Chemical inhibitors when timing is critical: a pharmacological concept for the maturation of T cell contacts

Cellular signal transduction proceeds through a complex network of molecular interactions and enzymatic activities. The timing of these molecular events is critical for the propagation of a signal and the generation of a specific cellular response. To define the timing of signalling events, we introduce the combination of high-resolution confocal microscopy with the application of small-molecule inhibitors at various stages of signal transduction in T cells. Inhibitors of Src-family tyrosine kinases and actin dynamics were employed to dissect the role of the lymphocyte-specific tyrosine kinase Lck in the formation and maintenance of T cell receptor/CD3-dependent contacts. Anti-CD3epsilon-coated coverslips served as a highly defined stimulus. The kinetics of the recruitment of the yellow fluorescent protein-tagged signalling protein ZAP-70 were detected by high-resolution confocal microscopy. The analysis revealed that at 5 min after receptor engagement, Lck activity was required for maintenance of contacts. In contrast, after 20 min of receptor engagement, the contacts were Lck-independent. The relevance of the timing of inhibitor application provides a pharmacological concept for the maturation of T cell-substrate contacts.     

The Influence of Cooling Rate on the Specific Volume of Isotactic Poly(propylene) at Elevated Pressures

Summary: We used a custom designed dilatometer to measure quantitatively the time evolution of the specific volume of (semi‐crystalline) polymers for an unusual combined wide range of cooling rates and elevated pressures, covering processing conditions. For an isotactic poly(propylene), applying the Schneider rate equations for quiescent crystallization, experimental results are compared to numerical predictions. Average cooling rates imposed during crystallization of the material vary from 0.1 to 35 °C · s^?1 while pressures range from 20 to 60 MPa. The results show the well‐known profound influence of pressure and cooling rate on the specific volume. An increasing cooling rate shifts the crystallization temperature T_c towards lower temperatures, increases the final specific volume, and the transition due to crystallization is more gradual and widespread. For the highest cooling rate applied, the shift in T_c is as much as 30 °C, while the final specific volume increases up to 1.4%. Increasing pressure has an opposite effect on the shift in T_c, while the final specific volume, after pressure release, also increases. Finally, a comparison of numerical predictions with experimental data shows that the crystallization temperature T_c is consistently predicted too low, and that the predictions at high cooling rate are sensitive to (small) variations in model parameters.

Influence of cooling rate on the specific volume of iPP.     

Relating catalyst structure and composition to the water–gas shift activity of Cu–Zn-based mixed-oxide catalysts

In order to investigate the effect of cerium oxide on Cu–Zn-based mixed-oxide catalysts four catalyst samples were characterized by means of XRD, in situ XANES and thermogravimetric analysis. The activity of the catalyst samples was tested for the forward water–gas shift reaction. Cerium oxide was found to increase the crystallinity of the ZnO phase indicating a segregation of the Cu and ZnO phases. The TOF of the water–gas shift reaction based on chemisorption data was found to be independent of composition and preparation conditions of the four catalyst samples. In contrast, the catalyst stability depends on composition and preparation conditions. Cerium oxide impregnated before calcination of the hydrotalcite-based Cu–Zn precursors leads to a more stable water–gas shift catalyst.     

Counting and particle transmission efficiency of the aerodynamic particle sizer

The aerodynamic particle sizer (APS) measures the size distributions of particles with aerodynamic diameter between 0.5 and in real time. To provide accurate size distributions, the APS must measure both particle size and concentration correctly. The objective of this study was to characterize the counting efficiency of the APS as a function of particle size (0.8–), particle type (liquid or solid), and APS model number (3310 vs. 3321). For solid particles, counting efficiencies ranged between 85% and 99%. For liquid droplets, counting efficiencies progressively declined from 75% at 0.8-μm drops to 25% for 10-μm drops. Fluorometric wash tests indicated that transmission losses occur when larger droplets impact on the instrument's inner nozzle. However, transmission losses did not account entirely for the reduced droplet counting efficiencies, indicating that additional losses may have occurred downstream of the inner nozzle. Between instrument comparisons revealed that although multiple APSs report similar number concentrations, small deviations in particle sizing can produce substantial errors when number concentrations are converted to mass concentrations.     

Cuticular Hydrocarbons as Sex Pheromone of the Bee <Emphasis Type="Italic">Colletes cunicularius</Emphasis> and the Key to its Mimicry by the Sexually Deceptive Orchid, <Emphasis Type="Italic">Ophrys exaltata</Emphasis>

Male Colletes cunicularius bees pollinate the orchid, Ophrys exaltata, after being sexually deceived by the orchid’s odor-mimicry of the female bee’s sex pheromone. We detected biologically active volatiles of C. cunicularius by using gas chromatographic–electroantennographic detection (GC-EAD) with simultaneous flame ionization detection. After identification of the target compounds by coupled gas chromatography–mass spectrometry (GC-MS), we performed behavioral tests using synthetic blends of the active components. We detected 22 EAD active compounds in cuticular extracts of C. cunicularius females. Blends of straight chain, odd-numbered alkanes and (Z)-7-alkenes with 21–29 carbon atoms constituted the major biologically active compounds. Alkenes were the key compounds releasing mating behavior, especially those with (Z)-7 unsaturation. Comparison of patterns of bee volatiles with those of O. exaltata subsp. archipelagi revealed that all EAD-active compounds were also found in extracts of orchid labella. Previous studies of the mating behavior in C. cunicularius showed linalool to be an important attractant for patrolling males. We confirmed this with synthetic linalool but found that it rarely elicited copulatory behavior, in accordance with previous studies. A blend of active cuticular compounds with linalool elicited both attraction and copulation behavior in patrolling males. Thus, linalool appears to function as a long-range attractant, whereas cuticular hydrocarbons are necessary for inducing short-range mating behavior.     

Molecular Networking for Drug Toxicities Studies: The Case of Hydroxychloroquine in COVID-19 Patients

Using drugs to treat COVID-19 symptoms may induce adverse effects and modify patient outcomes. These adverse events may be further aggravated in obese patients, who often present different illnesses such as metabolic-associated fatty liver disease. In Rennes University Hospital, several drug such as hydroxychloroquine (HCQ) have been used in the clinical trial HARMONICOV to treat COVID-19 patients, including obese patients. The aim of this study is to determine whether HCQ metabolism and hepatotoxicity are worsened in obese patients using an in vivo/in vitro approach. Liquid chromatography high resolution mass spectrometry in combination with untargeted screening and molecular networking were employed to study drug metabolism in vivo (patient’s plasma) and in vitro (HepaRG cells and RPTEC cells). In addition, HepaRG cells model were used to reproduce pathophysiological features of obese patient metabolism, i.e., in the condition of hepatic steatosis. The metabolic signature of HCQ was modified in HepaRG cells cultured under a steatosis condition and a new metabolite was detected (carboxychloroquine). The RPTEC model was found to produce only one metabolite. A higher cytotoxicity of HCQ was observed in HepaRG cells exposed to exogenous fatty acids, while neutral lipid accumulation (steatosis) was further enhanced in these cells. These in vitro data were compared with the biological parameters of 17 COVID-19 patients treated with HCQ included in the HARMONICOV cohort. Overall, our data suggest that steatosis may be a risk factor for altered drug metabolism and possibly toxicity of HCQ.     

The Discovery and Structure-Activity Evaluation of (+)-Floyocidin B and Synthetic Analogs

Tuberculosis represents one of the ten most common courses of death worldwide and the emergence of multidrug-resistant M. tuberculosis makes the discovery of novel anti-tuberculosis active structures an urgent priority. Here, we show that (+)-floyocidin B representing the first example of a novel dihydroisoquinoline class of fungus-derived natural products, displays promising antitubercular hit properties. (+)-Floyocidin B was identified by activity-guided extract screening and its structure was unambiguously determined by total synthesis. The absolute configuration was deduced from a key synthesis intermediate by single crystal X-ray diffraction analysis. A hit series was generated by the isolation of further natural congeners and the synthesis of analogs of (+)-floyocidin B. Extensive biological and physicochemical profiling of this series revealed first structure-activity relationships and set the basis for further optimization and development of this novel antitubercular scaffold.     

Alterations in Serum Polyunsaturated Fatty Acids and Eicosanoids in Patients with Mild to Moderate Chronic Obstructive Pulmonary Disease (COPD)

Smoking is a major risk factor for several diseases including chronic obstructive pulmonary disease (COPD). To better understand the systemic effects of cigarette smoke exposure and mild to moderate COPD—and to support future biomarker development—we profiled the serum lipidomes of healthy smokers, smokers with mild to moderate COPD (GOLD stages 1 and 2), former smokers, and never-smokers (n = 40 per group) (ClinicalTrials.gov registration: {"type":"clinical-trial","attrs":{"text":"NCT01780298","term_id":"NCT01780298"}}NCT01780298). Serum lipidome profiling was conducted with untargeted and targeted mass spectrometry-based lipidomics. Guided by weighted lipid co-expression network analysis, we identified three main trends comparing smokers, especially those with COPD, with non-smokers: a general increase in glycero(phospho)lipids, including triglycerols; changes in fatty acid desaturation (decrease in ω-3 polyunsaturated fatty acids, and an increase in monounsaturated fatty acids); and an imbalance in eicosanoids (increase in 11,12- and 14,15-DHETs (dihydroxyeicosatrienoic acids), and a decrease in 9- and 13-HODEs (hydroxyoctadecadienoic acids)). The lipidome profiles supported classification of study subjects as smokers or non-smokers, but were not sufficient to distinguish between smokers with and without COPD. Overall, our study yielded further insights into the complex interplay between smoke exposure, lung disease, and systemic alterations in serum lipid profiles.     

Chemical Attraction of Gall Midge Pollinators (Cecidomyiidae: Cecidomyiinae) to Anthurium acutangulum (Araceae)

Flowering plants often use chemical signals to attract their pollinators, and compounds that elicit attraction are known for several groups of pollinators. For other pollinators such as gall midges, however, compounds responsible for their attraction to flowers are largely unknown. Here, we describe the pollination biology of Anthurium acutangulum, a Neotropical aroid species found to be attractive to gall midges. We collected and analyzed its floral scent by dynamic headspace collections and gas chromatography coupled to mass spectrometry, and identified compounds responsible for pollinator attraction. The inflorescences were almost exclusively visited by gall midges (females; Cecidomyiidae: Cecidomyiinae) and released a strong scent reminiscent of freshly cut cucumber, mainly (5S,7S)-trans-conophthorin, (E2,Z6)-2,6-nonadienal, and cis-conophthorin. Behavioral assays with the two most abundant compounds identified (E2,Z6)-2,6-nonadienal as being highly attractive to the female gall midge pollinators, whereas (5S,7S)-trans-conophthorin was not attractive. Overall, we introduce a new specialized gall midge pollination system and identify the chemical mediating communication between the pollinators and their host plants.