Synergistic effects of nisin and thymol on antimicrobial activities in Listeria monocytogenes and Bacillus subtilis.

Nisin Z and thymol were tested, alone and in combination, for antibacterial activity against Listeria monocytogenes ATCC 7644 and Bacillus subtilis ATCC 33712. The antibacterial effect of nisin Z, produced by Lactococcus lactis KE3 isolated from the traditional Moroccan fermented milk, was greatly potentiated by sub-inhibitory concentrations of thymol in both bacterial strains. Our data showed that the concentration of nisin required for effective control of food-borne pathogenic bacteria could be considerably lowered by the use of thymol in combination. The use of low concentrations of nisin could lead to a less favourable condition for the occurrence of nisin-resistant bacterial sub-populations.

Cellular pharmacology of lipophilic anthracyclines in human tumor cells in culture selected for resistance to doxorubicin.

We have studied the cytotoxicity and intracellular accumulation of two lipophilic anthracyclines, pirarubicin and idarubicin, as compared to doxorubicin, in two human tumor cell lines, MCF7 and K562, and in their doxorubicin-resistant counterparts, presenting the multidrug-resistant (MDR) phenotype. The new lipophilic anthracyclines were found to present a higher cytotoxicity and accumulation than the reference anthracycline, doxorubicin, and there was a significant inverse correlation between drug accumulation and IC50 in both cell types. With the aim of identifying the reasons for the higher cytotoxicity and accumulation of lipophilic anthracyclines, we used and compared the efficiency of three MDR modulators, verapamil, quinine and S-9788. We showed that all three were able to sensitize the resistant cells to the three anthracyclines, but with different efficiencies, S-9788 being the most active reverter and quinine the least active at equimolar doses. We also observed that there was no correlation between the abilities of a modulator to reverse resistance and to restore drug accumulation. In view of the sustained activity of the modulators to increase pirarubicin and idarubicin cytotoxicity and accumulation, as they do for doxorubicin, we conclude that the better efficiency of lipophilic anthracyclines is likely to be due to their high uptake rate rather than to a decreased activity of P-glycoprotein on these drug substrates.

Decreased faecal exoglycosidase activities identify a subset of patients with active Crohn's disease.

1. alpha 1-Proteinase inhibitor (alpha 1-antitrypsin) is excreted in a deglycosylated form (M(r) 38,000) in the faeces of healthy subjects and in patients with quiescent Crohn's disease. By contrast, in most patients with active Crohn's disease, alpha 1-proteinase inhibitor is excreted in a glycosylated form (M(r) 51,000). 2. Faecal extracts containing deglycosylated alpha 1-proteinase inhibitor are able to deglycosylate alpha 1-proteinase inhibitor by an exoglycosidic process. Conversely, we demonstrate that in faecal extracts from patients excreting glycosylated alpha 1-proteinase inhibitor, glycosidase activities, such as N-acetyl-beta-glucosaminidase (EC 3.2.1.30), alpha-mannosidase (EC 3.2.1.24) and particularly beta-galactosidase (EC 3.2.1.23), are strongly decreased. 3. Degradation of glycosidases by proteases could not explain the decreased glycosidase activity in these faecal extracts. 4. Our data suggest that a modification of the bacterial colonic flora (or of its metabolic activity) occurs in most patients with active Crohn's disease and could be responsible for an impaired colonic salvage of carbohydrates.

A simple method for the measurement of different forms of alpha 1 proteinase inhibitor in the faeces of patients with Crohn's disease.

Alpha-1 proteinase inhibitor (alpha 1PI), formerly named alpha 1-antitrypsin, is excreted in the faeces of patients with Crohn's disease as isoforms clearly separated by SDS-PAGE and immunoblot analysis. Relapses in Crohn's disease are generally associated with the appearance in faeces of M(rs) 51,000 and 45,000 glycosylated forms of alpha 1PI, as compared with normal subjects and most of the patients in quiescent phases of their disease who excrete an M(r) 38,000 unglycosylated form of alpha 1PI. We used their differential Concanavalin-A reactivity to design a specific test. The proposed assay is potentially helpful for the follow-up of patients under therapy and for early recognition of attacks of Crohn's disease.

Deglycosylation of alpha 1-proteinase inhibitor is impaired in the faeces of patients with active inflammatory bowel disease (Crohn's disease).

1. alpha 1-Proteinase inhibitor (alpha 1-antitrypsin) was excreted in the faeces of patients with inflammatory bowel disease in different molecular forms: Mr-51,000 and Mr-45,000 forms were widely found in the stools of patients with active disease, whereas a Mr-38,000 species was frequently recovered from healthy subjects and patients with quiescent disease (Mizon, Becuwe, Balduyck et al. Clin. Chem. 1988; 34, 2268-70). 2. N-Terminal sequencing of the Mr-38,000 form of alpha 1-proteinase inhibitor, after SDS/PAGE and electrotransfer on polyvinyl difluoride membranes, showed that it differed from plasma alpha 1-proteinase inhibitor by the loss of 17 N-terminal amino acids. 3. Carbohydrate analysis of the isolated Mr-38,000 form revealed a total lack of neutral sugars. 4. In contrast, the Mr-51,000 form of alpha 1-proteinase inhibitor is glycosylated and thus could be differentiated by virtue of its reactivity with concanavalin A. The analysis of 25 faecal extracts from patients with Crohn's disease allowed us to confirm that the presence of the glycosylated form of alpha 1-proteinase inhibitor was closely related to the degree of inflammation. 5. From these data, it may be hypothesized that the hydrolytic activity of some glycosidases is greatly reduced in active Crohn's disease.

Functional and immunoreactive alpha 1 proteinase inhibitor in bronchoalveolar lavages: methodological studies.

The functional activity of alpha 1 proteinase inhibitor (alpha 1PI) in bronchoalveolar lavages (BAL) was determined with an automated method, using its inhibitory capacity against porcine pancreatic elastase. Immunoreactive alpha 1PI was measured by immunonephelometry-laser (INL). These two methods may generally be applied on unconcentrated samples. Precision and accuracy of both methods are studied. INL was preferably used to electroimmunodiffusion (EID) because it gave unchanged values after alpha 1PI had reacted with proteases. In BAL, for some specimens, the alpha 1PI content evaluated by EID was underestimated with respect to its measurement by INL. The degree of underestimation is related to the presence of non-functional forms of alpha 1PI.