Prospective Longitudinal Assessment of Quality of Life After Stereotactic Ablative Radiotherapy for Oligometastases: Analysis of the Population-based SABR-5 Phase II Trial

AIMS

To evaluate longitudinal patient-reported quality of life (QoL) in patients treated with stereotactic ablative radiotherapy (SABR) for oligometastases.

MATERIALS AND METHODS

The SABR-5 trial was a population-based single-arm phase II study of SABR to up to five sites of oligometastases, conducted in six regional cancer centres in British Columbia, Canada from 2016 to 2020. Prospective QoL was measured using treatment site-specific QoL questionnaires at pre-treatment baseline and at 3, 6, 9, 12, 15, 18, 21, 24, 30 and 36 months after treatment. Patients with bone metastases were assessed with the Brief Pain Inventory (BPI). Patients with liver, adrenal and abdominopelvic lymph node metastases were assessed with the Functional Assessment of Chronic Illness Therapy-Abdominal Discomfort (FACIT-AD). Patients with lung and intrathoracic lymph node metastases were assessed with the Prospective Outcomes and Support Initiative (POSI) lung questionnaire. The two one-sided test procedure was used to assess equivalence between the worst QoL score and the baseline score of individual patients. The mean QoL at all time points was used to determine the trajectory of QoL response after SABR. The proportion of patients with 'stable', 'improved' or 'worsened' QoL was determined for all time points based on standard minimal clinically important differences (MCID; BPI worst pain = 2, BPI functional interference score [FIS] = 0.5, FACIT-AD Trial Outcome Index [TOI] = 8, POSI = 3).

RESULTS

All enrolled patients with baseline QoL assessment and at least one follow-up assessment were analysed (n = 133). On equivalence testing, the patients' worst QoL scores were clinically different from baseline scores and met MCID (BPI worst pain mean difference: 1.8, 90% confidence interval 1.19 to 2.42]; BPI FIS mean difference: 1.68, 90% confidence interval 1.15 to 2.21; FACIT-AD TOI mean difference: -8.76, 90% confidence interval -11.29 to -6.24; POSI mean difference: -4.61, 90% confidence interval -6.09 to -3.14). However, the mean FIS transiently worsened at 9, 18 and 21 months but eventually returned to stable levels. The mean FACIT and POSI scores also worsened at 36 months, albeit with a limited number of responses (n = 4 and 8, respectively). Most patients reported stable QoL at all time points (range: BPI worst pain 71-82%, BPI FIS 45-78%, FACIT-AD TOI 50-100%, POSI 25-73%). Clinically significant stability, worsening and improvement were seen in 70%/13%/18% of patients at 3 months, 53%/28%/19% at 18 months and 63%/25%/13% at 36 months.

CONCLUSIONS

Transient decreases in QoL that met MCID were seen between patients' worst QoL scores and baseline scores. However, most patients experienced stable QoL relative to pre-treatment levels on long-term follow-up. Further studies are needed to characterise patients at greatest risk for decreased QoL.

Predictors of Quality of Life Decline in Patients with Oligometastases treated with Stereotactic Ablative Radiotherapy: Analysis of the Population-Based SABR-5 Phase II Trial

AIMS

Most patients experience stable quality of life (QoL) after stereotactic ablative radiotherapy (SABR) treatment for oligometastases. However, a subset of patients experience clinically relevant declines in QoL on post-treatment follow-up. This study aimed to identify risk factors for QoL decline.

MATERIALS AND METHODS

The SABR-5 trial was a population-based single-arm phase II study of SABR to up to five sites of oligometastases. Prospective QoL was measured using treatment site-specific tools at pre-treatment baseline and 3, 6, 9, 12, 15, 18, 21, 24, 30 and 36 months after treatment. The time to persistent QoL decline was calculated as the time from SABR to the first decline in QoL score meeting minimum clinically important difference with no improvement to baseline score on subsequent assessments. Univariable and multivariable logistic regression analyses were carried out to determine factors associated with QoL decline.

RESULTS

One hundred and thirty-three patients were included with a median follow-up of 32 months (interquartile range 25-43). Thirty-five patients (26%) experienced a persistent decline in QoL. The median time until persistent QoL decline was not reached. The cumulative incidence of QoL decline at 2 and 3 years were 22% (95% confidence interval 14.0-29.6) and 40% (95% confidence interval 28.0-51.2), respectively. In multivariable analysis, disease progression (odds ratio 5.23, 95% confidence interval 1.59-17.47, P = 0.007) and adrenal metastases (odds ratio 9.70, 95% confidence interval 1.41-66.93, P = 0.021) were associated with a higher risk of QoL decline. Grade 3 or higher (odds ratio 3.88, 95% confidence interval 0.92-16.31, P = 0.064) and grade 2 or higher SABR-associated toxicity (odds ratio 2.24, 95% confidence interval 0.85-5.91, P = 0.10) were associated with an increased risk of QoL decline but did not reach statistical significance.

CONCLUSIONS

Disease progression and adrenal lesion site were associated with persistent QoL decline following SABR. The development of grade 3 or higher toxicities was also associated with an increased risk, albeit not statistically significant. Further studies are needed, focusing on the QoL impact of metastasis-directed therapies.

Methodological approach: using a within-subjects design in the marble burying assay

In 2016, the National Institutes of Health mandated the use of both male and female mice in funded research. The use of both sexes is an important variable to consider; however, it comes with negative consequences such as increased animal expenses. One way to combat these negatives is to explore the option of using a within-subjects design (repeated measures) in behavioral assays that historically use a between-subjects design. Our study aimed to determine if a within-subjects design can be utilized in the marble burying assay. The marble burying assay is used as a tool for screening putative anxiolytic compounds as the assay is thought to measure obsessive-compulsive disorder- or anxiety-like behaviors. First, we compared the effects of sex and digging medium (corn cob or Sani Chip) on the number of marbles buried using CD-1 mice. Second, we determined if mice would continue to bury marbles after repeated exposures to the test arena. Lastly, we tested three positive controls (buspirone, ketamine, and fluoxetine). We found that mice buried significantly more marbles within Sani Chip digging medium, and no sex differences were observed. Next, the number of marbles buried and locomotor activity remained consistent across four test sessions. The positive controls buspirone (3.2-10 mg/kg) ketamine (32 mg/kg), and fluoxetine (10 mg/kg) decreased the number of marbles buried using the within-subjects design. These data suggest that a within-subjects design is optimal for the marble burying assay as it will reduce the number of animals and increase statistical power.

How physiotherapists attend to the human aspects of care when working with people with low back pain: a thematic analysis

Pain is a multidimensional experience. Physiotherapy has attempted to enhance earlier biomedical approaches to patient care through approaches like the 'biopsychosocial' model. Nevertheless, physiotherapy continues to focus on biomedical and/or behavioural aspects of care. We critically investigated how physiotherapists attend to human (psychosocial, emotional, existential, and moral) aspects of low back pain care. We co-analysed ethnographic data with researchers, patients, and physiotherapists using concepts of conforming, tinkering and abandoning 'scripts'. Data included observations of 28 physiotherapy interactions between 26 patients and 10 physiotherapists and 7 researcher-clinician dialogues. Analysis suggests when conforming to scripts, clinicians have difficulty recognising and responding to emotions; time pressure limited clinicians focus, and a biological focus often distracted from psychosocial aspects of people's back pain experiences. In contrast, tinkering with or abandoning scripts allowed space to broaden the focus. Drawing from theorists such as Butler (1999) and Gibson et al. (2020) our analysis contributes to health sociology, arguing that 'tinkering' with or 'abandoning' scripts can foster more humanistic, flexible and reflexive approaches to care. Although health sociologists have explored tinkering, abandoning is new; within physiotherapy, it encapsulates being able to respond with agility to non-physical elements of care without constraint from traditional ways of thinking and doing.

Uncertainty in low back pain care - insights from an ethnographic study

PURPOSE

To explore how uncertainty plays out in low back pain (LBP) care and investigate how clinicians manage accompanying emotions/tensions.

MATERIALS AND METHODS

We conducted ethnographic observations of clinical encounters in a private physiotherapy practice and a public multidisciplinary pain clinic. Our qualitative reflexive thematic analysis involved abductive thematic principles informed by Fox and Katz (medical uncertainty) and Ahmed (emotions).

RESULTS

We identified three themes. (1) Sources of uncertainty: both patients and clinicians expressed uncertainty during clinical encounters (e.g., causes of LBP, mismatch between imaging findings and presentation). Such uncertainty was often accompanied by emotions - anger, tiredness, frustration. (2) Neglecting complexity: clinicians often attempted to decrease uncertainty and associated emotions by providing narrow answers to questions about LBP. At times, clinicians' denial of uncertainty also appeared to deny patients the right to make informed decisions about treatments. (3) Attending to uncertainty?: clinicians attended to uncertainty through logical reasoning, reassurance, acknowledgement, personalising care, shifting power, adjusting language and disclosing risks.

CONCLUSIONS

Uncertainty pervades LBP care and is often accompanied by emotions, emphasising the need for a healthcare culture that recognises the emotional dimensions of patient-clinician interactions and prepares clinicians and patients to be more accepting of, and clearly communicate about, uncertainty.IMPLICATIONS FOR REHABILITATIONUncertainty pervades LBP care and is often accompanied by emotions.Neglecting complexity in LBP care may compromise person-centred care.Acknowledging uncertainty can enhance communication, balance patient-clinician relationships and address human aspects of care.

Repurposed dihydroorotate dehydrogenase inhibitors with efficacy against drug-resistant Acinetobacter baumannii

New antimicrobials are needed for the treatment of extensively drug-resistant Acinetobacter baumannii. The de novo pyrimidine biosynthetic enzyme dihydroorotate dehydrogenase (DHODH) is a validated drug target for malaria and human autoimmune diseases. We provide genetic evidence that A. baumannii DHODH (AbDHODH) is essential for bacterial survival in rodent infection models. We chemically validate the target by repurposing a unique library of ~450 triazolopyrimidine/imidazopyrimidine analogs developed for our malaria DHODH program to identify 21 compounds with submicromolar activity on AbDHODH. The most potent (DSM186, DHODH IC50 28 nM) had a minimal inhibitory concentration of ≤1 µg/ml against geographically diverse A. baumannii strains, including meropenem-resistant isolates. A structurally related analog (DSM161) with a long in vivo half-life conferred significant protection in the neutropenic mouse thigh infection model. Encouragingly, the development of resistance to these compounds was not identified in vitro or in vivo. Lastly, the X-ray structure of AbDHODH bound to DSM186 was solved to 1.4 Å resolution. These data support the potential of AbDHODH as a drug target for the development of antimicrobials for the treatment of A. baumannii and potentially other high-risk bacterial infections.

A catalyst for transforming health systems and person-centred care: Canadian national position statement on patient-reported outcomes

Background

Patient-reported outcomes (pros) are essential to capture the patient's perspective and to influence care. Although pros and pro measures are known to have many important benefits, they are not consistently being used and there is there no Canadian pros oversight. The Position Statement presented here is the first step toward supporting the implementation of pros in the Canadian health care setting.

Methods

The Canadian pros National Steering Committee drafted position statements, which were submitted for stakeholder feedback before, during, and after the first National Canadian Patient Reported Outcomes (canpros) scientific conference, 14-15 November 2019 in Calgary, Alberta. In addition to the stakeholder feedback cycle, a patient advocate group submitted a section to capture the patient voice.

Results

The canpros Position Statement is an outcome of the 2019 canpros scientific conference, with an oncology focus. The Position Statement is categorized into 6 sections covering 4 theme areas: Patient and Families, Health Policy, Clinical Implementation, and Research. The patient voice perfectly mirrors the recommendations that the experts reached by consensus and provides an overriding impetus for the use of pros in health care.

Conclusions

Although our vision of pros transforming the health care system to be more patient-centred is still aspirational, the Position Statement presented here takes a first step toward providing recommendations in key areas to align Canadian efforts. The Position Statement is directed toward a health policy audience; future iterations will target other audiences, including researchers, clinicians, and patients. Our intent is that future versions will broaden the focus to include chronic diseases beyond cancer.

A novel method to test non-exclusive hypotheses applied to Arctic ice projections from dependent models

A major conundrum in climate science is how to account for dependence between climate models. This complicates interpretation of probabilistic projections derived from such models. Here we show that this problem can be addressed using a novel method to test multiple non-exclusive hypotheses, and to make predictions under such hypotheses. We apply the method to probabilistically estimate the level of global warming needed for a September ice-free Arctic, using an ensemble of historical and representative concentration pathway 8.5 emissions scenario climate model runs. We show that not accounting for model dependence can lead to biased projections. Incorporating more constraints on models may minimize the impact of neglecting model non-exclusivity. Most likely, September Arctic sea ice will effectively disappear at between approximately 2 and 2.5 K of global warming. Yet, limiting the warming to 1.5 K under the Paris agreement may not be sufficient to prevent the ice-free Arctic.

Metabolic tumour volume is prognostic in patients with non-small-cell lung cancer treated with stereotactic ablative radiotherapy

Introduction

Stereotactic ablative radiotherapy (sabr) is a relatively new technique for the curative-intent treatment of patients with inoperable early-stage non-small-cell lung cancer (nsclc). Previous studies have demonstrated a prognostic value for positron emission tomography-computed tomography (pet/ct) parameters, including maximal standardized uptake value (suv_max), metabolic tumour volume (mtv), and total lesion glycolysis (tlg) in lung cancer patients. We aimed to determine which pet/ct parameter is most prognostic of local control (lc) and overall survival (os) in patients treated with sabr for nsclc.

Methods

We conducted a retrospective review of patients treated with sabr for stage I inoperable nsclc at BC Cancer between 2009 and 2013. The Akaike information criterion was used to compare the prognostic value of the various pet/ct parameters.

Results

The study included 134 patients with a median age of 76 years. Median tumour diameter was 2.2 cm, gross tumour volume was 8.1 mL, suv_max was 7.9, mtv was 2.4 mL, and tlg was 10.9 suv·mL. The 2-year lc was 92%, and os was 66%. On univariate and multivariate analysis, imaging variables including tumour size, gross tumour volume, suv_max, mtv, and tlg were all associated with worse lc. Tumour size was not associated with significantly worse os, but other imaging variables were. The pet/ct parameter most prognostic of lc was mtv. Compared with suv_max, tlg and mtv were more prognostic of os.

Conclusions

In patients with early-stage nsclc treated with sabr, mtv appears to be prognostic of lc and os.

Antibody Dependent Enhancement of Acinetobacter baumannii Infection in a Mouse Pneumonia Model

Acinetobacter baumannii has become a pathogen of increasing medical importance because of the emergence of multidrug-resistant strains and the high rate of mortality of infected patients. Promising animal study results have been reported recently with active and passive immunization against A. baumannii virulence factors. In the present study, a monoclonal IgG3 antibody, 8E3, was developed with specificity for the K2 capsular polysaccharide of A. baumannii, and its therapeutic potential was assessed. 8E3 enhanced macrophage-mediated bactericidal activity against the A. baumannii clinical strain AB899. However, 8E3 treatment (passive immunization) of AB899-infected mice led to a substantial increase in mortality and to substantial increases in bacterial load in blood, lung, and in splenic samples. In vitro investigations showed a large binding capacity in the supernatant of bacterial cultures, suggesting that shed capsule components act as a binding sink for 8E3. Investigations of 8E3 pharmacokinetics in mice demonstrated that unbound concentrations of the antibody dropped below detection limits within 24 hours after a 200 mg/kg dose. However, total concentrations of antibody declined slowly, with an apparent terminal half-life (t _1/2) of 6.7-8.0 days, suggesting that the vast majority of 8E3 in blood is bound (e.g., with soluble capsule components in blood). We hypothesize that high concentrations of 8E3-capsule immune complexes act to inhibit bacterial clearance in vivo. To the best of our knowledge, this is the first demonstration of antibody-dependent enhancement of A. baumannii infection, and these observations highlight the complexity of antibody-based therapy for A. baumannii infections.

Assessing post-radiotherapy handover notes from a family physician perspective

Background

Across our province, post-radiotherapy (rt) handover notes are sent to family physicians (fps) after rt. Based on previous fp feedback, we created a revised post-radiotherapy handover note with more information requested by fps. The purpose of this study was to determine whether the revised handover note improved the note as a communication aid.

Methods

Potential common and rare treatment side effects, oncologist contact information, and treatment intent were added to the revised handover note. Both versions were sent alongside a questionnaire to fps. Paired t-tests were carried out to compare satisfaction differences.

Results

There was a response rate of 37% for the questionnaires. Significantly greater clarity in the following categories was observed: responsibility for patient follow-up (mean score improvement of 1.2 on a 7-point Likert scale, p < 0.001), follow-up schedule (1.1, p < 0.001) as well as how and when to contact the oncologist (1.4, p = 0.001). Family physicians were also more content with how the institute transitioned care back to them (1.5, p = 0.012). Overall, fps were generally satisfied with the content of the revised post-rt handover note and noted improvement over the previous version. The frequency of investigations and institute supports initiated such as counselling services were suggested further additions.

Conclusions

The inclusion of potential treatment side effects, oncologist contact information, treatment intent and a well-laid out follow-up schedule were essential information needed by fps for an effective post-rt completion note. With these additions, the revised post-rt handover note showed significant improvement.

The Capsular Polysaccharide of Acinetobacter baumannii Is an Obstacle for Therapeutic Passive Immunization Strategies

Acinetobacter baumannii has become an important concern for human health due to rapid development and wide spread of antimicrobial-resistant strains and high mortality associated with the infection. Passive immunizations with antisera targeting outer membrane proteins (OMPs) have shown encouraging results in protecting mice from A. baumannii infection, but monoclonal anti-OMP antibodies have not been developed, and their potential therapeutic properties have not been explored. The goal of this report is to evaluate the antibacterial activity of monoclonal antibodies (MAbs) targeting outer membrane protein A (OmpA) of A. baumannii Five anti-OmpA MAbs were developed using hybridoma technology and showed strong binding to strain ATCC 19606. However, low antibody binding was observed when they were tested against six clinical isolates, which included extensively drug-resistant strains. In contrast, high binding to an isogenic K1 capsule-negative mutant (AB307.30) was shown, suggesting that capsular polysaccharide mediated the inhibition of MAb binding to OmpA. Anti-OmpA MAbs increased the macrophage-mediated bactericidal activity of AB307.30 but failed to increase phagocytic killing of capsule-positive strains. Capsular polysaccharide was also protective against complement-mediated bactericidal activity in human ascites in the presence and absence of opsonization. Lastly, passive immunization with anti-OmpA MAbs did not confer protection against challenge with AB307-0294, the encapsulated parent strain of AB307.30, in a mouse sepsis infection model. These results reveal the important role of capsule polysaccharide in shielding OmpA and thereby inhibiting anti-OmpA MAb binding to clinical isolates. This property of capsule hindered the therapeutic utility of anti-OmpA MAbs, and it may apply to other conserved epitopes in A. baumannii.

Neoadjuvant systemic therapy in breast cancer: use and trends in radiotherapy practice

BACKGROUND

The use of neoadjuvant systemic therapy (nast) in the treatment of breast cancer is increasing, and the role of adjuvant radiation therapy (rt) in that setting is uncertain. We sought to review and report the use of nast, its trends over time, and its relationship with the prescribing patterns of locoregional rt in a provincial cancer system.

METHODS

Patients with stages i-iii breast cancer diagnosed during 2007-2012 were identified using a provincial database. Patient, tumour, and treatment characteristics were extracted. Multivariable logistic regression analyses were used to assess associations with the use of nast. Kaplan-Meier and Cox regression were used for survival analyses.

RESULTS

Of the 11,658 patients who met the inclusion criteria, 602 (5%) had received nast. Use of nast was more frequent in stage iii patients (53%) than in stages i and ii patients (2%). In clinically lymph-node positive patients, a pathology assessment was made approximately 50% of the time. Higher clinical tumour stage and increasing clinical nodal stage predicted for increasing use of nast and of nodal rt after nast, but pathologic nodal status after nast was not associated with use of nodal rt. A statistically significant survival difference was observed between patients in the nast and no-nast groups, but that significance disappeared in a multivariable Cox regression analysis.

CONCLUSIONS

This population-based study demonstrated 5% use of nast for breast cancer. Most patients received nodal rt after nast, and nodal rt was not associated with pathologic stage after nast. Findings likely reflect the realities of clinical practice and show that reliance on clinical nodal staging results in outcomes similar to those reported in the literature.

Cryoneurolysis to treat the pain and symptoms of knee osteoarthritis: a multicenter, randomized, double-blind, sham-controlled trial

OBJECTIVE

Evaluate the efficacy and safety/tolerability of cryoneurolysis for reduction of pain and symptoms associated with knee osteoarthritis (OA).

DESIGN

Randomized, double-blind, sham-controlled, multicenter trial with a 6-month follow-up in patients with mild-to-moderate knee OA. Patients were randomized 2:1 to cryoneurolysis targeting the infrapatellar branch of the saphenous nerve (IPBSN) or sham treatment. The primary endpoint was the change from baseline to Day 30 in the Western Ontario and McMaster Osteoarthritis Index (WOMAC) pain score adjusted by the baseline score and site. Secondary endpoints, including visual analogue scale (VAS) pain score and total WOMAC score, were tested in a pre-defined order.

RESULTS

The intent-to-treat (ITT) population consisted of 180 patients (n = 121 active treatment, n = 59 sham treatment). Compared to the sham group, patients who received active treatment had a statistically significant greater change from baseline in the WOMAC pain subscale score at Day 30 (P = 0.0004), Day 60 (P = 0.0176), and Day 90 (P = 0.0061). Patients deemed WOMAC pain responders at Day 120 continued to experience a statistically significant treatment effect at Day 150. Most expected side effects were mild in severity and resolved within 30 days. The incidence of device- or procedure-related adverse events was similar in the two treatment groups with no occurrence of serious or unanticipated adverse device effects (ADE).

CONCLUSIONS

Cryoneurolysis of the IPBSN resulted in statistically significant decreased knee pain and improved symptoms compared to sham treatment for up to 150 days, and appeared safe and well tolerated.

Structure of shikimate kinase, an in vivo essential metabolic enzyme in the nosocomial pathogen Acinetobacter baumannii, in complex with shikimate

Acinetobacter baumannii is an opportunistic Gram-negative pathogen that is an important cause of healthcare-associated infections exhibiting high mortality rates. Clinical isolates of multidrug-resistant (MDR) and extremely drug-resistant (XDR) A. baumannii strains are increasingly being observed. Compounding this concern is the dearth of new antibacterial agents in late-stage development that are effective against MDR and XDR A. baumannii. As part of an effort to address these concerns, two genes (aroA and aroC) of the shikimate pathway have previously been determined to be essential for the growth and survival of A. baumannii during host infection (i.e. to be essential in vivo). This study expands upon these results by demonstrating that the A. baumannii aroK gene, encoding shikimate kinase (SK), is also essential in vivo in a rat soft-tissue infection model. The crystal structure of A. baumannii SK in complex with the substrate shikimate and a sulfate ion that mimics the binding interactions expected for the β-phosphate of ATP was then determined to 1.91 Å resolution and the enzyme kinetics were characterized. The flexible shikimate-binding domain and LID region are compared with the analogous regions in other SK crystal structures. The impact of structural differences and sequence divergence between SKs from pathogenic bacteria that may influence antibiotic-development efforts is discussed.

A magnetic particle time-of-flight (MagPTOF) diagnostic for measurements of shock- and compression-bang time at the NIF (invited)

A magnetic particle time-of-flight (MagPTOF) diagnostic has been designed to measure shock- and compression-bang time using D(3)He-fusion protons and DD-fusion neutrons, respectively, at the National Ignition Facility (NIF). This capability, in combination with shock-burn weighted areal density measurements, will significantly constrain the modeling of the implosion dynamics. This design is an upgrade to the existing particle time-of-flight (pTOF) diagnostic, which records bang times using DD or DT neutrons with an accuracy better than ±70 ps [H. G. Rinderknecht et al., Rev. Sci. Instrum. 83, 10D902 (2012)]. The inclusion of a deflecting magnet will increase D(3)He-proton signal-to-background by a factor of 1000, allowing for the first time simultaneous measurements of shock- and compression-bang times in D(3)He-filled surrogate implosions at the NIF.

The K1 capsular polysaccharide from Acinetobacter baumannii is a potential therapeutic target via passive immunization

The emergence of extremely resistant and panresistant Gram-negative bacilli, such as Acinetobacter baumannii, requires consideration of nonantimicrobial therapeutic approaches. The goal of this report was to evaluate the K1 capsular polysaccharide from A. baumannii as a passive immunization target. Its structure was determined by a combination of mass spectrometric and nuclear magnetic resonance (NMR) techniques. Molecular mimics that might raise the concern for autoimmune disease were not identified. Immunization of CD1 mice demonstrated that the K1 capsule is immunogenic. The monoclonal antibody (MAb) 13D6, which is directed against the K1 capsule from A. baumannii, was used to determine the seroprevalence of the K1 capsule in a collection of 100 A. baumannii strains. Thirteen percent of the A. baumannii isolates from this collection were seroreactive to MAb 13D6. Opsonization of K1-positive strains, but not K1-negative strains, with MAb 13D6 significantly increased neutrophil-mediated bactericidal activity in vitro (P < 0.05). Lastly, treatment with MAb 13D6 3 and 24 h after bacterial challenge in a rat soft tissue infection model resulted in a significant decrease in the growth/survival of a K1-positive strain compared to that of a K1-negative strain or to treatment with a vehicle control (P < 0.0001). These data support the proof of principle that the K1 capsule is a potential therapeutic target via passive immunization. Other serotypes require assessment, and pragmatic challenges exist, such as the need to serotype infecting strains and utilize serotype-specific therapy. Nonetheless, this approach may become an important therapeutic option with increasing antimicrobial resistance and a diminishing number of active antimicrobials.

Charged-particle spectroscopy for diagnosing shock ρR and strength in NIF implosions

The compact Wedge Range Filter (WRF) proton spectrometer was developed for OMEGA and transferred to the National Ignition Facility (NIF) as a National Ignition Campaign diagnostic. The WRF measures the spectrum of protons from D-(3)He reactions in tuning-campaign implosions containing D and (3)He gas; in this work we report on the first proton spectroscopy measurement on the NIF using WRFs. The energy downshift of the 14.7-MeV proton is directly related to the total ρR through the plasma stopping power. Additionally, the shock proton yield is measured, which is a metric of the final merged shock strength.

A novel particle time of flight diagnostic for measurements of shock- and compression-bang times in D3He and DT implosions at the NIF

The particle-time-of-flight (pTOF) diagnostic, fielded alongside a wedge range-filter (WRF) proton spectrometer, will provide an absolute timing for the shock-burn weighted ρR measurements that will validate the modeling of implosion dynamics at the National Ignition Facility (NIF). In the first phase of the project, pTOF has recorded accurate bang times in cryogenic DT, DT exploding pusher, and D(3)He implosions using DD or DT neutrons with an accuracy better than ±70 ps. In the second phase of the project, a deflecting magnet will be incorporated into the pTOF design for simultaneous measurements of shock- and compression-bang times in D(3)He-filled surrogate implosions using D(3)He protons and DD-neutrons, respectively.

Biofilm formed by a hypervirulent (hypermucoviscous) variant of Klebsiella pneumoniae does not enhance serum resistance or survival in an in vivo abscess model

A new hypervirulent (hypermucoviscous) clinical variant of Klebsiella pneumoniae (hvKP) has emerged over the last decade. Our goal is to identify new mechanisms, which increase the virulence hvKP. It has been shown that hvKP strains produce more biofilm than "classical" stains of K. pneumoniae, therefore we hypothesized that biofilm formation may contribute to the pathogenesis of systemic infection. To test this hypothesis, transposon mutants of the model pathogen hvKP1 were generated and screened for decreased production of biofilm. Three mutant constructs with disruptions in glnA [putatively encodes glutamine synthetase, hvKP1 glnA:: EZ::TN < KAN-2 > (glnA::Tn)], sucD [putatively encodes succinyl-CoA synthase α subunit, hvKP1 sucD:: EZ::TN < KAN-2 > (sucD::Tn)], and tag [putatively encodes transcriptional antiterminator of glycerol uptake operon, hvKP1 tag:: EZ::TN < KAN-2 > (tag::Tn)] were chosen for further characterization and use in biologic studies. Quantitative assays performed in rich laboratory medium and human ascites confirmed the phenotype and a hypermucoviscosity assay established that capsule production was not affected. However, compared with its wild-type parent, neither planktonic cells nor biofilms of glnA::Tn, sucD::Tn and tag::Tn displayed a change to the bactericidal activity of 90% human serum. Likewise, when assessed in a rat subcutaneous abscess model, the growth and survival of glnA::Tn, sucD::Tn and tag::Tn in abscess fluid was similar to hvKP1. In this report we identify three new genes that contribute to biofilm formation in hvKP1. However, decreased biofilm production due to disruption of these genes does not affect the sensitivity of these mutant constructs to 90% human serum when in planktonic form or within a biofilm. Further, their virulence in an in vivo abscess model was unaffected.

P5-01-15: The Functional Role of the Estrogen-Regulated Gene GREB1: Characterization of a Novel GREB1 Knockout Mouse Model

Background: Gene regulated in breast cancer 1 (GREB1) was initially discovered in breast cancers as an estrogen-regulated gene that mediates estrogen-stimulated cell proliferation and is a candidate clinical marker for response to endocrine therapy. However, little is known of the functional role of GREB1 protein in normal breast tissue or breast cancers.

Methods: To address this unknown role, our laboratory designed and created a novel Greb1 Knockout Mouse model (C57/bl MEL Greb1 KO). This constitutive model results in the loss of Greb1 mRNA and protein expression in cells where expression of Cre recombinase promotes the cleavage of exon 1 and intron 1 of the gene encoding Greb1. ROSA26 Cre C57/b1 MEL Greb1 KO mice heterozygous for the floxed Greb1 allele were crossed to generate experimental litters. Initial experiments were designed to evaluate if the complete loss of Greb1 expression in offspring homozygous for the floxed Greb1 allele was lethal during gestation. Experimental litters were tail clipped and genotyped using gDNA and genotype-specific PCR.

Results: Offspring homozygous for the floxed Greb1 allele were identified in expected Mendelian ratios with wild type and heterozygous siblings. Loss of Greb1 expression was confirmed using RT-PCR, in situ hybridization and immunoblotting. Loss of both Greb1 alleles was not observed to be lethal during gestation for either male or female pups. Preliminary gross observation of these homozygous KO mice revealed no overt anatomical differences, however, they were 25–30% smaller than their heterozygous and wild-type siblings. Breeding experiments are underway to determine the fertility of crossbred Greb1 homozygous KO mice. Imaging experiments and necropsy with histochemical analysis of tissues will reveal any alteration in architecture and function. These findings will be summarized in this presentation.

Discussion: As GREB1 has been identified as an estrogen-regulated gene involved in breast cancer cell proliferation and a potential target for new therapeutic strategies, it is important to understand the contribution of GREB1 to the differentiation, development and function of normal tissues as well as in breast cancers. Characterization of this novel Greb1 KO mouse model will provide answers to these functional questions surrounding GREB1.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-01-15.

Hypervirulent K. pneumoniae secretes more and more active iron-acquisition molecules than "classical" K. pneumoniae thereby enhancing its virulence

Background

A new hypervirulent (hypermucoviscous) clinical variant of Klebsiella pneumoniae (hvKP) has emerged over the last decade. Our goal is to identify new mechanisms, which increase the virulence hvKP compared to “classic” K. pneumoniae (cKP).

Methodology/Principal Findings

Various growth assays were performed in human ascites, human serum, and laboratory medium with the hvKP strain hvKP1 (wt), randomly chosen blood isolates of cKP strains (cKP1-4), and mutant constructs deficient in the secretion of selected compounds. An in vivo mouse model that mimics infection due to hvKP and a quantitative siderophore assay were also used. It was established that a molecule(s)/factor(s) was secreted by hvKP1 significantly enhanced its growth and/or survival in human ascites. This molecule(s)/factor(s) also increased the growth and/or survival of hvKP1 in serum ex vivo and in an in vivo mouse model that measures metastatic spread after subcutaneous challenge, thereby further establishing biologic significance. Although features such as a size of <3kD, heat stability, and growth characteristics in ascites suggested this molecule(s) was a quorum-sensing compound, data presented demonstrates that this molecule(s)/factor(s) is involved in iron uptake and is likely a siderophore(s) or another iron-acquisition molecule. Although it is known that iron acquisition is critical for virulence, a novel aspect of this observation is that hvKP1 produces quantitatively more siderophores that appear to be biologically more active (increased affinity for iron or more resistant to host factors) than those produced by cKP strains.

Conclusions/Significance

The data presented delineates a new mechanism by which hvKP increases its pathogenic potential compared to cKP strains. This paradigm may be broadly applicable to other extraintestinal gram-negative bacilli.

In vivo and in vitro activity of the siderophore monosulfactam BAL30072 against Acinetobacter baumannii

OBJECTIVES

New antibiotics that are active against multidrug-resistant (MDR) Acinetobacter baumannii are urgently needed. BAL30072, a siderophore monosulfactam antibiotic that rapidly penetrates the outer membrane of A. baumannii and has potent activity against most isolates, including those harbouring AmpC β-lactamases and metallo- (class B) or OXA- (class D) carbapenemases, is being developed to meet that need.

METHODS

We assessed the in vitro activity of BAL30072, meropenem and the combination of BAL30072 and meropenem (2:1 and 1:1 ratios) by MIC and time-kill studies. Proof-of-principle in vivo efficacy was determined using a rat soft-tissue infection model. Five diverse strains with defined phenotypic and genetic profiles were tested (AB307-0294, AB8407, AB1697, AB3340 and AB0057).

RESULTS

In microdilution assays, combining BAL30072 with meropenem lowered meropenem MICs 2-8-fold. In time-kill studies, the BAL30072 and meropenem combinations resulted in bactericidal concentrations 2-8-fold lower than those of meropenem or BAL30072 alone. In the rat model, BAL30072 was active against four of five strains (AB307-0294, AB8407, AB1697 and AB3340), including meropenem-susceptible and -non-susceptible strains. AB0057 was the only strain resistant to BAL30072 in vivo and in vitro (MIC >64 mg/L). Meropenem was active in vivo against two of the five strains tested (AB307-0294 and AB3340). Both BAL30072 and BAL30072 with meropenem were equally effective in vivo.

CONCLUSIONS

These data support the continued evaluation of BAL30072 for use in the treatment of infections caused by MDR A. baumannii.

Central nervous system crystal-storing histiocytosis: neuroimaging, neuropathology, and literature review

CSH is a very uncommon lesion and is distinctly unusual in the brain. We report a case of CSH within the brain parenchyma in a 27-year-old woman with Crohn disease. Advanced radiologic imaging and anatomic pathology correlation allow this report to serve as a reference for future similar cases.