239 research outputs found

    Oxic-anoxic regime shifts mediated by feedbacks between biogeochemical processes and microbial community dynamics

    Get PDF
    The role of microbial communities in regime shifts is poorly understood. Here, the authors use a mathematical model and field data from a seasonally stratified lake to show that gradual environmental changes can induce oxic-anoxic regime shifts mediated by microbial community dynamics and redox processes

    Proton therapy for seminoma testis

    Get PDF
    Seminoma testis wordt gekenmerkt door een hoge ziektevrije en algehele overleving. Bij beperkt lymfogeen gemetastaseerde ziekte is para-aortale en para-iliacale radiotherapie een curatieve behandeloptie. Het belangrijkste nadeel van deze behandeling is het verhoogde risico op secundaire maligniteiten nadien. Dit lijkt voornamelijk te gelden voor tumoren van de maag, pancreas, nieren en blaas. Het risico op tumorinductie is afhankelijk van de bestralingsdosis die op het orgaan komt. Met protonentherapie is het mogelijk om de dosis op deze organen te verminderen ten opzichte van fotonentherapie. Vanaf maart 2022 wordt deze behandeling aangeboden in de drie Nederlandse protonencentra. Dit artikel beschrijft de indicaties en onderbouwing voor het gebruik van protonentherapie bij patiënten met een seminoom. Daarnaast worden enkele technische aspecten besproken.Seminoma testis patients have high cure and survival rates. Radiotherapy to the para-aortic and para-iliac lymph nodes is a curative treatment option for patients with limited lymph node metastases. The most important risk following treatment is secondary tumor induction. This seems to be the case especially for tumors of the stomach, pancreas, kidneys and urinary bladder. The risk of tumor induction depends on the radiation dose delivered to a specific organ. Proton therapy has the unique capacity to reduce dose to these organs, when compared to conventional photon therapy. Starting in March 2022, proton therapy is offered in all three proton centers in the Netherlands. This article describes indications for treatment, technical aspects and scientific grounds for the use of proton therapy in seminoma patients.</p

    Proton therapy for seminoma testis

    Get PDF
    Seminoma testis wordt gekenmerkt door een hoge ziektevrije en algehele overleving. Bij beperkt lymfogeen gemetastaseerde ziekte is para-aortale en para-iliacale radiotherapie een curatieve behandeloptie. Het belangrijkste nadeel van deze behandeling is het verhoogde risico op secundaire maligniteiten nadien. Dit lijkt voornamelijk te gelden voor tumoren van de maag, pancreas, nieren en blaas. Het risico op tumorinductie is afhankelijk van de bestralingsdosis die op het orgaan komt. Met protonentherapie is het mogelijk om de dosis op deze organen te verminderen ten opzichte van fotonentherapie. Vanaf maart 2022 wordt deze behandeling aangeboden in de drie Nederlandse protonencentra. Dit artikel beschrijft de indicaties en onderbouwing voor het gebruik van protonentherapie bij patiënten met een seminoom. Daarnaast worden enkele technische aspecten besproken.Seminoma testis patients have high cure and survival rates. Radiotherapy to the para-aortic and para-iliac lymph nodes is a curative treatment option for patients with limited lymph node metastases. The most important risk following treatment is secondary tumor induction. This seems to be the case especially for tumors of the stomach, pancreas, kidneys and urinary bladder. The risk of tumor induction depends on the radiation dose delivered to a specific organ. Proton therapy has the unique capacity to reduce dose to these organs, when compared to conventional photon therapy. Starting in March 2022, proton therapy is offered in all three proton centers in the Netherlands. This article describes indications for treatment, technical aspects and scientific grounds for the use of proton therapy in seminoma patients.</p

    Membrane-Catalyzed Aggregation of Islet Amyloid Polypeptide Is Dominated by Secondary Nucleation

    Get PDF
    Type II diabetes is characterized by the loss of pancreatic β-cells. This loss is thought to be a consequence of membrane disruption, caused by the aggregation of islet amyloid polypeptide (IAPP) into amyloid fibrils. However, the molecular mechanisms of IAPP aggregation in the presence of membranes have remained unclear. Here, we use kinetic analysis to elucidate the aggregation mechanism of IAPP in the presence of mixed zwitterionic and anionic lipid membranes. The results converge to a model in which aggregation on the membrane is strongly dominated by secondary nucleation, that is, the formation of new nuclei on the surface of existing fibrils. The critical nucleus consists of a single IAPP molecule, and anionic lipids catalyze both primary and secondary nucleation, but not elongation. The fact that anionic lipids promote secondary nucleation implies that these events take place at the interface between the membrane and existing fibrils, demonstrating that fibril growth occurs at least to some extent on the membrane surface. These new insights into the mechanism of IAPP aggregation on membranes may help to understand IAPP toxicity and will be important for the development of therapeutics to prevent β-cell death in type II diabetes

    Associations of early changes in lung ultrasound aeration scores and mortality in invasively ventilated patients: a post hoc analysis

    Get PDF
    Background: Lung ultrasound (LUS) in an emerging technique used in the intensive care unit (ICU). The derivative LUS aeration score has been shown to have associations with mortality in invasively ventilated patients. This study assessed the predictive value of baseline and early changes in LUS aeration scores in critically ill invasively ventilated patients with and without ARDS (Acute Respiratory Distress Syndrome) on 30- and 90-day mortality. Methods: This is a post hoc analysis of a multicenter prospective observational cohort study, which included patients admitted to the ICU with an expected duration of ventilation for at least 24 h. We restricted participation to patients who underwent a 12-region LUS exam at baseline and had the primary endpoint (30-day mortality) available. Logistic regression was used to analyze the primary and secondary endpoints. The analysis was performed for the complete patient cohort and for predefined subgroups (ARDS and no ARDS). Results: A total of 442 patients were included, of whom 245 had a second LUS exam. The baseline LUS aeration score was not associated with mortality (1.02 (95% CI: 0.99 – 1.06), p = 0.143). This finding was not different in patients with and in patients without ARDS. Early deterioration of the LUS score was associated with mortality (2.09 (95% CI: 1.01 – 4.3), p = 0.046) in patients without ARDS, but not in patients with ARDS or in the complete patient cohort. Conclusion: In this cohort of critically ill invasively ventilated patients, the baseline LUS aeration score was not associated with 30- and 90-day mortality. An early change in the LUS aeration score was associated with mortality, but only in patients without ARDS. Trial registration: ClinicalTrials.gov, ID NCT04482621
    corecore