The structural components of the Azotobacter vinelandii iron-only nitrogenase, AnfDKG, form a protein complex within the plant mitochondrial matrix

A long-held goal of synthetic biology has been the transfer of a bacterial nitrogen-fixation pathway into plants to reduce the use of chemical fertiliser on crops such as rice, wheat and maize. There are three classes of bacterial nitrogenase, named after their metal requirements, containing either a MoFe-, VFe- or FeFe-cofactor, that converts N₂ gas to ammonia. Relative to the Mo-nitrogenase the Fe-nitrogenase is not as efficient for catalysis but has less complex genetic and metallocluster requirements, features that may be preferable for engineering into crops. Here we report the successful targeting of bacterial Fe-nitrogenase proteins, AnfD, AnfK, AnfG and AnfH, to plant mitochondria. When expressed as a single protein AnfD was mostly insoluble in plant mitochondria, but coexpression of AnfD with AnfK improved its solubility. Using affinity-based purification of mitochondrially expressed AnfK or AnfG we were able to demonstrate a strong interaction of AnfD with AnfK and a weaker interaction of AnfG with AnfDK. This work establishes that the structural components of the Fe-nitrogenase can be engineered into plant mitochondria and form a complex, which will be a requirement for function. This report outlines the first use of Fe-nitrogenase proteins within a plant as a preliminary step towards engineering an alternative nitrogenase into crops.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Severity of oEsophageal Anastomotic Leak in patients after oesophagectomy: the SEAL score

Background

Anastomotic leak (AL) is a common but severe complication after oesophagectomy. It is unknown how to determine the severity of AL objectively at diagnosis. Determining leak severity may guide treatment decisions and improve future research. This study aimed to identify leak-related prognostic factors for mortality, and to develop a Severity of oEsophageal Anastomotic Leak (SEAL) score.

Methods

This international, retrospective cohort study in 71 centres worldwide included patients with AL after oesophagectomy between 2011 and 2019. The primary endpoint was 90-day mortality. Leak-related prognostic factors were identified after adjusting for confounders and were included in multivariable logistic regression to develop the SEAL score. Four classes of leak severity (mild, moderate, severe, and critical) were defined based on the risk of 90-day mortality, and the score was validated internally.

Results

Some 1509 patients with AL were included and the 90-day mortality rate was 11.7 per cent. Twelve leak-related prognostic factors were included in the SEAL score. The score showed good calibration and discrimination (c-index 0.77, 95 per cent c.i. 0.73 to 0.81). Higher classes of leak severity graded by the SEAL score were associated with a significant increase in duration of ICU stay, healing time, Comprehensive Complication Index score, and Esophagectomy Complications Consensus Group classification.

Conclusion

The SEAL score grades leak severity into four classes by combining 12 leak-related predictors and can be used to the assess severity of AL after oesophagectomy.

POS1088 EFFICACY OF SUBCUTANEOUS TANEZUMAB FOR THE TREATMENT OF OSTEOARTHRITIS OF THE KNEE OR HIP: A POST-HOC SUBGROUP ANALYSIS OF PATIENTS FROM A RANDOMIZED, NSAID-CONTROLLED STUDY WITH A HISTORY OF DEPRESSION, ANXIETY, OR INSOMNIA

Background:

Tanezumab is a monoclonal antibody directed against nerve growth factor. It is in development for the treatment of moderate to severe chronic pain associated with osteoarthritis (OA) in adult patients for whom other treatments are ineffective or not appropriate. Phase 3 clinical trials have demonstrated the efficacy of subcutaneous tanezumab versus placebo for pain and function outcomes over various timepoints. Largely similar change from baseline was demonstrated in an oral nonsteroidal anti-inflammatory drug (NSAID)-controlled study.1,2,3,4 The efficacy of some other OA therapies can be dampened in patients with depression, anxiety, or insomnia.5,6,7

Objectives:

A post-hoc analysis to explore the efficacy of subcutaneous tanezumab after 16 weeks treatment, as compared to oral NSAID, in patients with OA and a history of depression, anxiety, or insomnia at baseline.

Methods:

Subgroup analysis of data from a randomized, double-blind, double-dummy, active-controlled phase 3 study of subcutaneous tanezumab (2.5 mg or 5 mg every 8 weeks) vs twice daily oral NSAID in patients (≥18 years) with radiographically-confirmed moderate to severe hip or knee OA (Kellgren-Lawrence grade ≥2; NCT02528188).4 Co-primary efficacy endpoints were change from baseline to week 16 in Western Ontario and McMaster Universities OA Index (WOMAC*) Pain and Physical Function subscale scores (both ≥5/10 at randomisation; increasing score indicates increasing pain/disability), and Patient’s Global Assessment of OA (PGA-OA, ≥3/5 at randomisation; increasing score indicates poorer condition). Enrolled patients had a history of inadequate pain relief with acetaminophen; inadequate pain relief with/intolerance to/contraindication to tramadol or opioids; or an unwillingness to take opioids. Patients were on a stable dose of NSAID for ≥30 days before screening. Data are presented as least squares (LS) mean change from baseline to week 16 for the whole population and for subgroups of patients with/without a history of depression, anxiety, or insomnia at baseline. Exploratory statistical analysis was conducted by analysis of covariance. P values were not adjusted for multiplicity. This exploratory post-hoc analysis was not part of the pre-specified hypothesis testing plan or included in any sample size calculations; therefore, comparisons between treatment arms or patient subgroups should be interpreted with caution.

Results:

Overall, 2996 patients were randomized and received at least one dose of study treatment (subcutaneous tanezumab 2.5 mg: n=1002; subcutaneous tanezumab 5 mg: n=998; oral NSAID: n=996). In this population (comprising patients with or without a history of anxiety, depression or insomnia), all treatments were associated with notable and largely similar magnitude improvements in WOMAC Pain, WOMAC Physical Function, and PGA-OA at week 16 (Figure 1). Across treatment groups, differences in LS mean change from baseline in patients with and without a history of depression, anxiety or insomnia ranged between 0 - 0.34 for WOMAC Pain and Physical Function and 0 - 0.19 for PGA-OA.

Conclusion:

Patients with a history of depression, anxiety, or insomnia did not appear to experience dampened improvements in pain or function with tanezumab or NSAID, as compared to those without.

References:

[1]Schnitzer T, et al. JAMA. 2019;322(1):37-48;

[2]Berenbaum F, et al. Ann Rheum Dis. 2020;79(6):800-10;

[3]Schnitzer T, et al. Semin Arthritis Rheum. 2020;50(3):387-93;

[4]Hochberg M, et al. Arthritis Rheumatol. In Press;

[5]Sharma A, et al. Open Access Rheumatol. 2016;31(8):103-13;

[6]Mallen C, et al. PLoS Med. 2017;14(4):e1002273;

[7]Campbell C, et al. Arthritis Care Res. 2015;67(10):1387-96.

Acknowledgements:

Study sponsored by Pfizer and Eli Lilly and Company. Editorial support was provided by Jennifer Bodkin of Engage Scientific Solutions and funded by Pfizer and Eli Lilly and Company.

Disclosure of Interests:

Philip J Mease Speakers bureau: AbbVie, Amgen, Bristol Myers Squibb, Celgene, Janssen, Eli Lilly and Company, Novartis, Pfizer, UCB, Consultant of: AbbVie, Amgen, Boehringer Ingelheim, Bristol Myers Squibb, Celgene, Galapagos, Gilead, GlaxoSmithKline, Janssen, Eli Lilly and Company, Novartis, Pfizer, Sun, UCB, Grant/research support from: AbbVie, Amgen, Bristol Myers Squibb, Celgene, Janssen, Eli Lilly and Company, Novartis, Pfizer, Sun, UCB, Theresa Mallick-Searle Speakers bureau: Allergan, Abbvie, Eli Lilly and Company, Salix, Consultant of: Pfizer, Eli Lilly and Company, Elizabeth Johnston Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Lars Viktrup Shareholder of: Eli Lilly and Company, Employee of: Eli Lilly and Company, Dominique Menuet Employee of: Pfizer, Ruoyong Yang Employee of: Pfizer, Robert J Fountaine Shareholder of: Pfizer, Employee of: Pfizer.

483 Complete Sciatic Nerve Transection from A Closed Femoral Fracture: A Case Report

Introduction

Complete transection of the sciatic nerve following a closed femoral fracture is exceedingly uncommon. Delayed diagnosis may result due to this unrecognised injury pattern.

Case Description:

An 18-year-old male motorcyclist was referred following a significantly displaced closed, femoral fracture. The patient was sedated at the scene and transferred to theatre for definitive fixation, where an open reduction was performed via an anterior approach. Symptoms of paresthesia and weakness were reported immediately postoperatively, and formal neurological examination prompted an emergency MRI. On this basis, the patient was transferred to plastics and underwent surgical exploration, where complete transection of the sciatic nerve was identified just proximal to the bifurcation into the common peroneal and tibial nerve. A nerve gap of five centimetres was identified requiring reconstruction with grouped fascicular sural nerve grafts.

Discussion:

Complete transection of the sciatic nerve is a devastating injury that compromises the function of the posterior compartment of the thigh and all motor function below the knee. To our knowledge, reports of complete sciatic nerve transection secondary to a closed fracture of the femoral shaft are extremely rare in the pertinent literature, with only two other cases reported to date.

489 The Role of Sentinel Lymph Node Biopsy in Cutaneous Head and Neck Melanoma: A Systematic Review and Meta-Analysis

Introduction

and

Aims

Method

This review follows the PRISMA guidelines. Database searches for MEDLINE and EMBASE were constructed to retrieve human studies published between 1st January 2010 and 1st July 2020 assessing the role and accuracy of sentinel lymph node biopsy in cutaneous malignant melanoma of the head and neck. Articles were independently screened by two reviewers and critically appraised using the MINORS criteria. The primary outcomes consisted of the sentinel node identification rate and test-performance measures, including the false-negative rate and the posttest probability negative.

Results

A total of 27 studies, including 4688 patients, met the eligibility criteria. Statistical analysis produced weighted summary estimates for the sentinel node identification rate of 97.3% (95% CI, 95.9% to 98.6%), the false-negative rate of 21.3% (95% CI, 17.0% to 25.4%) and the posttest probability negative of 4.8% (95% CI, 3.9% to 5.8%).

Discussion

Twin-beam sub-shot-noise raster-scanning microscope

By exploiting the quantised nature of light, we demonstrate a sub-shot-noise scanning optical transmittance microscope. Our microscope demonstrates, with micron scale resolution, a factor of improvement in precision of 1.76(9) in transmittance estimation gained per probe photon relative to the theoretical model, a shot-noise-limited source of light, in an equivalent single-pass classical version of the same experiment using the same number of photons detected with a 90% efficient detector. This would allow us to observe photosensitive samples with nearly twice the precision, without sacrificing image resolution or increasing optical power to improve signal-to-noise ratio. Our setup uses correlated twin-beams produced by parametric down-conversion, and a hybrid detection scheme comprising photon-counting-based feed-forward and a highly efficient CCD camera.

Combining role-play with interactive simulation to motivate informed climate action: Evidence from the World Climate simulation

Climate change communication efforts grounded in the information deficit model have largely failed to close the gap between scientific and public understanding of the risks posed by climate change. In response, simulations have been proposed to enable people to learn for themselves about this complex and politically charged topic. Here we assess the impact of a widely-used simulation, World Climate, which combines a socially and emotionally engaging role-play with interactive exploration of climate change science through the C-ROADS climate simulation model. Participants take on the roles of delegates to the UN climate negotiations and are challenged to create an agreement that meets international climate goals. Their decisions are entered into C-ROADS, which provides immediate feedback about expected global climate impacts, enabling them to learn about climate change while experiencing the social dynamics of negotiations. We assess the impact of World Climate by analyzing pre- and post-survey results from >2,000 participants in 39 sessions in eight nations. We find statistically significant gains in three areas: (i) knowledge of climate change causes, dynamics and impacts; (ii) affective engagement including greater feelings of urgency and hope; and (iii) a desire to learn and do more about climate change. Contrary to the deficit model, gains in urgency were associated with gains in participants’ desire to learn more and intent to act, while gains in climate knowledge were not. Gains were just as strong among American participants who oppose government regulation of free markets–a political ideology that has been linked to climate change denial in the US–suggesting the simulation’s potential to reach across political divides. The results indicate that World Climate offers a climate change communication tool that enables people to learn and feel for themselves, which together have the potential to motivate action informed by science.

Intratumoural evolutionary landscape of high-risk prostate cancer: the PROGENY study of genomic and immune parameters

BACKGROUND

Intratumoural heterogeneity (ITH) is well recognised in prostate cancer (PC), but its role in high-risk disease is uncertain. A prospective, single-arm, translational study using targeted multiregion prostate biopsies was carried out to study genomic and T-cell ITH in clinically high-risk PC aiming to identify drivers and potential therapeutic strategies.

PATIENTS AND METHODS

Forty-nine men with elevated prostate-specific antigen and multiparametric-magnetic resonance imaging detected PC underwent image-guided multiregion transperineal biopsy. Seventy-nine tumour regions from 25 patients with PC underwent sequencing, analysis of mutations, copy number and neoepitopes combined with tumour infiltrating T-cell subset quantification.

RESULTS

We demonstrated extensive somatic nucleotide variation and somatic copy number alteration heterogeneity in high-risk PC. Overall, the mutational burden was low (0.93/Megabase), but two patients had hypermutation, with loss of mismatch repair (MMR) proteins, MSH2 and MSH6. Somatic copy number alteration burden was higher in patients with metastatic hormone-naive PC (mHNPC) than in those with high-risk localised PC (hrlPC), independent of Gleason grade. Mutations were rarely ubiquitous and mutational frequencies were similar for mHNPC and hrlPC patients. Enrichment of focal 3q26.2 and 3q21.3, regions containing putative metastasis drivers, was seen in mHNPC patients. We found evidence of parallel evolution with three separate clones containing activating mutations of β-catenin in a single patient. We demonstrated extensive intratumoural and intertumoural T-cell heterogeneity and high inflammatory infiltrate in the MMR-deficient (MMRD) patients and the patient with parallel evolution of β-catenin. Analysis of all patients with activating Wnt/β-catenin mutations demonstrated a low CD8+/FOXP3+ ratio, a potential surrogate marker of immune evasion.

CONCLUSIONS

The PROGENY (PROstate cancer GENomic heterogeneitY) study provides a diagnostic platform suitable for studying tumour ITH. Genetic aberrations in clinically high-risk PC are associated with altered patterns of immune infiltrate in tumours. Activating mutations of Wnt/β-catenin signalling pathway or MMRD could be considered as potential biomarkers for immunomodulation therapies.

CLINICAL TRIALS.GOV IDENTIFIER

NCT02022371.

Abstract AP30: PHASE IB/II WITH EXPANSION OF PATIENTS AT THE MTD STUDY OF OLAPARIB PLUS WEEKLY (METRONOMIC) CARBOPLATIN AND PACLITAXEL IN RELAPSED OVARIAN CANCER PATIENTS

BACKGROUND: We established the olaparib tablet maximum tolerated dose (MTD) at 150 mg bid, dose limiting toxicities (DLT's) and response to therapy or carboplatin, paclitaxel and olaparib tablet given simultaneously, reported at ASCO 2014. This abstract will include data from both the phase 1b and the phase 2 expansion.

METHODS: A total of 54 subjects were evaluated in this trial, 14 in phase 1b and 40 in phase 2. Eligibility required measurable disease, adequate organ function and ECOG performance status of ~ 2. Subjects had to have failed first line platinum containing chemotherapy. BRCA testing was conducted as available. Subjects received the metronomic therapy of paclitaxel 60mg/m2 IV and carboplatin AUC 2 IV weekly, 3 weeks out of 4, and olaparib tablets at 150 mg bid administered orally for 3 consecutive days (D1-D3) every week for each cycle. Subjects were assessed for toxicity and response according to the protocol. Subjects that reached a confirmed complete remission were transitioned to olaparib tablets only, 300 mg bid until disease progression.

RESULTS: Median age was 58 and median number of prior regimens was 4. There have been no deaths due to the study regimen. One patient had grade 4 neutropenia and an allergic reaction to carboplatin. The common grade 3/4 toxicities were caused by the chemotherapy (neutropenia. anemia and thrombocytopenia). Two patients had mild GI toxicities. One patient had a skin rash. There was no evidence of cardiac, hepatic, or pulmonary toxicities in any of these patients. 25% of subjects had a complete remission (CR), 31% had PR, 23% had SD and 21% had

PD. Of the 13 CRs, 4 were BRCA negative. PFS median for BRCA positive subjects is 12.6 months vs 4.8 months for BRCA negative subjects. OS median for BRCA positive subjects is 24 months vs 16 months for BRCA negative subjects. All of the CR's are alive.

CONCLUSION: Olaparib tablet can be safely administered simultaneously with a weekly regimen of carboplatin and paclitaxel in heavily pretreated ovarian cancer patients. Olaparib appears to be highly effective in BRCA positive subjects. This is the first successful combination of olaparib tablets with carboplatin and paclitaxel that has been well tolerated.

Citation Format: Rivkin SE, Moon J, Iriarte D, Sloan H, Wiseman C, Klee M, Ference K, Drescher C, Veljovich D, Bondurant A, Peters W, Jiang P, Goodman G, Park M, Fer M, Shah C, Johnston E, Kaplan H, Wahl T, Ellis E. PHASE IB/II WITH EXPANSION OF PATIENTS AT THE MTD STUDY OF OLAPARIB PLUS WEEKLY (METRONOMIC) CARBOPLATIN AND PACLITAXEL IN RELAPSED OVARIAN CANCER PATIENTS [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr AP30.

Abstract OT2-01-07: A phase 2 study of abemaciclib plus pembrolizumab for patients with hormone receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC)

Background:

Abemaciclib is a small molecule inhibitor of both cyclin-dependent kinase (CDK) 4 and CDK6 administered orally twice daily on a continuous schedule. In I3Y-MC-JPBA, a phase I study, abemaciclib demonstrated acceptable safety, tolerability, and single-agent activity as monotherapy in different tumor types, including HR+ MBC (Patnaik A,et al. Cancer Discov 2016;6:1–14). In MONARCH 1, a phase 2 study, abemaciclib demonstrated a 19.7% objective response rate (ORR) with a median duration of response (DoR) of 8.6 months, median progression-free survival (PFS) of 6.0 months, and clinical benefit rate (CBR) of 42.4% in patients with HR+, HER2- MBC whose disease progressed on or after endocrine therapy and chemotherapy (Dickler, M. et al. American Society of Clinical Oncology (ASCO), abstract #510 (2016).). Pembrolizumab is a humanized monoclonal antibody against the programmed death receptor-1 (PD-1) protein that has shown preliminary efficacy in single-arm monotherapy trials in ER+/HER2- advanced breast cancer.

Trial design:

This open-label, phase 2 study will evaluate the safety and preliminary efficacy of abemaciclib 150 mg given orally every 12 hours on days 1-21 of a 21-day cycle in combination with intravenous pembrolizumab 200 mg on day 1 of a 21-day cycle in approximately 75 patients with stage IV non-small cell lung cancer or HR+, HER2- MBC (ClinicalTrials.gov NCT02779751). The study will include 3 disease-specific cohorts, each with approximately 25 patients. Only the HR+, HER2- MBC cohort will be presented here.

Eligibility criteria:

Eligible patients for the MBC cohort include women with confirmed HR+, HER2- MBC who have completed at least 1 but no more than 2 prior chemotherapy regimens in the metastatic setting; will provide tumor tissue prior to and after treatment (cycle 3, day 1); have measurable disease (RECIST v.1.1), adequate organ function, an ECOG performance status ≤1, and a life expectancy ≥12 weeks; are ≥18 yrs of age and able to swallow oral medications; and have not received treatment with any CDK 4 and 6 inhibitors or PD-1 or PD-L1 inhibitors.

Specific aims:

The primary objective is to characterize the safety profile of the combination of abemaciclib and pembrolizumab. Key secondary objectives include ORR, DoR, disease control rate (DCR), PFS, overall survival (OS), and characterization of pharmacokinetics.

Statistical methods:

The safety population includes patients who received at least one dose of study drug. ORR, DoR, DCR, and PFS analyses will be evaluated according to RECIST v.1.1 and irRECIST for disease progression. Time-to-event variables, such as DoR, PFS, and OS, will be estimated by Kaplan-Meier methodology. An interim analysis of safety and preliminary efficacy may occur for each cohort after all patients have completed (or discontinued from) approximately 24 weeks of treatment. The final analysis of OS will occur based on data collected for approximately 12 months after the last patient receives treatment.

Target accrual:

Approximately 75 patients are planned for the trial; 25 patients will comprise the MBC cohort.

Contact information: 1-877-CTLILLY (1-877-285-4559).

Citation Format: Rugo H, Tolaney S, Dickler M, Kabos P, Ho C-L, Wildiers H, Jerusalem G, Alés-Martínez JE, Hossain A, Johnston E, Gianni L. A phase 2 study of abemaciclib plus pembrolizumab for patients with hormone receptor positive (HR+), HER2 negative (HER2-) metastatic breast cancer (MBC) [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT2-01-07.

Video game training enhances cognitive control in older adults

Cognitive control is defined by a set of neural processes that allow us to interact with our complex environment in a goal-directed manner. Humans regularly challenge these control processes when attempting to simultaneously accomplish multiple goals (multitasking), generating interference as the result of fundamental information processing limitations. It is clear that multitasking behaviour has become ubiquitous in today's technologically dense world, and substantial evidence has accrued regarding multitasking difficulties and cognitive control deficits in our ageing population. Here we show that multitasking performance, as assessed with a custom-designed three-dimensional video game (NeuroRacer), exhibits a linear age-related decline from 20 to 79 years of age. By playing an adaptive version of NeuroRacer in multitasking training mode, older adults (60 to 85 years old) reduced multitasking costs compared to both an active control group and a no-contact control group, attaining levels beyond those achieved by untrained 20-year-old participants, with gains persisting for 6 months. Furthermore, age-related deficits in neural signatures of cognitive control, as measured with electroencephalography, were remediated by multitasking training (enhanced midline frontal theta power and frontal-posterior theta coherence). Critically, this training resulted in performance benefits that extended to untrained cognitive control abilities (enhanced sustained attention and working memory), with an increase in midline frontal theta power predicting the training-induced boost in sustained attention and preservation of multitasking improvement 6 months later. These findings highlight the robust plasticity of the prefrontal cognitive control system in the ageing brain, and provide the first evidence, to our knowledge, of how a custom-designed video game can be used to assess cognitive abilities across the lifespan, evaluate underlying neural mechanisms, and serve as a powerful tool for cognitive enhancement.

Video game training enhances cognitive control in older adults

Cognitive control is defined by a set of neural processes that allow us to interact with our complex environment in a goal-directed manner. Humans regularly challenge these control processes when attempting to simultaneously accomplish multiple goals (multitasking), generating interference as the result of fundamental information processing limitations. It is clear that multitasking behaviour has become ubiquitous in today's technologically dense world, and substantial evidence has accrued regarding multitasking difficulties and cognitive control deficits in our ageing population. Here we show that multitasking performance, as assessed with a custom-designed three-dimensional video game (NeuroRacer), exhibits a linear age-related decline from 20 to 79 years of age. By playing an adaptive version of NeuroRacer in multitasking training mode, older adults (60 to 85 years old) reduced multitasking costs compared to both an active control group and a no-contact control group, attaining levels beyond those achieved by untrained 20-year-old participants, with gains persisting for 6 months. Furthermore, age-related deficits in neural signatures of cognitive control, as measured with electroencephalography, were remediated by multitasking training (enhanced midline frontal theta power and frontal-posterior theta coherence). Critically, this training resulted in performance benefits that extended to untrained cognitive control abilities (enhanced sustained attention and working memory), with an increase in midline frontal theta power predicting the training-induced boost in sustained attention and preservation of multitasking improvement 6 months later. These findings highlight the robust plasticity of the prefrontal cognitive control system in the ageing brain, and provide the first evidence, to our knowledge, of how a custom-designed video game can be used to assess cognitive abilities across the lifespan, evaluate underlying neural mechanisms, and serve as a powerful tool for cognitive enhancement.

SU-D-BRB-01: 4D-CT Lung Ventilation Images Vary with 4D-CT Sorting Techniques

PURPOSE

4D-CT ventilation imaging is a novel promising technique for lung functional imaging and has potential as a biomarker for radiation pneumonitis, but has not been validated in human subjects. The current 4D- CT technique with phase-based sorting results in artifacts at an alarmingly high frequency (90%), which may introduce variations into ventilation calculations. The purpose of this study was to quantify the variability of 4D- CT ventilation imaging to 4D-CT sorting techniques.

METHODS

Two 4D-CT images were generated from the same data set by: (1) phase-based; (2) anatomic similarity- and abdominal displacement-based sorting for five patients. Two ventilation image sets (V_phase and V_anat) were then calculated by deformable image registration of peak-exhale and peak-inhale4D-CT images and quantification of regional volume change based on Hounsfield unit change. The variability of 4D-CT ventilation imaging wasquantified using the voxel-based Spearman rank correlation coefficients and Dice similarity coefficients (DSC) for the spatial overlap of segmented low- functional lung regions. The relationship between the abdominal motionrange variation and ventilation variation was also assessed using linearregression. Furthermore, the correlations between V_phase or V_anat and SPECT ventilation images (assumed ground-truth) were compared.

RESULTS

In general, displacement- and anatomic similarity-based sorting reduced 4D- CT artifacts compared to phase-based sorting. The voxel-based correlationsbetween V_phase and V_anat were only moderate (range, 0.57-0.77). The DSCs for the low-functional lung regions were moderate to substantial (0.58-0.70). The relationship between the motion range variation and ventilation variation was strong on average (R2=0.79±0.25), suggesting that ventilation variations are related to 4D-CT artifacts. Vanat was found to improve correlations with SPECT ventilation images compared to V_phase.

CONCLUSIONS

4D-CT ventilation images vary markedly with 4D-CT sorting techniques. 4D-CT artifacts should be considered as a significant source of variation in 4D-CT ventilation imaging during its validation. This study wassupported in part by NIH/NCI R01 93626. SK and CL are employees ofPhilips Research.

Surgical treatment of intracranial hypertension in encephalic cryptococcosis

The incidence of cryptococcosis has risen sharply together with the growing number of patients with Acquired Immunodeficiency Syndrome (AIDS). Cryptococcal meningitis is nowadays the most common intracranial non-viral infection in such cases. One of its most serious complications is intracranial hypertension (ICH), a situation that can lead either to early death, or disabling sequelae. The authors analyse a series of 10 cases of encephalic cryptococcosis with ICH, and describe the clinical course, diagnosis, medical and surgical treatment, and evolution. The physiopathology of ICH in these patients is discussed, proposing placement of a ventriculo-peritoneal shunt as the primary and emergency treatment, even when ventricular enlargement might be absent. Although the present series is certainly small, from the preceding discussion and according to an extensive bibliographical review, our conclusion is that patients with encephalic cryptococcosis and uncontrollable ICH should receive surgical treatment, consisting of an emergency diversion of the CSF, because serial lumbar punctures are not enough to improve the clinical course, that if left to its natural evolution would lead to a fatal outcome in a short time. In spite of the fact that CSF shunts were carried out on immunocompromised patients, no superinfections occurred.