Imipenem/funobactam (formerly XNW4107) in vivo pharmacodynamics against serine carbapenemase-producing Gram-negative bacteria: a novel modelling approach for time-dependent killing.

BACKGROUND: Imipenem/funobactam (formerly XNW4107) is a novel ß-lactam/ß-lactamase inhibitor with activity against MDR Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacterales strains. Using a neutropenic murine thigh infection model, we aimed to determine the pharmacokinetic/pharmacodynamic (PK/PD) index, relative to funobactam exposure, that correlated most closely with the in vivo efficacy of imipenem/funobactam combination and the magnitude of index required for efficacy against serine carbapenemase-producing clinical strains. METHODS: Dose-fractionation was conducted against three strains. Imipenem human-simulated regimen (HSR, 500 mg q6h 1 h infusion) efficacy in combination with escalating funobactam exposures against seven A. baumannii, four P. aeruginosa and four Klebsiella pneumoniae (imipenem/funobactam MICs 0.25-16 mg/L) was assessed as 24 h change in log10cfu/thigh. RESULTS: Increased funobactam fractionation enhanced efficacy, indicating time-dependent killing. Changes in log10cfu/thigh versus %fT > MIC were poorly predictive of efficacy; bactericidal activity was observed at %fT > MIC = 0%. Across different threshold plasma funobactam concentrations (CTs), %fT > CT(1 mg/L) had the highest correlation with efficacy. Normalizing the %fT > CT = 1 mg/L index to the respective isolate imipenem/funobactam MIC ([%fT > CT]/MIC) allowed integration of the isolate's susceptibility, which further enhanced the correlation. Median (%fT > CT[1 mg/L])/MIC values associated with 1-log reductions were 9.82 and 9.90 for A. baumannii and P. aeruginosa, respectively. Median (%fT > CT[1 mg/L])/MIC associated with stasis was 55.73 for K. pneumoniae. Imipenem/funobactam 500/250 mg q6h 1 h infusion HSR produced >1-log kill against 6/7 A. baumannii, 4/4 P. aeruginosa and stasis against 4/4 K. pneumoniae. CONCLUSIONS: Imipenem/funobactam showed potent in vivo efficacy against serine carbapenemase-producers. The novel PK/PD index (%fT > CT)/MIC appeared to best describe in vivo activity.

Engineering stability, longevity, and miscibility of microtubule-based active fluids.

Microtubule-based active matter provides insight into the self-organization of motile interacting constituents. We describe several formulations of microtubule-based 3D active isotropic fluids. Dynamics of these fluids is powered by three types of kinesin motors: a processive motor, a non-processive motor, and a motor which is permanently linked to a microtubule backbone. Another modification uses a specific microtubule crosslinker to induce bundle formation instead of a non-specific polymer depletant. In comparison to the already established system, each formulation exhibits distinct properties. These developments reveal the temporal stability of microtubule-based active fluids while extending their reach and the applicability.

In vivo selective inhibition of TRPC6 by antagonist BI 749327 ameliorates fibrosis and dysfunction in cardiac and renal disease.

Transient receptor potential canonical type 6 (TRPC6) is a nonselective receptor-operated cation channel that regulates reactive fibrosis and growth signaling. Increased TRPC6 activity from enhanced gene expression or gain-of-function mutations contribute to cardiac and/or renal disease. Despite evidence supporting a pathophysiological role, no orally bioavailable selective TRPC6 inhibitor has yet been developed and tested in vivo in disease models. Here, we report an orally bioavailable TRPC6 antagonist (BI 749327; IC50 13 nM against mouse TRPC6, t1/2 8.5-13.5 hours) with 85- and 42-fold selectivity over the most closely related channels, TRPC3 and TRPC7. TRPC6 calcium conductance results in the stimulation of nuclear factor of activated T cells (NFAT) that triggers pathological cardiac and renal fibrosis and disease. BI 749327 suppresses NFAT activation in HEK293T cells expressing wild-type or gain-of-function TRPC6 mutants (P112Q, M132T, R175Q, R895C, and R895L) and blocks associated signaling and expression of prohypertrophic genes in isolated myocytes. In vivo, BI 749327 (30 mg/kg/day, yielding unbound trough plasma concentration ∼180 nM) improves left heart function, reduces volume/mass ratio, and blunts expression of profibrotic genes and interstitial fibrosis in mice subjected to sustained pressure overload. Additionally, BI 749327 dose dependently reduces renal fibrosis and associated gene expression in mice with unilateral ureteral obstruction. These results provide in vivo evidence of therapeutic efficacy for a selective pharmacological TRPC6 inhibitor with oral bioavailability and suitable pharmacokinetics to ameliorate cardiac and renal stress-induced disease with fibrosis.

The potential of a lecture series in changing intent and experience among health professionals to conduct research in a large hospital: a retrospective pre-post design.

BACKGROUND: Promoting research capacity within public health can encourage and engage employees to undertake research, utilising their understanding of the complex needs that exist within the public health system to provide more relevant research outcomes. Despite this, there are a number of reasons cited by health care professionals as to why research is not undertaken, and a lack of support for research participation results in missed opportunities for experienced clinical and public health staff to gain research experience, expand the evidence base, and promote and support research. The aim of this study is to identify if education in research, delivered through a series of lectures at a large tertiary referral hospital, results in an increase in the experience and intent to conduct research. METHODS: A series of six lectures to aid in the understanding and development of research were delivered to health employees, health care professionals, students and their associates within a large public Australian hospital. Following these lectures, a validated instrument was developed and asked respondents to assess their research activity, research training history, and experience in conducting research using a retrospective pre/post- test design. RESULTS: Over half (57.1%) of respondents (n = 49) reported no previous researcher education training prior to the lectures. Following the lectures, reported researcher experience increased significantly in the areas of writing a research protocol, using qualitative research methods, publishing research, writing and presenting a research report, analysing and interpreting results, using quantitative research methods, generating research ideas, and applying for research funding. At 6 months following the lecture series intent to be involved in further research was seen in the areas of submitting an ethics application, analysing qualitative and quantitative research data, and research funding applications. CONCLUSIONS: Six one hour face to face research lectures can improve self-reported levels of intention to become involved in research as well as research experience amongst hospital health care professionals at 6 months. This traditional modality of education should still be considered as relevant strategy in building research capacity as measured innovatively using a retrospective pre/post test methodology.

Selective CB2 receptor agonists. Part 1: the identification of novel ligands through computer-aided drug design (CADD) approaches.

Computer-aided drug design scaffold hopping strategies were utilized to identify new classes of CB2 agonists when compounds of an established series with low nanomolar potency were challenging to optimize for good drug-like properties. Use of ligand-based design strategies through BI Builder (a tool for de novo design) and PharmShape (a virtual screening software package) approaches led to the discovery of new chemotypes. Specifically, compounds containing azetidine-, proline-, and piperidine-based cores were found to have low nanomolar and picomolar CB2 agonist activities with drug-like properties considered appropriate for early profiling.

Selective CB2 receptor agonists. Part 3: the optimization of a piperidine-based series that demonstrated efficacy in an in vivo neuropathic pain model.

A novel class of potent cannabinoid receptor 2 (CB2) agonists based on a (S)-piperidine scaffold was identified using ligand-based pharmacophore models. Optimization of solubility and metabolic stability led to the identification of several potent CB2 agonists (e.g., 30) that displayed selectivity over cannabinoid receptor 1 (CB1) and acceptable drug like properties. In rats, compound 30 demonstrated a favorable pharmacokinetic profile and efficacy in a Streptozotocin-induced diabetic neuropathy model, with full reversal of mechanical hyperalgesia.

Selective CB2 receptor agonists. Part 2: Structure-activity relationship studies and optimization of proline-based compounds.

Through a ligand-based pharmacophore model (S)-proline based compounds were identified as potent cannabinoid receptor 2 (CB2) agonists with high selectivity over the cannabinoid receptor 1 (CB1). Structure-activity relationship investigations for this compound class lead to oxo-proline compounds 21 and 22 which combine an impressive CB1 selectivity profile with good pharmacokinetic properties. In a streptozotocin induced diabetic neuropathy model, 22 demonstrated a dose-dependent reversal of mechanical hyperalgesia.

Ethical considerations in the management of Ebola virus disease.

Is it ethically appropriate in some circumstances for HCWs to decline to care for patients with EVD? How should treatment decisions be made regarding limitation of therapy for patients with EVD? There are two main ethical questions regarding the critical care of patients with EVD in an Australian setting: Is it ethically appropriate in some circumstances for HCWs to decline to care for patients with EVD? How should treatment decisions be made regarding limitation of therapy for patients with EVD? The key concern is ensuring that no patient is denied therapy that should be provided, while preventing unnecessary risk to HCWs. It is imperative to develop an approach that facilitates rigorous, evidence-based and ethically justifiable decision making, which should include a predetermined, institutionally endorsed process for assessing difficult clinical scenarios as they arise.

Effect of Blood Product Resuscitation on Cefazolin Pharmacokinetics in Trauma Patients.

Background: Antibiotics are frequently administered prophylactically to trauma patients with various injury patterns to prevent infectious complications. Trauma patients may also require large volume resuscitation with blood products. Limited data are available to support antibiotic dosing recommendations in this population. We hypothesized that we would be able to develop a population pharmacokinetic model of cefazolin, a frequently used antibiotic in the trauma scenario, from remnant blood samples by pharmacokinetic analysis of trauma patients. Methods: Remnant plasma from standard of care chemistry/hematology assessments was retrieved within 48 h of collection and assayed to determine cefazolin concentrations. Population pharmacokinetic analyses were conducted in Pmetrics using R. Linear regression was conducted to assess the effect of blood product resuscitation volume on cefazolin pharmacokinetic parameters. Results: Cefazolin concentrations best fitted a two-compartment model (Akaike information criterion: 443.9). The mean ± standard deviation parameters were total body clearance (4.3 ± 1.9L), volume of the central compartment (Vc: 7.7 ± 6.9L), and intercompartment transfer constants (k12: 1.3 ± 0.98 h-1, k21: 0.6 ± 0.45 h-1). No statistical relationships were observed between blood products, volume of blood products, and cefazolin clearance or Vc (R2: 0.0004-0.21, p = 0.08-0.95). Using a 5,000-patient Monte Carlo simulation, 2 g with repeated dosing every 2 h until end of surgery was required to achieve 93.2% probability of 100% free time above the minimum inhibitory concentration (MIC) (fT > MIC) at the ECOFF value for Staphylococcus aureus (2 mg/L). Conclusions: In these 15 trauma patients receiving blood transfusion, no relationship with blood volume resuscitation and cefazolin pharmacokinetics was observed. On the basis of this pharmacokinetic model, frequent cefazolin doses are required to maintain 100% fT > MIC.

Cefiderocol is Not Sequestered in an Ex Vivo Extracorporeal Membrane Oxygenation (ECMO) Circuit.

BACKGROUND AND OBJECTIVE: Extracorporeal membrane oxygenation (ECMO) is used in critically ill patients that require respiratory and/or cardiac support. Cefiderocol is a novel siderophore antibiotic that may require use in infected critically ill patients supported by ECMO. The objective of this study was to determine the loss of cefiderocol through an ex vivo adult ECMO circuit using a Quadrox-iD oxygenator. METHODS: A 3/8-inch, simulated, ex vivo closed-loop ECMO circuit was prepared with a Quadrox-iD adult oxygenator and primed with fresh whole blood. Cefiderocol was administered into the circuit to achieve a starting concentration of approximately 90 mg/L. Post-oxygenator blood samples were collected at 0, 0.25, 0.5, 1, 2, 4, 6, 12, and 24 h after the addition of the drug to determine the loss in the circuit. A glass control jar was prepared with the same blood matrix and maintained at the same temperature to determine drug degradation. The experiment was conducted in triplicate. The rate of cefiderocol loss in the ECMO circuit was compared with that in the control by one-way analysis of variance. RESULTS: At 0 h, the difference between the pre- and post-oxygenator concentrations was - 4 ± 4% (range 0 to - 7%). After 24 h, the cefiderocol percent reduction was similar between the ECMO circuit and control (50% ± 13 vs. 50% ± 9, p = 1.0). CONCLUSIONS: The degradation rate of cefiderocol did not differ significantly within the ECMO circuit and control, suggesting no loss due to sequestration or adsorption. Pharmacokinetic studies in patients supported by ECMO are warranted to determine final dosing recommendations.

Pharmacodynamic Thresholds for Beta-Lactam Antibiotics: A Story of Mouse Versus Man.

Beta-lactams remain a critical member of our antibiotic armamentarium and are among the most commonly prescribed antibiotic classes in the inpatient setting. For these agents, the percentage of time that the free concentration remains above the minimum inhibitory concentration (%fT > MIC) of the pathogen has been shown to be the best predictor of antibacterial killing effects. However, debate remains about the quantity of fT > MIC exposure needed for successful clinical response. While pre-clinical animal based studies, such as the neutropenic thigh infection model, have been widely used to support dosing regimen selection for clinical development and susceptibility breakpoint evaluation, pharmacodynamic based studies in human patients are used validate exposures needed in the clinic and for guidance during therapeutic drug monitoring (TDM). For the majority of studied beta-lactams, pre-clinical animal studies routinely demonstrated the fT > MIC should exceed approximately 40-70% fT > MIC to achieve 1 log reductions in colony forming units. In contrast, clinical studies tend to suggest higher exposures may be needed, but tremendous variability exists study to study. Herein, we will review and critique pre-clinical versus human-based pharmacodynamic studies aimed at determining beta-lactam exposure thresholds, so as to determine which targets may be best suited for optimal dosage selection, TDM, and for susceptibility breakpoint determination. Based on our review of murine and clinical literature on beta-lactam pharmacodynamic thresholds, murine based targets specific to each antibiotic are most useful during dosage regimen development and susceptibility breakpoint assessment, while a range of exposures between 50 and 100% fT > MIC are reasonable to define the beta-lactam TDM therapeutic window for most infections.

Non-steroidal dissociated glucocorticoid agonists: indoles as A-ring mimetics and function-regulating pharmacophores.

We report a SAR of non-steroidal glucocorticoid mimetics that utilize indoles as A-ring mimetics. Detailed SAR is discussed with a focus on improving PR and MR selectivity, GR agonism, and in vitro dissociation profile. SAR analysis led to compound (R)-33 which showed high PR and MR selectivity, potent agonist activity, and reduced transactivation activity in the MMTV and aromatase assays. The compound is equipotent to prednisolone in the LPS-TNF model of inflammation. In mouse CIA, at 30 mg/kg compound (R)-33 inhibited disease progression with an efficacy similar to the 3 mg/kg dose of prednisolone.

1,4-Diazepane compounds as potent and selective CB2 agonists: optimization of metabolic stability.

A high-throughput screening campaign has identified 1,4-diazepane compounds which are potent Cannabinoid receptor 2 agonists with excellent selectivity against the Cannabinoid receptor 1. This class of compounds suffered from low metabolic stability. Following various strategies, compounds with a good stability in liver microsomes and rat PK profile have been identified.

Effects of D-cycloserine administration on weekly nonemotional memory tasks in healthy participants.

BACKGROUND: The application of weekly doses of D-cycloserine (DCS) to the enhancement of exposure-based treatments has been a particular achievement of translational research. It is not known, however, whether this enhancement effect can be extended to other forms of learning. In this study, we investigated the relative benefit of DCS versus placebo for enhancing nonemotional verbal and nonverbal memory across weekly trials. METHODS: We randomized healthy participants to weekly doses of 50 mg DCS or placebo, with 33 participants completing a 5-week protocol. Participants completed baseline neuropsychological evaluation and then 4 subsequent weeks of repeated learning tasks. RESULTS: No improvement was found in immediate or delayed memory following single doses of DCS for the memory tasks repeated on a weekly basis. Trends for an advantage of DCS were evident for novel word lists given each week. CONCLUSIONS: The learning tasks in our study were particularly distinct from the extinction learning paradigms that have shown strong DCS effects, and we were unable to demonstrate useful DCS effects with these nonemotional stimuli. Additional research is needed to elucidate the bounds of DCS augmentation effects on therapeutic learning.

Extinction retention predicts improvement in social anxiety symptoms following exposure therapy.

BACKGROUND: Several researchers have argued that basic research on extinction learning can guide efforts to enhance the efficacy of exposure-based therapy. At the basis of this translational research paradigm is the assumption that extinction retention is important to the outcome of exposure-based therapy. This study is the first to examine the relationship between extinction retention, which comprises the amount of fear reduction that is retained between two exposure sessions and improvement in anxiety symptoms following exposure treatment. METHODS: Adults (N=90), participating in two separate studies, who received three sessions of repeated exposure to public speaking provided ratings of peak fear during exposure treatment and completed the Liebowitz Social Anxiety Scale Self-Report version, LSAS-SR, Baker et al. [2002: Behav Res Ther 40:701-715] at baseline, posttreatment, and follow-up. RESULTS: After controlling for within-session extinction, extinction retention accounted for significant variance in the improvement of LSAS-SR scores over time. CONCLUSIONS: Our findings suggest that the consolidation of extinction learning into long-term memory is associated with improvements in fear and avoidance related to social situations following exposure therapy. Implications for exposure therapy augmentation studies are discussed.

Morpholine containing CB2 selective agonists.

Identification and optimization of two classes of CB2 selective agonists are described. A representative from each class is profiled in a murine model of inflammation and each shows similar efficacy to prednisolone upon oral dosing.

Proteolytic cleavage of host proteins by the Group IV viral proteases of Venezuelan equine encephalitis virus and Zika virus.

The alphaviral nonstructural protein 2 (nsP2) cysteine proteases (EC 3.4.22.-) are essential for the proteolytic processing of the nonstructural (ns) polyprotein and are validated drug targets. A common secondary role of these proteases is to antagonize the effects of interferon (IFN). After delineating the cleavage site motif of the Venezuelan equine encephalitis virus (VEEV) nsP2 cysteine protease, we searched the human genome to identify host protein substrates. Here we identify a new host substrate of the VEEV nsP2 protease, human TRIM14, a component of the mitochondrial antiviral-signaling protein (MAVS) signalosome. Short stretches of homologous host-pathogen protein sequences (SSHHPS) are present in the nonstructural polyprotein and TRIM14. A 25-residue cyan-yellow fluorescent protein TRIM14 substrate was cleaved in vitro by the VEEV nsP2 protease and the cleavage site was confirmed by tandem mass spectrometry. A TRIM14 cleavage product also was found in VEEV-infected cell lysates. At least ten other Group IV (+)ssRNA viral proteases have been shown to cleave host proteins involved in generating the innate immune responses against viruses, suggesting that the integration of these short host protein sequences into the viral protease cleavage sites may represent an embedded mechanism of IFN antagonism. This interference mechanism shows several parallels with those of CRISPR/Cas9 and RNAi/RISC, but with a protease recognizing a protein sequence common to both the host and pathogen. The short host sequences embedded within the viral genome appear to be analogous to the short phage sequences found in a host's CRISPR spacer sequences. To test this algorithm, we applied it to another Group IV virus, Zika virus (ZIKV), and identified cleavage sites within human SFRP1 (secreted frizzled related protein 1), a retinal Gs alpha subunit, NT5M, and Forkhead box protein G1 (FOXG1) in vitro. Proteolytic cleavage of these proteins suggests a possible link between the protease and the virus-induced phenotype of ZIKV. The algorithm may have value for selecting cell lines and animal models that recapitulate virus-induced phenotypes, predicting host-range and susceptibility, selecting oncolytic viruses, identifying biomarkers, and de-risking live virus vaccines. Inhibitors of the proteases that utilize this mechanism may both inhibit viral replication and alleviate suppression of the innate immune responses.

Reducing anxiety sensitivity with exercise.

BACKGROUND: Exercise interventions repeatedly have been shown to be efficacious for the treatment of depression, and initial studies indicate similar efficacy for the treatment of anxiety conditions. To further study the potential beneficial role of prescriptive exercise for anxiety-related conditions, we examined the role of exercise in reducing fears of anxiety-related sensations (anxiety sensitivity). METHODS: We randomly assigned 60 participants with elevated levels of anxiety sensitivity to a 2-week exercise intervention, a 2-week exercise plus cognitive restructuring intervention, or a waitlist control condition. Assessment of outcome was completed at pretreatment, midtreatment, 1-week posttreatment, and 3-week follow-up. RESULTS: We found that both exercise conditions led to clinically significant changes in anxiety sensitivity that were superior to the waitlist condition, representing a large controlled effect size (d=2.15). Adding a cognitive component did not facilitate the effects of the exercise intervention. Consistent with hypotheses, changes in anxiety sensitivity mediated the beneficial effects of exercise on anxious and depressed mood. CONCLUSIONS: We discuss these findings in terms of the potential role of exercise as an additional psychosocial intervention for conditions such as panic disorder, where anxiety sensitivity is a prominent component of pathology.

Discovery and optimization of p38 inhibitors via computer-assisted drug design.

Integration of computational methods, X-ray crystallography, and structure-activity relationships will be disclosed, which lead to a new class of p38 inhibitors that bind to p38 MAP kinase in a Phe out conformation.

Systematic literature review of oral hygiene practices for intensive care patients receiving mechanical ventilation.

BACKGROUND: Oropharyngeal colonization with pathogenic organisms contributes to the development of ventilator-associated pneumonia in intensive care units. Although considered basic and potentially nonessential nursing care, oral hygiene has been proposed as a key intervention for reducing ventilator-associated pneumonia. Nevertheless, evidence from randomized controlled trials that could inform best practice is limited. OBJECTIVE: To appraise the peer-reviewed literature to determine the best available evidence for providing oral care to intensive care patients receiving mechanical ventilation and to document a research agenda for this important activity in optimizing patients' outcomes. METHODS: Articles published from 1985 to 2006 in English and indexed in the CINAHL, MEDLINE, Joanna Briggs Institute, Cochrane Library, EMBASE, and DARE databases were searched by using the key terms oral hygiene, oral hygiene practices, oral care, mouth care, mouth hygiene, intubated, mechanically ventilated, intensive care, and critical care. Reference lists of retrieved journal articles were searched for publications missed during the primary search. Finally, the Google search engine was used to do a comprehensive search of the World Wide Web to ensure completeness of the search. The search strategy was verified by a health librarian. RESULTS: The search yielded 55 articles: 11 prospective controlled trials, 20 observational studies, and 24 descriptive reports. Methodological issues and the heterogeneity of samples precluded meta-analysis. CONCLUSIONS: Despite the importance of providing oral hygiene to intensive care patients receiving mechanical ventilation, high-level evidence from rigorous randomized controlled trials or high-quality systematic reviews that could inform clinical practice is scarce.