon CGG did not appear in coding frames, including termination sites, and tRNA(ArgCCG) pairing with codon CGG, was not detected. These facts suggest that CGG is a nonsense (unassigned and untranslatable) codon--i.e., not assigned to arginine or to any other amino acid. We have investigated whether CGG is really an unassigned codon by using a cell-free translation system prepared from M. capricolum. Translation of synthetic mRNA containing in-frame CGG codons does not result in "read-through" to codons beyond the CGG codons--i.e., translation ceases just before CGG. Sucrose-gradient centrifugation profiles of the reaction mixture have shown that the bulk of peptide that has been synthesized is attached to 70S ribosomes and is released upon further incubation with puromycin. The result suggests that the peptide is in the P site of ribosome in the form of peptidyl-tRNA, leaving the A site empty. When in-frame CGG codons are replaced by UAA codons in mRNA, no read-through occurs beyond UAA, just as in the case of CGG. However, the synthesized peptide is released from 70S ribosomes, presumably by release factor 1. These data suggest strongly that CGG is an unassigned codon and differs from UAA in that CGG is not used for termination.     

Randomized, controlled trial of lateral node dissection vs. nerve-preserving resection in patients with rectal cancer after preoperative radiotherapy

PURPOSE: The effectiveness of preoperative radiation therapy for advanced lower rectal carcinoma to preserve the function of pelvic organs and reduce local recurrences was examined in a prospective, randomized, controlled study. METHODS: Fifty-one patients with a diagnosis of localized and resectable adenocarcinoma of the lower rectum undergoing 50 Gy of preoperative radiotherapy were recruited into the trial between April 1993 and March 1995. The patients were randomly allocated to complete autonomic nerve-preserving surgery without lateral node dissection (D1), or surgery with dissection of the lateral lymph nodes including autonomic nerves (D2) followed by oral administration of carmofur for one year. RESULTS: No difference was observed in either survival or disease-free survival between D1 and D2 groups. There was no difference between the two groups in terms of recurrence rate. A significant difference was observed in urinary and sexual function (P= 0.02 and 0.02, respectively) one year after surgery between D1 and D2 groups. CONCLUSION: This study suggests that lateral node dissection is not necessary in terms of curability for patients with advanced carcinoma of the lower rectum who undergo preoperative radiotherapy.Supported in part by a grant from the Ministry of Health and Welfare of Japan and in part by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan.     

Determination of transmembrane topology of an inward-rectifying potassium channel from Arabidopsis thaliana based on functional expression in Escherichia coli

We report here that the inward-rectifying potassium channels KAT1 and AKT2 were functionally expressed in K⁺ uptake-deficient Escherichia coli. Immunological assays showed that KAT1 was translocated into the cell membrane of E. coli. Functional assays suggested that KAT1 was inserted topologically correctly into the cell membrane. In control experiments, the inactive point mutation in KAT1, T256R, did not complement for K⁺ uptake in E. coli. The inward-rectifying K⁺ channels of plants share a common hydrophobic domain comprising at least six membrane-spanning segments (S1–S6). The finding that a K⁺ channel can be expressed in bacteria was further exploited to determine the KAT1 membrane topology by a gene fusion approach using the bacterial reporter enzymes, alkaline phosphatase, which is active only in the periplasm, and β-galactosidase. The enzyme activity from the alkaline phosphatase and β-galactosidase fusion plasmid showed that the widely predicted S1, S2, S5, and S6 segments were inserted into the membrane. Although the S3 segment in the alkaline phosphatase fusion protein could not function as an export signal, the replacement of a negatively charged residue inside S3 with a neutral amino acid resulted in an increase in alkaline phosphatase activity, which indicates that the alkaline phosphatase was translocated into the periplasm. For membrane translocation of S3, the neutralization of a negatively charged residue in S3 may be required presumably because of pairing with a positively charged residue of S4. These results revealed that KAT1 has the common six transmembrane-spanning membrane topology that has been predicted for the Shaker superfamily of voltage-dependent K⁺ channels. Furthermore, the functional complementation of a bacterial K⁺ uptake mutant in this study is shown to be an alternative expression system for plant K⁺ channel proteins and a potent tool for their topological analysis.     

Overexpression of p53 protein and histologic grades of dysplasia in colorectal adenomas

PURPOSE: To clarify the relation between tumor-suppressor gene p53 expression and histologic grades of dysplasia in colorectal adenomas, we performed immunohistochemical analysis in a series of 59 colorectal polyps and 40 advanced carcinomas. METHODS: Adenomatous polyps were stained by hematoxylin and eosin and classified into mild, moderate, and severe dysplasia (intramucosal carcinoma), according to the World Health Organization's classification. RESULTS: p53 was positive in 7.1 percent (2/28) of mild, 29.4 percent (5/17) of moderate, and 62.5 percent (5/8) of severe dysplasia. In submucosal and advanced carcinomas, positivity rates were 75 percent (3/4) and 47.5 percent (19/40), respectively. Different staining patterns were found, according to grades of dysplasia. In the adenomas with mild or moderate dysplasia, a few focal crypts showed localized p53-positive staining. Adenomas with severe dysplasia had two different staining types. One was a focal staining type as shown in mild or moderate dysplasia; the other was a diffuse staining type, in which glands with mild or moderate dysplasia, surrounding severe dysplasia area, were also stained. Submucosal and advanced carcinomas showed a strong positive staining in cancer cells only. CONCLUSIONS: Overexpression of p53 protein in adenomas with mild or moderate dysplasia and existence of two types of expression in adenomas with severe dysplasia were observed. These facts suggested the possible existence of different pathways in the adenoma to carcinoma progression.     

Mucin-producing adenoma associated with pancreas divisum and hepatic hilar carcinoma: An autopsy case

We present the autopsy case of an 82-year-old Japanese woman with a mucin-producing adenoma accompanied by pancreas divisum and a hepatic hilar carcinoma. She had suffered from a cholangiocellular carcinoma at the hepatic hilus for 2 months, which was treated with radiation and chemotherapy. She did not complain of any abdominal pain. Obstructive jaundice deteriorated despite percutaneous transhepatic bile duct drainage, and she died of hepatic insufficiency. At autopsy, a hepatic tumor was confirmed to have caused severe obstructive jaundice. Histological examinations showed moderately to poorly differentiated cholangiocellular adenocarcinoma with squamous metaplasia, probably due to radiation. A yellowish mucinous tumor was found in the head of the pancreas near the minor papilla. It consisted of multiple rice-sized cystic lesions with thin septa. Although it had no capsule, its margin was clear. Neither a wide opening of the major or minor papilla nor mucous drainage was observed. Gross examinations revealed unfused pancreatic ducts. The slightly dilated dorsal duct and a branch of the mildly dilatated ventral duct showed tumor involvement. Histological examinations showed mild atypia of the epithelia, and this pancreatic tumor was diagnosed as branch duct-type mucin-producing adenoma with postradiation dysplasia. The combination of a mucin-producing tumor and pancreas divisum is rare, and this is only the third reported case.