Toshihiko Saitoh

ω-Hydroxylation of docosahexaenoic acid or arachidonic acid in human colonic well differentiated adenocarcinoma homogenate

Human colonic well differentiated adenocarcinoma homogenate was incubated with NADPH and docosahexaenoic acid (22:6(n-3)) or arachidonic acid (20:4(n-6)) as a substrate. On a selected ion monitoring chromatogram obtained with reversed phase-high-performance liquid chromatography thermospray mass spectrometry, omega-hydroxydocosahexaenoic acid (omega-HDHE) or omega-hydroxyeicosatetraenoic acid (omega-HETE) from an incubation mixture of the homogenate was detected in significant amount, compared to that from a colonic region remote from the carcinoma. In contrast, epoxydocosapentaenoic acids and the dihydroxy derivatives from 22:6(n-3) or epoxyeicosatrienoic acids and the dihydroxy derivatives from 20:4(n-6) were detected in low amounts, compared to that from a colonic region remote from the carcinoma. The results suggest that highly active NADPH-dependent omega-oxidations of polyunsaturated fatty acids occur in colonic adenocarcinoma homogenate.

High-performance liquid chromatography-thermospray mass spectrometry of ω-carboxyleukotriene B4 and ω-hydroxyleukotriene B4 from an incubation mixture of human colonic well-differentiated adenocarcinoma homogenate

A method for the analysis of omega-carboxyleukotriene B4 and omega-hydroxyleukotriene B4 in human colonic carcinoma homogenate is described. The hydroxy groups of the leukotriene metabolite were acetylated by acetic anhydride, and the mixture was partially purified on a Sep-Pak C18 cartridge and analysed by reversed-phase HPLC-thermospray MS. Generally, the base ion, [MH-2(60)]+, is produced through elimination of two acetic acid (60 mass units) molecules from the protonated molecular ion. On selected-ion monitoring, standard curves for omega-carboxy- or omega-hydroxyleukotriene B4 showed a linear relationship over the range 72-1500 pmol. The assay based on selected-ion monitoring was applied to an extract from human colonic carcinoma homogenate. When a homogenate of human colonic well-differentiated adenocarcinoma was incubated with NADPH and leukotriene B4 (60.6 nmol) as a substrate, the conversion of precursor leukotriene B4 to omega-carboxyleukotriene B4 or omega-hydroxyleukotriene B4 was 0.33 or 3.17%, respectively. Based on these results, it is suggested that carcinoma cells themselves or leukocytes at the hostsite in a region of human colonic well-differentiated adenocarcinoma are performing omega-oxidation through NADPH-dependent omega-hydroxylation of leukotriene B4.

Experience with Percutaneous Electronic Choledochoscopy

Experience with percutaneous choledochoscopy using a prototype electronic choledochoscope (Pentax ECN‐1530) is presented herein. This electronic endoscope is 5.3 mm in outside diameter at the tip and has a forceps channel 2.0 mm in diameter. The outside diameter is 0.4 mm larger, while the forceps channel diameter is 0.2 mm smaller, than that of the conventional fiberoptic choledochoscope (FCN‐15X) produced by the same company. Although the new electronic choledochoscope could be inserted through a 16 Fr in size fistula, we considered an 18 Fr fistula to be preferable for insertion without resistance. Various types of accessory equipment for endoscopic treatment, such as an electrohydraulic Shockwave lithotriptor (EHL) and an Nd‐YAG laser, could be used without difficulty. The electronic choledochoscope was useful for examining bile duct carcinoma invasion to the hepatic side and evaluating the efficacy of various multi‐modal treatments, as it provided observation of the bile duct mucosa in great detail due to a very clear dynamic image. Moreover, endoscopic treatment was also greatly facilitated because it provided a clear view on a large, bright monitor screen for the surgeons. We therefore believe that this new electronic choledochoscope is very useful for the accurate diagnosis and treatment of biliary diseases.

Overexpression of cyclin A and p53 in hepatocellular carcinomas. Wild P53 downregurate cyclin a promoter activity

Backround: The p16 INK4a tumor suppressor gene induces a cell cycle G1 arrest. It is the second most commonly inactivated gene identified in human cancers after p53. The p16 gene has been shown to be inactivated in nearly all human colon cancer cell lines and half of colon cancers and adenomas. While the p16 gene has been demonstrated to be inactivated primarily by promoter DNA methylation in hepatocellular carcinomas, there have been no studies examining p16 expression in premalignant liver lesions . Design: 17 macroregenerative and dysplastic nodules and 2 hepatocellular carcinomas from 15 hepatectomy specimens in patients undergoing transplantation for hepatitis C cirrhosis were examined by immunohistochemistry and methylation sensitive polymerase chain reaction (PeR). The nodules were less than 2 cm in diameter and clinically undetected . Sections were stained with anti-human pl6 monoclonal antibody . Human sporadic colon adenocarcinomas served as positive controls . Staining for p16 was considered positive if nuclear staining was greater than cytoplasmic staining. Methylation sensitive PCR was performed on bisulfite-treated DNA extracted from microdissected paraffin sections. Results: No nuclear staining was detected in the macroregenerative or dysplastic nodules. Two nodules demonstrated weak cytoplasmic staining . The surrounding cirrhotic liver showed cytoplasmic and no nuclear staining . Bile ductules at the margins of the nodules showed positive staining and served as internal positive controls. The 2 hepatocellular carcinomas showed a distinct lack of nuclear or cytoplasmic staining. Negative controls lacked cytoplasmic and nuclear staining. One hepatocellular carcinoma and two macroregenerative nodules had methylated p16 gene promoters , while two of the surrounding cirrhotic liver samples had unmethylated pl6 gene promoters. One macroregenerative nodule also showed evidence of both methylated and unmethylated pl6 forms. Conclusions: In patients with hepatitis C, clinically undetected macroregenerative and dysplastic nodules show an absence of pl6 staining. It is likely that pl6 gene methylation is responsible for suppression ofpl6 expression in these nodules. This supports previous observations that a high percentage of hepatocellular carcinomas have inactive p16 genes and suggests that p16 inactivation occurs early in liver tumor progression.

A Case of Chronic Pancreatitis Associated with a Pancreato-gastric Fistula

Abstract: A 51‐year‐old man presented complaining of frequent diarrhea. An ultrasonography and abdominal CT scan revealed a tumor in the tail of the pancreas. An endoscopic retrograde pancreatography revealed contrast medium flowing over the pancreas through the main pancreatic duct. A balloon cathether was then passed into the pancreatic duct, and the scope alone was retracted to the stomach. Maintaining the stomach under endoscopic observation, ICG was injected through the balloon catheter, whereupon it was seen to flow out from two small depressions in the center of a small elevated lesion in the posterior wall of the upper gastric corpus. Based on these endoscopic findings, a diagnosis of chronic pancreatitis with an associated pancreato‐gastric fistula was made.