Cost-Effectiveness of Axicabtagene Ciloleucel for Adult Patients With Relapsed or Refractory Follicular Lymphoma in the United States.

OBJECTIVES: The results of a recent single-arm trial (ZUMA-5) of axicabtagene ciloleucel (axi-cel) for relapsed/refractory (r/r) follicular lymphoma (FL) demonstrated high rates of durable response and tolerable toxicity among treated patients. To quantify the value of axi-cel compared with standard of care (SOC) to manage r/r FL patients who have had at least 2 prior lines of systemic therapy (3L+), a cost-effectiveness model was developed from a US third-party payer perspective. METHODS: A 3-state partitioned-survival cost-effectiveness model was developed with a lifetime horizon. Patient-level analyses of the 36-month ZUMA-5 (axi-cel) and SCHOLAR-5 (SOC) studies were used to extrapolate progression-free and overall survivals. After 5 years of survival, an estimated 40% of the modeled population was assumed to experience long-term remission based on literature. Results include the incremental cost-effectiveness ratio (ICER) measured as incremental cost per quality-adjusted life year (QALY) gained. One-way sensitivity analysis, probabilistic sensitivity analysis, and scenario analyses were performed. All outcomes were discounted 3% per year. RESULTS: Axi-cel led to an increase of 4.28 life-years, 3.64 QALYs, and a total cost increase of $321 192 relative to SOC, resulting in an ICER of $88 300 per QALY. Across all parameters varied in the one-way sensitivity analysis, the ICER varied between $133 030 and $67 277. In the probabilistic sensitivity analysis, axi-cel had a 99% probability of being cost-effective across 5000 iterations using a $150 000 willingness-to-pay threshold. CONCLUSIONS: Given the robustness of the model results and sensitivity analyses, axi-cel is expected to be a cost-effective treatment in 3L+ r/r FL.

Clinical outcomes in patients relapsed/refractory after ≥2 prior lines of therapy for follicular lymphoma: a systematic literature review and meta-analysis.

BACKGROUND: Patients with follicular lymphoma (FL) can have high response rates to early lines of treatment. However, among FL patients relapsed/refractory (r/r) after ≥2 prior lines of therapy (LOT), remission tends to be shorter and there is limited treatment guidance. This study sought to evaluate the clinical outcomes for r/r FL after ≥2 prior LOT identified through systematic literature review. METHODS: Eligible studies included comparative or non-comparative interventional or observational studies of systemic therapies among adults with FL r/r after ≥2 prior LOT published prior to 31st May 2021. Prior LOT must have included an anti-CD20 monoclonal antibody and an alkylating agent, in combination or separately. Overall response rate (ORR) and complete response (CR) were estimated using inverse-variance weighting with Freeman-Tukey double-arcsine transformations. Kaplan-Meier (KM) curves for progression-free survival (PFS) and overall survival (OS) estimated by reconstructing digitized curves using the Guyot algorithm, and survival analyses were conducted, stratified by ≥2 prior LOT and ≥ 3 prior LOT groups (as defined in the source material). Restricting the analyses to the observational cohorts was investigated as a sensitivity analysis. RESULTS: The analysis-set included 20 studies published between 2014 and 2021. Studies were primarily US and/or European based, with the few exceptions using treatments approved in US/Europe. The estimated ORR was 58.47% (95% confidence interval [CI]: 51.13-65.62) and proportion of patients with CR was 19.63% (95% CI: 15.02-24.68). The median OS among those ≥2 prior LOT was 56.57 months (95% CI: 47.8-68.78) and median PFS was 9.78 months (95% CI: 9.01-10.63). The 24-month OS decreased from 66.50% in the ≥2 prior LOT group to 59.51% in the ≥3 prior LOT group, with a similar trend in PFS at 24-month (28.42% vs 24.13%). CONCLUSIONS: This study found that few r/r FL patients with ≥2 prior LOT achieve CR, and despite some benefit, approximately 1/3 of treated patients die within 24 months. The shorter median PFS with increasing prior LOT suggest treatment durability is suboptimal in later LOT. These findings indicate that patients are underserved by treatments currently available in the US and Europe.

FAM83D directs protein kinase CK1α to the mitotic spindle for proper spindle positioning.

The concerted action of many protein kinases helps orchestrate the error-free progression through mitosis of mammalian cells. The roles and regulation of some prominent mitotic kinases, such as cyclin-dependent kinases, are well established. However, these and other known mitotic kinases alone cannot account for the extent of protein phosphorylation that has been reported during mammalian mitosis. Here we demonstrate that CK1α, of the casein kinase 1 family of protein kinases, localises to the spindle and is required for proper spindle positioning and timely cell division. CK1α is recruited to the spindle by FAM83D, and cells devoid of FAM83D, or those harbouring CK1α-binding-deficient FAM83DF283A/F283A knockin mutations, display pronounced spindle positioning defects, and a prolonged mitosis. Restoring FAM83D at the endogenous locus in FAM83D-/- cells, or artificially delivering CK1α to the spindle in FAM83DF283A/F283A cells, rescues these defects. These findings implicate CK1α as new mitotic kinase that orchestrates the kinetics and orientation of cell division.

RecA bundles mediate homology pairing between distant sisters during DNA break repair.

DNA double-strand break (DSB) repair by homologous recombination has evolved to maintain genetic integrity in all organisms. Although many reactions that occur during homologous recombination are known, it is unclear where, when and how they occur in cells. Here, by using conventional and super-resolution microscopy, we describe the progression of DSB repair in live Escherichia coli. Specifically, we investigate whether homologous recombination can occur efficiently between distant sister loci that have segregated to opposite halves of an E. coli cell. We show that a site-specific DSB in one sister can be repaired efficiently using distant sister homology. After RecBCD processing of the DSB, RecA is recruited to the cut locus, where it nucleates into a bundle that contains many more RecA molecules than can associate with the two single-stranded DNA regions that form at the DSB. Mature bundles extend along the long axis of the cell, in the space between the bulk nucleoid and the inner membrane. Bundle formation is followed by pairing, in which the two ends of the cut locus relocate at the periphery of the nucleoid and together move rapidly towards the homology of the uncut sister. After sister locus pairing, RecA bundles disassemble and proteins that act late in homologous recombination are recruited to give viable recombinants 1-2-generation-time equivalents after formation of the initial DSB. Mutated RecA proteins that do not form bundles are defective in sister pairing and in DSB-induced repair. This work reveals an unanticipated role of RecA bundles in channelling the movement of the DNA DSB ends, thereby facilitating the long-range homology search that occurs before the strand invasion and transfer reactions.

High resolution imaging reveals heterogeneity in chromatin states between cells that is not inherited through cell division.

BACKGROUND: Genomes of eukaryotes exist as chromatin, and it is known that different chromatin states can influence gene regulation. Chromatin is not a static structure, but is known to be dynamic and vary between cells. In order to monitor the organisation of chromatin in live cells we have engineered fluorescent fusion proteins which recognize specific operator sequences to tag pairs of syntenic gene loci. The separation of these loci was then tracked in three dimensions over time using fluorescence microscopy. RESULTS: We established a work flow for measuring the distance between two fluorescently tagged, syntenic gene loci with a mean measurement error of 63 nm. In general, physical separation was observed to increase with increasing genomic separations. However, the extent to which chromatin is compressed varies for different genomic regions. No correlation was observed between compaction and the distribution of chromatin markers from genomic datasets or with contacts identified using capture based approaches. Variation in spatial separation was also observed within cells over time and between cells. Differences in the conformation of individual loci can persist for minutes in individual cells. Separation of reporter loci was found to be similar in related and unrelated daughter cell pairs. CONCLUSIONS: The directly observed physical separation of reporter loci in live cells is highly dynamic both over time and from cell to cell. However, consistent differences in separation are observed over some chromosomal regions that do not correlate with factors known to influence chromatin states. We conclude that as yet unidentified parameters influence chromatin configuration. We also find that while heterogeneity in chromatin states can be maintained for minutes between cells, it is not inherited through cell division. This may contribute to cell-to-cell transcriptional heterogeneity.

Replication and segregation of an Escherichia coli chromosome with two replication origins.

Characterized bacteria, unlike eukaryotes and some archaea, initiate replication bidirectionally from a single replication origin contained within a circular or linear chromosome. We constructed Escherichia coli cells with two WT origins separated by 1 Mb in their 4.64-Mb chromosome. Productive bidirectional replication initiated synchronously at both spatially separate origins. Newly replicated DNA from both origins was segregated sequentially as replication progressed, with two temporally and spatially separate replication termination events. Replication initiation occurred at a cell volume identical to that of cells with a single WT origin, showing that initiation control is independent of cellular and chromosomal oriC concentration. Cells containing just the ectopic origin initiated bidirectional replication at the expected cell mass and at the normal cellular location of that region. In all strains, spatial separation of sister loci adjacent to active origins occurred shortly after their replication, independently of whether replication initiated at the normal origin, the ectopic origin, or both origins.

Health Technology Reassessment: Addressing Uncertainty in Economic Evaluations of Oncology Drugs at Time of Reimbursement Using Long-Term Clinical Trial Data.

The evidence base to support reimbursement decision making for oncology drugs is often based on short-term follow-up trial data, and attempts to address this uncertainty are not typically undertaken once a reimbursement decision is made. To address this gap, we sought to conduct a reassessment of an oncology drug (pembrolizumab) for patients with advanced melanoma which was approved based on interim data with a median 7.9 months of follow-up and for which long-term data have since been published. We developed a three-health-state partitioned survival model based on the phase 3 KEYNOTE-006 clinical trial data using patient-level data reconstruction techniques based on an interim analysis. We used a standard survival analysis and parametric curve fitting techniques to extrapolate beyond the trial follow-up time, and the model structure and inputs were derived from the literature. Five-year long-term follow-up data from the trial were then used to re-evaluate the cost-effectiveness of pembrolizumab versus ipilimumab for treatment of advanced melanoma. The best fitting parametric curves and corresponding survival extrapolations for reconstructed interim data and long-term data reconstructed from KEYNOTE-006 were different. An analysis of the 5 year long-term follow-up data generated a base case incremental cost-effectiveness ratio (ICER) that was 28% higher than the ICER based on interim trial data. Our findings suggest that there may be a trade-off between certainty and the ICER. Conducting health technology re-assessments of certain oncology products on the basis of longer-term data availability, especially for those health technology adoption decisions made based on immature clinical data, may be of value to decision makers.

The p97/VCP segregase is essential for arsenic-induced degradation of PML and PML-RARA.

Acute Promyelocytic Leukemia is caused by expression of the oncogenic Promyelocytic Leukemia (PML)-Retinoic Acid Receptor Alpha (RARA) fusion protein. Therapy with arsenic trioxide results in degradation of PML-RARA and PML and cures the disease. Modification of PML and PML-RARA with SUMO and ubiquitin precedes ubiquitin-mediated proteolysis. To identify additional components of this pathway, we performed proteomics on PML bodies. This revealed that association of p97/VCP segregase with PML bodies is increased after arsenic treatment. Pharmacological inhibition of p97 altered the number, morphology, and size of PML bodies, accumulated SUMO and ubiquitin modified PML and blocked arsenic-induced degradation of PML-RARA and PML. p97 localized to PML bodies in response to arsenic, and siRNA-mediated depletion showed that p97 cofactors UFD1 and NPLOC4 were critical for PML degradation. Thus, the UFD1-NPLOC4-p97 segregase complex is required to extract poly-ubiquitinated, poly-SUMOylated PML from PML bodies, prior to degradation by the proteasome.

ParticleStats: open source software for the analysis of particle motility and cytoskeletal polarity.

The study of dynamic cellular processes in living cells is central to biology and is particularly powerful when the motility characteristics of individual objects within cells can be determined and analysed statistically. However, commercial programs only offer a limited range of inflexible analysis modules and there are currently no open source programs for extensive analysis of particle motility. Here, we describe ParticleStats (http://www.ParticleStats.com), a web server and open source programs, which input the X,Y coordinate positions of objects in time, and output novel analyses, graphical plots and statistics for motile objects. ParticleStats comprises three separate analysis programs. First, ParticleStats:Directionality for the global analysis of polarity, for example microtubule plus end growth in Drosophila oocytes. Second, ParticleStats:Compare for the analysis of saltatory movement in terms of runs and pauses. This can be applied to chromosome segregation and molecular motor-based movements. Thirdly ParticleStats:Kymographs for the analysis of kymograph images, for example as applied to separation of chromosomes in mitosis. These analyses have provided key insights into molecular mechanisms that are not possible from qualitative analysis alone and are widely applicable to many other cell biology problems.

Cost-Effectiveness of Brexucabtagene Autoleucel versus Best Supportive Care for the Treatment of Relapsed/Refractory Mantle Cell Lymphoma following Treatment with a Bruton's Tyrosine Kinase Inhibitor in Canada.

For patients with Mantle Cell Lymphoma (MCL), there is no recognized standard of care for relapsed/refractory (R/R) disease after treatment with a Bruton's tyrosine kinase inhibitor (BTKi). Brexucabtagene autoleucel (brexu-cel) represents a promising new treatment modality in MCL. We explored whether brexu-cel was cost-effective for the treatment of R/R MCL. We developed a partitioned survival mixture cure approach to model the costs and outcomes over a lifetime horizon. The clinical data were derived from the ZUMA-2 clinical trial. The costs were estimated from the publicly available Canadian databases, published oncology literature, and pan-Canadian Oncology Drug Review economic guidance reports. The health state utilities were sourced from the ibrutinib submission to the National Institute for Health and Care Excellence for R/R MCL and supplemented with values from the published oncology literature. In the base case over a lifetime horizon, brexu-cel generated an incremental 9.56 life-years and an additional 7.03 quality-adjusted life-years compared to BSC, while associated with CAD 621,933 in additional costs. The resultant incremental cost-utility ratio was CAD 88,503 per QALY gained compared with BSC. Based on this analysis, we found brexu-cel to be a cost-effective use of healthcare resources relative to BSC for treatment of adult patients with R/R MCL previously treated with a BTKi in Canada, though additional research is needed to confirm these results using longer follow-up data.

The Cost Effectiveness of Axicabtagene Ciloleucel Versus Best Supportive Care in the Treatment of Adult Patients with Relapsed or Refractory Large B-Cell Lymphoma (LBCL) After Two or More Lines of Systemic Therapy in Canada.

BACKGROUND AND OBJECTIVE: Axicabtagene ciloleucel (axi-cel) received marketing authorisation in Canada for the treatment of relapsed or refractory large B-cell lymphoma after two or more lines of systemic therapy, and the clinical and economic value of axi-cel to patients and the healthcare system should be examined. The objective of this analysis is to determine, from societal and public healthcare payer perspectives, the cost effectiveness of axi-cel versus best supportive care for patients with relapsed or refractory large B-cell lymphoma in Canada. METHODS: A pharmacoeconomic model was developed and populated with clinical data derived from the ZUMA-1 and SCHOLAR-1 studies using a propensity score-matched comparison. A partitioned survival mixture-cure modelling approach was taken to characterise the potential curative effect of axi-cel therapy in large B-cell lymphoma. Healthcare resource utilisation and adverse event data were based on results from ZUMA-1, and utility values were derived from ZUMA-1 data supplemented with published literature. Costs (in 2021 Canadian dollars) were taken from publicly available Canadian cost databases and published literature. Benefits and costs were discounted at 1.5% per year, and sensitivity analyses were conducted to assess the robustness of the results. RESULTS: In the base case, axi-cel generated an incremental 6.2 life-years compared to best supportive care, corresponding to 4.6 additional quality-adjusted life-years, and was associated with $606,010 in additional costs. The incremental cost-utility ratio was $132,747 per quality-adjusted life-year gained compared with best supportive care from a societal perspective ($106,392 per quality-adjusted life-year gained from a public healthcare payer perspective). Key drivers of the analysis included progression-free survival and overall survival values for axi-cel. CONCLUSIONS: The results of this analysis suggest that axi-cel may be considered a cost-effective allocation of resources compared with best supportive care for the treatment of adult patients with relapsed or refractory large B-cell lymphoma in Canada.

Appraisals by Health Technology Assessment Agencies of Economic Evaluations Submitted as Part of Reimbursement Dossiers for Oncology Treatments: Evidence from Canada, the UK, and Australia.

Publicly funded healthcare systems, including those in Canada, the United Kingdom (UK), and Australia, often use health technology assessment (HTA) to inform drug reimbursement decision-making, based on dossiers submitted by manufacturers, and HTA agencies issue publicly available reports to support funding recommendations. However, the level of information reported by HTA agencies in these reports may vary. To provide insights on this issue, we describe and assess the reporting of economic methods in recent oncology HTA recommendations from the Canadian Agency for Drugs and Technologies in Health (CADTH), National Institute for Health and Care Excellence (NICE), and Pharmaceutical Benefits Advisory Committee (PBAC). Publicly available HTA recommendations and reports for oncology drugs issued by CADTH over a 2-year period, 2019-2020, were identified and compared with the corresponding HTA documents from NICE and the PBAC. Reporting of key model characteristics and attributes, survival analysis methods, methodological criticisms, and re-assessment of the economic results were characterized using descriptive statistics. Dichotomous differences in the methodological criticisms observed between the three agencies were assessed using Cochran's Q tests and substantiated using pairwise McNemar tests. Chi-squared tests were used to assess the dichotomous differences in the reporting of methods and explore the potential relationships between categorical variables, where appropriate. HTAs published by CADTH, NICE, and the PBAC consistently reported a broad spectrum of descriptive information on the economic models submitted by manufacturers. While common economic evaluation attributes were well-reported across the three HTA agencies, significant differences in the reporting of survival analysis methods and methodological criticisms were observed. NICE consistently reported more comprehensive information, compared to either CADTH or PBAC. Despite these differences, broadly similar recommendation rates were observed between CADTH and NICE. The PBAC was found to be more restrictive. Based on our 2-year sample of oncology, the HTAs published by CADTH matched with the corresponding HTAs from NICE and PBAC; we observed important variations in the reporting of economic evidence, especially technical aspects, such as survival analysis, across the three agencies. In addition to guidelines for HTA submissions by manufacturers, the community of HTA agencies should also have common standards for reporting the results of their assessments, though the information and opinions reported may differ.

Founder cell configuration drives competitive outcome within colony biofilms.

Bacteria can form dense communities called biofilms, where cells are embedded in a self-produced extracellular matrix. Exploiting competitive interactions between strains within the biofilm context can have potential applications in biological, medical, and industrial systems. By combining mathematical modelling with experimental assays, we reveal that spatial structure and competitive dynamics within biofilms are significantly affected by the location and density of the founder cells used to inoculate the biofilm. Using a species-independent theoretical framework describing colony biofilm formation, we show that the observed spatial structure and relative strain biomass in a mature biofilm comprising two isogenic strains can be mapped directly to the geographical distributions of founder cells. Moreover, we define a predictor of competitive outcome that accurately forecasts relative abundance of strains based solely on the founder cells' potential for radial expansion. Consequently, we reveal that variability of competitive outcome in biofilms inoculated at low founder density is a natural consequence of the random positioning of founding cells in the inoculum. Extension of our study to non-isogenic strains that interact through local antagonisms, shows that even for strains with different competition strengths, a race for space remains the dominant mode of competition in low founder density biofilms. Our results, verified by experimental assays using Bacillus subtilis, highlight the importance of spatial dynamics on competitive interactions within biofilms and hence to related applications.

Onwards and Upwards: A Systematic Survey of Economic Evaluation Methods in Oncology.

INTRODUCTION: The type of methods used in economic evaluations of health technology can lead to results that may influence decisions. Despite the potential impact on decision making, there is very little documentation of methods used in economic evaluation in oncology pertaining to key assumptions and extrapolation methods of survival benefits, especially in terms of survival analysis techniques and methods for extrapolation. OBJECTIVES: The primary objectives of this study were to identify, examine, and describe the methods used in economic evaluations in oncology over a 10-year period, while secondary objectives included examining the use of identified methods across different geographic regions. METHODS: A systematic search of the published oncology literature was conducted to identify economic evaluations of advanced or metastatic cancers published between 2010 and 2019 using the PUBMED, Ovid MEDLINE, and EMBASE databases. A random sample was taken, and information on type of study, data source, modeling techniques, and survival analysis methods were abstracted and descriptively summarized. RESULTS: A total of 8481 abstracts were identified and 76 economic evaluations were abstracted and assessed. Most identified studies were from North America (38%), East Asia (21%), continental Europe (18%), or the UK (16%), and most commonly focused on lung cancer (18%), colorectal cancer (16%), or breast cancer (13%). A large majority of studies were based on data from randomized controlled trials (82%), utilized a cost-utility approach (82%), and took a public healthcare system perspective (83%). Common model structures included Markov (49%) and partitioned survival (17%). Fitted parametric curves were the most commonly used extrapolation method (89%) for overall survival and most often utilized the Weibull distribution (64%). Secondary assessments showed modest regional variation in the use of identified methods, including the use of fitted parametric curves, testing of the proportional hazards assumption, and validation of results. CONCLUSION: A majority of papers in the study sample reported basic characteristics of study type, data source used, modeling techniques, and utilization of survival analysis methods. However, greater detail in reporting extrapolation methods, statistical analyses, and validation of results could be potential improvements, especially across regions, in order to support greater consistency in decision making. Future research could document the diffusion of novel modeling techniques into economic evaluation.

Pharmacological rescue of impaired mitophagy in Parkinson's disease-related LRRK2 G2019S knock-in mice.

Parkinson's disease (PD) is a major and progressive neurodegenerative disorder, yet the biological mechanisms involved in its aetiology are poorly understood. Evidence links this disorder with mitochondrial dysfunction and/or impaired lysosomal degradation - key features of the autophagy of mitochondria, known as mitophagy. Here, we investigated the role of LRRK2, a protein kinase frequently mutated in PD, in this process in vivo. Using mitophagy and autophagy reporter mice, bearing either knockout of LRRK2 or expressing the pathogenic kinase-activating G2019S LRRK2 mutation, we found that basal mitophagy was specifically altered in clinically relevant cells and tissues. Our data show that basal mitophagy inversely correlates with LRRK2 kinase activity in vivo. In support of this, use of distinct LRRK2 kinase inhibitors in cells increased basal mitophagy, and a CNS penetrant LRRK2 kinase inhibitor, GSK3357679A, rescued the mitophagy defects observed in LRRK2 G2019S mice. This study provides the first in vivo evidence that pathogenic LRRK2 directly impairs basal mitophagy, a process with strong links to idiopathic Parkinson's disease, and demonstrates that pharmacological inhibition of LRRK2 is a rational mitophagy-rescue approach and potential PD therapy.

An adaptive non-local means filter for denoising live-cell images and improving particle detection.

Fluorescence imaging of dynamical processes in live cells often results in a low signal-to-noise ratio. We present a novel feature-preserving non-local means approach to denoise such images to improve feature recovery and particle detection. The commonly used non-local means filter is not optimal for noisy biological images containing small features of interest because image noise prevents accurate determination of the correct coefficients for averaging, leading to over-smoothing and other artifacts. Our adaptive method addresses this problem by constructing a particle feature probability image, which is based on Haar-like feature extraction. The particle probability image is then used to improve the estimation of the correct coefficients for averaging. We show that this filter achieves higher peak signal-to-noise ratio in denoised images and has a greater capability in identifying weak particles when applied to synthetic data. We have applied this approach to live-cell images resulting in enhanced detection of end-binding-protein 1 foci on dynamically extending microtubules in photo-sensitive Drosophila tissues. We show that our feature-preserving non-local means filter can reduce the threshold of imaging conditions required to obtain meaningful data.

Semi-automated quantitation of mitophagy in cells and tissues.

Mitophagy is a natural phenomenon and entails the lysosomal degradation of mitochondria by the autophagy pathway. In recent years, the development of fluorescent pH-sensitive mitochondrial reporters has greatly facilitated the monitoring of mitophagy by distinguishing between cytosolic mitochondria or those delivered to acidic lysosomes. We recently published the mito-QC reporter, which consists of a mitochondrial outer membrane-localised tandem mCherry-GFP tag. This allows the quantification of mitophagy via the increase in red-only mCherry signal that arises when the GFP signal is quenched upon mitochondrial delivery to lysosomes. Here we develop a macro for FIJI, the mito-QC Counter, and describe its use to allow reliable and consistent semi-automated quantification of mitophagy. In this methods article we describe step-by-step how to detect and quantify mitophagy and show that mitophagy levels can be reliably calculated in different cell lines and under distinct stimuli. Finally, we show that the mito-QC Counter can be used to quantify mitophagy in tissues of mito-QC transgenic mice. We demonstrate that mitophagy levels in skeletal muscle correlates with glycolytic activity. Our present data show that the mito-QC Counter macro for FIJI enables the robust quantification of mitophagy both in vitro and in vivo.

Novel Confocal-Laser-Scanning-Microscopy and conventional measures investigating eroded dentine following dentifrice dab-on and brushing abrasion.

OBJECTIVES: To validate novel non-contacting Confocal-Laser-Scanning-Microscopy (CLSM) methodology with conventional Contacting Profilometry (CP) measures investigating brushing or dab-on of stannous-fluoride dentifrice on early aggressive dentine erosion. METHODS: 75 polished human dentine samples were prepared and eroded in agitated 6% citric acid then randomly allocated into 5 intervention groups; artificial saliva control (1); controlled use of a pressure sensitive counter-rotating oscillatory powered toothbrush with sodium-fluoride NaF (2) or stannous-fluoride SnF2 (3), and dab-on application of NaF (4) or SnF2 (5). Samples underwent three cycles of intervention and 2-min agitated 6 % citric acid challenges. CLSM images were taken and 3D reconstructions produced of step height using a developed software algorithm. In addition, 20 % samples were randomised and profiled using CP to measure step height and surface roughness. Vickers's diamond micro-hardness testing was carried out on all samples. RESULTS: Comparing CLSM and CP; Pearson correlation was 0.77 and Intra-class correlation 0.81 (p = 0.01). There were no significant statistical differences in step height between groups using both CLSM and CP. From baseline, SnF2 brushing (3) increased micro-hardness more than control (1) (p = 0.03), NaF (4) and SnF2 dab-on (5) (p ≤ 0.001), and increased surface roughness more than control (p = 0.02), NaF brushing (2) and NaF dab-on (4) (p ≤ 0.017). Dab-on of SnF2 (5) produced rougher surfaces than control (1) (p = 0.014) and reduced hardness compared with NaF brushing (p = 0.04). CONCLUSIONS: Good agreement and correlation exists between CLSM and CP measures in dentine. There were no significant differences in surface loss after interventions between groups. Compared with control, SnF2 application increased dentine surface roughness and SnF2 controlled powered brushing application increased dentine hardness, likely caused by exposure of uneroded dentine. CLINICAL SIGNIFICANCE: Isosurfaces produced using CLSM can be used to represent dentine step height loss. They show good correlation and agreement with conventional CP measures, following early aggressive erosion-abrasion cycles of dentine. The CLSM and computer algorithm therefore provides an accurate, standalone and non-contacting three-dimensional measurement of early dentine wear. Stannous-fluoride brushing, and dab-on application offer no benefits following early aggressive erosion in dentine. To reduce dentine wear, limiting erosive challenges and avoiding brushing post-erosion is advised.

BIAFLOWS: A Collaborative Framework to Reproducibly Deploy and Benchmark Bioimage Analysis Workflows.

Image analysis is key to extracting quantitative information from scientific microscopy images, but the methods involved are now often so refined that they can no longer be unambiguously described by written protocols. We introduce BIAFLOWS, an open-source web tool enabling to reproducibly deploy and benchmark bioimage analysis workflows coming from any software ecosystem. A curated instance of BIAFLOWS populated with 34 image analysis workflows and 15 microscopy image datasets recapitulating common bioimage analysis problems is available online. The workflows can be launched and assessed remotely by comparing their performance visually and according to standard benchmark metrics. We illustrated these features by comparing seven nuclei segmentation workflows, including deep-learning methods. BIAFLOWS enables to benchmark and share bioimage analysis workflows, hence safeguarding research results and promoting high-quality standards in image analysis. The platform is thoroughly documented and ready to gather annotated microscopy datasets and workflows contributed by the bioimaging community.

In Vivo Imaging of the Segregation of the 2 Chromosomes and the Cell Division Proteins of Rhodobacter sphaeroides Reveals an Unexpected Role for MipZ.

Coordinating chromosome duplication and segregation with cell division is clearly critical for bacterial species with one chromosome. The precise choreography required is even more complex in species with more than one chromosome. The alpha subgroup of bacteria contains not only one of the best-studied bacterial species, Caulobacter crescentus, but also several species with more than one chromosome. Rhodobacter sphaeroides is an alphaproteobacterium with two chromosomes, but, unlike C. crescentus, it divides symmetrically rather than buds and lacks the complex CtrA-dependent control mechanism. By examining the Ori and Ter regions of both chromosomes and associated ParA and ParB proteins relative to cell division proteins FtsZ and MipZ, we have identified a different pattern of chromosome segregation and cell division. The pattern of chromosome duplication and segregation resembles that of Vibrio cholerae, not that of Agrobacterium tumefaciens, with duplication of the origin and terminus regions of chromosome 2 controlled by chromosome 1. Key proteins are localized to different sites compared to C. crescentus OriC1 and ParB1 are localized to the old pole, while MipZ and FtsZ localize to the new pole. Movement of ParB1 to the new pole following chromosome duplication releases FtsZ, which forms a ring at midcell, but, unlike reports for other species, MipZ monomers do not form a gradient but oscillate between poles, with the nucleotide-bound monomer and the dimer localizing to midcell. MipZ dimers form a single ring (with a smaller diameter) close to the FtsZ ring at midcell and constrict with the FtsZ ring. Overproduction of the dimer form results in filamentation, suggesting that MipZ dimers are regulating FtsZ activity and thus septation. This is an unexpected role for MipZ and provides a new model for the integration of chromosome segregation and cell division.IMPORTANCE Cell division has to be coordinated with chromosome segregation to ensure the stable inheritance of genetic information. We investigated this coordination in the multichromosome bacterium Rhodobacter sphaeroides By examining the origin and terminus regions of the two chromosomes, the ParA-like ATPase MipZ and FtsZ, we showed that chromosome 1 appears to be the "master" chromosome connecting DNA segregation and cell division, with MipZ being critical for coordination. MipZ shows an unexpected localization pattern, with MipZ monomers interacting with ParB of the chromosome 1 at the cell poles whereas MipZ dimers colocalize with FtsZ at midcell during constriction, both forming dynamic rings. These data suggest that MipZ has roles in R. sphaeroides in both controlling septation and coordinating chromosome segregation with cell division.