An Arctic strait of two halves: The changing dynamics of nutrient uptake and limitation across the Fram Strait

The hydrography of the Arctic Seas is being altered by ongoing climate change, with knock-on effects to nutrient dynamics and primary production. As the major pathway of exchange between the Arctic and the Atlantic, the Fram Strait hosts two distinct water masses in the upper water column, northward flowing warm and saline Atlantic Waters in the east, and southward flowing cold and fresh Polar Surface Water in the west. Here, we assess how physical processes control nutrient dynamics in the Fram Strait using nitrogen isotope data collected during 2016 and 2018. In Atlantic Waters, a weakly stratified water column and a shallow nitracline reduce nitrogen limitation. To the west, in Polar Surface Water, nitrogen limitation is greater because stronger stratification inhibits nutrient resupply from deeper water and lateral nitrate supply from central Arctic waters is low. A historical hindcast simulation of ocean biogeochemistry from 1970 to 2019 corroborates these findings and highlights a strong link between nitrate supply to Atlantic Waters and the depth of winter mixing, which shoaled during the simulation in response to a local reduction in sea-ice formation. Overall, we find that while the eastern Fram Strait currently experiences seasonal nutrient replenishment and high primary production, the loss of winter sea ice and continued atmospheric warming has the potential to inhibit deep winter mixing and limit primary production in the future

Myasthenia gravis: Opportunistische Zytomegalievirus-Infektion nach langzeitiger Azathioprin-Therapie [Myasthenia gravis. Opportunistic cytomegalovirus infection after long-term azathioprine therapy]

Opportunistic infections after long-term treatment with azathioprine (AZA) have not been noted in patients with myasthenia gravis (MG). We report on a 56-year-old woman with generalized MG who presented with cytomegalovirus infection after being treated with AZA for 17 years. The indication for immunosuppressive treatment in MG should be regularly reconfirmed, particularly since at least 50% of patients can discontinue AZA after two to four years without risk of exacerbation

Chronische HIV- und chronische HBV-Infektion mit Erythrozyturie und Proteinurie

A medical examination, undertaken in an apparently healthy 30-year-old man because of his occupational exposure to chemicals, revealed haematuria and proteinuria. Physical examination was unremarkable except for oral hair-leukoplakia and swelling of the cervical, supraclavicular, axillary and inguinal lymph nodes. Examination of the urine demonstrated selective glomerular proteins (1.5 g/24 h) and dysmorphic erythrocytes. SGOT and SGPT activities were raised (73 and 129 IU/l, respectively). Active hepatitis B virus (HBV) and human immunodeficiency virus (HIV-1) infections were demonstrated virologically. The CD4+ count in blood was reduced to 200 cells/microliter. Renal biopsy showed an IgA nephropathy. Antiretroviral treatment with zidovudine and lamivudine were started. SGOT and SGPT activities and HIV load fell steadily, while CD4+ cell count rose markedly. Renal functions have remained stable during the past 6 months. Signs of glomerular damage are not unusual in systemic diseases, tumors or infections (Hepatitis B and HIV in this case) and they may be the first manifestations of the underlying diseas

Bewertung des ärztlichen Handels anhand virtueller Patienten

Background: The aim of this project is to simulate the complexity of typical medical situations in a computer programme and to base assessment scores on the chosen diagnostic and therapeutic approach.Methods: This online assessment tool is based on the virtual poly clinic "docs 'n drugs", a web-based training programme developed in Ulm. A clinical scenario is described and the student - in the role of the doctor - has to diagnose and treat a virtual patient. By the use of a rating editor the examiner categorizes possible actions whereby alternative and more complex pathways may also be considered. In this study the assessment tool is evaluated on 140 students solving three typical General Practice scenarios.Results so far: There is emerging evidence that it is possible to translate the chosen diagnostic approach into valid assessment scores and that this examination format is accepted by students.Outlook: This assessment tool seems to make medical thinking, i.e. the approach to a clinical problem, appraisable.Hintergrund: Ziel dieses Projektes ist es, die für das ärztliche Handeln typischen komplexen Entscheidungssituationen und -wege in Diagnostik und Therapie in elektronischer Form darzustellen und Lösungswege bewertbar zu machen.Methode: Basierend auf dem Ulmer e-learning-Programm "Docs 'n Drugs" wurde ein Prüfungstool entwickelt, in dem der Prüfling in der Rolle des Arztes einen virtuellen Patienten untersuchen und behandeln muss. Mit dem Bewertungseditor kategorisiert der Prüfende die möglichen Handlungsschritte, wobei auch alternative Lösungswege berücksichtigt werden. Die Evaluation dieses Prüfungstool erfolgt in einer Studie mit 140 Studierenden anhand von drei allgemeinmedizinischen Fällen.Bisherige Ergebnisse: Es zeichnet sich ab, dass der diagnostische Lösungsweg mit dieser Methode bewertet und eine solche Prüfungsform von Studenten akzeptiert werden kann. Ausblick: Ein solches Prüfungstool scheint die ärztliche Denk- und Vorgehensweise bewertbar zu machen