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25 result(s) for "Westermann, Mark"
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Early effects of erythropoietin on serum hepcidin and serum iron bioavailability in healthy volunteers
Hepcidin regulates plasma iron bioavailability and subsequently iron availability for erythropoiesis. rHuEPO has been reported to decrease hepcidin expression in case of repeated subcutaneous injections. Thus, hepcidin level measurement could be a candidate marker for detection of rHuEPO abuse. However, when used for doping, rHuEPO can be injected intravenously and the scheme of injection is unknown. Our aim was to evaluate the early effects of a single intravenous rHuEPO injection on serum hepcidin levels. Fourteen male healthy volunteers received one intravenous injection of 50 U/Kg of rHuEPO during a placebo-controlled, randomized, double-blind, cross-over study. Serum hepcidin, quantified by a competitive ELISA method and iron parameters was then evaluated for 24 h. Serum levels of hepcidin were significantly increased 4 h after rHuEPO injection when compared with placebo injection (78.3 ± 55.5 vs. 57.5 ± 34.6 ng/ml, respectively; +36%, p  < 0.05), whereas iron and transferrin saturation dramatically decreased 12 h after rHuEPO injection when compared with placebo injection (9.2 ± 3.5 vs. 15.8 ± 4.2 μg/l, respectively; −42%, p  < 0.05 and 14.8 ± 5.0 vs. 26.3 ± 6.4%, respectively; −44%, p  < 0.05). In addition, 12 and 24 h after rHuEPO injection serum hepcidin levels were lower compared with placebo injection (41.6 ± 27.4 vs. 56.6 ± 28.1 ng/ml after 12 h; −27%, p  < 0.05 and 26.0 ± 29.6 vs. 81.2 ± 29.4 ng/ml after 24 h; −68%, p  < 0.05). Intravenous injection of recombinant EPO induces a precocious and transient increase of serum hepcidin leading to a transient decrease of iron bioavailability. The transitory increase and dynamics of its concentration make difficult the practical use of hepcidin to detect rHuEPO doping.
Keeping Candida commensal: how lactobacilli antagonize pathogenicity of Candida albicans in an in vitro gut model
The intestine is the primary reservoir of Candida albicans that can cause systemic infections in immunocompromised patients. In this reservoir, the fungus exists as a harmless commensal. However, antibiotic treatment can disturb the bacterial microbiota, facilitating fungal overgrowth and favoring pathogenicity. The current in vitro gut models that are used to study the pathogenesis of C. albicans investigate the state in which C. albicans behaves as a pathogen rather than as a commensal. We present a novel in vitro gut model in which the fungal pathogenicity is reduced to a minimum by increasing the biological complexity. In this model, enterocytes represent the epithelial barrier and goblet cells limit C. albicans adhesion and invasion. Significant protection against C. albicans-induced necrotic damage was achieved by the introduction of a microbiota of antagonistic lactobacilli. We demonstrated a time-, dose- and species-dependent protective effect against C. albicans-induced cytotoxicity. This required bacterial growth, which relied on the presence of host cells, but was not dependent on the competition for adhesion sites. Lactobacillus rhamnosus reduced hyphal elongation, a key virulence attribute. Furthermore, bacterial-driven shedding of hyphae from the epithelial surface, associated with apoptotic epithelial cells, was identified as a main and novel mechanism of damage protection. However, host cell apoptosis was not the driving mechanism behind shedding. Collectively, we established an in vitro gut model that can be used to experimentally dissect commensal-like interactions of C. albicans with a bacterial microbiota and the host epithelial barrier. We also discovered fungal shedding as a novel mechanism by which bacteria contribute to the protection of epithelial surfaces. This article has an associated First Person interview with the joint first authors of the paper.
Clinical chemistry score versus high-sensitivity cardiac troponin I and T tests alone to identify patients at low or high risk for myocardial infarction or death at presentation to the emergency department
Testing for high-sensitivity cardiac troponin (hs-cTn) may assist triage and clinical decision-making in patients presenting to the emergency department with symptoms of acute coronary syndrome; however, this could result in the misclassification of risk because of analytical variation or laboratory error. We sought to evaluate a new laboratory-based risk-stratification tool that incorporates tests for hs-cTn, glucose level and estimated glomerular filtration rate to identify patients at risk of myocardial infarction or death when presenting to the emergency department. We constructed the clinical chemistry score (CCS) (range 0–5 points) and validated it as a predictor of 30-day myocardial infarction (MI) or death using data from 4 cohort studies involving patients who presented to the emergency department with symptoms suggestive of acute coronary syndrome. We calculated diagnostic parameters for the CCS score separately using high-sensitivity cardiac troponin I (hs-cTnI) and high-sensitivity cardiac troponin T (hs-cTnT). For the combined cohorts (n = 4245), 17.1% of participants had an MI or died within 30 days. A CCS score of 0 points best identified low-risk participants: the hs-cTnI CCS had a sensitivity of 100% (95% confidence interval [CI] 99.5%–100%), with 8.9% (95% CI 8.1%–9.8%) of the population classified as being at low risk of MI or death within 30 days; the hs-cTnT CCS had a sensitivity of 99.9% (95% CI 99.2%–100%), with 10.5% (95% CI 9.6%–11.4%) of the population classified as being at low risk. The CCS had better sensitivity than hs-cTn alone (hs-cTnI < 5 ng/L: 96.6%, 95% CI 95.0%–97.8%; hs-cTnT < 6 ng/L: 98.2%, 95% CI 97.0%–99.0%). A CCS score of 5 points best identified patients at high risk (hs-cTnI CCS: specificity 96.6%, 95% CI 96.0%–97.2%; 11.2% [95% CI 10.3%–12.2%] of the population classified as being at high risk; hs-cTnT CCS: specificity 94.0%, 95% CI 93.1%–94.7%; 13.1% [95% CI 12.1%–14.1%] of the population classified as being at high risk) compared with using the overall 99th percentiles for the hs-cTn assays (specificity of hs-cTnI 93.2%, 95% CI 92.3–94.0; specificity of hs-cTnT 73.8%, 95% CI 72.3–75.2). The CCS score at the chosen cut-offs was more sensitive and specific than hs-cTn alone for risk stratification of patients presenting to the emergency department with suspected acute coronary syndrome. Study registration: ClinicalTrials.gov, nos. NCT01994577; NCT02355457
Identification of flubendazole as potential anti-neuroblastoma compound in a large cell line screen
Flubendazole was shown to exert anti-leukaemia and anti-myeloma activity through inhibition of microtubule function. Here, flubendazole was tested for its effects on the viability of in total 461 cancer cell lines. Neuroblastoma was identified as highly flubendazole-sensitive cancer entity in a screen of 321 cell lines from 26 cancer entities. Flubendazole also reduced the viability of five primary neuroblastoma samples in nanomolar concentrations thought to be achievable in humans and inhibited vessel formation and neuroblastoma tumour growth in the chick chorioallantoic membrane assay. Resistance acquisition is a major problem in high-risk neuroblastoma. 119 cell lines from a panel of 140 neuroblastoma cell lines with acquired resistance to various anti-cancer drugs were sensitive to flubendazole in nanomolar concentrations. Tubulin-binding agent-resistant cell lines displayed the highest flubendazole IC 50 and IC 90 values but differences between drug classes did not reach statistical significance. Flubendazole induced p53-mediated apoptosis. The siRNA-mediated depletion of the p53 targets p21, BAX, or PUMA reduced the neuroblastoma cell sensitivity to flubendazole with PUMA depletion resulting in the most pronounced effects. The MDM2 inhibitor and p53 activator nutlin-3 increased flubendazole efficacy while RNAi-mediated p53-depletion reduced its activity. In conclusion, flubendazole represents a potential treatment option for neuroblastoma including therapy-refractory cells.
Management of different cardiovascular risk factors with a combination tablet (polypill)
The multifactorial origin of cardiovascular diseases has led to polypharmacy in primary and secondary prophylaxis with evidence-based medications, such as statins, antihypertensive drugs and platelet aggregation inhibitors. The number of prescribed drugs correlates inversely to adherence and can lead to treatment failure. Fixed-dose combination drugs (polypills) could increase the medication adherence of patients, reduce risks and prevent cardiovascular events. This review is based on publications that were retrieved from Medline (via PubMed) and The Cochrane Library. The clinical database ClinicalTrials.gov. was also considered. In the studies on primary prevention conducted to date, fixed-dose combinations showed a superior control of risk factors, e.g. hypertension and low-density lipoprotein (LDL) cholesterol compared to placebo and at least non-inferiority compared to usual care. In secondary prevention, the effect of the polypill is mostly on the reduction of blood pressure and LDL cholesterol in non-adherent patients; however, evidence that fixed-drug combinations reduce cardiovascular morbidity and mortality compared to standard therapy is lacking. The polypill can be considered as an alternative to polypharmacy after a risk-benefit assessment, especially in non-adherent patients. Ongoing studies are investigating the effect of the polypill on cardiovascular events. Current polypills are limited by the lack of sufficient dosages of the individual components to avoid overtreatment and undertreatment at the individual treatment level.
Testing of the Survivin Suppressant YM155 in a Large Panel of Drug-Resistant Neuroblastoma Cell Lines
The survivin suppressant YM155 is a drug candidate for neuroblastoma. Here, we tested YM155 in 101 neuroblastoma cell lines (19 parental cell lines, 82 drug-adapted sublines). Seventy seven (77) cell lines displayed YM155 IC50s in the range of clinical YM155 concentrations. ABCB1 was an important determinant of YM155 resistance. The activity of the ABCB1 inhibitor zosuquidar ranged from being similar to that of the structurally different ABCB1 inhibitor verapamil to being 65-fold higher. ABCB1 sequence variations may be responsible for this, suggesting that the design of variant-specific ABCB1 inhibitors may be possible. Further, we showed that ABCC1 confers YM155 resistance. Previously, p53 depletion had resulted in decreased YM155 sensitivity. However, TP53-mutant cells were not generally less sensitive to YM155 than TP53 wild-type cells in this study. Finally, YM155 cross-resistance profiles differed between cells adapted to drugs as similar as cisplatin and carboplatin. In conclusion, the large cell line panel was necessary to reveal an unanticipated complexity of the YM155 response in neuroblastoma cell lines with acquired drug resistance. Novel findings include that ABCC1 mediates YM155 resistance and that YM155 cross-resistance profiles differ between cell lines adapted to drugs as similar as cisplatin and carboplatin.
Précis of Neuroconstructivism: How the Brain Constructs Cognition
Neuroconstructivism: How the Brain Constructs Cognition proposes a unifying framework for the study of cognitive development that brings together (1) constructivism (which views development as the progressive elaboration of increasingly complex structures), (2) cognitive neuroscience (which aims to understand the neural mechanisms underlying behavior), and (3) computational modeling (which proposes formal and explicit specifications of information processing). The guiding principle of our approach is context dependence, within and (in contrast to Marr [1982]) between levels of organization. We propose that three mechanisms guide the emergence of representations: competition, cooperation, and chronotopy; which themselves allow for two central processes: proactivity and progressive specialization. We suggest that the main outcome of development is partial representations, distributed across distinct functional circuits. This framework is derived by examining development at the level of single neurons, brain systems, and whole organisms. We use the terms encellment, embrainment, and embodiment to describe the higher-level contextual influences that act at each of these levels of organization. To illustrate these mechanisms in operation we provide case studies in early visual perception, infant habituation, phonological development, and object representations in infancy. Three further case studies are concerned with interactions between levels of explanation: social development, atypical development and within that, developmental dyslexia. We conclude that cognitive development arises from a dynamic, contextual change in embodied neural structures leading to partial representations across multiple brain regions and timescales, in response to proactively specified physical and social environment.
Management verschiedener kardiovaskulärer Risikofaktoren mit einem Kombinationspräparat („Polypill“)
Zusammenfassung Hintergrund Die multifaktorielle Genese kardiovaskulärer Erkrankungen hat in der Primär- und Sekundärprophylaxe zur Polypharmazie mit evidenzbasierten Therapeutika wie Statinen, Antihypertensiva und Thrombozytenhemmern geführt. Die Anzahl verschriebener Phamaka korreliert umgekehrt mit der Adhärenz, was die Effektivität der Therapie beeinträchtigen kann. Fixe Kombinationspräparate („Polypill“) könnten die Adhärenz der Patienten steigern und damit kardiovaskulären Ereignissen vorbeugen. Methoden Literaturrecherche in Medline (via PubMed) und The Cochrane Library sowie der Studiendatenbank ClinicalTrials.gov. Ergebnisse In den bisher durchgeführten Studien zur kardiovaskulären Primärprävention zeigt die Polypill eine überlegene Kontrolle der Risikofaktoren (Hypertonie, „Low-density-lipoprotein“-Cholesterin [LDL-C]) gegenüber Placebo und gegenüber einer Standardtherapie aus Einzelpräparaten mindestens eine Nichtunterlegenheit. In der Sekundärprävention zeigen Kombinationspräparate vorwiegend Vorteile bei nichtadhärenten Patienten bezüglich Blutdruckkontrolle und Reduktion der LDL-C-Konzentration. Der Nachweis, dass die Polypill die kardiovaskuläre Morbidität und Mortalität gegenüber einer Standardtherapie absenkt, steht aus. Schlussfolgerung Kombinationspräparate sind nach Risiko-Nutzen-Einschätzung als Alternative zur Polypharmazie, insbesondere bei nichtadhärenten Patienten in Erwägung zu ziehen. Inwieweit durch die erwiesene Senkung der Risikofaktoren kardiovaskuläre Ereignisse verhindert werden können, ist Gegenstand laufender Untersuchungen. Limitiert sind die gegenwärtigen Polypills durch eine zu geringe Auswahl an Dosierungen der Einzelwirkstoffe, um eine Über- und Untertherapie in der individuellen Behandlung zu vermeiden.
Studying development in the 21 st Century
In this response, we consider four main issues arising from the commentaries to the target article. These include further details of the theory of interactive specialization, the relationship between neuroconstructivism and selectionism, the implications of neuroconstructivism for the notion of representation, and the role of genetics in theories of development. We conclude by stressing the importance of multidisciplinary approaches in the future study of cognitive development and by identifying the directions in which neuroconstructivism can expand in the Twenty-first Century.
Studying development in the 21st Century
In this response, we consider four main issues arising from the commentaries to the target article. These include further details of the theory of interactive specialization, the relationship between neuroconstructivism and selectionism, the implications of neuroconstructivism for the notion of representation, and the role of genetics in theories of development. We conclude by stressing the importance of multidisciplinary approaches in the future study of cognitive development and by identifying the directions in which neuroconstructivism can expand in the Twenty-first Century.