La sélection du taux de transmission des parasites par l'absence périodique de l'hôte

traduction en françaisTaduction française de l'aticle paru dans la revue Evolutionary Ecology (DOI 10.1007/s10682-010-9387-0 )In diesem Artikel wird die Auswirkung der periodischen Abwesenheit der Wirtspflanze auf die Entwicklung der Übertragungsraten von Pathogenen unter Verwendung von Maximierungstechniken von R0 untersucht. Die physiologische Folge einer erhöhten Übertragungsrate kann entweder eine erhöhte Virulenz sein (Kompromiss zwischen Übertragung und Virulenz) oder ein verringertes Überleben zwischen den Jahreszeiten (Kompromiss zwischen Übertragung und Überleben). Die Ergebnisse zeigen, dass der Typ des Kompromisses die Richtung der Auswahl bestimmt. Mit einem Kompromiss zwischen Übertragung und Virulenz wählen längere Abwesenheitszeiten vom Host die höheren Übertragungsraten aus. Mit einem Kompromiss zwischen Übertragung und Überleben zwischen den Jahreszeiten werden aber schwächere Übertragungsraten ausgewählt. Die Tatsache, dass für den Kompromiss zwischen Übertragung und Virulenz die beiden Kompromissparameter während der Anwesenheit der Wirtpflanze auftreten, während für den Kompromiss zwischen Übertragung und Überleben einer während der Anwesenheit der Wirtpflanze (Übertragung) und das andere (Überleben) während der Abwesenheit der Wirtpflanze ist die Hauptursache für diesen Unterschied in der Richtung der Selektion. Außerdem scheint die Abwesenheitszeit der Wirtpflanze der bestimmende Faktor für die Übertragungsrate des Erregers zu sein. Ein Vergleich von pflanzenpathologischen Systemen mit kontrastierenden biologischen Merkmalen zeigt, dass Pflanzenpathogene in der Luft bei längerer Abwesenheit vom Wirt anders reagieren als bodengetragene Pflanzenpathogene.Cet article explore l'effet de l'absence périodique de l'hôte sur l'évolution des taux de transmission des agents pathogènes en utilisant des techniques de maximisation de R0. La conséquence physiologique d'un taux de transmission accru peut être soit une virulence accrue (compromis entre transmission et virulence), soit une réduction de la survie entre les saisons (compromis entre transmission et survie). Les résultats révèlent que le type de compromis détermine la direction de la sélection, avec des périodes plus longues d'absence de l'hôte qui sélectionnent des taux de transmission plus élevés avec un compromis entre la transmission et la virulence, mais des taux de transmission plus faibles avec un compromis entre la transmission et la survie entre les saisons. Le fait que, pour le compromis entre transmission et virulence, les deux paramètres de compromis interviennent pendant la présence de l'hôte, alors que pour le compromis transmission-survie, l'un opère pendant la présence de l'hôte (transmission) et l'autre (survie) pendant la période d'absence de l'hôte, est la principale cause de cette différence dans le sens de la sélection. De plus, la période d'absence de l'hôte semble être le facteur déterminant du taux de transmission du pathogène. La comparaison de systèmes phytopathologiques qui présentent des caractéristiques biologiques contrastées suggère que les agents pathogènes des plantes présents dans l'air réagissent différemment à des périodes d'absence plus longues de l'hôte que les agents pathogènes des plantes transmis par le sol

Comparative interactomics analysis of different ALS-associated proteins identifies converging molecular pathways

Amyotrophic lateral sclerosis (ALS) is a devastating neurological disease with no effective treatment available. An increasing number of genetic causes of ALS are being identified, but how these genetic defects lead to motor neuron degeneration and to which extent they affect common cellular pathways remains incompletely understood. To address these questions, we performed an interactomic analysis to identify binding partners of wild-type (WT) and ALS-associated mutant versions of ATXN2, C9orf72, FUS, OPTN, TDP-43 and UBQLN2 in neuronal cells. This analysis identified several known but also many novel binding partners of these proteins

Impaired dendritic cell proinflammatory cytokine production in psoriatic arthritis

Item does not contain fulltextOBJECTIVE: The pathogenesis of psoriatic arthritis (PsA) remains poorly understood. The underlying chronic inflammatory immune response is thought to be triggered by unknown environmental factors potentially arising from a defective immune function. We undertook this study to determine whether an impaired acute inflammatory response by dendritic cells (DCs) might compromise the clearance of bacteria and predispose to chronic inflammation. METHODS: We determined cytokine production by DCs from healthy controls and from patients with rheumatoid arthritis, PsA, and psoriasis in response to Mycobacterium tuberculosis, Mycobacterium avium paratuberculosis, and a range of other bacteria and Toll-like receptor (TLR) ligands. Phenotypic differences involved in cellular responses against (myco)bacteria were determined by quantitative polymerase chain reaction and flow cytometry. RESULTS: The secretion of proinflammatory cytokines by PsA DCs was impaired upon in vitro challenge with mycobacteria and TLR-2 ligands. This impairment was associated with elevated serum levels of C-reactive protein. The expression of TLR-2 and other receptors known to mediate mycobacterial recognition was unaltered. In contrast, the intracellular TLR inhibitors suppressor of cytokine signaling 3 and A20 were more highly expressed in DCs from PsA patients. PsA DCs further demonstrated up-regulated levels of ATG16L1, NADPH oxidase 2, and LL37, which are molecules implicated in the immune response against intracellular bacteria. CONCLUSION: Our findings indicate that DCs from PsA patients have a disordered immune response toward some species of (myco)bacteria. This might predispose to impaired immune responses to, and in turn impaired clearance of, these bacteria, setting the stage for the chronic inflammation of joints, entheses, skin, and the gut

Late reproduction is associated with extended female survival but not with familial longevity

Research question: Are age at last childbirth and number of children, as facets of female reproductive health, related to individual lifespan or familial longevity? Design: This observational study included 10,255 female participants from a multigenerational historical cohort, the LINKing System for historical family reconstruction (LINKS), and 1258 female participants from 651 long-lived families in the Leiden Longevity Study (LLS). Age at last childbirth and number of children, as outcomes of reproductive success, were compared with individual and familial longevity using the LINKS dataset. In addition, the genetic predisposition in the form of a polygenic risk score (PRS) for age at menopause was studied in relation to familial longevity using the LLS dataset. Results: For each year increase in the age of the birth of the last child, a woman's lifespan increased by 0.06 years (22 days; P = 0.002). The yearly risk for having a last child was 9% lower in women who survived to the oldest 10% of their birth cohort (hazard ratio 0.91, 95% CI 0.86–0.95). Women who came from long-living families did not have a higher mean age of last childbirth. There was no significant association between familial longevity and genetic predisposition to age at menopause. Conclusions: Female reproductive health associates with a longer lifespan. Familial longevity does not associate to extended reproductive health. Other factors in somatic maintenance that support a longer lifespan are likely to have an impact on reproductive health

The Coarse-Grained Plaque: A Divergent Aβ Plaque-Type in Early-Onset Alzheimer’s Disease

Alzheimer’s disease (AD) is characterized by amyloid-beta (Aβ) deposits, which come in myriad morphologies with varying clinical relevance. Previously, we observed an atypical Aβ deposit, referred to as the coarse-grained plaque. In this study, we evaluate the plaque’s association with clinical disease and perform in-depth immunohistochemical and morphological characterization. The coarse-grained plaque, a relatively large (Ø ≈ 80 µm) deposit, characterized as having multiple cores and Aβ-devoid pores, was prominent in the neocortex. The plaque was semi-quantitatively scored in the middle frontal gyrus of Aβ-positive cases (n = 74), including non-demented cases (n = 15), early-onset (EO)AD (n = 38), and late-onset (LO)AD cases (n = 21). The coarse-grained plaque was only observed in cases with clinical dementia and more frequently present in EOAD compared to LOAD. This plaque was associated with a homozygous APOE ε4 status and cerebral amyloid angiopathy (CAA). In-depth characterization was done by studying the coarse-grained plaque’s neuritic component (pTau, APP, PrPC), Aβ isoform composition (Aβ40, Aβ42, AβN3pE, pSer8Aβ), its neuroinflammatory component (C4b, CD68, MHC-II, GFAP), and its vascular attribution (laminin, collagen IV, norrin). The plaque was compared to the classic cored plaque, cotton wool plaque, and CAA. Similar to CAA but different from classic cored plaques, the coarse-grained plaque was predominantly composed of Aβ40. Furthermore, the coarse-grained plaque was distinctly associated with both intense neuroinflammation and vascular (capillary) pathology. Confocal laser scanning microscopy (CLSM) and 3D analysis revealed for most coarse-grained plaques a particular Aβ40 shell structure and a direct relation with vessels. Based on its morphological and biochemical characteristics, we conclude that the coarse-grained plaque is a divergent Aβ plaque-type associated with EOAD. Differences in Aβ processing and aggregation, neuroinflammatory response, and vascular clearance may presumably underlie the difference between coarse-grained plaques and other Aβ deposits. Disentangling specific Aβ deposits between AD subgroups may be important in the search for disease-mechanistic-based therapies

False negative NIPT results: Risk figures for chromosomes 13,18 and 21 based on chorionic villi results in 5967 cases and literature review

Non-invasive prenatal testing (NIPT) demonstrated a small chance for a false negative result. Since the "fetal" DNA in maternal blood originates from the cytotrophoblast of chorionic villi (CV), some false negative results will have a biological origin. Based on our experience with cytogenetic studies of CV, we tried to estimate this risk. 5967 CV samples of pregnancies at high risk for common aneuplodies were cytogenetically investigated in our centre between January 2000 and December 2011. All cases of fetal trisomy 13,18 and 21 were retrospectively studied for the presence of a normal karyotype or mosaicism < 30% in short-term cultured (STC-) villi. 404 cases of trisomies 13,18 and 21 were found amongst 5967 samples (6,8%). Of these 404 cases, 14 (3,7%) had a normal or low mosaic karyotype in STC-villi and therefore would potentially be missed with NIPT. It involved 2% (5/242) of all trisomy 21 cases and 7.3% (9/123) of all trisomy 18 cases. In 1:426 (14/5967) NIPT samples of patients at high risk for common aneuploidies, a trisomy 18 or 21 will potentially be missed due to the biological phenomenon of absence of the chromosome aberration in the cytotrophoblast

Theory- and evidence-based best practices for physical activity counseling for adults with spinal cord injury

This project used a systematic and integrated knowledge translation (IKT) approach to co-create theory- and evidence-based best practices for physical activity counseling for adults with spinal cord injury (SCI). Guided by the IKT Guiding Principles, we meaningfully engaged research users throughout this project. A systematic approach was used. An international, multidisciplinary expert panel (n = 15), including SCI researchers, counselors, and people with SCI, was established. Panel members participated in two online meetings to discuss the best practices by drawing upon new knowledge regarding counselor-client interactions, current evidence, and members’ own experiences. We used concepts from key literature on SCI-specific physical activity counseling and health behavior change theories. An external group of experts completed an online survey to test the clarity, usability and appropriateness of the best practices. The best practices document includes an introduction, the best practices, things to keep in mind, and a glossary. Best practices focused on how to deliver a conversation and what to discuss during a conversation. Examples include: build rapport, use a client-centred approach following the spirit of motivational interviewing, understand your client’s physical activity barriers, and share the SCI physical activity guidelines. External experts (n = 25) rated the best practices on average as clear, useful, and appropriate. We present the first systematically co-developed theory- and evidence-based best practices for SCI physical activity counseling. The implementation of the best practices will be supported by developing training modules. These new best practices can contribute to optimizing SCI physical activity counseling services across settings.</p

Comparative interactomics analysis of different ALS-associated proteins identifies converging molecular pathways

Amyotrophic lateral sclerosis (ALS) is a devastating neurological disease with no effective treatment available. An increasing number of genetic causes of ALS are being identified, but how these genetic defects lead to motor neuron degeneration and to which extent they affect common cellular pathways remains incompletely understood. To address these questions, we performed an interactomic analysis to identify binding partners of wild-type (WT) and ALS-associated mutant versions of ATXN2, C9orf72, FUS, OPTN, TDP-43 and UBQLN2 in neuronal cells. This analysis identified several known but also many novel binding partners of these proteins. Interactomes of WT and mutant ALS proteins were very similar except for OPTN and UBQLN2, in which mutations caused loss or gain of protein interactions. Several of the identified interactomes showed a high degree of overlap: shared binding partners of ATXN2, FUS and TDP-43 had roles in RNA metabolism; OPTN- and UBQLN2-interacting proteins were related to protein degradation and protein transport, and C9orf72 interactors function in mitochondria. To conf

The co-development and evaluation of an e-learning course on spinal cord injury physical activity counselling:a randomized controlled trial

Background: Health, fitness and lifestyle professionals can play important roles in promoting physical activity in groups at risk of developing an inactive lifestyle, such as people with spinal cord injury (SCI). Tailored counselling is a promising tool to promote and improve physical activity levels. To support professionals to effectively have a conversation about physical activity with clients with SCI, evidence-based training and resources are needed. This project aimed to (1) co-develop an e-learning course on best practices for SCI physical activity counselling and, (2) examine the effectiveness and usability of this course. Methods: Guided by the technology-enhanced learning (TEL) evaluation framework, we used a systematic, multistep approach to co-develop and evaluate an e-learning course. The development process was informed by input and feedback from a diverse group of end-users and experts (n &gt; 160) via online surveys and (think-aloud) interviews. A randomized controlled trial was used to compare learning outcomes (post-knowledge and self-efficacy) between participants who completed the course (intervention group) and the wait-listed control group. Usability, learning experiences, and satisfaction were assessed among all participants. Results: Forty-one participants (21 intervention-group; 20 control-group) with various backgrounds (e.g., lifestyle counsellors, physiotherapists, occupational therapists, recreation therapists, fitness trainers) enrolled in the randomized controlled trial. After completing the course, participants in the intervention group showed significantly improved knowledge on the best practices for SCI physical activity counselling and higher self-efficacy for using these best practices in conversations with clients with SCI compared to the control group (p &lt;.001). Participants reported above average usability scores, positive learning experiences, and high levels of satisfaction when completing the course. Conclusion: We used a systematic, multi-step, theory-informed approach to co-develop and evaluate an evidence-based e-learning course on SCI physical activity counselling to support professionals to promote physical activity in their daily practices. The overall positive findings demonstrate that the e-learning course is feasible and ready for further implementation in various health and community settings. Implementation of the e-learning course can help professionals improve the physical activity support they provide to their clients, and subsequently increase physical activity participation in people with SCI.</p

A simplified protocol for the generation of cortical brain organoids

Human brain organoid technology has the potential to generate unprecedented insight into normal and aberrant brain development. It opens up a developmental time window in which the effects of gene or environmental perturbations can be experimentally tested. However, detection sensitivity and correct interpretation of phenotypes are hampered by notable batch-to-batch variability and low reproducibility of cell and regional identities. Here, we describe a detailed, simplified protocol for the robust and reproducible generation of brain organoids with cortical identity from feeder-independent induced pluripotent stem cells (iPSCs). This self-patterning approach minimizes media supplements and handling steps, resulting in cortical brain organoids that can be maintained over prolonged periods and that contain radial glial and intermediate progenitors, deep and upper layer neurons, and astrocytes