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Search Results: 1 - 10 of 167428 matches for " Douwe E. Atsma "
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Human Embryonic and Fetal Mesenchymal Stem Cells Differentiate toward Three Different Cardiac Lineages in Contrast to Their Adult Counterparts
Arti A. Ramkisoensing, Dani?l A. Pijnappels, Sa?d F. A. Askar, Robert Passier, Jim Swildens, Marie José Goumans, Cindy I. Schutte, Antoine A. F. de Vries, Sicco Scherjon, Christine L. Mummery, Martin J. Schalij, Douwe E. Atsma
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024164
Abstract: Mesenchymal stem cells (MSCs) show unexplained differences in differentiation potential. In this study, differentiation of human (h) MSCs derived from embryonic, fetal and adult sources toward cardiomyocytes, endothelial and smooth muscle cells was investigated. Labeled hMSCs derived from embryonic stem cells (hESC-MSCs), fetal umbilical cord, bone marrow, amniotic membrane and adult bone marrow and adipose tissue were co-cultured with neonatal rat cardiomyocytes (nrCMCs) or cardiac fibroblasts (nrCFBs) for 10 days, and also cultured under angiogenic conditions. Cardiomyogenesis was assessed by human-specific immunocytological analysis, whole-cell current-clamp recordings, human-specific qRT-PCR and optical mapping. After co-culture with nrCMCs, significantly more hESC-MSCs than fetal hMSCs stained positive for α-actinin, whereas adult hMSCs stained negative. Furthermore, functional cardiomyogenic differentiation, based on action potential recordings, was shown to occur, but not in adult hMSCs. Of all sources, hESC-MSCs expressed most cardiac-specific genes. hESC-MSCs and fetal hMSCs contained significantly higher basal levels of connexin43 than adult hMSCs and co-culture with nrCMCs increased expression. After co-culture with nrCFBs, hESC-MSCs and fetal hMSCs did not express α-actinin and connexin43 expression was decreased. Conduction velocity (CV) in co-cultures of nrCMCs and hESC-MSCs was significantly higher than in co-cultures with fetal or adult hMSCs. In angiogenesis bioassays, only hESC-MSCs and fetal hMSCs were able to form capillary-like structures, which stained for smooth muscle and endothelial cell markers.Human embryonic and fetal MSCs differentiate toward three different cardiac lineages, in contrast to adult MSCs. Cardiomyogenesis is determined by stimuli from the cellular microenvironment, where connexin43 may play an important role.
Myocardial Structural Alteration and Systolic Dysfunction in Preclinical Hypertrophic Cardiomyopathy Mutation Carriers
Kai Hang Yiu, Douwe E. Atsma, Victoria Delgado, Arnold C. T. Ng, Tomasz G. Witkowski, See Hooi Ewe, Dominique Auger, Eduard R. Holman, Anneke M. van Mil, Martijn H. Breuning, Hung Fat Tse, Jeroen J. Bax, Martin J. Schalij, Nina Ajmone Marsan
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036115
Abstract: Background To evaluate the presence of myocardial structural alterations and subtle myocardial dysfunction during familial screening in asymptomatic mutation carriers without hypertrophic cardiomyopathy (HCM) phenotype. Methods and Findings Sixteen HCM families with pathogenic mutation were studied and 46 patients with phenotype expression (Mut+/Phen+) and 47 patients without phenotype expression (Mut+/Phen?) were observed. Twenty-five control subjects, matched with the Mut+/Phen? group, were recruited for comparison. Echocardiography was performed to evaluate conventional parameters, myocardial structural alteration by calibrated integrated backscatter (cIBS) and global and segmental longitudinal strain by speckle tracking analysis. All 3 groups had similar left ventricular dimensions and ejection fraction. Basal anteroseptal cIBS was the highest in Mut+/Phen+ patients (?14.0±4.6 dB, p<0.01) and was higher in Mut+/Phen? patients as compared to controls (?17.0±2.3 vs. ?22.6±2.9 dB, p<0.01) suggesting significant myocardial structural alterations. Global and basal anteroseptal longitudinal strains (?8.4±4.0%, p<0.01) were the most impaired in Mut+/Phen+ patients as compared to the other 2 groups. Although global longitudinal strain was similar between Mut+/Phen? group and controls, basal anteroseptal strain was lower in Mut+/Phen? patients (?14.1±3.8%, p<0.01) as compared to controls (?19.9±2.9%, p<0.01), suggesting a subclinical segmental systolic dysfunction. A combination of >?19.0 dB basal anteroseptal cIBS or >?18.0% basal anteroseptal longitudinal strain had a sensitivity of 98% and a specificity of 72% in differentiating Mut+/Phen? group from controls. Conclusion The use of cIBS and segmental longitudinal strain can differentiate HCM Mut+/Phen? patients from controls with important clinical implications for the family screening and follow-up of these patients.
Novel Approaches to Treat Experimental Pulmonary Arterial Hypertension: A Review
S. Umar,P. Steendijk,D. L. Ypey,D. E. Atsma,E. E. van der Wall,M. J. Schalij,A. van der Laarse
Journal of Biomedicine and Biotechnology , 2010, DOI: 10.1155/2010/702836
Abstract: Background. Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by an increase in pulmonary artery pressure leading to right ventricular (RV) hypertrophy, RV failure, and ultimately death. Current treatments can improve symptoms and reduce severity of the hemodynamic disorder but gradual deterioration in their condition often necessitates a lung transplant. Methods and Results. In experimental models of PAH, particularly the model of monocrotaline-induced pulmonary hypertension, efficacious treatment options tested so far include a spectrum of pharmacologic agents with actions such as anti-mitogenic, proendothelial function, proangiogenic, antiinflammatory and antioxidative. Emerging trends in PAH treatment are gene and cell therapy and their combination, like (progenitor) cells enriched with eNOS or VEGF gene. More animal data should be collected to investigate optimal cell type, in vitro cell transduction, route of administration, and number of cells to inject. Several recently discovered and experimentally tested interventions bear potential for therapeutic purposes in humans or have been shown already to be effective in PAH patients leading to improved life expectation and better quality of life. Conclusion. Since many patients remain symptomatic despite therapy, we should encourage research in animal models of PAH and implement promising treatments in homogeneous groups of PAH patients.
Think Globally Act Locally: The Case for Symphysiotomy
Douwe Arie Anne Verkuyl
PLOS Medicine , 2007, DOI: 10.1371/journal.pmed.0040071
Abstract: When expatriate doctors from developed countries working in sub-Saharan Africa suggest to the local doctors and midwives that symphysiotomies should sometimes be done, they are silenced neither with quotations from the medical literature nor with tales of patients seen, but with: “If symphysiotomies are such good operations why don't you perform them at home?” Here is why.
Equality and Diversity in the Dutch Welfare State
van Houten, Douwe
Social Work and Society , 2007,
Abstract: Under the Constitution, the equality principle is very important in the Netherlands. This article argues that there is little evidence for equal citizenship in the Netherlands. There is anti-discrimination legislation in the Netherlands, but it is not very robust. The core argument in this article is that the equality principle must be supplemented by the diversity principle. Diversity is multi-dimensional and can refer to religion, philosophy of life, political persuasion, race (ethnicity), gender, nationality, sexual orientation, age, disability and chronic illness. In this paper multi-culturalism and disability are taken into account and we make a comparison of the social position of disabled people and people from ethnic minorities. Policies on diversity are needed to arrive at diverse citizenship in a varied society. This implies that a distinction has to be made between political citizenship and cultural citizenship. The former has to do with equality, and the latter with diversity.
Professionalisering en arbeidsdeling
Douwe van Houten
Journal of Social Intervention : Theory and Practice , 2008,
Abstract: Professionalism refers to a social division of labour (Emile Durkheim), but is confronted with the logic of markets and managerialism that disturbs the logic of professionalism. Markets and management have to do with a technical division of labour (Adam Smith) to optimize profits in a capitalist economy. The last 25 years professionals in the field of welfare and health are confronted with both forms of division of labour and their corresponding logics. What are the implications of this double logic for professional practices? The argument is that the logic of market and management and the logic of professionalism in theory can not be combined, but in practice occur both anyway. We have to deal with a policy paradox with two contrasting principles. For professionals the logic of professionalism, with its own morality, is decisive. The moral basis of professional work is connected with the ethics of care in which attentiveness is an important moral dimension. Since managers can not observe professionals at work, they can not force them to actually give priority to the principles underlying the market logic. They can try to regulate their work but can not, fortunatenately the athor thinks, induce the primacy of the market logic.
Kritische interventiestudies – Essay
Douwe van Houten
Journal of Social Intervention : Theory and Practice , 2008,
Abstract: In this essay, a critical stance towards the study and daily practice of social intervention is advocated. According to the author, scientists as well as practitioners should stimulate and enhance (self-)criticism in the social sector. Currently, the Dutch social sector and its academic surroundings – including the journal Sociale Interventie (Social Intervention) – lack that kind of critical attitude. The English journal Critical Social Policy can serve as an example. This journal provides the opportunity for debate and critical reflection on social policy and social intervention.
Een kritiek op de Wet maatschappelijke ondersteuning - discussiebijdrage/essay
Douwe van Houten
Journal of Social Intervention : Theory and Practice , 2008,
Werken aan inclusie
Douwe van Houten
Journal of Social Intervention : Theory and Practice , 2009,
Abstract: This article elucidates the concepts of inclusion and diversity, and describes several examples of inclusive practices in Dutch society. The author explains his interpretation of diversity and combines this perspective with the concept of equality. He states that this combination is very important in an inclusive society. He concludes by sketching some general characteristics of the best practices described in the article.
Transit-Time Spin Field-Effect-Transistor
Ian Appelbaum,Douwe Monsma
Physics , 2007, DOI: 10.1063/1.2752015
Abstract: We propose and analyze a four-terminal metal-semiconductor device that uses hot-electron transport through thin ferromagnetic films to inject and detect a charge-coupled spin current transported through the conduction band of an arbitrary semiconductor. This provides the possibility of realizing a spin field-effect-transistor in Si, using electrostatic transit-time control in a perpendicular magnetic field, rather than Rashba effect with spin-orbit interaction.
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