Uncoupling Between Dinitrogen Fixation and Primary Productivity in the Eastern Mediterranean Sea

In the nitrogen (N)-impoverished photic zones of many oceanic regions, prokaryotic organisms fixing atmospheric dinitrogen (N2; diazotrophs) supply an essential source of new nitrogen and fuel primary production. We measured dinitrogen fixation and primary productivity (PP) during the thermally stratified summer period in different water regimes of the oligotrophic eastern Mediterranean Sea, including the Cyprus Eddy and the Rhodes Gyre. Low N2 fixation rates were measured (0.8-3.2μmol N m-2 d-1) excluding 10-fold higher rates in the Rhodes Gyre and Cyprus Eddy (~20μmol N m-2 d-1). The corresponding PP increased from east to west (200-2500μmol C m-2 d-1), with relatively higher productivity recorded in the Rhodes Gyre and Cyprus Eddy (2150 and 2300μmol C m-2 d-1, respectively). These measurements demonstrate that N2 fixation in the photic zone of the eastern Mediterranean Sea contributes only negligibly by direct inputs to PP (i.e., cyanobacterial diazotrophs) and is in fact uncoupled from PP. By contrast, N2 fixation is significantly coupled to bacterial productivity and to net heterotrophic areas, suggesting that heterotrophic N2 fixation may in fact be significant in this ultraoligotrophic system. This is further substantiated by the high N2 fixation rates we measured from aphotic depths and by the results of phylogenetic analysis in other studies showing an abundance of heterotrophic diazotrophs

A Case of Acute Disseminated Encephalomyelitis in a MIddle-Aged Adult

BACKGROUND Acute disseminated encephalomyelitis (ADEM) is a monophasic inflammatory demyelinating disorder of the white matter that is often preceded by viral infection or recent vaccination. Encephalopathy and focal neurological deficits usually manifest one to three weeks after a prodromal illness with neurologic decline progressing rapidly over days to weeks. Approximately 25% of patients will develop multiple sclerosis (MS) within five years of initial presentation of ADEM but the majority of individuals do not progress beyond three months.4 ADEM is most commonly seen in children and young adults, where prognosis is favorable, but very few cases have been reported of middle-aged or elderly patients. The clinical course of these patients as compared to younger patients with ADEM is unclear. Here we present a case of ADEM in a middle-aged adult that recovered well after treatment with high-dose corticosteroids. Pages: 15-17

Neuroplasticity in Young Age: Computer-Based Early Neurodevelopment Classifier

Neurodevelopmental syndromes, a continuously growing issue, are impairments in the growth and development of the brain and CNS which are pronounced in a variety of emotional, cognitive, motor and social skills. Early assessment and detection of typical, clinically correlated early signs of developmental abnormalities is crucial for early and effective intervention, supporting initiation of early treatment and minimizing neurological and functional deficits. Successful early interventions would then direct to early time windows of higher neural plasticity. Various syndromes are reflected in early vocal and motor characteristics, making them suitable indicators of an infant’s neural development. Performance of the computerized classifiers we developed shows approximately 90% accuracy on a database of diagnosed babies. The results demonstrate the potential of vocal and motor analysis for computer-assisted early detection of neurodevelopmental insults

Learning through the eyes of another

Over the past decade, rapid technological advancements and budget constraints have increased the de­mand for online education (Martin et al., 2020). Furthermore, the COVID-19 pandemic has vastly ac­cele­ra­ted this trend, compelling almost all education providers to migrate their courses to online learning platforms (Theelen & Van Breukelen, 2022). In view of other profound crises that affect mobility, such as climate change, political instabilities and future pandemics, it is safe to assume that online learning will remain in demand, even in a post-pandemic world ) (Bayne et al., 2020). In this context, while educational research has made significant progress in establishing design principles that ensure effective online teaching and learning, the main focus of this scholarly work is on the acquisition of declarative knowledge and cognitive skills. Moreover, since very little is known about the online teaching and distance learning of psychomotor skills (Kouhia et al., 2021; Lehtiniemi et al., 2023), this paper and exhibition explore how eye-tracking technology (ETT) creates unique opportunities to improve craft education in hybrid and distant learning settings

Are online support groups always beneficial? A qualitative exploration of the empowering and disempowering processes of participation within HIV/AIDS-related online support groups

BACKGROUND: Human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) is one of the leading concerns in healthcare. Individuals living with HIV/AIDS are often confronted with tremendous physical and psychosocial challenges. Online support groups can provide a valuable source of information, advice and support, and a medium through which individuals living with HIV/AIDS can interact with each other and share their experiences. However, very little is known about how online support group might promote empowerment and the potential disadvantages associated with online support group use among individuals living with HIV/AIDS. OBJECTIVES: The present study explored the potential empowering and disempowering processes, and empowering outcomes of online support group use among individuals with HIV/AIDS. DESIGN, SETTINGS, PARTICIPANTS: A total of 115 HIV-positive online support group members were recruited from HIV-related online support groups. They completed an online survey exploring their experiences of online support group use. RESULTS: Thematic analysis revealed six empowering processes arising from use of online support groups: exchanging information, sharing experiences, connecting to others, encountering emotional support, finding recognition and understanding, and helping others. Six empowering outcomes were identified: increased optimism, emotional well-being, social well-being, being better informed, improved disease management, and feeling confident in the relationship with physicians. Potentially disempowering processes were also identified which included: being unable to connect physically, inappropriate behaviour online, declining real life relationships, and information overload and misinformation. CONCLUSION: Findings suggest ways through which individuals with HIV/AIDS may be empowered although some problematic features specific to the online context may also be present

Intercellular Transfer of Oncogenic H-Ras at the Immunological Synapse

Immune cells establish dynamic adhesive cell–cell interactions at a specific contact region, termed the immunological synapse (IS). Intriguing features of the IS are the formation of regions of plasma membrane fusion and the intercellular exchange of membrane fragments between the conjugated cells. It is not known whether upon IS formation, intact intracellular proteins can transfer from target cells to lymphocytes to allow the transmission of signals across cell boundaries. Here we show by both FACS and confocal microscopy that human lymphocytes acquire from the cells they scan the inner-membrane protein H-Ras, a G-protein vital for common lymphocyte functions and a prominent participant in human cancer. The transfer was cell contact-dependent and occurred in the context of cell-conjugate formation. Moreover, the acquisition of oncogenic H-RasG12V by natural killer (NK) and T lymphocytes had important biological functions in the adopting lymphocytes: the transferred H-RasG12V induced ERK phosphorylation, increased interferon-γ and tumor necrosis factor-α secretion, enhanced lymphocyte proliferation, and augmented NK-mediated target cell killing. Our findings reveal a novel mode of cell-to-cell communication—allowing lymphocytes to extend the confines of their own proteome—which may moreover play an important role in natural tumor immunity

A Theoretical Exploration of Birhythmicity in the p53-Mdm2 Network

Experimental observations performed in the p53-Mdm2 network, one of the key protein modules involved in the control of proliferation of abnormal cells in mammals, revealed the existence of two frequencies of oscillations of p53 and Mdm2 in irradiated cells depending on the irradiation dose. These observations raised the question of the existence of birhythmicity, i.e. the coexistence of two oscillatory regimes for the same external conditions, in the p53-Mdm2 network which would be at the origin of these two distinct frequencies. A theoretical answer has been recently suggested by Ouattara, Abou-Jaoudé and Kaufman who proposed a 3-dimensional differential model showing birhythmicity to reproduce the two frequencies experimentally observed. The aim of this work is to analyze the mechanisms at the origin of the birhythmic behavior through a theoretical analysis of this differential model. To do so, we reduced this model, in a first step, into a 3-dimensional piecewise linear differential model where the Hill functions have been approximated by step functions, and, in a second step, into a 2-dimensional piecewise linear differential model by setting one autonomous variable as a constant in each domain of the phase space. We find that two features related to the phase space structure of the system are at the origin of the birhythmic behavior: the existence of two embedded cycles in the transition graph of the reduced models; the presence of a bypass in the orbit of the large amplitude oscillatory regime of low frequency. Based on this analysis, an experimental strategy is proposed to test the existence of birhythmicity in the p53-Mdm2 network. From a methodological point of view, this approach greatly facilitates the computational analysis of complex oscillatory behavior and could represent a valuable tool to explore mathematical models of biological rhythms showing sufficiently steep nonlinearities