Encapsulation of copper phenanthroline within horse spleen apoferritin: characterisation, cytotoxic activity and ability to retain temozolomide

Protein capsules are promising drug delivery vehicles for cancer research therapies. Apoferritin (AFt) is a self-assembling 12 nm diameter hollow nanocage with many desirable features for drug delivery, however, control of drug retention inside the protein cage remains challenging. Here we report the encapsulation of copper(ii)-1,10-phenanthroline (Cu(phen)) within the horse spleen AFt (HSAFt) nanocage, by diffusion of the metal through the pores between the protein subunits. Transmission electron microscopy revealed the formation of organised copper adducts inside HSAFt, without affecting protein integrity. These structures proved stable during storage (>4 months at -20 °C). Exposure to physiologically relevant conditions (37 °C) showed some selectivity in cargo release after 24 h at pH 5.5, relevant to the internalisation of AFt within the endosome (60% release), compared to pH 7.4, relevant to the bloodstream (40% release). Co-encapsulation of temozolomide, a prodrug used to treat glioblastoma multiforme, and Cu(phen) enabled entrapment of an average of 339 TMZ molecules per cage. In vitro results from MTT and clonogenic assays identified cytotoxic activity of the Cu(phen), HSAFt-Cu(phen) and HSAFt-Cu(phen)-TMZ adducts against colorectal cancer cells (HCT-116) and glioblastoma cells (U373V, U373M). However, the presence of the metal also contributed to more potent activity toward healthy MRC5 fibroblasts, a result that requires further investigation to assess the clinical viability of this system.

Socioeconomic inequalities in cervical cancer mortality in Canada, 1990 and 2019: a trend analysis

OBJECTIVE

It is increasingly recognized that those of lower socioeconomic status (SES) are disproportionately affected by cancer mortality. The association between cervical cancer mortality and SES have been reported; however, it remains poorly understood in the Canadian population. Thus, this study investigates trends in income and education inequalities in cervical cancer mortality in Canada over the last three decades.

STUDY DESIGN

Trend analysis.

METHODS

A dataset constructed at the census division level (n = 280), comprising the Canadian Vital Statistics Death Database, the Canadian Census of Population, and the National Household Survey was used to measure cervical cancer mortality in Canada. Income and education inequalities in cervical cancer mortality were measured using age-standardized Concentration index (C).

RESULTS

Crude cervical cancer mortality rates decreased significantly during the study period. Age-standardized C values were negative for the majority of years for income and education inequalities, reaching significance in some years. Trend analyses indicated an increasing concentration of cervical cancer mortality amongst those with lower education levels.

CONCLUSION

Despite recent decreases in cervical cancer mortality rates, socioeconomic inequalities in cervical cancer mortality in Canada are persistent. Notably, those of lower income and education levels are disproportionately affected, underscoring an opportunity to improve clinical outcomes by addressing these inequalities.

ATR inhibition using gartisertib enhances cell death and synergises with temozolomide and radiation in patient-derived glioblastoma cell lines

Glioblastoma cells can restrict the DNA-damaging effects of temozolomide (TMZ) and radiation therapy (RT) using the DNA damage response (DDR) mechanism which activates cell cycle arrest and DNA repair pathways. Ataxia-telangiectasia and Rad3-Related protein (ATR) plays a pivotal role in the recognition of DNA damage induced by chemotherapy and radiation causing downstream DDR activation. Here, we investigated the activity of gartisertib, a potent ATR inhibitor, alone and in combination with TMZ and/or RT in 12 patient-derived glioblastoma cell lines. We showed that gartisertib alone potently reduced the cell viability of glioblastoma cell lines, where sensitivity was associated with the frequency of DDR mutations and higher expression of the G2 cell cycle pathway. ATR inhibition significantly enhanced cell death in combination with TMZ and RT and was shown to have higher synergy than TMZ+RT treatment. MGMT promoter unmethylated and TMZ+RT resistant glioblastoma cells were also more sensitive to gartisertib. Analysis of gene expression from gartisertib treated glioblastoma cells identified the upregulation of innate immune-related pathways. Overall, this study identifies ATR inhibition as a strategy to enhance the DNA-damaging ability of glioblastoma standard treatment, while providing preliminary evidence that ATR inhibition induces an innate immune gene signature that warrants further investigation.

Comparison between [68Ga]Ga-PSMA-617 and [18F]FET PET as Imaging Biomarkers in Adult Recurrent Glioblastoma

The aim of this prospective clinical study was to evaluate the potential of the prostate specific membrane antigen (PSMA) targeting ligand, [68Ga]-PSMA-Glu-NH-CO-NH-Lys-2-naphthyl-L-Ala-cyclohexane-DOTA ([68Ga]Ga-PSMA-617) as a positron emission tomography (PET) imaging biomarker in recurrent glioblastoma patients. Patients underwent [68Ga]Ga-PSMA-617 and O-(2-[18F]-fluoroethyl)-L-tyrosine ([18F]FET) PET scans on two separate days. [68Ga]Ga-PSMA-617 tumour selectivity was assessed by comparing tumour volume delineation and by assessing the intra-patient correlation between tumour uptake on [68Ga]Ga-PSMA-617 and [18F]FET PET images. [68Ga]Ga-PSMA-617 tumour specificity was evaluated by comparing its tumour-to-brain ratio (TBR) with [18F]FET TBR and its tumour volume with the magnetic resonance imaging (MRI) contrast-enhancing (CE) tumour volume. Ten patients were recruited in this study. [68Ga]Ga-PSMA-617-avid tumour volume was larger than the [18F]FET tumour volume (p = 0.063). There was a positive intra-patient correlation (median Pearson r = 0.51; p < 0.0001) between [68Ga]Ga-PSMA-617 and [18F]FET in the tumour volume. [68Ga]Ga-PSMA-617 had significantly higher TBR (p = 0.002) than [18F]FET. The [68Ga]Ga-PSMA-617-avid tumour volume was larger than the CE tumour volume (p = 0.0039). Overall, accumulation of [68Ga]-Ga-PSMA-617 beyond [18F]FET-avid tumour regions suggests the presence of neoangiogenesis in tumour regions that are not overly metabolically active yet. Higher tumour specificity suggests that [68Ga]-Ga-PSMA-617 could be a better imaging biomarker for recurrent tumour delineation and secondary treatment planning than [18F]FET and CE MRI.

Platelet proteo-transcriptomic profiling validates mediators of thrombosis and proteostasis in patients with myeloproliferative neoplasms

Patients with chronic Myeloproliferative Neoplasms (MPN) including polycythemia vera (PV) and essential thrombocythemia (ET) exhibit unique clinical features, such as a tendency toward thrombosis and hemorrhage, and risk of disease progression to secondary bone marrow fibrosis and/or acute leukemia. Although an increase in blood cell lineage counts (quantitative features) contribute to these morbid sequelae, the significant qualitative abnormalities of myeloid cells that contribute to vascular risk are not well understood. Here, we address this critical knowledge gap via a comprehensive and untargeted profiling of the platelet proteome in a large (n= 140) cohort of patients (from two independent sites) with an established diagnosis of PV and ET (and complement prior work on the MPN platelet transcriptome from a third site). We discover distinct MPN platelet protein expression and confirm key molecular impairments associated with proteostasis and thrombosis mechanisms of potential relevance to MPN pathology. Specifically, we validate expression of high-priority candidate markers from the platelet transcriptome at the platelet proteome (e.g., calreticulin (CALR), Fc gamma receptor (FcγRIIA) and galectin-1 (LGALS1) pointing to their likely significance in the proinflammatory, prothrombotic and profibrotic phenotypes in patients with MPN. Together, our proteo-transcriptomic study identifies the peripherally-derived platelet molecular profile as a potential window into MPN pathophysiology and demonstrates the value of integrative multi-omic approaches in gaining a better understanding of the complex molecular dynamics of disease.

Vasculogenic Mimicry Occurs at Low Levels in Primary and Recurrent Glioblastoma

Vasculogenic mimicry (VM), the ability of tumour cells to form functional microvasculature without an endothelial lining, may contribute to anti-angiogenic treatment resistance in glioblastoma. We aimed to assess the extent of VM formation in primary and recurrent glioblastomas and to determine whether VM vessels also express prostate-specific membrane antigen (PSMA), a pathological vessel marker. Formalin-fixed paraffin-embedded tissue from 35 matched pairs of primary and recurrent glioblastoma was immunohistochemically labelled for PSMA and CD34 and stained with periodic acid-Schiff (PAS). Vascular structures were categorised as endothelial vessels (CD34+/PAS+) or VM (CD34-/PAS+). Most blood vessels in both primary and recurrent tumours were endothelial vessels, and these significantly decreased in recurrent tumours (p < 0.001). PSMA was expressed by endothelial vessels, and its expression was also decreased in recurrent tumours (p = 0.027). VM was observed in 42.86% of primary tumours and 28.57% of recurrent tumours. VM accounted for only a small proportion of the tumour vasculature and VM density did not differ between primary and recurrent tumours (p = 0.266). The functional contribution of VM and its potential as a treatment target in glioblastoma require further investigation.

Catalysis enabled synthesis, structures, and reactivities of fluorinated S8-corona[n]arenes (n = 8-12)

Previously inaccessible large S₈-corona[n]arene macrocycles (n = 8-12) with alternating aryl and 1,4-C₆F₄ subunits are easily prepared on up to gram scales, without the need for chromatography (up to 45% yield, 10 different examples) through new high acceleration S_NAr substitution protocols (catalytic NR₄F in pyridine, R = H, Me, Bu). Macrocycle size and functionality are tunable by precursor and catalyst selection. Equivalent simple NR₄F catalysis allows facile late-stage S_NAr difunctionalisation of the ring C₆F₄ units with thiols (8 derivatives, typically 95+% yields) providing two-step access to highly functionalised fluoromacrocycle libraries. Macrocycle host binding supports fluoroaryl catalytic activation through contact ion pair binding of NR₄F and solvent inclusion. In the solid-state, solvent inclusion also intimately controls macrocycle conformation and fluorine-fluorine interactions leading to spontaneous self-assembly into infinite columns with honeycomb-like lattices.

Estimation of vaccine efficacy for variants that emerge after the placebo group is vaccinated

SARS‐CoV‐2 continues to evolve and the vaccine efficacy against variants is challenging to estimate. It is now common in phase III vaccine trials to provide vaccine to those randomized to placebo once efficacy has been demonstrated, precluding a direct assessment of placebo controlled vaccine efficacy after placebo vaccination. In this work, we extend methods developed for estimating vaccine efficacy post placebo vaccination to allow variant specific time varying vaccine efficacy, where time is measured since vaccination. The key idea is to infer counterfactual strain specific placebo case counts by using surveillance data that provide the proportions of the different strains. This blending of clinical trial and observational data allows estimation of strain‐specific time varying vaccine efficacy, or sieve effects, including for strains that emerge after placebo vaccination. The key requirements are that the surveillance strain distribution accurately reflects the strain distribution for a placebo group throughout follow‐up after placebo group vaccination, and that at least one strain is present before and after placebo vaccination. For illustration, we develop a Poisson approach for an idealized design under a rare disease assumption and then use a proportional hazards model to address staggered entry, staggered crossover, and smoothly varying strain specific vaccine efficacy. We evaluate these methods by theoretical work and simulations, and demonstrate that useful estimation of the efficacy profile is possible for strains that emerge after vaccination of the placebo group. An important principle is to incorporate sensitivity analyses to guard against misspecification of the strain distribution.

A novel semiautomated method for background activity and biological tumour volume definition to improve standardisation of 18F-FET PET imaging in glioblastoma

Background

Multicentre clinical trials evaluating the role of ¹⁸F-Fluoroethyl-l-tyrosine (¹⁸F-FET) PET as a diagnostic biomarker in glioma management have highlighted a need for standardised methods of data analysis. ¹⁸F-FET uptake normalised against background in the contralateral brain is a standard imaging technique to delineate the biological tumour volume (BTV). Quantitative analysis of ¹⁸F-FET PET images requires a consistent and robust background activity. Currently, defining background activity involves the manual selection of an arbitrary region of interest, a process that is subject to large variability. This study aims to eliminate methodological errors in background activity definition through the introduction of a semiautomated method for region of interest selection. A new method for background activity definition, involving the semiautomated generation of mirror-image (MI) reference regions, was compared with the current state-of-the-art method, involving manually drawing crescent-shape (gCS) reference regions. The MI and gCS methods were tested by measuring values of background activity and resulting BTV of ¹⁸F-FET PET scans of ten patients with recurrent glioblastoma multiforme generated from inputs provided by seven readers. To assess intra-reader variability, each scan was evaluated six times by each reader. Intra- and inter-reader variability in background activity and BTV definition was assessed by means of coefficient of variation.

Results

Compared to the gCS method, the MI method showed significantly lower intra- and inter-reader variability both in background activity and in BTV definition.

Conclusions

The proposed semiautomated MI method minimises intra- and inter-reader variability, providing a valuable approach for standardisation of ¹⁸F-FET PET quantitative parameters.

Trial registration ANZCTR, ACTRN12618001346268. Registered 9 August 2018, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374253

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-022-00438-2.

Low tumour-infiltrating lymphocyte density in primary and recurrent glioblastoma

Immunotherapies targeting tumour-infiltrating lymphocytes (TILs) that express the immune checkpoint molecule programmed cell death-1 (PD-1) have shown promise in preclinical glioblastoma models but have had limited success in clinical trials. To assess when glioblastoma is most likely to benefit from immune checkpoint inhibitors we determined the density of TILs in primary and recurrent glioblastoma. Thirteen cases of matched primary and recurrent glioblastoma tissue were immunohistochemically labelled for CD3, CD8, CD4 and PD-1, and TIL density assessed. CD3+ TILs were observed in all cases, with the majority of both primary (69.2%) and recurrent (61.5%) tumours having low density of TILs present. CD8+ TILs were observed at higher densities than CD4+ TILs in both tumour groups. PD-1+ TILs were sparse and present in only 25% of primary and 50% of recurrent tumours. Quantitative analysis of TILs demonstrated significantly higher CD8+ TIL density at recurrence (p = 0.040). No difference was observed in CD3+ (p = 0.191), CD4+ (p = 0.607) and PD-1+ (p = 0.070) TIL density between primary and recurrent groups. This study shows that TILs are present at low densities in both primary and recurrent glioblastoma. Furthermore, PD-1+ TILs were frequently absent, which may provide evidence as to why anti-PD-1 immunotherapy trials have been largely unsuccessful in glioblastoma.

DNA damage repair in glioblastoma: current perspectives on its role in tumour progression, treatment resistance and PIKKing potential therapeutic targets

BACKGROUND

The aggressive, invasive and treatment resistant nature of glioblastoma makes it one of the most lethal cancers in humans. Total surgical resection is difficult, and a combination of radiation and chemotherapy is used to treat the remaining invasive cells beyond the tumour border by inducing DNA damage and activating cell death pathways in glioblastoma cells. Unfortunately, recurrence is common and a major hurdle in treatment, often met with a more aggressive and treatment resistant tumour. A mechanism of resistance is the response of DNA repair pathways upon treatment-induced DNA damage, which enact cell-cycle arrest and repair of DNA damage that would otherwise cause cell death in tumour cells.

CONCLUSIONS

In this review, we discuss the significance of DNA repair mechanisms in tumour formation, aggression and treatment resistance. We identify an underlying trend in the literature, wherein alterations in DNA repair pathways facilitate glioma progression, while established high-grade gliomas benefit from constitutively active DNA repair pathways in the repair of treatment-induced DNA damage. We also consider the clinical feasibility of inhibiting DNA repair in glioblastoma and current strategies of using DNA repair inhibitors as agents in combination with chemotherapy, radiation or immunotherapy. Finally, the importance of blood-brain barrier penetrance when designing novel small-molecule inhibitors is discussed.

Estimation of Vaccine Efficacy for Variants that Emerge After the Placebo Group Is Vaccinated

SARS-CoV-2 continues to evolve and the vaccine efficacy against variants is challenging to estimate. It is now common in phase III vaccine trials to provide vaccine to those randomized to placebo once efficacy has been demonstrated, precluding a direct assessment of placebo controlled vaccine efficacy after placebo vaccination. In this work we extend methods developed for estimating vaccine efficacy post placebo vaccination to allow variant specific time varying vaccine efficacy, where time is measured since vaccination. The key idea is to infer counterfactual strain specific placebo case counts by using surveillance data that provide the proportions of the different strains. This blending of clinical trial and observational data allows estimation of strain-specific time varying vaccine efficacy, or sieve effects, including for strains that emergent after placebo vaccination. The key requirements are that surveillance strain distribution accurately reflect the strain distribution for a placebo group, throughout follow-up after placebo group vaccination and that at least one strain is present before and after placebo vaccination. For illustration, we develop a Poisson approach for an idealized design under a rare disease assumption and then use a proportional hazards modeling to better reflect the complexities of field trials with staggered entry, crossover, and smoothly varying strain specific vaccine efficacy We evaluate these by theoretical work and simulations, and demonstrate that useful estimation of the efficacy profile is possible for strains that emerge after vaccination of the placebo group. An important principle is to incorporate sensitivity analyses to guard against mis-specfication of the strain distribution. We also provide an approach for use when genotyping of the infecting strains of the trial participants has not been done.

Posttransplant Lymphoproliferative Disorder After Solid Organ Transplant: A Heterogeneous, Aggressive Disorder

Posttransplant lymphoproliferative disorder (PTLD) is a rare complication of solid organ transplant. We identified 40 patients diagnosed with PTLD between 2009 and 2020 and analyzed their presentation, treatment strategies, and outcomes. Median age at diagnosis was 52.5 years (range 21.3 to 79). Median duration of immunosuppression was 95 months (range 4 to 292). Diffuse large B cell lymphoma (n = 16, 40%) and Burkitt lymphoma (n = 6, 15%) were the most common histological subtypes. First-line therapy varied. The median number of treatment lines was 1 (range 0 to 4). Sixteen patients (40%) achieved complete response after first-line therapy. Nineteen patients (47.5%) relapsed or progressed and received salvage therapy; 45% were alive at the end of the study period (median survival 52 months; range 1 to 266; 95% confidence interval 0 to 104). Causes of death included lymphoma-related (45.5%), therapy-related (27.3%), and other (27.3%). Five (22.7%) died within 3 months of diagnosis. Pearson's r test identified disease stage (P = .045) and proliferation index (P = .005) as negative predictors of response to frontline therapy. Bone marrow involvement (P = .033) and increased age (P = .018) were significant predictors of survival. Early mortality and poor response to frontline therapy are common, outlining the need for improved treatment strategies.

A Phase II Study of Biodegradable Stents Plus Palliative Radiotherapy in Oesophageal Cancer

AIMS

Self-expanding metal stents provide rapid improvement of dysphagia in oesophageal cancer but are associated with complications. The aim of the present study was to test the effectiveness of an alternative treatment of combining biodegradable stents with radiotherapy.

MATERIALS AND METHODS

A Simon two-stage single-arm prospective phase II trial design was used to determine the efficacy of biodegradable stents plus radiotherapy in patients with dysphagia caused by oesophagus cancer who were unsuitable for radical treatment. Fourteen patients were recruited and data from 12 were included in the final analyses.

RESULTS

Five of 12 patients met the primary end point: one stent-related patient death; four further interventions for dysphagia within 16 weeks of stenting (41.7%, 95% confidence interval 15.2-72.3%). The median time to a 10-point deterioration of quality of life was 2.7 weeks. Nine patients died within 52 weeks of registration. The median time to death from any cause was 15.0 weeks (95% confidence interval 9.6-not reached).

CONCLUSION

The high re-intervention observed, which met the pre-defined early stopping criteria, meant that the suggested alternative treatment was not sufficiently effective to be considered for a larger scale trial design. Further work is needed to define the place of biodegradable stents in the management of malignant oesophageal strictures.

Modifying the m6A brain methylome by ALKBH5-mediated demethylation: a new contender for synaptic tagging

Synaptic plasticity processes, which underlie learning and memory formation, require RNA to be translated local to synapses. The synaptic tagging hypothesis has previously been proposed to explain how mRNAs are available at specific activated synapses. However how RNA is regulated, and which transcripts are silenced or processed as part of the tagging process is still unknown. Modification of RNA by N6-methyladenosine (m⁶A/m) influences the cellular fate of mRNA. Here, by advanced microscopy, we showed that m⁶A demethylation by the eraser protein ALKBH5 occurs at active synaptic ribosomes and at synapses during short term plasticity. We demonstrated that at activated glutamatergic post-synaptic sites, both the YTHDF1 and YTHDF3 reader and the ALKBH5 eraser proteins increase in co-localisation to m⁶A-modified RNAs; but only the readers showed high co-localisation to modified RNAs during late-stage plasticity. The YTHDF1 and YTHFDF3 readers also exhibited differential roles during synaptic maturation suggesting that temporal and subcellular abundance may determine specific function. m⁶A-sequencing of human parahippocampus brain tissue revealed distinct white and grey matter m⁶A methylome profiles indicating that cellular context is a fundamental factor dictating regulated pathways. However, in both neuronal and glial cell-rich tissue, m⁶A effector proteins are themselves modified and m⁶A epitranscriptional and posttranslational modification processes coregulate protein cascades. We hypothesise that the availability m⁶A effector protein machinery in conjunction with RNA modification, may be important in the formation of condensed synaptic nanodomain assemblies through liquid-liquid phase separation. Our findings support that m⁶A demethylation by ALKBH5 is an intrinsic component of the synaptic tagging hypothesis and a molecular switch which leads to alterations in the RNA methylome, synaptic dysfunction and potentially reversible disease states.

Etoposide and olaparib polymer-coated nanoparticles within a bioadhesive sprayable hydrogel for post-surgical localised delivery to brain tumours

Glioblastoma is a malignant brain tumour with a median survival of 14.6 months from diagnosis. Despite maximal surgical resection and concurrent chemoradiotherapy, reoccurrence is inevitable. To try combating the disease at a stage of low residual tumour burden immediately post-surgery, we propose a localised drug delivery system comprising of a spray device, bioadhesive hydrogel (pectin) and drug nanocrystals coated with polylactic acid-polyethylene glycol (NCPPs), to be administered directly into brain parenchyma adjacent to the surgical cavity. We have repurposed pectin for use within the brain, showing in vitro and in vivo biocompatibility, bio-adhesion to mammalian brain and gelling at physiological brain calcium concentrations. Etoposide and olaparib NCPPs with high drug loading have shown in vitro stability and drug release over 120 h. Pluronic F127 stabilised NCPPs to ensure successful spraying, as determined by dynamic light scattering and transmission electron microscopy. Successful delivery of Cy5-labelled NCPPs was demonstrated in a large ex vivo mammalian brain, with NCPP present in the tissue surrounding the resection cavity. Our data collectively demonstrates the pre-clinical development of a novel localised delivery device based on a sprayable hydrogel containing therapeutic NCPPs, amenable for translation to intracranial surgical resection models for the treatment of malignant brain tumours.

IMMU-51. PROFILING THE IMMUNE SYSTEM IN PRIMARY AND RECURRENT GLIOBLASTOMA

Immunotherapy has been shown to have benefit in some solid tumours including melanoma where immune infiltration can be pronounced. Until recently the central nervous system was thought to be immune privileged. Whilst research has shown that immune cells are capable of infiltrating tumours from glioblastoma patients, to date immunotherapy trials have not consistently shown a benefit in these patients. The aim of this study was to profile the immune system in primary and recurrent tumours from glioblastoma patients. Formalin-fixed paraffin-embedded sections of primary and matched recurrent tumours from 13 patients with glioblastoma were processed for immunohistochemical labelling of a range of immune cell markers. Immune infiltration was scored on digitally scanned immunolabelled sections using a categorical system of 0 (absent), 1 (present), 2 (moderate) and 3 (marked). CD3+ cells were observed in three topographical locations within primary and recurrent glioblastoma tumours namely the tumour proper, perivascular spaces and associated with haemorrhages within the tumour. CD3+ cell infiltration into the tumour proper was present (Score = 1) in 7 of 13 primary and recurrent tumours. Only one case (case #9) had CD3+ infiltration scores > 1 for both primary (score = 3) and recurrent tumour (score = 2). CD3+ cells were observed in perivascular spaces in 10 of the 13 cases of primary and recurrent glioblastoma. Only case #9 had CD3+ cells in perivascular spaces that was scored >1 for both primary and recurrent tumours. In conclusion, whilst CD3+ infiltration was observed in the tumour proper and perivascular spaces within both primary and recurrent glioblastomas, the level of infiltration was quite low in this small cohort and as such requires further investigation in a larger cohort.

TMIC-41. PROSTATE SPECIFIC MEMBRANE ANTIGEN EXPRESSION IN PRIMARY AND RECURRENT GLIOBLASTOMA

Patients with glioblastoma almost always suffer a recurrence of an aggressive treatment resistant tumour and succumb within months highlighting the need to develop treatment options for recurrent glioblastoma. One potential target is prostate specific membrane antigen (PSMA) expressed on the new vessels in primary glioblastoma tumours. This study compared the expression of PSMA in primary and recurrent glioblastoma tumours. Formalin-fixed paraffin-embedded sections of primary and matched recurrent tumours from 13 patients with glioblastoma were processed for PSMA immunohistochemical labelling. PSMA expression was scored from digitally scanned sections using a categorical system (Total PSMA expression = PSMA label intensity (0–3) x percent PSMA-positive blood vessels). Little PSMA labelling was observed in any adjacent ‘unaffected’ brain tissue. PSMA was localised to blood vessels including those displaying microvascular proliferation in 12/13 primary and 9/13 recurrent glioblastoma tumours. Total PSMA expression scores ranged from 0 – 230 (maximum score = 300) and was divided into low and high expression based on a median split (median = 57) of PSMA expression across all tumours. Regression analysis showed a significant difference in PSMA expression between primary and recurrent glioblastoma (p = 0.04) with PSMA being highly expressed in ~70% of primary and only 31% of recurrent glioblastoma. Three cases displayed high expression in both primary and recurrent glioblastoma and one case had no PSMA expression at all. In conclusion, whilst higher expression of PSMA was detected in more primary tumours, 70%+ of all primary and recurrent tumours expressed PSMA to some extent adding evidence that this may be a useful target for treatment of glioblastoma. Larger cohorts and other techniques for detecting PSMA are needed to provide further evidence for PSMA’s utility as a target and to further define which glioblastoma patients are most likely to benefit from this approach.

Familial genetic risks: how can we better navigate patient confidentiality and appropriate risk disclosure to relatives?

This article investigates a high-profile and ongoing dilemma for healthcare professionals (HCPs), namely whether the existence of a (legal) duty of care to genetic relatives of a patient is a help or a hindrance in deciding what to do in cases where a patient's genetic information may have relevance to the health of the patient's family members. The English case ABC v St George's Healthcare NHS Trust and others considered if a duty of confidentiality owed to the patient and a putative duty of care to the patient's close relatives could coexist in this context. This article examines whether embracing the concept of coexisting duties could enable HCPs to respect duties in line with their clinical judgement, thereby providing legal support and clarity to professionals to allow them to provide the best possible genetics service to both the patient and their family. We argue that these dual duties, framed as a novel, composite duty to consider the interests of genetic relatives, could allow HCPs to exercise and act on their professional judgements about the relative value of information to family members, without fears of liability for negligence or breach of confidence.

Abstract 1796: p53 regulation of osteoblast differentiation is mediated through specific microRNAs

We have previously shown a role for tumor suppressor gene p53 in the transcriptional activation of several bone-specific genes in osteoblast differentiation. In this study, we used a screen for microRNAs to look for ones that were p53 dependent and differentiation dependent. In a model of invitro osteoblast differentiation, our previous work has established that p53 levels generally increase around day 4 of differentiation and represent the timeline when p53 transcriptionally regulates bone-specific gene expression. In these experiments, we used MC3T3-E1 osteoblasts to stably reduced p53 levels using specific shRNAs. These cells were initially characterized for the reduction in p53 levels and then compared with MC3T3E1 cells stably transfected with a scrambled control (Control MC3T3E1 cells). MicroRNAs were isolated from day 0 and day 4 after treatment with differentiation promoting (DP) media. A microRNA profiling service utilizing a microarray detection system analyzed over 1000 different microRNAs in control and DP treated cells to determine differentiation specific microRNAs expression. This array provided us with information about a number of genes that underwent alterations during differentiation in a p53 dependent manner. We validated several of the changes using realtime PCR and selected two microRNAs to study in detail. These two microRNAs (mIR 34b and 140) were increased two fold during normal differentiation but showed a dramatic reduction in expression when p53 levels were reduced. We ectopically expressed these microRNAs in MC3T3-E1 cells and created stable lines. Cells carrying mIR34b showed a decrease in cell proliferation rates when compared to mIR140 expressing and control cells. P53 levels directly correlated with microRNA 34b expression but not mIR140. MiR 140 ectopic expression affected Bone morphogenetic protein expression (BMP2), an important bone anabolic agent that is also p53 regulated. Putative target binding sites for bone-specific transcription factors Runx2, SP7, Vitamin D receptor (VDR) were found for mIR34b and 140 and were utilized in luciferase reporter assays to confirm microRNA specific interactions. These studies provided evidence and confirmed for us that the p53 regulation of osteoblast differentiation is also mediated through specific microRNAs that directly target important bone-specific genes.

Citation Format: Elisha Pendleton, Shivang Shah, Oliver Couture, Teresa Kusper, Mustafa Broachwalla, Lauren Alt, Michael Fay, Nalini Chandar. p53 regulation of osteoblast differentiation is mediated through specific microRNAs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1796.

Continuous synthesis of Zn2Al–CO3layered double hydroxides: a comparison of bench, pilot and industrial scale syntheses

Zn₂Al–CO₃was produced continuously at bench (g h⁻¹), pilot (100s g h⁻¹) and industrial scale (10s kg h⁻¹).

Dehydrative Cross-Coupling of 1-Phenylethanol Catalysed by Palladium Nanoparticles Formed in situ Under Acidic Conditions

A dehydrative cross-coupling of 1-phenylethanol catalysed by sugar derived, in situ formed palladium(0) nanoparticles under acidic conditions is realised. The acidic conditions allow for use of alcohols as a feedstock in metal-mediated coupling reactions via their in situ dehydration and subsequent cross-coupling. Extensive analysis of the size and morphology of the palladium nanoparticles formed in situ showed that the zero-valent metal was surrounded by hydrophilic hydroxyl groups. EDX-TEM imaging studies using a prototype silicon drift detector provided insight into the problematic role of molecular oxygen in the system. This increased understanding of the catalyst deactivation allowed for the development of the cross-coupling methodology. A 250-12,000 fold increase in molar efficiency was observed when compared to related two-step protocols that use alternative feedstocks for the palladium-mediated synthesis of stilbenes. This work opens up a new research area in which the active catalyst is formed, stabilised and regenerated by a renewable sugar.

Poaching empties critical Central African wilderness of forest elephants

Elephant populations are in peril everywhere, but forest elephants in Central Africa have sustained alarming losses in the last decade [1]. Large, remote protected areas are thought to best safeguard forest elephants by supporting large populations buffered from habitat fragmentation, edge effects and human pressures. One such area, the Minkébé National Park (MNP), Gabon, was created chiefly for its reputation of harboring a large elephant population. MNP held the highest densities of elephants in Central Africa at the turn of the century, and was considered a critical sanctuary for forest elephants because of its relatively large size and isolation. We assessed population change in the park and its surroundings between 2004 and 2014. Using two independent modeling approaches, we estimated a 78-81% decline in elephant numbers over ten years - a loss of more than 25,000 elephants. While poaching occurs from within Gabon, cross-border poaching largely drove the precipitous drop in elephant numbers. With nearly 50% of forest elephants in Central Africa thought to reside in Gabon [1], their loss from the park is a considerable setback for the preservation of the species.

How well do services for young people with long term conditions deliver features proposed to improve transition?

BACKGROUND

For young people with long-term conditions, transition from child to adult-oriented health services is a critical period which, if not managed well, may lead to poor outcomes. There are features of transition services which guidance and research suggest improve outcomes. We studied nine such features, calling them 'proposed beneficial features': age-banded clinic; meet adult team before transfer; promotion of health self-efficacy; written transition plan; appropriate parent involvement; key worker; coordinated team; holistic life-skills training; transition manager for clinical team. We aimed to describe the extent to which service providers offer these nine features, and to compare this with young people's reported experience of them.

METHODS

A longitudinal, mixed methods study followed 374 young people as their care moved from child to adult health services. Participants had type 1 diabetes, cerebral palsy or autism spectrum disorder with additional mental health difficulties. Data are reported from the first two visits, one year apart.

RESULTS

Three hundred four (81.3%) of the young people took part in the second visit (128 with diabetes, 91 with autism, 85 with cerebral palsy). Overall, the nine proposed beneficial features of transition services were poorly provided. Fewer than half of services stated they provided an age-banded clinic, written transition plan, transition manager for clinical team, a protocol for promotion of health self-efficacy, or holistic life-skills training. To varying degrees, young people reported that they had not experienced the features which services said they provided. For instance, the agreement for written transition plan, holistic life-skills training and key worker, was 30, 43 and 49% respectively. Agreement was better for appropriate parent involvement, age-banded clinic, promotion of health self-efficacy and coordinated team at 77, 77, 80 and 69% respectively. Variation in the meaning of the features as experienced by young people and families was evident from qualitative interviews and observations.

CONCLUSIONS

UK services provide only some of the nine proposed beneficial features for supporting healthcare transition of young people with long term conditions. Observational studies or trials which examine the influence of features of transition services on outcomes should ensure that the experiences of young people and families are captured, and not rely on service specifications.

Structure and solvents effects on the optical properties of sugar-derived carbon nanodots

Carbon nanodots are a new and intriguing class of fluorescent carbon nanomaterials and are considered a promising low cost, nontoxic alternative to traditional inorganic quantum dots in applications such as bioimaging, solar cells, photocatalysis, sensors and others. Despite the abundant available literature, a clear formation mechanism for carbon nanodots prepared hydrothermally from biomass precursors along with the origins of the light emission are still under debate. In this paper, we investigate the relationships between the chemical structure and optical properties of carbon nanodots prepared by the hydrothermal treatment of glucose. Our major finding is that the widely reported excitation-dependent emission originates from solvents used to suspend the as-prepared carbon nanodots, while emission from dry samples shows no excitation-dependence. Another important highlight is that the hydrothermal conversion of biomass-derivatives under subcritical conditions leads to a heterogeneous mixture of amorphous-like nanoparticles, carbon onion-type and crystalline carbons composed of at least three different phases. The potential chemical reaction pathways involved in the formation of these hydrothermal carbon products along with a comprehensive structural and optical characterization of these systems is also provided.

Feasibility and acceptability of combining cognitive behavioural therapy techniques with swallowing therapy in head and neck cancer dysphagia

BACKGROUND

Head and neck cancer squamous cell carcinoma (HNSSC) patients report substantial rates of clinically significant depression and/or anxiety, with dysphagia being a predictor of distress and poorer quality of life. Evidence-based dysphagia interventions largely focus on the remediation of physical impairment. This feasibility study evaluates an intervention which simultaneously uses a psychological therapy approach combined with swallowing impairment rehabilitation.

METHODS

This prospective single cohort mixed-methods study, recruited HNSCC patients with dysphagia, from two institutions. The intervention combined Cognitive Behavioural Therapy with swallowing therapy (CB-EST), was individually tailored, for up to 10 sessions and delivered by a speech and language therapist. Primary acceptability and feasibility measures included recruitment and retention rates, data completion, intervention fidelity and the responsiveness of candidate outcome measures. Measures included a swallowing questionnaire (MDADI), EORTC-QLQH&N35, dietary restrictions scale, fatigue and function scales and the Hospital Anxiety and Depression Scale (HADS), administered pre-, post-CB-EST with three month follow-up and analysed using repeated measures ANOVA. Qualitative interviews were conducted to evaluate intervention processes.

RESULTS

A total of 30/43 (70%) eligible patients agreed to participate and 25 completed the intervention. 84% were male, mean age 59 yrs. Patients were between 1 and 60 months (median 4) post-cancer treatment. All patients had advanced stage disease, treated with surgery and radiotherapy (38%) or primary chemoradiotherapy (62%). Pre to post CB-EST data showed improvements in MDADI scores (p = 0.002), EORTC-QLQH&N35 (p = 0.006), dietary scale (p < 0.0001), fatigue (p = 0.002) but no change in function scales or HADS. Barriers to recruitment were the ability to attend regular appointments and patient suitability or openness to a psychological-based intervention.

CONCLUSIONS

CB-EST is a complex and novel intervention, addressing the emotional, behavioural and cognitive components of dysphagia alongside physical impairment. Preliminary results are promising. Further research is required to evaluate efficacy and effectiveness.

Cousins, Genetic Diagnosis and Liability of Clinicians: Smith & Another V University of Leicester NHS Trust [2016] EWHC 817 (QB)

This comment analyses the recent High Court decision in Smith & Another v University of Leicester NHS Trust. In this case, the court struck out a claim brought by a patient's second cousins regarding their failure to provide the patient with an accurate diagnosis, which would have resulted in the claimants being diagnosed with hereditary disease earlier than they in fact were. The claimants argued that the doctors' failure to conduct the test caused harm and a duty of care was owed in respect of the patient's relatives. The defendant conceded the issue of foreseeable harm but argued a duty was not fair, just, and reasonable when treating the patient and no other, or, alternately, if the duty was to inform then the cousins was insufficiently proximate. It is argued in this comment that the judge was correct to reject the claim but that aspects of the judgment demanded greater analysis.

Exploring the potential duty of care in clinical genomics under UK law

Genome-wide sequencing technologies are beginning to be used in projects that have both clinical diagnostic and research components. The clinical application of this technology, which generates a huge amount of information of varying diagnostic certainty, involves addressing a number of challenges to establish appropriate standards. In this article, we explore the way that UK law may respond to three of these key challenges and could establish new legal duties in relation to feedback of findings that are unrelated to the presenting condition (secondary, additional or incidental findings); duties towards genetic relatives as well as the patient and duties on the part of researchers and professionals who do not have direct contact with patients. When considering these issues, the courts will take account of European and international comparisons, developing guidance and relevant ethical, social and policy factors. The UK courts will also be strongly influenced by precedent set in case law.

Screening for Atrial Fibrillation

Approximately 10% of ischemic strokes are associated with atrial fibrillation (AF) first diagnosed at the time of stroke. Detecting asymptomatic AF would provide an opportunity to prevent these strokes by instituting appropriate anticoagulation. The AF-SCREEN international collaboration was formed in September 2015 to promote discussion and research about AF screening as a strategy to reduce stroke and death and to provide advocacy for implementation of country-specific AF screening programs. During 2016, 60 expert members of AF-SCREEN, including physicians, nurses, allied health professionals, health economists, and patient advocates, were invited to prepare sections of a draft document. In August 2016, 51 members met in Rome to discuss the draft document and consider the key points arising from it using a Delphi process. These key points emphasize that screen-detected AF found at a single timepoint or by intermittent ECG recordings over 2 weeks is not a benign condition and, with additional stroke factors, carries sufficient risk of stroke to justify consideration of anticoagulation. With regard to the methods of mass screening, handheld ECG devices have the advantage of providing a verifiable ECG trace that guidelines require for AF diagnosis and would therefore be preferred as screening tools. Certain patient groups, such as those with recent embolic stroke of uncertain source (ESUS), require more intensive monitoring for AF. Settings for screening include various venues in both the community and the clinic, but they must be linked to a pathway for appropriate diagnosis and management for screening to be effective. It is recognized that health resources vary widely between countries and health systems, so the setting for AF screening should be both country- and health system-specific. Based on current knowledge, this white paper provides a strong case for AF screening now while recognizing that large randomized outcomes studies would be helpful to strengthen the evidence base.

Short-Course Radiation plus Temozolomide in Elderly Patients with Glioblastoma

BACKGROUND

Glioblastoma is associated with a poor prognosis in the elderly. Survival has been shown to increase among patients 70 years of age or younger when temozolomide chemotherapy is added to standard radiotherapy (60 Gy over a period of 6 weeks). In elderly patients, more convenient shorter courses of radiotherapy are commonly used, but the benefit of adding temozolomide to a shorter course of radiotherapy is unknown.

METHODS

We conducted a trial involving patients 65 years of age or older with newly diagnosed glioblastoma. Patients were randomly assigned to receive either radiotherapy alone (40 Gy in 15 fractions) or radiotherapy with concomitant and adjuvant temozolomide.

RESULTS

A total of 562 patients underwent randomization, 281 to each group. The median age was 73 years (range, 65 to 90). The median overall survival was longer with radiotherapy plus temozolomide than with radiotherapy alone (9.3 months vs. 7.6 months; hazard ratio for death, 0.67; 95% confidence interval [CI], 0.56 to 0.80; P<0.001), as was the median progression-free survival (5.3 months vs. 3.9 months; hazard ratio for disease progression or death, 0.50; 95% CI, 0.41 to 0.60; P<0.001). Among 165 patients with methylated O⁶-methylguanine-DNA methyltransferase (MGMT) status, the median overall survival was 13.5 months with radiotherapy plus temozolomide and 7.7 months with radiotherapy alone (hazard ratio for death, 0.53; 95% CI, 0.38 to 0.73; P<0.001). Among 189 patients with unmethylated MGMT status, the median overall survival was 10.0 months with radiotherapy plus temozolomide and 7.9 months with radiotherapy alone (hazard ratio for death, 0.75; 95% CI, 0.56 to 1.01; P=0.055; P=0.08 for interaction). Quality of life was similar in the two trial groups.

CONCLUSIONS

In elderly patients with glioblastoma, the addition of temozolomide to short-course radiotherapy resulted in longer survival than short-course radiotherapy alone. (Funded by the Canadian Cancer Society Research Institute and others; ClinicalTrials.gov number, NCT00482677 .).

Borderline resectable pancreas adenocarcinoma managed with neoadjuvant chemoradiotherapy: A prospective case series

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Background: Borderline resectable pancreas cancers (BRPC) often require vascular reconstruction, have higher rates of operative margin positivity and confer a poor prognosis. In 2014, our high-volume pancreatectomy, gastrointestinal tumor multidisciplinary treatment (GI MDT) group endorsed a consensus anatomical definition of BRPC consistent with NCCN criteria. Diagnostic and staging tests were standardized and a neoadjuvant chemoradiotherapy protocol adopted with the goals to (1) improve R0 resection rate and (2) prevent futile surgery in rapidly progressive disease. Methods: Neoadjuvant chemoradiotherapy (CRT) consisted of 50.4Gy in 28# and concurrent capecitabine 830mg/m2 bd. Pancreatectomy was planned 4-8 weeks later unless repeat imaging showed progressive disease. Comprehensive, prospectively defined data items were collected on all patients (pts) diagnosed with BRPC. Results: Nine pts have been diagnosed with BRPC by the GI MDT. Seven pts received full dose of CRT, one pt progressed during CRT hence stopped early and one pt didn’t receive CRT due to significant deterioration beforehand. CRT was tolerable in all eight pts who received it; there were no dose modifications for toxicity. Post-CRT, three pts underwent curative-intent resection and all are still alive (494, 319 and 172 days post-CRT). One was found to have a solitary liver metastasis during surgery (resected), R1 resection (SMV margin involvement) of T3N1 tumor and is receiving palliative chemotherapy. Two other pts underwent R0 resections (T3N0, T3N1) with histopathologic response to CRT. Four pts showed progressive disease on post-CRT imaging (all local & distant progression) and subsequently received palliative therapy. Median survival (first dose CRT to death) in the 5 CRT pts who have succumbed was 509 days (range 363-577). Conclusions: In this small prospective, unselected cohort the majority of pts diagnosed with BRPC demonstrated disease progression during/after neoadjuvant CRT and did not proceed to surgical resection, underscoring the poor prognosis of this pancreas cancer subset. Neoadjuvant CRT is well tolerated and did not preclude subsequent surgery in those patients with stable disease.

A sensing mechanism for the detection of carbon nanotubes using selective photoluminescent probes based on ionic complexes with organic dyes

The multifunctional properties of carbon nanotubes (CNTs) make them a powerful platform for unprecedented innovations in a variety of practical applications. As a result of the surging growth of nanotechnology, nanotubes present a potential problem as an environmental pollutant, and as such, an efficient method for their rapid detection must be established. Here, we propose a novel type of ionic sensor complex for detecting CNTs - an organic dye that responds sensitively and selectively to CNTs with a photoluminescent signal. The complexes are formed through Coulomb attractions between dye molecules with uncompensated charges and CNTs covered with an ionic surfactant in water. We demonstrate that the photoluminescent excitation of the dye can be transferred to the nanotubes, resulting in selective and strong amplification (up to a factor of 6) of the light emission from the excitonic levels of CNTs in the near-infrared spectral range, as experimentally observed via excitation-emission photoluminescence (PL) mapping. The chirality of the nanotubes and the type of ionic surfactant used to disperse the nanotubes both strongly affect the amplification; thus, the complexation provides sensing selectivity towards specific CNTs. Additionally, neither similar uncharged dyes nor CNTs covered with neutral surfactant form such complexes. As model organic molecules, we use a family of polymethine dyes with an easily tailorable molecular structure and, consequently, tunable absorbance and PL characteristics. This provides us with a versatile tool for the controllable photonic and electronic engineering of an efficient probe for CNT detection.

Health-related quality of life among Indigenous Australians diagnosed with cancer

PURPOSE

Health-related quality of life (HRQoL) and associated factors were assessed among 155 Indigenous Australian adult cancer patients 6 months post-diagnosis.

METHODS

The Assessment of Quality of Life-4D Questionnaire was used to assess HRQoL. Differences in the median utility score among subgroups of interest were examined using nonparametric tests. Factors associated with excellent HRQoL were assessed through logistic regression.

RESULTS

Participants' mean age was 52 years (range 20-78), and the majority were female (60 %), unemployed (72 %), and recruited from outpatients clinics (64 %). Breast cancer (27 %) was the most common diagnosis. The median HRQoL score was 0.62; 14 % of participants reported excellent HRQoL (>0.90). After adjusting for age, admission status, and treatment, excellent HRQoL was more likely among participants of Torres Strait Islander origin [adjusted odds ratio (AOR) 3.68; 95 % CI 1.23-11.01], those living in regional areas (AOR 5.59; 95 % CI 1.42-22.06), and those whose main language spoken at home was not English (AOR 3.60; 95 % CI 1.08-11.99) and less likely among those reporting less contact with Indigenous people (AOR 0.23; 95 % CI 0.68-0.81).

CONCLUSION

Assessing HRQoL is important to identifying and improving the length and quality of cancer survivorship, especially in groups that have significantly poorer cancer outcomes, such as Indigenous Australians. Acknowledging the study's observational nature, we found HRQoL was lower than reported for other Australians, and we identified some socio-demographic factors that were associated with excellent HRQoL. Such assessments are an important component of identifying and evaluating appropriate interventions to improve the health and well-being of Indigenous cancer patients.

How does hybridization influence the decision making process in conservation? The genus Orchis (Orchidaceae) as a case history

Hybridization is a fundamental process in biology and can lead to new evolutionary lineages. However, if the parental taxa involved are rare, difficult decisi- ons may have to be made regarding the conservation of the biological process versus the conservation of the parental taxa. The genus Orchis in Europe is a good example of a group of species in which these types of questions arise as several of the species hybridize where they co-occur. The example used here relates to O. militaris, O. purpurea and O. simia in the anthropomorphic group (so called because the labellum has lobes thought to resemble arms and legs). All three species are widespread in Europe, al- though they are rare in large parts of their ranges, and they have substantial areas of overlap in distribution. All three are rare in Britain, occurring predominantly in south east England. Orchis militaris and O. simia and are only known from two and three natural sites in England, respectively. Orchis purpurea is less rare, but is still geographically localized. 

Allotetraploid evolution in Dactylorhiza (Orchidaceae)

One of the most perplexing problems in Western European terrestrial orchid taxonomy has been how to deal with the large numbers of taxa that have been described for the allopolyploid taxa, which are the products of hybridization between taxa in the Dactylorhiza maculata (L.) Soó group and the D. incarnata (L.) Soó group.

Where is the radiobiology and pharmacology research to improve outcomes in glioblastoma?

Personalized medicine has been helpful for drug development in diseases with single and relatively stable gene mutations. The benefit for complex solid tumours with heterogeneous and changing genetic profiles is less clear. Whether it is efficient to continue diverting resources from combined biological and pharmacological approaches to trial new and existing genetic 'targeted therapies' for brain tumours is unknown but of developing concern in resource constrained environments.

Reinforcer devaluation as a consequence of acute nicotine exposure and withdrawal

RATIONALE

Nicotine discontinuation produces behaviors in rats that are congruent with anhedonia, and these symptoms may be related to the devaluation of non-nicotine reinforcers.

OBJECTIVE

Four separate experiments were performed to explore the parameters surrounding nicotine-induced reinforcer devaluation.

METHODS

In Experiments 1 and 2, nicotine (0.1 or 0.3 mg/kg) or 0.3 mg/kg nicotine plus 1.0 mg/kg mecamylamine was delivered to rats prior to progressive ratio (PR) schedule sessions in which sucrose was used as a reinforcer. In order to evaluate (a) reinforcer enhancement by nicotine and (b) reinforcer devaluation in the absence of nicotine, all rats experienced two PR schedule sessions per day for 10 days. Experiment 3 involved nicotine (0.3 mg/kg) and a visual stimulus in place of sucrose reinforcement. In Experiment 4, rats received nicotine (0.3 mg/kg) either before or after a single PR schedule session for 10 days.

RESULTS

Experiments 1 and 2 demonstrate that reinforcer devaluation is related to the occupation of nicotinic-acetylcholine receptors. Results from Experiment 3 provide some evidence that devaluation occurs with either sucrose or visual-stimulus reinforcement. Experiment 4 demonstrates that a necessary condition for reinforcer devaluation to occur is the concurrent exposure to the reinforcer and nicotine.

CONCLUSIONS

Reinforcer devaluation in rats emerges rapidly in a progressive, orderly fashion that coincides with accumulated exposure to nicotine. These results suggest that reinforcer devaluation may be a feature of nicotine that contributes to the abuse liability of tobacco products.

Using the apparent diffusion coefficient to identifying MGMT promoter methylation status early in glioblastoma: importance of analytical method

INTRODUCTION

Accurate knowledge of O(6)-methylguanine methyltransferase (MGMT) gene promoter subtype in patients with glioblastoma (GBM) is important for treatment. However, this test is not always available. Pre-operative diffusion MRI (dMRI) can be used to probe tumour biology using the apparent diffusion coefficient (ADC); however, its ability to act as a surrogate to predict MGMT status has shown mixed results. We investigated whether this was due to variations in the method used to analyse ADC.

METHODS

We undertook a retrospective study of 32 patients with GBM who had MGMT status measured. Matching pre-operative MRI data were used to calculate the ADC within contrast enhancing regions of tumour. The relationship between ADC and MGMT was examined using two published ADC methods.

RESULTS

A strong trend between a measure of 'minimum ADC' and methylation status was seen. An elevated minimum ADC was more likely in the methylated compared to the unmethylated MGMT group (U = 56, P = 0.0561). In contrast, utilising a two-mixture model histogram approach, a significant reduction in mean measure of the 'low ADC' component within the histogram was associated with an MGMT promoter methylation subtype (P < 0.0246).

CONCLUSION

This study shows that within the same patient cohort, the method selected to analyse ADC measures has a significant bearing on the use of that metric as a surrogate marker of MGMT status. Thus for dMRI data to be clinically useful, consistent methods of data analysis need to be established prior to establishing any relationship with genetic or epigenetic profiling.