Locoregional mitomycin C injection for esophageal stricture after endoscopic submucosal dissection.

This prospective study aimed to evaluate the feasibility and safety of locoregional mitomycin C (MMC) injection to treat refractory esophageal strictures after endoscopic submucosal dissection (ESD) for superficial esophageal carcinoma. Patients with dysphagia and strictures that were refractory to repeated endoscopic balloon dilation (EBD) were eligible. After EBD, MMC was injected into the dilated site. Between June 2009 and August 2010, five patients were recruited. The treatment was performed once in two patients and twice in three patients with recurrent dysphagia or restenosis. In all patients, passing a standard endoscope through the site was easy and the dysphagia grade improved (grade 3→1 in 3 patients, grade 4→2 in 2 patients). No serious complications were noted. During the observation period of 4.8 months, neither recurrent dysphagia nor re-stricture appeared in any of the patients. The combination of locoregional MMC injections and EBD is feasible and safe for the treatment of esophageal strictures after ESD.Recently, endoscopic submucosal dissection (ESD) has been developed and accepted as a new endoscopic treatment for gastrointestinal tumors. ESD is a promising treatment for superficial esophageal carcinoma (SEC), and it has a reliable en bloc resection rate. However, the application of ESD for widespread lesions is challenging because of the high risk of the development of severe strictures, which lead to a low quality of life after ESD. Although endoscopic balloon dilation (EBD) is effective for benign strictures, it needs to be performed frequently until the dysphagia disappears 1. Mitomycin C (MMC), which is a chemotherapeutic agent derived from some Streptomyces species 2, reduces scar formation when topically applied to a surgical lesion. MMC has been applied to treat strictures in a variety of anatomical locations, including a variety of organs 3. The aim of this study was to prospectively evaluate both the feasibility and the safety of locoregional MMC injection therapy in patients with refractory esophageal strictures after ESD for SEC.

Formation of platelet-activating factor-like phospholipids by Fe2+/ascorbate/EDTA-induced lipid peroxidation.

We have identified novel phospholipids together with platelet-activating factor and its 1-acyl analogues in purified fractions from a bovine brain lipid extract. These novel compounds were phospholipids with an sn-2-short-chain monocarboxylyl, dicarboxylyl or omega-hydroxymonocarboxylyl group. The profiles of these three types of phospholipids suggest that they were formed by lipid peroxidation. To examine this possibility, we peroxidized synthetic phosphatidylcholines (PC) with an sn-2-polyunsaturated fatty acyl group and PC from bovine brain, with Fe2+/ascorbate/EDTA, and analyzed the secondary degradation products retaining a glycerol backbone by fast atom bombardment-mass spectrometry and GC-MS. Results showed the formation of four kinds of PC with a short-chain monocarboxylate, dicarboxylate, dicarboxylate semialdehyde or omega-hydroxymonocarboxylate moiety. The chain lengths of these PC were related to the position of the double bond vicinal to the esterified carbonyl group in the sn-2-long-chain acyl moiety of the parent PC. The molecular heterogeneity of secondary products formed by the oxidative degradation of bovine brain PC resembled those of the unique phospholipids that we previously detected in the fractions with platelet-activating factor-like activity purified from a bovine brain lipid extract, although the former lacked the species with an acetyl group. These results suggest that all the novel phospholipids with a short-chain acyl group in the brain lipid extract except that with an acetyl group were produced by lipid peroxidation.

Exogenous phosphatidic acid with saturated short-chain fatty acyl groups induces superoxide anion release from guinea pig peritoneal polymorphonuclear leukocytes by three different mechanisms.

Treatment of suspensions of guinea pig peritoneal polymorphonuclear leukocytes (PMN) with four species of phosphatidate (PA) containing short-chain fatty acids induced sustained superoxide anion (O2-) production after a lag time. The rank order of efficiency of these PAs in triggering O2- production was PA8:0 [1,2-dioctanoyl-sn-glycerol-3-phosphate (GP)] > PA10:0 (1,2-didecanoyl-GP) > PA6:0 (1,2-dicaproyl-GP) > > PA12:0 (1,2-dilauroyl-GP). The O2- release from PMN stimulated with PA10:0 or PA12:0, but not with PA6:0 or PA8:0, was lowered by the addition of 1 mM extracellular Ca2+. Studies with various inhibitors showed that the mechanism of multiphasic O2- production induced by PA8:0 depended on its concentration: 1 and 3 microM PA8:0 induced O2- production constantly after a lag time through a protein kinase-dependent mechanism that was inhibited by 100 nM staurosporine. With concentrations of PA of 10 microM or more, an additional mechanism that was independent of protein kinase became operative and predominant over the protein kinase-dependent one. This protein kinase-independent mechanism was inhibited selectively by 80 microM TMB-8. Concentrations of 30, 60 and 100 microM PA first elicited transient O2- production via another protein kinase-dependent mechanism that was more sensitive to H-7 than to staurosporine, and then sustained O2- production, mainly driven by the protein kinase-independent mechanism. Metabolism of exogenously added [14C]PA8:0 in intact PMN was examined in the presence and absence of propranolol. Results suggest that PA itself is more important rather than its degradation products such as diacylglycerol, in inducing O2- production via three different mechanisms described above.

Effective use of rabbit gastric antral mucosal slices in prostaglandin synthesis and metabolism studies.

Intact slice preparations of rabbit stomach (antral mucosa, corporal mucosa, antral muscle and corporal muscle) were incubated and the released prostaglandins (PGs) were measured by reverse-phase high-performance liquid chromatography using 9-anthryldiazomethane for derivatization. With respect to total PG production, the highest amounts were generated by antral mucosal slices. Antral mucosal slices produced PGE2, 6-keto PGF1 alpha, thromboxane B2, PGF2 alpha and PGD2 (in descending order of magnitude) and possessed a high capacity for producing 13,14-dihydro-15-keto derivatives of both PGE2 and PGF2 alpha. Studies utilizing aspirin, EGTA or Ca2+ revealed that PG release by antral mucosal slices in the present in vitro system reflects a composite of the activities of phospholipase A3, PG cyclooxygenase and PG-metabolizing enzymes. These results show that antral mucosal slices will be useful in physiological and pharmacological studies on PG synthesis and metabolism of the stomach.

Secretory expression of the human serum albumin gene in the yeast, Saccharomyces cerevisiae.

We have fused a cDNA gene encoding mature human serum albumin (HSA) to several secretory leader-encoding sequences. The hybrid genes were cloned into an episomal vector under the control of several yeast promoters and then introduced into yeast cells. The GAL1 promoter in combination with either the native HSA pre-sequence or a modified HSA pre-sequence gave the highest production of immunoreactive HSA, 90 mg/liter being reached in a shake flask culture. The invertase pre-sequence, the mating factor alpha 1 prepro-sequence, and the modified HSA pre-sequence directed accurate processing. In contrast, the chicken lysozyme pre-sequence and the native HSA pre-sequence directed incorrect processing. Episomal vectors were unstable within the host cells under non-selective culture conditions. To improve the plasmid stability, the hybrid genes were incorporated into an integrative vector. Transformants carrying multicopies of the plasmid integrated at the LEU2 locus stably secreted HSA. The highest yield of 65 mg/liter in a shake flask culture was obtained with the combination of the yeast glyceraldehyde-3-phosphate dehydrogenase promoter and the modified HSA pre-sequence. By constructing transformed strains containing multicopies of plasmids integrated at both the chromosome LEU2 and HIS4 loci, we have obtained a stable strain that continuously secretes as much as 85 mg HSA per liter of culture medium.