Use of Pistacia lentiscus mastic for sustained-release system of chlorocresol and benzoic acid for in vitro prevention of bacterial colonization of silicon urinary catheter.

Urinary tract infections (UTI) are among the most common types of nosocomial infections. Patients with indwelling urinary catheters are at the highest risk of getting infections. A sustained-release method of chlorocresol and benzoic acid using a varnish of Pistacia lentiscus mastic was developed to prevent catheter colonization by Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Pseudomonas aeruginosa. Coatings of both antiseptics significantly reduced the number of colonizing bacteria on silicon urinary catheters for 72 h. Chlorocresol-coated catheters were significantly (P ≤ 0·05) more effective than benzoic acid. Except for the Pr. mirabilis, chlorocresol completely inhibited the colonization of catheters by the tested bacteria for 48 h. Nonetheless, the colonization of catheters by Pr. mirabilis was significantly reduced after 48 and 72 h by more than 3·5 logs. Although benzoic acid failed to completely inhibit bacterial growth, it significantly reduced the colonization of the catheters by all the tested bacteria by more than two logs for 72 h. The inhibition of colonization of catheters was confirmed by examining the tested catheters by scanning electron microscopy. The obtained results indicate the potential benefits of using mastic as a varnish for sustaining the release of chlorocresol and benzoic acid to prevent and reduce the colonization of urinary catheters by bacteria.

In vitro effect of low concentrations of oltipraz on the antioxidant defence of mouse hepatocytes and Schistosoma mansoni worms.

The direct effects of oltipraz (OPZ) on mouse hepatocytes and Schistosoma mansoni worms are studied in vitro at a concentration range of 5-25 micromol/L following one- and three-hour incubations. Oxidative stress is reflected by increases in malondialdehyde (MDA), representing the end products of lipid peroxidation, and depletion of glutathione (GSH), representing protective thiol groups. Activities of glutathione peroxidase isoenzymes, GST and GR as components of antioxidative defence are also determined. The opposite effects of low concentrations of OPZ on mammalian hepatocytes and S. mansoni worms were confirmed. In incubation with S. mansoni, addition of OPZ resulted in significantly increased production of MDA, together with depletion of GSH, both of which were time- and OPZ concentration-dependent. In incubation with mouse hepatocytes, however, there was little change in MDA concentrations, and a gradual increase in GSH levels, both of which were time- and concentration-dependent. Addition of OPZ to the incubation media also affected the activities of antioxidant enzymes. Although total GPx activity increased in both mammalian hepatocyte and S. mansoni experiments, the opposite was noted with the selenium-dependent isoenzyme. While there was a gradual increase in sGPx in hepatocytes, there was a time- and concentration-dependent inhibition in the worm isoenzyme. Contrasting results were also obtained with GR. While increased activity was obtained with the enzyme from mouse hepatocytes, the worm enzyme was inhibited, especially at the upper end of the OPZ concentration range and also following longer periods of incubation. The increase in GST activity followed the same qualitative pattern in both hepatocytes and schistosomes. Therefore, OPZ given in doses that maintain a serum concentration in the range 5-25 micromol/L induces biochemical changes in mouse hepatocytes that could be utilised for chemo-preventive purposes and prevention of oxidative damage. However, progressive oxidative damage to S. mansoni worms occurred despite some protective biochemical changes.

Antioxidants as adjuvant therapy in rheumatoid disease. A preliminary study.

The aim of the present study was to assess the therapeutic value of adding a high dose of vitamin E or an antioxidant combination to the treatment regimen of the rheumatoid disease. The study was carried out on 30 patients with rheumatoid disease diagnosed according to the criteria of American Rheumatism Association (ARA), subvided into three equal groups. Patients in group I received a standard treatment of intramuscular methotrexate (CAS 59-05-2; 12.5 mg/week), oral sulphasalazine (CAS 599-79-1; 0.5 g b.i.d.) and indometacin (CAS 53-86-1; 100 mg suppository at bed-time). In group II the patients received the standard treatment plus a combination of antioxidants. Patients in group III received a high dose of vitamin E (400 mg t.i.d.) in addition to the standard treatment. The disease state was evaluated using Ritchle's articular score index and the duration of morning stiffness. Laboratory evaluations included the rheumatoid factor, erythrocyte sedimentation rate (ESR), plasma levels of vitamin E and malonedialdehyde (MDA), and the activity of glutathione peroxidase (GPx). In the group receiving the standard regimen, the patients started to feel tangible improvement by the end of the second month. With adjuvant therapy of either the antioxidant combination or a high dose of vitamin E the symptoms of arthritis were better controlled from the first month. By the end of the second month, the values of the three monitoring tests were significantly decreased indicating better control of the disease. The percentage increase in the activity of GPx was highest in patients taking the antioxidant combination and least in those taking the standard treatment. The decrease in plasma MDA followed the same pattern. With adjuvant therapy, the vitamin E level in plasma increased with the duration of treatment. The results obtained in the present study are encouraging. The clinical improvement and the shift in the disease indices towards normal make the use of antioxidants as adjuvant therapy in rheumatoid disease worth pursuing.

Multiple isoelectric forms of bacterial penicillin-binding proteins: artefacts or genuine cellular components?

Some bacterial penicillin-binding proteins (PBPs) are reported to exist as multiple isoelectric forms. Other PBPs were examined by two-dimensional electrophoresis to establish whether multiple isoelectric forms are widespread amongst PBPs. Bacillus subtilis PBPs 3 and 5 and Escherichia coli PBPs 1b alpha and 1b gamma focussed as discrete spots with no evidence of multiple isoforms. However, E. coli PBPs 1b beta and 4 displayed isoelectric variants. The results are discussed in relation to current models of bacterial peptidoglycan structure.

Prediction of signal sequence-dependent protein translocation in bacteria: assessment of the Escherichia coli minicell system.

The use of phenethyl alcohol (PEA) as a probe for signal sequence-dependent protein translocation in minicells was examined. Processing of beta-lactamases and tonA was inhibited by PEA at concentrations which did not affect production of the alpha and gamma forms of penicillin binding protein (PBP) lb. The PBPlbs are believed to lack leader sequences whereas the other proteins contain them. Processing of a beta-lactamase which shares the murein-lipoprotein export pathway was relatively resistant to PEA, consistent with previous findings in whole bacteria. The results reported here suggest that PEA is a suitable probe for leader sequences in the minicell system. By using PEA we predict that PBP4 does not require a leader sequence for membrane insertion.

Mutations affecting penicillin-binding proteins 2a, 2b and 3 in Bacillus subtilis alter cell shape and peptidoglycan metabolism.

Bacillus subtilis mutants with altered penicillin-binding proteins (PBPs), or altered expression of PBPs, were isolated by screening for changes in susceptibility to beta-lactam antibiotics. Mutations affecting only PBPs 2a, 2b and 3 were isolated. Cell shape and peptidoglycan metabolism were examined in representative mutants. Cells of a PBP 2a mutant (UB8521) were usually twisted whereas PBP 2b (UB8524) and 3 (UB8525) mutants produced helices, particularly after growth at 41 degrees C. The PBP 2a mutant (UB8521) had a higher peptidoglycan synthetic activity than its parent strain whereas the opposite applied to the PBP 2b mutant UB8524. The PBP 3 mutant (UB8525) had a similar peptidoglycan synthetic activity to that of the parent strain when grown at 37 degrees C, but 40% higher activity after growth at 41 degrees C. The PBP 2a mutant (UB8521) exhibited the same wall thickening activity as the parent, but the PBP 2b and 3 mutants (UB8524 and UB8525) were partially defective in this respect. The changes in the susceptibility of PBP 2a, 2b and 3 mutants to beta-lactam antibiotics imply that these PBPs are killing targets, consistent with the fact that these PBPs are also important for shape determination and peptidoglycan synthesis.