An analytical method was developed for determining macrolide antibiotics in treated wastewater effluents and in ambient water based on solid-phase extraction and LC/MS analysis as well as on LC/MS/MS for structural confirmation. In wastewater treatment plants (WWTPs) macrolides are only partly eliminated and can therefore reach the aquatic environment. In treated effluents from three WWTPs in Switzerland, clarithromycin, roxithromycin, and erythromycin-H2O, the main degradation product of erythromycin, were found. The most abundant, clarithromycin, reflects the consumption pattern of macrolide antibiotics. Summer concentrations of clarithromycin varied between 57 and 330 ng/L in treated WWTP effluents. In the WWTP Kloten-Opfikon seasonal differences revealed a load two times higher in winter than in summer. The higher abundance of erythromycin-H2O in the effluent of WWTP Kloten-Opfikon can be explained by distinct consumption patterns due to the main international airport of Switzerland in the catchment area. In the Glatt River clarithromycin reached concentrations of up to 75 ng/L. Mass flux determinations in treated effluents and in river water in the Glatt Valley watershed showed that elimination of clarithromycin along the river stretch of 36 km is insignificant (<20%). Investigations in the Glatt River before and after the diversion of the largest WWTP revealed an observable decrease in clarithromycin loads.

Signaling through the T cell receptor (TCR) controls adaptive immune responses. Antigen binding to TCRαβ transmits signals through the plasma membrane to induce phosphorylation of the CD3 cytoplasmic tails by incompletely understood mechanisms. Here we show that cholesterol bound to the TCRβ transmembrane region keeps the TCR in a resting, inactive conformation that cannot be phosphorylated by active kinases. Only TCRs that spontaneously detached from cholesterol could switch to the active conformation (termed primed TCRs) and then be phosphorylated. Indeed, by modulating cholesterol binding genetically or enzymatically, we could switch the TCR between the resting and primed states. The active conformation was stabilized by binding to peptide-MHC, which thus controlled TCR signaling. These data are explained by a model of reciprocal allosteric regulation of TCR phosphorylation by cholesterol and ligand binding. Our results provide both a molecular mechanism and a conceptual framework for how lipid-receptor interactions regulate signal transduction.

Background:The TCR forms nanoclusters in the plasma membrane independent of ligand binding. Results: Membrane cholesterol and sphingomyelin facilitate TCR nanoclustering, thereby enhancing the avidity toward the ligand. Conclusion:The membrane lipid composition regulates the degree of TCR nanoclustering and thus T-cell sensitivity. Significance: This work contributes to the understanding of the consequences of specific lipid-membrane protein interactions.

Environmental analytical studies show that trace concentrations of antibacterial agents (antibiotics) occur in hospital and municipal wastewaters and in the aquatic environment. Fluoroquinolones and macrolides, two important human-use antibiotic classes, were studied in detail. The results are discussed regarding input sources and behavior in wastewater treatment and rivers. The fluoroquinolones ciprofloxacin and norfloxacin are substantially eliminated in wastewater treatment (80-90%) by sorption transfer to sewage sludge. In digested sludges the fluoroquinolones occur at mg/kg levels. Ciprofloxacin and norfloxacin are further removed in the Glatt river by 66 and 48%, respectively. The most abundant macrolide clarithromycin was detected at 57 to 330 ng/l concentrations in treated wastewater effluents. Different compositions of the macrolides (clarithromycin and erythromycin-H 2 O) determined in treated effluents of three wastewater treatment plants can be explained by distinct consumption patterns, in one case due to an international airport located in the catchment area. Residual levels of clarithromycin in the Glatt river were up to 75 ng/l with no apparent removal in the river. These results provide important information on environmental exposures, which can be incorporated into environmental risk assessments of the particular chemicals.

The killer cell lectin-like receptor G1 (KLRG1) is an inhibitory receptor expressed by memory T cells and NK cells in man and mice. It is frequently used as a cell differentiation marker and members of the cadherin family are ligands for KLRG1. The present study provides new insights into the interaction of mouse KLRG1 with E-cadherin. Firstly, we demonstrate that co-engagement of KLRG1 and CD3/TCR in a spatially linked manner was required for inhibition arguing against the notion that KLRG1-ligation per se transmits inhibitory signals. Secondly, experiments with T cells carrying Y 7 F-mutant KLRG1 molecules with a replacement of the tyrosine residue to phenylalanine in the single ITIM indicated that the inhibitory activity of KLRG1 is counteracted to some degree by increased interaction of KLRG1 1 T cells with E-cadherin expressing target cells. Thirdly, we demonstrate that deletion of the first or the second external domain of E-cadherin abolished reactivity in KLRG1-reporter cell assays. Finally, we made the intriguing observation that KLRG1 formed multimeric protein complexes in T cells in addition to the previously described mono-and dimeric molecules.

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Kocsis GF, Pipis J, Fekete V, Kovács-Simon A, Odendaal L, Molnár É , Giricz Z, Janáky T, van Rooyen J, Csont T, Ferdinandy P. Lovastatin interferes with the infarct size-limiting effect of ischemic preconditioning and postconditioning in rat hearts. Am J Physiol Heart Circ Physiol 294: H2406-H2409, 2008. First published March 21, 2008 doi:10.1152/ajpheart.00862.2007.-Statins have been shown to be cardioprotective; however, their interaction with endogenous cardioprotection by ischemic preconditioning and postconditioning is not known. In the present study, we examined if acute and chronic administration of the 3-hydroxy-3-methylglutaryl CoA reductase inhibitor lovastatin affected the infarct size-limiting effect of ischemic preconditioning and postconditioning in rat hearts. Wistar rats were randomly assigned to the following three groups: 1) vehicle (1% methylcellulose per os for 12 days), 2) chronic lovastatin (15 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 per os for 12 days), and 3) acute lovastatin (1% methylcellulose per os for 12 days and 50 mol/l lovastatin in the perfusate). Hearts isolated from the three groups were either subjected to a nonconditioning (aerobic perfusion followed by 30-min coronary occlusion and 120-min reperfusion, i.e., test ischemia-reperfusion), preconditioning (three intermittent periods of 5-min ischemia-reperfusion cycles before test ischemia-reperfusion), or postconditioning (six cycles of 10-s ischemia-reperfusion after test ischemia) perfusion protocol. Preconditioning and postconditioning significantly decreased infarct size in vehicle-treated hearts. However, preconditioning failed to decrease infarct size in acute lovastatin-treated hearts, but the effect of postconditioning remained unchanged. Chronic lovastatin treatment abolished postconditioning but not preconditioning; however, it decreased infarct size in the nonconditioned group. Myocardial levels of coenzyme Q9 were decreased in both acute and chronic lovastatin-treated rats. Western blot analysis revealed that both acute and chronic lovastatin treatment attenuated the phoshorylation of Akt; however, acute but not chronic lovastatin treatment increased the phosphorylation of p42 MAPK/ERK. We conclude that, although lovastatin may lead to cardioprotection, it interferes with the mechanisms of cardiac adaptation to ischemic stress. coronary occlusion; coenzyme Q9; Akt; p42 mitogen-activated protein kinase/extracellular signal-regulated kinase; statin STATINS, 3-hydroxy-3-methylglutaryl (HMG) CoA reductase inhibitors, inhibit the synthesis of mevalonate, a rate-limiting step in cholesterol biosynthesis. A number of large clinical trials have shown that chronic administration of statins have potent cholesterol-lowering effects and reduce cardiovascular morbidity and mortality (16,17). Since cardioprotection by statins was also observed in patients with normal cholesterol levels, it was proposed that statins may exert a broad spectrum of cholesterol-independent protective effects (13, 14, 19). Di Napoli et al. (4) showed that acute applicati...

Degradation products of nonionic surfactants of the nonylphenol polyethoxylate type (NPnEO) were reported recently to be estrogenic to fish at low microgram per litre concentrations. These estrogenic metabolites, including nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) as well as their corresponding carboxylic acids (NP1EC and NP2EC), were measured during 1997 and 1998 in sewage effluents and ambient waters in Switzerland in order to assess the effects of risk reduction measures introduced in 1986. Lipophilic metabolites (NP+NP1EO+NP2EO) were found in the examined secondary sewage effluents mostly at concentrations from 1 to 5 μg/L, while elevated levels were found in those sewage treatment plants which receive industrial effluents from textile finishing plants. The concentrations of the lipophilic nonylphenolic compounds in rivers ranged mainly from 0.05 to 0.3 μg/L with NP being most abundant. The total concentration of the nonylphenoxy carboxylic acids was significantly higher than that of the lipophilic metabolites. Despite a significant decrease of the environmental exposure levels of all nonylphenolic compounds subsequent to the introduction of risk reduction measures, the total concentration of estrogenic metabolites often exceeded the predicted no effect concentration (PNEC) of 0.33 μg/L proposed in a risk assessment report to the European Union.