Multidrug transporters in lactic acid bacteria

Gram-positive lactic acid bacteria possess several Multi-Drug Resistance systems (MDRs) that excrete out of the cell a wide variety of mainly cationic lipophilic cytotoxic compounds as well as many clinically relevant antibiotics. These MDRs are either proton/drug antiporters belonging to the major facilitator superfamily of secondary transporters or ATP-dependent primary transporters belonging to the ATP-binding cassette superfamily of transport proteins. Here we summarize the existing data on these MDRs and discuss recent observations that suggest the use of new strategies in the ongoing battle against drug-resistant microbial pathogens.     

Radioprotective effect of amifostine on parotid gland functioning is region dependent

PURPOSE: To investigation the protective ability of amifostine during partial irradiation of the rat parotid gland. METHODS AND MATERIALS: Single-dose X-ray irradiation was performed by use of collimators with conformal radiation portals for either the 100% volume (15 Gy) or the 50% cranial/caudal partial parotid gland volumes (30 Gy). Amifostine was administered intraperitoneally at a dose of 250 mg per kg body weight, 25 minutes before irradiation. Saliva flow rates, gland weights, and the tissues of the individual lobes were investigated up to 1 year after treatment. RESULTS: A clear protective effect of amifostine was found against loss of saliva flow, the altered appearance of gross morphology, loss of gland weight, and histopathologic changes for the 100% volume gland irradiations and for the 50% volume cranial irradiations but not for the 50% volume caudal irradiations. CONCLUSIONS: The protective ability of amifostine is strongly dependent on the irradiated glandular region and observed for later damage only. The major effect of the drug seems to be the prevention of volume effects caused by secondary damage that occurs in shielded parts of the gland. The results of the present study show that understanding of the anatomy and physiology of organs that are to be spared is necessary to ensure optimal preservation of function.     

A novel protein antigen of the malaria parasite Plasmodium falciparum, located on the surface of gametes and sporozoites

A Plasmodium falciparum cDNA clone was isolated of which the insert is transcribed at high rates as a 1.4-kb mRNA in the sexual stages of the malaria parasite. The cDNA clone contains a copy of a non-interrupted gene which codes for a protein of 157 amino acids (Mr = 16607). This 16-kDa protein does not contain repetitive sequences and is characterised by a putative N-terminal signal sequence, a hydrophobic membrane anchor sequence and a highly hydrophilic C-terminal region suggesting that it is an integral membrane protein. Rabbit antisera raised against a synthetic peptide covering amino acids 31-47 of the 16-kDa protein and against recombinant fusion proteins recognised the 16-kDa antigen in protein extracts of gametocytes, macrogamete/zygotes and sporozoites by Western blot analysis. The rabbit antisera also reacted with gametes, gametocytes and sporozoites in a standard immunofluorescence assay. By immunoelectron microscopy using the protein A-gold method the 16-kDa protein could be clearly visualised on the surface of macrogametes and sporozoites, whereas the antigen was not detectable in the asexual erythrocytic stages of the parasite. The 16-kDa antigen of P. falciparum therefore might have the potential to elicit a dual protective immune response against the sporozoite and sexual stage parasites.     

Development of thermotolerance in mouse fibroblast LM cells with modified membranes and after procaine treatment

Mouse fibroblast LM cells have been modified with respect to the content of polyunsaturated fatty acyl (PUFA) chains of the membrane phospholipids. The membranes of the modified cells were enriched in PUFA chains and were more fluid as compared to the normal cells, as judged by fluorescence polarization measurements. The thermosensitivity of the PUFA-substituted cells was enhanced. Thermotolerance in the PUFA-substituted fibroblasts could be induced to the same extent as in the nonsubstituted cells. The thermosensitivity in both the PUFA and the nonsubstituted fibroblasts could be enhanced by the treatment of procaine. Procaine could inhibit the triggering as well as the induction of thermotolerance. It is supposed that the mechanism of heat sensitization by procaine is different from the mechanism of preventing thermotolerance induction. The clinical implications of this finding are discussed.