Background and aims-Injuries caused by ischaemia and ischaemia/reperfusion in the small intestine have been widely accepted as resulting in necrosis. The aim of this study was to ascertain whether apoptosis also occurs. Methods-Intestinal epithelium from rats subjected to ischaemia (15-90 minutes) and ischaemia/reperfusion (15 minutes ischaemia followed by 15-75 minutes of reperfusion) was studied using histological, immunohistochemical, and molecular biological methods as well as FACS. Results-Mucosal injury was induced by both ischaemia and ischaemia/reperfusion. Detachment of epithelial cells from the villous stroma was an early morphological change indicating mucosal injury. More than 80% of the detached cells exhibited characteristic morphological features of apoptosis (condensation of chromatin and nuclear fragmentation).The remainder demonstrated necrotic features. The apoptotic cells eventually underwent spontaneous degeneration with membrane rupture, a process morphologically identical to necrosis. DNA fragmentation was also confirmed by immunohistochemical methods and agarose gel electrophoresis. Conclusion-Apoptosis is a major mode of cell death in the destruction of rat small intestinal epithelial cells induced by ischaemia and ischaemia/reperfusion injury. Disruption of epithelial cell-matrix interactions ("anoikis") may play an important part in induction of apoptosis in detached enterocytes. (Gut 1998;42:530-537)

Strain CS526 was isolated from frozen surimi and identified as a bacteriocin producer that had strong inhibitory activity against Listeria monocytogenes. Strain CS526 was identified as Carnobacterium piscicola by partial 16S rDNA sequence similarity. The ability of this bacteriocinogenic strain and nonbacteriocinogenic C. piscicola JCM5348 to inhibit the growth of L. monocytogenes was examined in culture broth incubated at 12 degrees C and cold-smoked salmon stored at 4, 12, and 20 degrees C. L. monocytogenes viable counts in the culture broth rapidly declined from 10(6) colony-forming units per ml to less than 10 colony-forming units per ml within 1 day at 12 degrees C in the presence of C. piscicola CS526. At 4 and 12 degrees C, inhibition of L. monocytogenes on salmon depended on the initial inoculum level of C. piscicola CS526. However, C. piscicola CS526 was bactericidal to L. monocytogenes within 21 and 12 days at 4 and 12 degrees C in cold-smoked salmon, respectively, even when the initial inoculum levels were low. C. piscicola CS526 suppressed the maximum cell number of L. monocytogenes by two and three log cycles, even at 20 degrees C. However, C. piscicola JCM5348 did not prevent the growth of the pathogen, except at 4 degrees C. Bacteriocin was detected in the samples coinoculated with C. piscicola CS526. The study shows that C. piscicola CS526 might have potential for biopreservation of refrigerated foods against L. monocytogenes.

No abstract

The bacteriocin piscicocin CS526 was inactivated by proteolytic enzymes, was stable at 100°C for 30 min, had a pH range of 2 to 8, and was active against Enterococcus, Listeria, Pediococcus, and Leuconostoc. The N-terminal sequence was YGNGL, not the YGNGV consensus motif common in class IIa bacteriocins (alternate residues underlined). The molecular mass of piscicocin CS526, which had a bactericidal mode of action, was ϳ4,430 Da.Bacteriocins are ribosomally synthesized proteins that inhibit bacteria closely related to the producer strain, food-borne pathogens, and spoilage bacteria (12,18). Carnobacterium piscicola CS526 inhibits Listeria monocytogenes growth in coldsmoked salmon (21). Several bacteriocin-producing carnobacteria have been reported (1,4,10,11,13,17). The objectives of this study were to purify and characterize piscicocin CS526.Preliminary characterization of the bacteriocin. To determine the effects of enzymes on the bacteriocin, the cell supernatants (180 l) of the culture neutralized with NaOH were incubated with 20 l of enzyme solutions (10 mg/ml in 50 mM phosphate buffer [pH 7.0]) at 35°C for 1 h. After boiling for 5 min, the residual activity was determined by the agar well diffusion assay (21). The inhibitory activity was completely destroyed by ␣-chymotrypsin, papain, proteinase K, and actinase and partly inhibited by trypsin (67% of residual activity). Other enzymes, such as catalase, RNase, and lipase, did not affect the activity.To determine the thermal stability, the cell supernatant of the neutralized culture was heated for 15 or 30 min at 70, 80, 90, 100, and 121°C and then assayed for activity. The inhibitory activity was completely stable after 30 min at 100°C but was partially inactivated at 121°C for 15 min (44% of residual activity).To determine the effect of pH on bacteriocin activity, 50 l of the cell supernatant was added to 950 l of tryptic soy broth with 0.6% yeast extract (TSBYE) adjusted with NaOH or HCl to different pH values. The samples were assayed for activity after 1 h at 25°C. The activity was completely stable at pH 2 to 8 but reduced at pH values of 9 to 11 (67, 44, and 30% of residual activity at pH 9, 10, and 11, respectively).The antagonistic effect of cell supernatant of an overnight culture of CS526 in TSBYE against 27 strains of gram-positive bacteria and 6 strains of gram-negative bacteria was determined by the agar well diffusion assay. Enterococcus faecalis JCM8726, Enterococcus faecium JCM8727, Enterococcus durans JCM8725, Enterococcus hirae JCM8729, Pediococcus pentosaceus JCM5890, Tetragenococcus halophilus JCM5888, and Leuconostoc mesenteroides subsp. mesenteroides JCM6124 were inhibited. L. monocytogenes IID578 and IID581, Listeria innocua FTHU8221, and Listeria grayi subsp. murrayi FTHU204 were also inhibited. Gram-positive spore-forming bacteria (Bacillus cereus JCM2152, Bacillus subtilis IFO13719, Bacillus megaterium IAM13418, Bacillus licheniformis IFO12107, Bacillus sphaericus IAM13420, and Paenibacillus polymyxa JCM2507) and gram-negative bac...

Abstract. The normal pancreas has an abundant blood flow, in contrast to pancreatic cancer, which is a hypovascular tumor. During hypoxia under a hypovascular environment, the transcription factor hypoxia-inducible factor-1α (HIF-1α) is activated. High HIF-1α expression reduces sensitivity to gemcitabine (GEM) which is used as a treatment for pancreatic cancer. The objective of this study was to clarify HIF-1α expression in pancreatic cancer and the association of its effects to GEM treatment. We used the human pancreatic ductal carcinoma cell lines AsPC-1 and BxPC-3 to evaluate cell proliferation, HIF-1α protein expression and sensitivity to GEM in a hypoxic environment of 1% O 2 in 48 pancreatic cancer patients who received adjuvant GEM treatment after pancreatectomy. We divided the patients according to HIF-1α expression and the presence of single nucleotide polymorphisms, and we based our evaluation on the adverse events associated with GEM chemotherapy and patient outcome. The hypoxic environment promoted cell proliferation, induced HIF-1α expression and increased GEM resistance, especially in AsPC-1 cells, which included a mutant homozygote for HIF-1α(C1772T). There were no significant differences between the HIF-1α(-) and HIF-1α(+) groups in either adverse events or patient outcomes. HIF-1α enhanced neo-microvascularity in a hypoxic environment and increased drug resistance. The period until recurrence was shorter in the patients with a strong HIF-1α expression, than that in those with a weak HIF-1α expression.