Stimulation of in vitro angiogenesis by hydrogen peroxide and the relation with ETS-1 in endothelial cells.

The purpose of this study was to examine the effect of hydrogen peroxide (H2O2) on angiogenesis in cultured endothelial cells. Endothelial cells obtained from bovine thoracic aorta (BAECs) were cultured between two layers of collagen type I to measure the tube formation which is a marker for angiogenesis. Addition of H2O2 (0.1-10 microM) to endothelial cells for various periods increased the rate of tube formation. The maximum stimulation of the tube formation was obtained when cells were exposed to 1 microM H2O2 for 30 min, and the enhancement of tube formation was blocked by catalase (10 U/ml). Both proliferation and migration of BAEC which are known to affect angiogenesis, were also stimulated by the addition of H2O2 (0.1 and 1 microM). Thus relatively low concentrations of H2O2 stimulated angiogenesis, proliferation and migration. Ets-1 is a member of the ets gene family of transcription factors, which binds to the ets binding motif in the cis-acting elements and regulates the expression of certain genes such as proteases including urokinase plasminogen activator (u-PA) and matrix metalloproteinase-1 (MMP-1). Interestingly, H2O2 increased the ets-1 mRNA level in BAECs compared with the basal level. The H2O2-stimulated angiogenesis was completely blocked by an ets-1 antisense oligonucleotide, but not by a mismatched oligonucleotide. These findings indicate that low concentrations of H2O2 stimulate angiogenesis in BAECs, and the stimulation mechanisms may partially involve the enhancement of proliferation and migration. Moreover, the H2O2-induced angiogenesis is likely to be mediated by the transcription factor ets-1.

[Biological characters of enterohemorrhagic Escherichia coli isolates from diarrhea patients in Saitama (1990-1992)].

A total of 16 strains of Enterohemorrhagic Escherichia coli (EHEC) isolated from diarrea patients in Saitama from 1990 to 1992 were tested for their serotype, verotoxin production, biochemical characteristics, antibiotics sensitivity and plasmid profiles. By serotype analysis, 14 strains from two outbreaks and 12 sporadic cases were classified as type O157:H7, one as O111:H-(not motility) and one as O128:H2. Typing of verotoxin by gene analysis using Polymerase Chain Reaction (PCR) showed that 9 of O157:H7 strains including two cases from outbreaks and O128:H2 have VT1 and VT2 genes, other O157:H7 have the VT2 gene and O111:H-has only the VT1 gene. Biochemical characteristic analysis indicated two strains of O157:H7 type from outbreaks were biotype II and the rest of O157:H7 were biotype I. One of the O157:H7 strain from a sporadic case showed positive for urease production. According to sensitivity tests against antibiotics, out of the O157:H7 group, one strain was resistant against ABPC, one against SM and two strains resistant to SM-TC. For plasmid profiles, all strains had 94 Kb plasmids and several smaller sizes of plasmids. But 5 strains of O157:H7 had 94 Kb plasmid only.

[The first report of traveler's diarrhea associated with a newly described toxigenic Vibrio cholerae O139 strain in Japan].

A newly described Vibrio cholerae O139 was isolated from a patient who had traveled in India on April 1993. The patient experienced 5 to 6 watery diarrhea per day after he returned to Japan. The isolated strain registered as K111 did not agglutinate with O1-O138 antiserum and agglutinated with O139 antiserum. This strain resembled V. cholerae O1 strain in biochemical characters and had ctx and zot, although was resistant to the vibrio static agent O/129. This is the first report of cholera-like illness by the newly described toxigenic V. cholerae O139 strain in Japan.