Hop resistance in the beer spoilage bacterium Lactobacillus brevis is mediated by the ATP-binding cassette multidrug transporter HorA.

Lactobacillus brevis is a major contaminant of spoiled beer. The organism can grow in beer in spite of the presence of antibacterial hop compounds that give the beer a bitter taste. The hop resistance in L.

An ABC-type multidrug transporter of Lactococcus lactis possesses an exceptionally broad substrate specificity.

LmrA is a 590-amino acid membrane protein which confers multidrug resistance on Lactococcus lactis cells by extruding amphiphilic compounds from the inner leaflet of the cytoplasmic membrane at the expense of ATP hydrolysis. Its structural and functional characteristics place it in the P-glycoprotein cluster of the ATP-binding cassette transporter superfamily, making it the first prokaryotic multidrug transporter of this cluster. The number of compounds recognized and transported by LmrA is remarkably vast and includes many lipophilic cations as well as a record of eight classes of clinically relevant broad-spectrum antibiotics.

Activation by gene amplification of pitB, encoding a third phosphate transporter of Escherichia coli K-12.

Two systems for the uptake of inorganic phosphate (P(i)) in Escherichia coli, PitA and Pst, have been described. A revertant of a pitA pstS double mutant that could grow on P(i) was isolated. We demonstrate that the expression of a new P(i) transporter, PitB, is activated in this strain by a gene amplification event.

Towards the molecular mechanism of prokaryotic and eukaryotic multidrug transporters.

Due to their ability to extrude structurally dissimilar cytotoxic drugs out of the cell, multidrug transporters are able to reduce the cytoplasmic drug concentration, and, hence, are able to confer drug resistance on human cancer cells and pathogenic microorganisms. This review will focus on the molecular properties of two bacterial multidrug transporters, the ATP-binding cassette transporter LmrA and the proton motive force-dependent major facilitator superfamily transporter LmrP, which each represent a major class of multidrug transport proteins encountered in pro- and eukaryotic cells. In spite of the structural differences between LmrA and LmrP, the molecular bases of their drug transport activity may turn out to be more similar than might currently appear.

Multidrug transport by ATP binding cassette transporters: a proposed two-cylinder engine mechanism.

The elevated expression of ATP binding cassette (ABC) multidrug transporters in multidrug-resistant cells interferes with the drug-based control of cancers and infectious pathogenic microorganisms. Multidrug transporters interact directly with the drug substrates. This review summarizes current insights into the mechanism(s) by which ATP hydrolysis is coupled to drug transport in bacterial LmrA and its human homolog P-glycoprotein.

Multidrug transporters in prokaryotic and eukaryotic cells: physiological functions and transport mechanisms.

Multidrug transporters mediate the extrusion of structurally unrelated drugs from prokaryotic and eukaryotic cells. As a result of this efflux activity, the cytoplasmic drug concentration in the cell is lowered to subtoxic levels and, hence, cells become multidrug resistant. The activity of multidrug transporters interferes with the drug-based control of tumours and infectious pathogenic microorganisms.

Extramedullary plasmacytoma of the breast simulating breast cancer.

A patient with a palpable mass in the breast suggestive of carcinoma underwent radical modified mastectomy. Surprisingly, histology of the tumor revealed an extramedullary plasmacytoma. Further diagnostic work up showed no evidence of underlying multiple myeloma.

Molecular basis of multidrug transport by ATP-binding cassette transporters: a proposed two-cylinder engine model.

ATP-binding cassette multidrug transporters are probably present in all living cells, and are able to export a variety of structurally unrelated compounds at the expense of ATP hydrolysis. The elevated expression of these proteins in multidrug resistant cells interferes with the drug-based control of cancers and infectious pathogenic microorganisms. Multidrug transporters interact directly with the drug substrates.

Velocity constancy in a virtual reality environment.

During everyday life the brain is continuously integrating multiple perceptual cues in order to allow us to make decisions and to guide our actions. In this study we have used a simulated (virtual reality--VR) visual environment to investigate how cues to speed judgments are integrated. There are two sources that could be used to provide signals for velocity constancy: temporal-frequency or distance cues.

Role of nitric oxide in the airway response to exercise in healthy and asthmatic subjects.

A role of nitric oxide (NO) has been suggested in the airway response to exercise. However, it is unclear whether NO may act as a protective or a stimulatory factor. Therefore, we examined the role of NO in the airway response to exercise by using N-monomethyl-L-arginine (L-NMMA, an NO synthase inhibitor), L-arginine (the NO synthase substrate), or placebo as pretreatment to exercise challenge in 12 healthy nonsmoking, nonatopic subjects and 12 nonsmoking, atopic asthmatic patients in a double-blind, crossover study.

Secondary and tertiary structure changes of reconstituted LmrA induced by nucleotide binding or hydrolysis. A fourier transform attenuated total reflection infrared spectroscopy and tryptophan fluorescence quenching analysis.

LmrA, a membrane protein of Lactococcus lactis, extrudes amphiphilic compounds from the inner leaflet of the cytoplasmic membrane, using energy derived from ATP hydrolysis. A combination of total reflection Fourier transform infrared spectroscopy, (2)H/H exchange, and fluorescence quenching experiments was used to investigate the effect of nucleotide binding and/or hydrolysis on the structure of LmrA reconstituted into proteoliposomes. These measurements allowed us to describe secondary structure changes of LmrA during the catalytic cycle.

Molecular properties of bacterial multidrug transporters.

One of the mechanisms that bacteria utilize to evade the toxic effects of antibiotics is the active extrusion of structurally unrelated drugs from the cell. Both intrinsic and acquired multidrug transporters play an important role in antibiotic resistance of several pathogens, including Neisseria gonorrhoeae, Mycobacterium tuberculosis, Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa, and Vibrio cholerae. Detailed knowledge of the molecular basis of drug recognition and transport by multidrug transport systems is required for the development of new antibiotics that are not extruded or of inhibitors which block the multidrug transporter and allow traditional antibiotics to be effective.

Cholic acid is accumulated spontaneously, driven by membrane deltapH, in many lactobacilli.

Many lactobacilli from various origins were found to apparently lack cholic acid extrusion activity. Cholic acid was accumulated spontaneously, driven by the transmembrane proton gradient. Accumulation is a newly identified kind of interaction between intestinal microbes and unconjugated bile acids and is different from extrusion and modification, which have been described previously.

Tissue damage after single high-dose intraoperative irradiation of the canine liver: evaluation in time by means of radionuclide imaging and light microscopy.

To establish the tolerance of liver tissue to single high-dose intraoperative irradiation, the histopathological changes in the canine liver after single high-dose intraoperative irradiation were investigated by means of radionuclide imaging and light microscopy. Intraoperative irradiation at doses of 0, 10, 20, 25 or 30 Gy was applied to a part of the liver of 25 beagles. Radionuclide imaging using (99m)Tc-sulfur colloid was performed at several times during follow-up.

Cholate resistance in Lactococcus lactis is mediated by an ATP-dependent multispecific organic anion transporter.

The cholate-resistant Lactococcus lactis strain C41-2, derived from wild-type L. lactis MG1363 through selection for growth on cholate-containing medium, displayed a reduced accumulation of cholate due to an enhanced active efflux. However, L.

Dysphagia lusoria: clinical aspects, manometric findings, diagnosis, and therapy.

Objective: The lusorian artery is a rare anomaly of the right subclavian artery. This artery arises from the aortic arch distal of the left subclavian artery, crossing the midline behind the esophagus. Normally this anomaly causes no symptoms.

The homodimeric ATP-binding cassette transporter LmrA mediates multidrug transport by an alternating two-site (two-cylinder engine) mechanism.

The bacterial LmrA protein and the mammalian multidrug resistance P-glycoprotein are closely related ATP-binding cassette (ABC) transporters that confer multidrug resistance on cells by mediating the extrusion of drugs at the expense of ATP hydrolysis. The mechanisms by which transport is mediated, and by which ATP hydrolysis is coupled to drug transport, are not known. Based on equilibrium binding experiments, photoaffinity labeling and drug transport assays, we conclude that homodimeric LmrA mediates drug transport by an alternating two-site transport (two-cylinder engine) mechanism.

Molecular pharmacological characterization of two multidrug transporters in Lactococcus lactis.

The active extrusion of cytotoxic compounds from the cell by multidrug transporters is one of the major causes of failure of chemotherapeutic treatment of tumor cells and of infections by pathogenic microorganisms. A multidrug transporter in Lactococcus lactis, LmrA, is a member of the ATP-binding cassette superfamily and a bacterial homolog of the human multidrug resistance P-glycoprotein. Another multidrug transporter in Lactococcus lactis, LmrP, belongs to the major facilitator superfamily, and is one example of a rapidly expanding group of secondary multidrug transporters in microorganisms.

Recent developments in the biochemistry and ecology of enhanced biological phosphorus removal.

Most of the genes encoding the enzymes involved in polyP synthesis and degradation and in phosphate transport have been studied in various Gram-negative bacteria. Progress has also been made in studying the biochemical mechanisms underlying the process of enhanced biological phosphorus removal (EBPR), in particular in lab-scale systems fed with acetate or acetate plus glucose as the sole carbon and energy sources. By applying 13C-NMR, previous models concerning anaerobic carbon metabolism have been advanced and the role of glycogen in providing reducing equivalents in EBPR is definitely demonstrated.

Coating of coverslips with glow-discharged carbon promotes cell attachment and spreading probably due to carboxylic groups.

Background: For high-resolution microscopy, cells have to be analyzed through thin glass coverslips. Therefore, it is necessary to culture cells on coverslips for preservation of cell morphology. We found cell attachment and spreading to be relatively slow processes, even when cells were plated on coated coverslips.

A scanning electron microscopic study of biliary stent materials.

Background: Clogging of biliary stents remains an important problem. In vitro studies have shown less sludge formation in Teflon stents. Recently, clinical studies with Teflon stents have produced contradictory results.

The purified and functionally reconstituted multidrug transporter LmrA of Lactococcus lactis mediates the transbilayer movement of specific fluorescent phospholipids.

Lactococcus lactis possesses an ATP-binding cassette transporter, LmrA, which is a homolog of the mammalian multidrug resistance (MDR) P-glycoprotein, and is able to transport a broad range of structurally unrelated amphiphilic drugs. A histidine tag was introduced at the N-terminus of LmrA to facilitate purification by nickel affinity chromatography. The histidine-tagged protein was overexpressed in L.

Structure-function analysis of multidrug transporters in Lactococcus lactis.

The active extrusion of cytotoxic compounds from the cell by multidrug transporters is one of the major causes of failure of chemotherapeutic treatment of tumor cells and of infections by pathogenic microorganisms. A multidrug transporter in Lactococcus lactis, LmrA, is a member of the ATP-binding cassette (ABC) superfamily and a bacterial homolog of the human multidrug resistance P-glycoprotein. Another multidrug transporter in L.

[Free air below the diaphragm: not always an acute surgical problem].

In three patients, two males aged 66 and 67 years with among other disorders chronic obstructive pulmonary disease (COPD) and one woman aged 24 years with a history of intestinal surgery and current abdominal pain, the chest X-ray showed free air below the diaphragm. The two males had no major abdominal symptoms, but they did have pneumonia. All were treated conservatively.