Short-term outcome after neoadjuvant high-dose-rate endorectal brachytherapy or short-course external beam radiotherapy in resectable rectal cancer.

AIM: Total mesorectal excision with preoperative radiotherapy reduces local recurrence in rectal cancer, but radiotherapy increases the risk of complications. This study compared the immediate postoperative outcome after external beam radiotherapy with outome after high-dose-rate endorectal brachytherapy (HDREBT). METHOD: Patients (n = 318) treated with preoperative HDREBT (6.5 Gy, daily, over 4 days) followed by surgery 4-8 weeks later were matched with 318 patients from the Swedish Rectal Cancer Register treated with short-course radiotherapy (SCRT; 5 Gy, daily, over 5 days) and surgery in the subsequent week and with 318 patients who had surgery only (i.e. no preoperative radiotherapy; RT-) All 954 patients were followed for 30 days after surgery. Complications were divided into surgical, cardiovascular and infectious. RESULTS: The SCRT group had fewer cardiovascular complications (3.1%) than did HDREBT (9.4%, P = 0.002) and RT- (7.2%, P = 0.03) groups. There was less perioperative bleeding in HDREBT patients (379.3 ml) than in SCRT (947.2 ml; P < 0.0001) or RT- (918.9 ml) patients, and the re-intervention rate was lower in HDREBT (4.1%) patients than in SCRT (14.2%; P = 0.005) and RT- (12.3%; P < 0.005) patients. The HDREBT group had fewer R2 resections than did the SCRT and RT- groups, but had a higher proportion of R0 resections compared with the RT- group (P = 0.03). CONCLUSION: No major differences in postoperative complications were found. HDREBT patients had a higher rate of cardiovascular complications, but less perioperative bleeding and fewer re-interventions. A longer interval between radiotherapy and surgery may be beneficial for tumour regression and this could be reflected in the number of radical resections.

Characterization and purification of mesentericin Y105, an anti-Listeria bacteriocin from Leuconostoc mesenteroides.

A Leuconostoc mesenteroides ssp. mesenteroides was isolated from goat's milk on the basis of its ability to inhibit the growth of Listeria monocytogenes. The antimicrobial effect was due to the presence in the culture medium of a compound, named mesentericin Y105, excreted by the Leuconostoc mesenteroides Y105. The compound displayed known features of bacteriocins from lactic acid bacteria. It appeared as a proteinaceous molecule exhibiting a narrow inhibitory spectrum limited to genus Listeria. The apparent relative molecular mass, as indicated by activity detection after SDS-PAGE, was 2.5-3.0 kDa. The bacteriocin was purified to homogeneity by a simple three-step procedure: a crude supernatant obtained from an early-stationary-phase culture in a defined medium was subjected to affinity chromatography on a blue agarose column, followed by ultrafiltration through a 5 kDa cut-off membrane, and finally by reverse-phase HPLC on a C4 column. Microsequencing of the pure bacteriocin and of tryptic fragments showed that mesentericin Y105 is a 36 amino acid polypeptide whose primary structure is close to that of leucocin A-UAL 187, which contains an extra residue at the C-terminus and displays only two differences in the overlapping sequence. However, unlike leucocin A-UAL 187, mesentericin Y105 displayed a bactericidal mode of action.

On-line visualization of the competitive behavior of antagonistic bacteria.

To study the interaction between cocultured Listeria monocytogenes and an antagonistic Leuconostoc strain producing an anti-Listeria bacteriocin, flow cytometry, a technique allowing on-line and real-time analysis, was used along with classical microbiological methods. Culture methods and flow cytometric measurements of the mixed culture over time point to a bactericidal action of the lactic acid-producing bacterial strain against L. monocytogenes cells.

Lysogenic strains of lactic Acid streptococci and lytic spectra of their temperate bacteriophages.

A total of 113 strains of mesophilic strains lactic streptococci of the species Streptococcus lactis, S. lactis subsp. diacetilactis, and S. cremoris, chosen from 291 strains that had been previously classified into six groups on the basis of their sensitivity to 132 virulent phages, were subjected to induction with mitomycin C. Among these strains, 43% produced phages capable of forming plaques of lysis on an indicator strain either spontaneously or after induction. There was a close correlation between the lytic spectra of temperate and virulent phages. Among the strains studied, 25% were shown to be indicator strains. These results emphasized the high probability of development of temperate phages in a starter culture containing mesophilic lactic streptococci and therefore their importance as a cause of accidents in cheese making.

Localization of active microorganisms in cheese by autoradiography.

By using an autoradiographic technique, one can follow, during ripening of a cheese, the distribution, size, and metabolic activity of microcolonies. Fragments of cheese were labeled with [H]leucine, fixed, and mounted in epoxy resin. After exposure and development, sections were examined by optical microscopy. In Camembert cheese, bacterial microcolonies synthesized protein rapidly during the beginning of the ripening process. At the end of the ripening process, active bacterial clusters were scarcer and of two types: (i) large microcolonies with reduced labeling, and (ii) microcolonies having the same size as those observed at the beginning of the ripening process, but with slight or no labeling.

Autoradiographic study of the localization and evolution of growth zones in bacterial colonies.

Incorporation of [3H]leucine in the bacteria of 18 to 48 h-old colonies of Pseudomonas aeruginosa, Pseudomonas putida, Bacillus thuringiensis, Staphylococcus aureus and Escherichia coli enabled the localization of bacterial multiplication sites by means of autoradiography of sagittal sections. In colonies where fast diameter expansion occurred, all the bacteria from the peripheral corona contributed to peripheral growth; in colonies where the expansion was slower, the growth rate of the bacteria in this region was heterogeneous. Besides this peripheral growth, a central region of bacterial multiplication was always found, but with variable localization and extension. In aerobic species, such as P. aeruginosa and P. putida, the central growth site was limited to the zone of oxygen penetration into the bacterial mass. However, in facultatively anaerobic species, bacterial multiplication dependend on nutrient supply. For 48 h-old colonies of S. aureus, a more complex localization of growth seemed to be affected simultaneously by nutrient penetration and accumulation of toxic substances.

[Autoradiographic study of a bacterial colony. Application to the effects of polymyxin on Pseudomonas aeruginosa colonies]. / Etude autoradiographique de la colonie bactérienne. Application aux effets de la polymyxine sur la colonie de Pseudomonas aeruginosa

The autoradiograph of a colony of Ps. a. which has been transferred, during growth, on a medium added with polymyxin and tritiate leucin makes it possible to locate an upper zone with a high metabolic activity and a basal zone with no metabolic activity. The latter, which consists of lysed cells, acts probably as a selective filter against the drug.