Evaluation of Blast Overpressure Exposure Effects on Concentration of Antibiotics in Mice

OBJECTIVE

Infection as sequelae to explosion-related injury is an enduring threat to our troops. There are limited data on the effects of blast on antibiotic pharmacokinetics (PK), pharmacodynamics (PD), and efficacy. The observational study presented here is our Institute's first attempt to address this issue by combining our existing interdepartmental blast, infection modeling, and in vivo PK/PD capabilities and was designed to determine the PK effects of blast on the first-line antibiotic, cefazolin, in an in vivo mouse model.

METHODS

A total of 160 male BALB/c mice were divided to sham and blast (exposed to blast overpressure of 19 psi) in two biological replicates. At 1 hour after blast/sham exposure, the animals received IV injection of cefazolin (328 mg/kg). Animals were euthanized at 3 minutes, 10 minutes, 15 minutes, 30 minutes, 1 hour, 3 hours, 6 hours, or 10 hours after the injection. Plasma and liver were analyzed for concentration of cefazolin using mass-spectrometry.

RESULTS

We observed increases in the concentration of cefazolin in the plasma and liver of blast exposed animals at later time points and increase in elimination half-life.

CONCLUSION

Our results indicate that blast-induced physiologic changes significantly influence cefazolin PK and suggest that efficacy could be affected in the context of the blast; assessment of efficacy and PD effects require further investigation. Metabolic changes resulting from blast may influence other classes of antibiotics and other therapeutics used with these injuries. Therefore, this may have important treatment considerations in other areas of military medicine.

Lead Optimization of Second-Generation Acridones as Broad-Spectrum Antimalarials

The global impact of malaria remains staggering despite extensive efforts to eradicate the disease. With increasing drug resistance and the absence of a clinically available vaccine, there is an urgent need for novel, affordable, and safe drugs for prevention and treatment of malaria. Previously, we described a novel antimalarial acridone chemotype that is potent against both blood-stage and liver-stage malaria parasites. Here, we describe an optimization process that has produced a second-generation acridone series with significant improvements in efficacy, metabolic stability, pharmacokinetics, and safety profiles. These findings highlight the therapeutic potential of dual-stage targeting acridones as novel drug candidates for further preclinical development.

THU0540 A PHASE 2B STUDY OF INTRAVENOUSLY (IV) ADMINISTERED TC 99M TILMANOCEPT TO DETERMINE DIFFERENTIAL UPTAKE, REPRODUCIBILITY OVER TIME AND IMAGE STABILITY IN HEALTHY SUBJECTS AND IN PATIENTS WITH RHEUMATOID ARTHRITIS (RA) ON STABLE TREATMENT

Background:

At present, there are no reliable noninvasive means to directly monitor disease activity in RA patients. Activated macrophages are a critical component of the inflammatory etiology of RA due to their role in prolonged RA joint inflammation and destruction through the release of pro-inflammatory cytokines and chemokines. Tc 99m tilmanocept is a radiopharmaceutical imaging agent that binds with high affinity to the macrophage mannose receptor CD206 that resides on activated macrophages. Previous clinical trials demonstrated safety and tolerability of Tc 99m tilmanocept, as well as a determination of optimal clinical dose and timeframe for RA imaging.

Objectives:

The current phase 2b study aims to evaluate reproducibility and stability of imaging and will assess quantitative Tc 99m tilmanocept uptake cut points that reliably enable discrimination between joints of healthy people and RA patients.

Methods:

The analysis cohort contained 18 healthy controls (HC) clinically free of inflammatory joint disease and 12 subjects with clinically diagnosed RA who are on stable anti-inflammatory and/or anti-rheumatic therapy. Each subject received a 150-mcg dose of tilmanocept radiolabeled with 10 mCi of Tc 99m in a 3mL IV injection. Injection was followed by planar imaging at 60 and 180 minutes for both HC and RA subjects on study Day 0 and repeated in RA subjects on Day 8. Images were quantitatively assessed to detect localization within synovial spaces of bilateral hands and wrists by determining average pixel intensity in each region of interest relative to average pixel intensity in a joint-specific reference region.

Results:

Data obtained from the interim analysis support the hypothesis that Tc 99m tilmanocept imaging can provide robust quantitative imaging in HC and RA subjects. Repeat images within and between days demonstrate root mean squared differences that are approximately 10% or less of the observed localization of Tc 99m tilmanocept. Qualitatively, images of HC indicated no disease-related site-specific localization, whereas localization is present in RA subjects at levels expected given the difference in macrophage number and density in different pathotypes of RA. Notably, images from patients with active RA exhibit the same localization patterns on images taken in a test-retest fashion on the same day as well as in subjects with images acquired on Day 0 and Day 8 (see Figure 1). These results show low imaging readout variability, enabling reliable quantification of joints with RA-involved macrophage-mediated inflammation. Analysis of the HC and RA images was used to determine initial quantitative “cut-points” to differentiate between joints with and without the inflammation typically seen in RA.

Figure 1.

Tilmanocept consistently localizes in areas of macrophage-driven inflammation, demonstrating low variability. RA patients exhibit reproducible localization over a 1-week period. Typical of healthy subjects, no evidence of inflammation-related Tc 99m tilmanocept uptake was observed in the healthy control. Images on the right show same patient imaged on 2 different days.

Conclusion:

Tc 99m tilmanocept imaging of the joints in healthy subjects as well as in patients with active RA under stable treatment is reproducible and stable over time. The results confirmed that the signal in joints of healthy subjects and RA patients can be quantified and used to establish cut points to distinguish inflamed and non-inflamed joints on a joint-by-joint basis. These results provide the foundation for a noninvasive, objective method to monitor activity in macrophage-driven inflammation in joints of patients with RA.

Disclosure of Interests:

Ayah Hussein Employee of: Currently employed by Navidea Biopharmaceuticals, David Ralph Consultant of: Previous consultant for Navidea Biopharmaceuticals, Employee of: Currently employed by Navidea Biopharmaceuticals, Beth Potter Employee of: Currently employed by Navidea Biopharmaceuticals, Bonnie Abbruzzese Employee of: Currently employed by Navidea Biopharmaceuticals, Rachael Hershey Employee of: Currently employed by Navidea Biopharmaceuticals, Katherine Repp Employee of: Previously employed by Navidea Biopharmaceuticals, Haya Shakhtra Employee of: Currently employed by Navidea Biopharmaceuticals, Mehak Goel Employee of: Currently employed by Navidea Biopharmaceuticals, Madison Palmer Employee of: Currently employed by Navidea Biopharmaceuticals, Allison Kissling Employee of: Previously employed by Navidea Biopharmaceuticals, Carley Hartings Employee of: Previously employed by Navidea Biopharmaceuticals, Michael Blue Employee of: Currently employed by Navidea Biopharmaceuticals, Michael Rosol Employee of: Currently employed by Navidea Biopharmaceuticals

Discovery and Structural Optimization of Acridones as Broad-Spectrum Antimalarials

Malaria remains one of the deadliest diseases in the world today. Novel chemoprophylactic and chemotherapeutic antimalarials are needed to support the renewed eradication agenda. We have discovered a novel antimalarial acridone chemotype with dual-stage activity against both liver-stage and blood-stage malaria. Several lead compounds generated from structural optimization of a large library of novel acridones exhibit efficacy in the following systems: (1) picomolar inhibition of in vitro Plasmodium falciparum blood-stage growth against multidrug-resistant parasites; (2) curative efficacy after oral administration in an erythrocytic Plasmodium yoelii murine malaria model; (3) prevention of in vitro Plasmodium berghei sporozoite-induced development in human hepatocytes; and (4) protection of in vivo P. berghei sporozoite-induced infection in mice. This study offers the first account of liver-stage antimalarial activity in an acridone chemotype. Details of the design, chemistry, structure-activity relationships, safety, metabolic/pharmacokinetic studies, and mechanistic investigation are presented herein.

Improving Relative Bioavailability of Oral Imidazolidinedione by Reducing Particle Size Using Homogenization and Ultra-Sonication

Particle size is an important determinant of gastrointestinal absorption of compounds administrated orally. The present study evaluates the effect of a reduction in particle size assessed by homogenization, sonication, and homogenization plus sonication on the bioavailability of imidazolidinedione (IZ), an antimalarial compound with known causal prophylactic activity and radical cure of relapsing malaria. Formulations were administrated intragastrically to mice, and blood samples were collected for LC-MS/MS analysis. The homogenization method manually decreased particle size with minimal variance, resulting in a mean particle diameter of 42.22 μm, whereas the probe sonication method evenly distributed pulses of sound to break apart particles, resulting in a mean diameter of 1.50 μm. Homogenization plus sonication resulted in a mean particle diameter of 1.44 μm, which was similar to that of the sonication method alone. The compound suspensions did not show a significant difference in mean particle size between the different vehicles. The sonically engineered microparticle delivers high sonic energy to the suspension leads to faster breakdown and stabilizing of the micronized particles when compared with homogenizer. The bioavailability of the small particle IZ formulation was 100%, compared to the 55.79% relative bioavailability of IZ with larger particle size. These initial data clearly show that a reduction in particle size of orally administered IZ with probe sonication could significantly increase bioavailability in rodent animals that is affected by a high first-pass effect.

Family History-Taking in Paediatrics: It’s Much More Than Just A Checklist

BACKGROUND: Family history (FH) is a risk factor for many conditions in pediatric practice; interest has increased in supporting systematic FH taking in this area by identifying core conditions for enquiry and developing point of care tools. There is little published about current practice to inform implementing such changes.

OBJECTIVES: To inform future FH taking interventions by identifying pediatricians' perceptions, attitudes, beliefs, and current practices.

DESIGN/METHODS: The Theoretical Domains Framework (TDF) was used to develop a comprehensive interview scheme. Semi-structured interviews were conducted with community and hospital-based pediatricians Analysis was by the constant comparison method, using a thematic approach. This study was funded by the Canadian Institutes of Health Research.

RESULTS: The data revealed FH taking to be a firmly embedded, but complex aspect of pediatric practice. Participants described FH as part of regular, holistic care, extending to social and interpersonal, as well as clinical purposes; in addition to disease risk assessment, FH information helped clarify diagnosis, and select medication; tailor the overall patient management based on family circumstances; and provide psychosocial support for parents. It was also used as a method to build a relationship with parents/carers. FH and social history information were inextricably linked and often appeared to be the same concept in participants’ minds. Participating pediatricians generally expressed confidence in their FH skills and reported tailoring their approach according to experience, after initial training early in their career. While acknowledging some challenges in ensuring accuracy, they were attuned to nuances in their interactions with parents and children which would affect whether, and what, they were told about illness in the family. Most were not concerned about formal evidence, and would not change their practice except for “good reason”.

CONCLUSION: The use of the TDF helped ensure a comprehensive approach to FH taking in pediatric practice. The findings suggest that FH taking in this setting is a complex activity, embedded in routine care. Recommendations for systematic enquiry about specific conditions cannot be seen as a simple additional activity to current practice. Efforts to make FH taking more systematic may founder if they fail to take into account pediatricians’ attitudes, perspectives, and practices. Further studies should explore and seek to confirm and expand our observations.

Pre-clinical evaluation of CYP 2D6 dependent drug-drug interactions between primaquine and SSRI/SNRI antidepressants

Background

The liver-stage anti-malarial activity of primaquine and other 8-aminoquinoline molecules has been linked to bio-activation through CYP 2D6 metabolism. Factors such as CYP 2D6 poor metabolizer status and/or co-administration of drugs that inhibit/interact with CYP 2D6 could alter the pharmacological properties of primaquine.

Methods

In the present study, the inhibitory potential of the selective serotonin reuptake inhibitor (SSRI) and serotonin norepinephrine reuptake inhibitor (SNRI) classes of antidepressants for CYP 2D6-mediated primaquine metabolism was assessed using in vitro drug metabolism and in vivo pharmacological assays.

Results

The SSRI/SNRI classes of drug displayed a range of inhibitory activities on CYP 2D6-mediated metabolism of primaquine in vitro (IC₅₀ 1–94 μM). Fluoxetine and paroxetine were the most potent inhibitors (IC₅₀ ~1 µM) of CYP 2D6-mediated primaquine metabolism, while desvenlafaxine was the least potent (IC₅₀ ~94 µM). The most potent CYP 2D6 inhibitor, fluoxetine, was chosen to investigate the potential pharmacological consequences of co-administration with primaquine in vivo. The pharmacokinetics of a CYP 2D6-dependent primaquine metabolite were altered upon co-administration with fluoxetine. Additionally, in a mouse malaria model, co-administration of fluoxetine with primaquine reduced primaquine anti-malarial efficacy.

Conclusions

These results are the first from controlled pre-clinical experiments that indicate that primaquine pharmacological properties can be modulated upon co-incubation/administration with drugs that are known to interact with CYP 2D6. These results highlight the potential for CYP 2D6-mediated drug–drug interactions with primaquine and indicate that the SSRI/SNRI antidepressants could be used as probe molecules to address the primaquine-CYP 2D6 DDI link in clinical studies. Additionally, CYP 2D6-mediated drug–drug interactions can be considered when examining the possible causes of human primaquine therapy failures.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1329-z) contains supplementary material, which is available to authorized users.

Ethosuximide and phenytoin dose-dependently attenuate acute nonconvulsive seizures after traumatic brain injury in rats

Acute seizures frequently occur following severe traumatic brain injury (TBI) and have been associated with poor patient prognosis. Silent or nonconvulsive seizures (NCS) manifest in the absence of motor convulsion, can only be detected via continuous electroencephalographic (EEG) recordings, and are often unidentified and untreated. Identification of effective anti-epileptic drugs (AED) against post-traumatic NCS remains crucial to improve neurological outcome. Here, we assessed the anti-seizure profile of ethosuximide (ETX, 12.5-187.5 mg/kg) and phenytoin (PHT, 5-30 mg/kg) in a spontaneously occurring NCS model associated with penetrating ballistic-like brain injury (PBBI). Rats were divided between two drug cohorts, PHT or ETX, and randomly assigned to one of four doses or vehicle within each cohort. Following PBBI, NCS were detected by continuous EEG monitoring for 72 h post-injury. Drug efficacy was evaluated on NCS parameters of incidence, frequency, episode duration, total duration, and onset latency. Both PHT and ETX attenuated NCS in a dose-dependent manner. In vehicle-treated animals, 69-73% experienced NCS (averaging 9-10 episodes/rat) with average onset of NCS occurring at 30 h post-injury. Compared with control treatment, the two highest PHT and ETX doses significantly reduced NCS incidence to 13-40%, reduced NCS frequency (1.8-6.2 episodes/rat), and delayed seizure onset: <20% of treated animals exhibited NCS within the first 48 h. NCS durations were also dose-dependently mitigated. For the first time, we demonstrate that ETX and PHT are effective against spontaneously occurring NCS following PBBI, and suggest that these AEDs may be effective at treating post-traumatic NCS.

Ketotifen is an antimalarial prodrug of norketotifen with blood schizonticidal and liver-stage efficacy

Ketotifen is known to exhibit antimalarial activity in mouse and monkey malaria models. However, the low plasma levels and short half life of the drug do not adequately explain its in vivo efficacy. We synthesized most of the known metabolites of ketotifen and evaluated their antimalarial activity and pharmacokinetics in mice. Norketotifen, the de-methylated metabolite of ketotifen, was a more potent antimalarial in vitro as compared to ketotifen, and exhibited equivalent activity in vivo against asexual blood and developing liver-stage parasites. After ketotifen dosing, norketotifen levels were much higher than ketotifen relative to the IC50s of the compounds against Plasmodium falciparum in vitro. The data support the notion that the antimalarial activity of ketotifen in mice is mediated through norketotifen.

A review of studies examining the nature of selection-based and topography-based verbal behavior

Selection-based (SB) verbal behavior, in most general terms, consists of selecting stimuli from an array, which presumably has some effect on a listener. Topography-based (TB) verbal behavior consists of responses with unique topographies (e.g. speaking, signing, writing) which is also presumed to have some effect on a listener. This article reviews research examining the nature of these two types of verbal behavior. Overall, TB verbal behavior appears to be more easily acquired and may also function to mediate some SB verbal behavior.

Attitude and knowledge about genetics and genetic testing

BACKGROUND

Increasing numbers of health care users may be confronted with new genetic knowledge and discoveries that offer new types of medical decision-making. How people use these new insights and make decisions about genetic risk depends, at least in part, on their knowledge and attitudes about human genetics.

METHODS

A postal survey administered to 560 women who had been offered prenatal screening in Ontario measured knowledge about, and attitudes toward, genetic testing and the uses of genetic information.

RESULTS

Respondents strongly supported the use of genetic information to improve disease diagnosis and to help understand disease causes; however, people also held a more critical attitude towards certain aspects of testing and genetic information. Relatively high levels of knowledge about genetics were also observed in this sample, although there were deficits in specific areas (e.g., transmission patterns).

CONCLUSIONS

Despite overall positive attitudes towards genetics, participants held more critical attitudes towards certain aspects of testing and the uses of genetic information. It would be unwise for genetics policy-makers and stakeholders to assume that a better-informed public would automatically be more supportive of all genetics research and new genetic discoveries.

Adrenocortical tumor with left renal vein, vena cava and intrahepatic venous extension

A 41 year old white female presented with upper respiratory distress and shortness of breath appeared on initial computed tomography (CT) scan to have a large left retroperitoneal mass with left renal vein extension including a mass up to the level of the atrium. This presentation suggested hypernephroma. She proved, however, to have an adrenal cortical carcinoma which displaced the kidney, exhibiting vascular invasion within the gland and non-adherent extension into the vena cava, atrium, common hepatic vein and left renal vein, where some adherence was present. This unusual tumor required extensive surgery for removal, including use of cardiopulmonary bypass, with good results.