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Carbapenems are vital antibiotics, but their efficacy is increasingly compromised by metallo-β-lactamases (MBLs). Here we report the discovery and optimization of potent broad-spectrum MBL inhibitors. A high-throughput screen for NDM-1 inhibitors identified indole-2-carboxylates (InCs) as potential β-lactamase stable β-lactam mimics. Subsequent structure–activity relationship studies revealed InCs as a new class of potent MBL inhibitor, active against all MBL classes of major clinical relevance. Crystallographic studies revealed a binding mode of the InCs to MBLs that, in some regards, mimics that predicted for intact carbapenems, including with respect to maintenance of the Zn(II)-bound hydroxyl, and in other regards mimics binding observed in MBL–carbapenem product complexes. InCs restore carbapenem activity against multiple drug-resistant Gram-negative bacteria and have a low frequency of resistance. InCs also have a good in vivo safety profile, and when combined with meropenem show a strong in vivo efficacy in peritonitis and thigh mouse infection models. The efficacy of carbapenem antibiotics can be compromised by metallo-β-lactamases, but a high-throughput screen followed by optimization has now enabled the discovery of indole-2-carboxylates (InCs) as potent broad-spectrum metallo-β-lactamase inhibitors. The results highlight the potential of InC–carbapenem combinations for clinical use as well as mechanism-guided approaches to combatting globally disseminated antibiotic resistant mechanisms.

PurposeTo evaluate the performance of artificial membranes in in vitro lipolysis-permeation assays useful for absorption studies of drugs loaded in lipid-based formulations (LBFs).MethodsPolycarbonate as well as PVDF filters were treated with hexadecane, or lecithin in n-dodecane solution (LiDo) to form artificial membranes. They were thereafter used as absorption membranes separating two compartments mimicking the luminal and serosal side of the intestine in vitro. Membranes were subjected to dispersions of an LBF that had been digested by porcine pancreatin and spiked with the membrane integrity marker Lucifer Yellow (LY). Three fenofibrate-loaded LBFs were used to explore the in vivo relevance of the assay.ResultsOf the explored artificial membranes, only LiDo applied to PVDF was compatible with lipolysis by porcine pancreatin. Formulation ranking based on mass transfer in the LiDo model exposed was the same as drug release in single-compartment lipolysis. Ranking based on observed apparent permeability coefficients of fenofibrate with different LBFs were the same as those obtained in a cell-based model.ConclusionsThe LiDo membrane was able to withstand lipolysis for a sufficient assay period. However, the assay with porcine pancreatin as digestive agent did not predict the in vivo ranking of the assayed formulations better than existing methods. Comparison with a Caco-2 based assay method nonetheless indicates that the in vitro in vivo relationship of this cell-free model could be improved with alternative digestive agents.

Abstract Genes and proteins show variable expression patterns throughout the human body. However, it is not clear whether relative differences in mRNA concentrations are retained on the protein level. Furthermore, inter-individual protein concentration variability within single tissue types has not been comprehensively explored. Here, we used the Gini index for in-depth concentration variability analysis of publicly available transcriptomics and proteomics data, and of an in-house proteomics dataset of human liver and jejunum from 38 donors. We found that the transfer of concentration variability from mRNA to protein is limited, that established ‘reference genes’ for data normalization vary markedly at the protein level, that protein concentrations cover a wide variability spectrum within single tissue types, and that concentration variability analysis can be a convenient starting point for identifying disease-associated proteins and novel biomarkers. Our results emphasize the importance of considering individual concentration levels, as opposed to population averages, for personalized systems biology analysis.

Specific mate recognition relies on the chemical senses in most animals, and especially in nocturnal insects. Two signal types mediate premating olfactory communication in terrestrial habitats: sex pheromones, which blend into an atmosphere of plant odorants. We show that host plant volatiles affect the perception of sex pheromone in males of the African cotton leafworm Spodoptera littoralis and that pheromone and plant volatiles are not perceived as independent messages. In clean air, S. littoralis males are attracted to single synthetic pheromone components or even the pheromone of a sibling species, oriental cotton leafworm S. litura. Presence of host plant volatiles, however, reduces the male response to deficient or heterospecific pheromone signals. That plant cues enhance discrimination of sex pheromone quality confirms the idea that specific mate recognition in noctuid moths has evolved in concert with adaptation to host plants. Shifts in either female host preference or sex pheromone biosynthesis give rise to new communication channels that have the potential to initiate or contribute to reproductive isolation.

Co-administering a low dose of colistin (CST) with ciprofloxacin (CIP) may improve the antibacterial effect against resistant Escherichia coli , offering an acceptable benefit-risk balance. This study aimed to quantify the interaction between ciprofloxacin and colistin in an in silico pharmacokinetic-pharmacodynamic model from in vitro static time-kill experiments (using strains with minimum inhibitory concentrations, MIC CIP 0.023–1 mg/L and MIC CST 0.5–0.75 mg/L). It was also sought to demonstrate an approach of simulating concentrations at the site of infection with population pharmacokinetic and whole-body physiologically based pharmacokinetic models to explore the clinical value of the combination when facing more resistant strains (using extrapolated strains with lower susceptibility). The combined effect in the final model was described as the sum of individual drug effects with a change in drug potency: for ciprofloxacin, concentration at half maximum killing rate (EC 50 ) in combination was 160% of the EC 50 in monodrug experiments, while for colistin, the change in EC 50 was strain-dependent from 54.1% to 119%. The benefit of co-administrating a lower-than-commonly-administrated colistin dose with ciprofloxacin in terms of drug effect in comparison to either monotherapy was predicted in simulated bloodstream infections and pyelonephritis. The study illustrates the value of pharmacokinetic-pharmacodynamic modelling and simulation in streamlining rational development of antibiotic combinations.

ABSTRACT Purpose Antibiotic dose predictions based on PK/PD indices rely on that the index type and magnitude is insensitive to the pharmacokinetics (PK), the dosing regimen, and bacterial susceptibility. In this work we perform simulations to challenge these assumptions for meropenem and Pseudomonas aeruginosa . Methods A published murine dose fractionation study was replicated in silico . The sensitivity of the PK/PD index towards experimental design, drug susceptibility, uncertainty in MIC and different PK profiles was evaluated. Results The previous murine study data were well replicated with f T > MIC selected as the best predictor. However, for increased dosing frequencies f AUC/MIC was found to be more predictive and the magnitude of the index was sensitive to drug susceptibility. With human PK f T > MIC and f AUC/MIC had similar predictive capacities with preference for f T > MIC when short t 1/2 and f AUC/MIC when long t 1/2 . Conclusions A longitudinal PKPD model based on in vitro data successfully predicted a previous in vivo study of meropenem. The type and magnitude of the PK/PD index were sensitive to the experimental design, the MIC and the PK. Therefore, it may be preferable to perform simulations for dose selection based on an integrated PK-PKPD model rather than using a fixed PK/PD index target.

The solute carrier 38 family (SLC38) is a family of 11 members. The most common substrate among these are alanine and glutamine, and members are present in a wide range of tissues with important functions for several biological processes, such as liver and brain function. Some of these transporters are better characterized than others and, in this paper, a behavioural characterization of SLC38A10-/- mice was carried out. A battery of tests for general activity, emotionality, motor function and spatial memory was used. Among these tests, the elevated plus maze, Y-maze, marble burying and challenging beam walk have not been tested on the SLC38A10-/- mice previously, while the open field and the rotarod tests have been performed by the International Mouse Phenotyping Consortium (IMPC). The results from this study, unlike the results from IMPC, showed that SLC38A10-/- mice spend less time in the wall zone in the open field test than WT mice, implying that SLC38A10 deficient mice have an increased explorative behavior, which suggests an important function of SLC38A10 in brain. The present study also confirmed IMPC’s data regarding rotarod performance and weight, showing that SLC38A10-/- mice do not have an affected motor coordination impairment and have a lower body weight than both SLC38A10+/- and SLC38A10+/+ mice. These results imply that a complete deficiency of the SLC38A10 protein might affect body weight homeostasis, but the underlying mechanisms needs to be studied further.

Purpose This work investigates improved utilization of ADAS-cog data (the primary outcome in Alzheimer’s disease (AD) trials of mild and moderate AD) by combining pharmacometric modeling and item response theory (IRT). Methods A baseline IRT model characterizing the ADAS-cog was built based on data from 2,744 individuals. Pharmacometric methods were used to extend the baseline IRT model to describe longitudinal ADAS-cog scores from an 18-month clinical study with 322 patients. Sensitivity of the ADAS-cog items in different patient populations as well as the power to detect a drug effect in relation to total score based methods were assessed with the IRT based model. Results IRT analysis was able to describe both total and item level baseline ADAS-cog data. Longitudinal data were also well described. Differences in the information content of the item level components could be quantitatively characterized and ranked for mild cognitively impairment and mild AD populations. Based on clinical trial simulations with a theoretical drug effect, the IRT method demonstrated a significantly higher power to detect drug effect compared to the traditional method of analysis. Conclusion A combined framework of IRT and pharmacometric modeling permits a more effective and precise analysis than total score based methods and therefore increases the value of ADAS-cog data.

Bedaquiline (BDQ) has shown great value in the treatment of multidrug‐resistant tuberculosis (MDR‐TB) in recent years. However, exposure–safety relationships must be explored to extend the use of BDQ. Two reported safety findings for BDQ are prolongation of the QTc interval and elevation of transaminase levels. In this study, we investigated the potential relationships between BDQ and/or its main metabolite (M2) pharmacokinetic (PK) metrics and QTcF interval or transaminase levels in patients with MDR‐TB using the approved dose regimen. Data from 429 patients with MDR‐TB from two phase IIb studies were analyzed via nonlinear mixed‐effects modeling. Individual model‐predicted concentrations and summary PK metrics were evaluated, respectively, in the QTcF interval and transaminase level exposure–response models. Investigation of further covariate effects was performed in both models. M2 concentrations were found to be responsible for the drug‐related QTcF increase in a model accounting for circadian rhythm patterns, time on study, effect of concomitant medication with QT liability, and patient demographics. Simulations with the final model suggested that doses higher than the approved dose (leading to increased M2 concentrations) are not expected to lead to a critical QTcF interval increase. No exposure–safety relationship could be described with transaminase levels despite previous reports of higher levels in patients treated with BDQ. The developed longitudinal models characterized the role of M2 concentrations in QTc interval prolongation and found no concentration dependency for transaminase level elevation, together suggesting that BDQ exposure at the high end of the observed range may not be associated with a higher risk of safety events.

Neutrophil granulocytes are key components of the host response against pathogens, and severe neutropenia, with neutrophil counts below 0.5 × 106 cells/mL, renders patients increasingly vulnerable to infections. Published in vitro (n = 7) and in vivo (n = 5) studies with time‐course information on bacterial and neutrophil counts were digitized to characterize the kinetics of neutrophil‐mediated bacterial killing and inform on the immune systems' contribution to the clearance of bacterial infections. A mathematical model for the in vitro dynamics of bacteria and the kinetics of neutrophil‐mediated phagocytosis and digestion was developed, which was extended to in vivo studies in immune‐competent and immune‐compromised mice. Neutrophil‐mediated bacterial killing was described by two first‐order processes—phagocytosis and digestion—scaled by neutrophil concentration, where 50% of the maximum was achieved at neutrophil counts of 1.19 × 106 cells/mL (phagocytosis) and 6.55 × 106 cells/mL (digestion). The process efficiencies diminished as the phagocytosed bacteria to total neutrophils ratio increased (with 50% reduction at a ratio of 3.41). Neutrophil in vivo dynamics were captured through the characterization of myelosuppressive drug effects and postinoculation neutrophil influx into lungs and by system differences (27% bacterial growth and 9.3% maximum capacity, compared with in vitro estimates). Predictions showed how the therapeutically induced reduction of neutrophil counts enabled bacterial growth, especially when falling below 0.5 × 106 cells/mL, whereas control individuals could deal with all tested bacterial burdens (up to 109 colony forming units/g lung). The model‐based characterization of neutrophil‐mediated bacterial killing simultaneously predicted data across in vitro and in vivo studies and may be used to inform the capacity of host–response at the individual level.