The structure of the bacterial leucine transporter from Aquifex aeolicus (LeuT Aa ) has been used as a model for mammalian Na ϩ /Cl Ϫ -dependent transporters, in particular the serotonin transporter (SERT). The crystal structure of LeuT Aa liganded to tricyclic antidepressants predicts simultaneous binding of inhibitor and substrate. This is incompatible with the mutually competitive inhibition of substrates and inhibitors of SERT. We explored the binding modes of tricyclic antidepressants by homology modeling and docking studies. Two approaches were used subsequently to differentiate between three clusters of potential docking poses: 1) a diagnostic SERT Y95F mutation, which greatly reduced the affinity for [ 3 H]imipramine but did not affect substrate binding; 2) competition binding experiments in the presence and absence of carbamazepine (i.e., a tricyclic imipramine analog with a short side chain that competes with [ 3 H]imipramine binding to SERT). Binding of releasers (parachloroamphetamine, methylene-dioxy-methamphetamine/ecstasy) and of carbamazepine were mutually exclusive, but Dixon plots generated in the presence of carbamazepine yielded intersecting lines for serotonin, MPP ϩ , paroxetine, and ibogaine. These observations are consistent with a model, in which 1) the tricyclic ring is docked into the outer vestibule and the dimethyl-aminopropyl side chain points to the substrate binding site; 2) binding of amphetamines creates a structural change in the inner and outer vestibule that precludes docking of the tricyclic ring; 3) simultaneous binding of ibogaine (which binds to the inward-facing conformation) and of carbamazepine is indicative of a second binding site in the inner vestibule, consistent with the pseudosymmetric fold of monoamine transporters. This may be the second low-affinity binding site for antidepressants.

Background-Recent data obtained in mouse models have initiated a controversy whether basophils are the key antigen-presenting cells (APCs) in allergy. Here, we investigate whether basophils are of importance for the presentation of allergen and the induction of T cell proliferation in allergic patients.

The structure of the bacterial leucine transporter LeuT Aa has been used as a model for mammalian Na + /Cl −-dependent transporters, in particular the serotonin transporter (SERT). The crystal structure of LeuT Aa liganded to tricyclic antidepressants predicts simultaneous binding of inhibitor and substrate. This is incompatible with the mutually competitive inhibition of substrates and inhibitors of SERT.

The objective of the present study was to evaluate whether cefpirome, a member of the latest class of broadspectrum cephalosporins, sufficiently penetrates subcutaneous adipose tissue in septic patients. After the administration of the drug at 2 g, tissue cefpirome concentrations in septic patients (n ‫؍‬ 11) and healthy controls (n ‫؍‬ 7) were determined over a period of 4 h by means of microdialysis. To assess the antibacterial effect of cefpirome at the target site, the measured pharmacokinetic profiles were simulated in vitro with select strains of Staphylococcus aureus and Pseudomonas aeruginosa. The tissue penetration of cefpirome was significantly impaired in septic patients compared with that in healthy subjects. For subcutaneous adipose tissue, the area under the concentration-versus-time curve values from 0 to 240 min were 13.11 ؎ 5.20 g ⅐ min/liter in healthy subjects and 6.90 ؎ 2.56 g ⅐ min/liter in septic patients (P < 0.05). Effective bacterial growth inhibition was observed in all in vitro simulations. This was attributed to the significantly prolonged half-life in tissue (P < 0.05), which kept the tissue cefpirome levels above the MICs for relevant pathogens for extended periods in the septic group. By consideration of a dosing interval of 8 h, the values for the time above MIC (T > MIC) in tissue were greater than 60% for pathogens for which the MIC was <4 mg/liter in all septic patients. The present data indicate that cefpirome is an appropriate agent for the treatment of soft tissue infections in septic patients. However, due to the high interindividual variability of the pharmacokinetics of cefpirome in tissue, dosing intervals of not more than 8 h should be preferred to ensure that susceptible bacterial strains are killed in each patient.

Duramycin (Moli1901) is being developed for the treatment of reduced mucociliary clearance in cystic fibrosis. This study was conducted to estimate lung residence time and systemic exposure and to assess whether duramycin causes an inflammatory response. Six volunteers were administered a single dose (7.5 mg) of nebulized duramycin and underwent bronchoscopies to obtain a composite data set for pharmacokinetic analysis; duramycin was measured in the cellular fraction of bronchoalveolar lavage fluid (BALF) (mainly alveolar macrophages) and brush biopsies (bronchial epithelial cells). The estimated t(1/2) of duramycin was approximately 5 days in brush biopsies and 25 to 91 days in BALF cells. Levels of duramycin in BALF (C (max) 800 ng/mg) exceeded those in brush biopsies by approximately 20-fold. Duramycin was absent from plasma and did not cause any detectable inflammatory response in pulmonary tissue as judged from the BALF profile of 14 relevant cytokines. Our data suggest that duramycin qualifies for intrapulmonary administration in cystic fibrosis (CF) patients.

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Fosfomycin extensively decreased mRNA levels and release of pro-inflammatory cytokines in human blood. The broad antimicrobial coverage of fosfomycin and its immunosuppressive effects could be clinically useful in patients with sepsis.

To evaluate the effect of fosfomycin on proinflammatory cytokines, a bolus of 2 ng of bacterial lipopolysaccharide/kg of body weight was injected intravenously into healthy volunteers. After 2 h, subjects received 8 g of fosfomycin or placebo in a randomized crossover study design. The resulting concentrations of tumor necrosis factor alpha, interleukin-1␤ (IL-1␤), and IL-6 expressed as protein and mRNA levels were almost identical with and without fosfomycin.