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We characterize the revenue-maximizing mechanism for time separable allocation problems in continuous time. The willingness-to-pay of each agent is private information and changes over time.We derive the dynamic revenue-maximizing mechanism, analyze its qualitative structure and frequently derive its closed form solution. In the leading example of repeat sales of a good or service, we establish that commonly observed contract features such as flat rates, free consumption units and two-part tariffs emerge as part of the optimal contract. We investigate in detail the environments in which the type of each agent follows an arithmetic or geometric Brownian motion or a mean-reverting process. We analyze the allocative distortions and show that depending on the nature of the private information the distortion might increase or decrease over time.

Background: The journal Methods of Information in Medicine, founded in 1962, has now completed its 50th volume. Its publications during the last five decades reflect the formation of a discipline that deals with information in biomedicine and health care.Objectives: To report about 1) the journal's origin, 2) the individuals who have significantly contributed to it, 3) trends in the journal's aims and scope, 4) influential papers and 5) major topics published in Methods over the years.Methods: Methods included analysing the correspondence and journal issues in the archives of the editorial office and of the publisher, citation analysis using the ISI and Scopus databases, and analysing the articles' Medical Subject Headings (MeSH) in MEDLINE.Results: In the journal's first 50 years 208 editorial board members and/or editors contributed to the journal's development, with most individuals coming from Europe and North America. The median time of service was 11 years. At the time of analysis 2,456 articles had been indexed with MeSH. Topics included computerized systems of various types, informatics methodologies, and topics related to a specific medical domain. Some MeSH topic entries were heavily and regularly represented in each of the journal's five decades (e.g. information systems and medical records), while others were important in a particular decade, but not in other decades (e.g. punched-card systems and systems integration). Seven papers were cited more than 100 times and these also covered a broad range of themes such as knowledge representation, analysis of biomedical data and knowledge, clinical decision support and electronic patient records.Conclusions: Methods of Information in Medicine is the oldest international journal in biomedical informatics. The journal's development over the last 50 years correlates with the formation of this new discipline. It has and continues to stress the basic methodology and scientific fundamentals of organizing, representing and analysing data, information and knowledge in biomedicine and health care. It has and continues to stimulate multidisciplinary communication on research that is devoted to high-quality, efficient health care, to quality of life and to the progress of biomedicine and the health sciences. [ABSTRACT FROM AUTHOR]

Stimulation of pancreatic beta cell regeneration could be a therapeutic lead to treat diabetes. Unlike humans, the zebrafish can efficiently regenerate beta cells, notably from ductal pancreatic progenitors. To gain insight into the molecular pathways involved in this process, we established the transcriptomic profile of the ductal cells after beta cell ablation in the adult zebrafish. These data highlighted the protein phosphatase calcineurin (CaN) as a new potential modulator of beta cell regeneration. We showed that CaN overexpression abolished the regenerative response, leading to glycemia dysregulation. On the opposite, CaN inhibition increased ductal cell proliferation and subsequent beta cell regeneration. Interestingly, the enhanced proliferation of the progenitors was paradoxically coupled with their exhaustion. This suggests that the proliferating progenitors are next entering in differentiation. CaN appears as a guardian which prevents an excessive progenitor proliferation to preserve the pool of progenitors. Altogether, our findings reveal CaN as a key player in the balance between proliferation and differentiation to enable a proper beta cell regeneration., Competing Interests: LM, DB, AL, CR, CD, CG, LF, BP, MV, IM No competing interests declared, (© 2023, Massoz et al.)

The liver is a remarkable organ that can regenerate in response to injury. Depending on the extent of injury, the liver can undergo compensatory hyperplasia or fibrosis. Despite decades of research, the molecular mechanisms underlying these processes are poorly understood. Here, we developed a new model to study liver regeneration based on cryoinjury. To visualise liver regeneration at cellular resolution, we adapted the CUBIC tissue-clearing approach. Hepatic cryoinjury induced a localised necrotic and apoptotic lesion characterised by inflammation and infiltration of innate immune cells. After this initial phase, we observed fibrosis, which resolved as regeneration re-established homeostasis in 30 days. Importantly, this approach enables the comparison of healthy and injured parenchyma within an individual animal, providing unique advantages to previous models. In summary, the hepatic cryoinjury model provides a fast and reproducible method for studying the cellular and molecular pathways underpinning fibrosis and liver regeneration., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

In mammalian hearts myocardial infarction produces a permanent collagen-rich scar. Conversely, in zebrafish a collagen-rich scar forms but is completely resorbed as the myocardium regenerates. The formation of cross-links in collagen hinders its degradation but cross-linking has not been well characterized in zebrafish hearts. Here, a library of fluorescent probes to quantify collagen oxidation, the first step in collagen cross-link (CCL) formation, was developed. Myocardial injury in mice or zebrafish resulted in similar dynamics of collagen oxidation in the myocardium in the first month after injury. However, during this time, mature CCLs such as pyridinoline and deoxypyridinoline developed in the murine infarcts but not in the zebrafish hearts. High levels of newly oxidized collagen were still seen in murine scars with mature CCLs. These data suggest that fibrogenesis remains dynamic, even in mature scars, and that the absence of mature CCLs in zebrafish hearts may facilitate their ability to regenerate., (© 2024. The Author(s).)

Restoring damaged β-cells in diabetic patients by harnessing the plasticity of other pancreatic cells raises the questions of the efficiency of the process and of the functionality of the new Insulin -expressing cells. To overcome the weak regenerative capacity of mammals, we used regeneration-prone zebrafish to study β-cells arising following destruction. We show that most new in s ulin cells differ from the original β-cells as they coexpress Somatostatin and Insulin. These bihormonal cells are abundant, functional and able to normalize glycemia. Their formation in response to β-cell destruction is fast, efficient, and age-independent. Bihormonal cells are transcriptionally close to a subset of δ-cells that we identified in control islets and that are characterized by the expression of somatostatin 1.1 ( sst1.1 ) and by genes essential for glucose-induced Insulin secretion in β-cells such as pdx1 , s lc2a2 and gck . We observed in vivo the conversion of monohormonal sst1.1- expressing cells to sst1.1+ ins + bihormonal cells following β-cell destruction. Our findings support the conclusion that sst1.1 δ-cells possess a pro-β identity enabling them to contribute to the neogenesis of Insulin-producing cells during regeneration. This work unveils that abundant and functional bihormonal cells benefit to diabetes recovery in zebrafish., Competing Interests: CC, LM, MD, DB, JB, AL, ET, CH, BP, MV, IM No competing interests declared, DS Senior editor, eLife, (© 2022, Carril Pardo et al.)

Competing Interests: Disclosure The authors report no conflicts of interest in this work.

The zebrafish is a popular animal model with well-known regenerative capabilities. To study regeneration in this fish, the nitroreductase/metronidazole-mediated system is widely used for targeted ablation of various cell types. Nevertheless, we highlight here some variability in ablation efficiencies with the metronidazole prodrug that led us to search for a more efficient and reliable compound. Herein, we present nifurpirinol, another nitroaromatic antibiotic, as a more potent prodrug compared to metronidazole to trigger cell-ablation in nitroreductase expressing transgenic models. We show that nifurpirinol induces robust and reliable ablations at concentrations 2,000 fold lower than metronidazole and three times below its own toxic concentration. We confirmed the efficiency of nifurpirinol in triggering massive ablation of three different cell types: the pancreatic beta cells, osteoblasts, and dopaminergic neurons. Our results identify nifurpirinol as a very potent prodrug for the nitroreductase-mediated ablation system and suggest that its use could be extended to many other cell types, especially if difficult to ablate, or when combined pharmacological treatments are desired., (© 2018 by the Wound Healing Society.)

Background: Defining the transcriptome and the genetic pathways of pancreatic cells is of great interest for elucidating the molecular attributes of pancreas disorders such as diabetes and cancer. As the function of the different pancreatic cell types has been maintained during vertebrate evolution, the comparison of their transcriptomes across distant vertebrate species is a means to pinpoint genes under strong evolutionary constraints due to their crucial function, which have therefore preserved their selective expression in these pancreatic cell types., Results: In this study, RNA-sequencing was performed on pancreatic alpha, beta, and delta endocrine cells as well as the acinar and ductal exocrine cells isolated from adult zebrafish transgenic lines. Comparison of these transcriptomes identified many novel markers, including transcription factors and signaling pathway components, specific for each cell type. By performing interspecies comparisons, we identified hundreds of genes with conserved enriched expression in endocrine and exocrine cells among human, mouse, and zebrafish. This list includes many genes known as crucial for pancreatic cell formation or function, but also pinpoints many factors whose pancreatic function is still unknown. A large set of endocrine-enriched genes can already be detected at early developmental stages as revealed by the transcriptomic profiling of embryonic endocrine cells, indicating a potential role in cell differentiation. The actual involvement of conserved endocrine genes in pancreatic cell differentiation was demonstrated in zebrafish for myt1b, whose invalidation leads to a reduction of alpha cells, and for cdx4, selectively expressed in endocrine delta cells and crucial for their specification. Intriguingly, comparison of the endocrine alpha and beta cell subtypes from human, mouse, and zebrafish reveals a much lower conservation of the transcriptomic signatures for these two endocrine cell subtypes compared to the signatures of pan-endocrine and exocrine cells. These data suggest that the identity of the alpha and beta cells relies on a few key factors, corroborating numerous examples of inter-conversion between these two endocrine cell subtypes., Conclusion: This study highlights both evolutionary conserved and species-specific features that will help to unveil universal and fundamental regulatory pathways as well as pathways specific to human and laboratory animal models such as mouse and zebrafish.

Background: Based on today's information and communication technologies the open access paradigm has become an important approach for adequately communicating new scientific knowledge., Objectives: Summarizing the present situation for journal transformation. Presenting criteria for adequate transformation as well as a specific approach for it. Describing our exemplary implementation of such a journal transformation., Methods: Studying the respective literature as well as discussing this topic in various discussion groups and meetings (primarily of editors and publishers, but also of authors and readers), with long term experience as editors and /or publishers of scientific publications as prerequisite., Results: There is a clear will, particularly of political and funding organizations, towards open access publishing. In spite of this, there is still a large amount of scientific knowledge, being communicated through subscription-based journals. For successfully transforming such journals into open access, sixteen criteria for a goal-oriented, stepwise, sustainable, and fair transformation are suggested. The Tandem Model as transformation approach is introduced. Our exemplary implementation is done in the Trans-O-MIM project. It is exploring strategies, models and evaluation metrics for journal transformation. As instance the journal Methods of Information in Medicine will apply the Tandem Model from 2017 onwards., Conclusions: Within Trans-O-MIM we will reach at least nine of the sixteen criteria for adequate transformation. It was positive to implement Trans-O-MIM as international research project. After first steps for transforming Methods have successfully been made, challenges will remain, among others, in identifying appropriate incentives for open access publishing in order to support its transformation.

Background: In contrast to mammals, the zebrafish has the remarkable capacity to regenerate its pancreatic beta cells very efficiently. Understanding the mechanisms of regeneration in the zebrafish and the differences with mammals will be fundamental to discovering molecules able to stimulate the regeneration process in mammals. To identify the pancreatic cells able to give rise to new beta cells in the zebrafish, we generated new transgenic lines allowing the tracing of multipotent pancreatic progenitors and endocrine precursors., Results: Using novel bacterial artificial chromosome transgenic nkx6.1 and ascl1b reporter lines, we established that nkx6.1-positive cells give rise to all the pancreatic cell types and ascl1b-positive cells give rise to all the endocrine cell types in the zebrafish embryo. These two genes are initially co-expressed in the pancreatic primordium and their domains segregate, not as a result of mutual repression, but through the opposite effects of Notch signaling, maintaining nkx6.1 expression while repressing ascl1b in progenitors. In the adult zebrafish, nkx6.1 expression persists exclusively in the ductal tree at the tip of which its expression coincides with Notch active signaling in centroacinar/terminal end duct cells. Tracing these cells reveals that they are able to differentiate into other ductal cells and into insulin-expressing cells in normal (non-diabetic) animals. This capacity of ductal cells to generate endocrine cells is supported by the detection of ascl1b in the nkx6.1:GFP ductal cell transcriptome. This transcriptome also reveals, besides actors of the Notch and Wnt pathways, several novel markers such as id2a. Finally, we show that beta cell ablation in the adult zebrafish triggers proliferation of ductal cells and their differentiation into insulin-expressing cells., Conclusions: We have shown that, in the zebrafish embryo, nkx6.1+ cells are bona fide multipotent pancreatic progenitors, while ascl1b+ cells represent committed endocrine precursors. In contrast to the mouse, pancreatic progenitor markers nkx6.1 and pdx1 continue to be expressed in adult ductal cells, a subset of which we show are still able to proliferate and undergo ductal and endocrine differentiation, providing robust evidence of the existence of pancreatic progenitor/stem cells in the adult zebrafish. Our findings support the hypothesis that nkx6.1+ pancreatic progenitors contribute to beta cell regeneration. Further characterization of these cells will open up new perspectives for anti-diabetic therapies.

The report deals with the demands set for a general surgeon in a developing country, which is in a state of conventional war. The pecularities concerning logistics and treatment at the base are dealt with. Conclusions for postgraduate surgical qualification are drawn.