Publications by authors named "Ark A"

Functional and phenotypic heterogeneity of dendritic cells (DCs) play crucial roles in facilitating the development of diverse immune responses essential for host protection. Here, we report that KDM5C, a histone lysine demethylase, regulates conventional or classical DC (cDC) and plasmacytoid DC (pDC) population heterogeneity and function. Mice deficient in KDM5C in DCs have increased proportions of cDC2Bs and cDC1s, which is partly dependent on type I interferon (IFN) and pDCs.

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Intrinsic or added immune activating molecules are key for most vaccines to provide desired immunity profiles but may increase systemic reactogenicity. Regulatory agencies require rabbit pyrogen testing (RPT) for demonstration of vaccine reactogenicity. Recently, the monocyte activation test (MAT) gained popularity as in vitro alternative, yet this assay was primarily designed to test pyrogen-free products.

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Respiratory infections caused by are reemerging despite high pertussis vaccination coverage. Since the introduction of the acellular pertussis vaccine in the late twentieth century, circulating strains increasingly lack expression of the vaccine component pertactin (Prn). In some countries, up to 90% of the circulating strains are deficient in Prn.

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Background: In the Netherlands, healthcare professionals attending patients in the last phase of life, can consult an expert palliative care team (PCT) in case of complex problems. There are two types of PCTs: regional PCTs, which are mainly consulted by general practitioners, and hospital PCTs, which are mainly consulted by healthcare professionals in the hospital. Integration of these PCTs is expected to facilitate continuity of care for patients receiving care in different settings.

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Unlabelled: One of the most difficult aspects of providing removable dentures, for both the patient and the dentist, is the tooth selection process. The aim of this study was to assess the effectiveness of augmented reality (AR) on patient experience of the tooth selection process.

Materials And Methods: 3D scanning of upper anterior teeth of various shapes and sizes allowed for the creation of a virtual library that were subsequently used to programme an AR software application, 'ToothPick'.

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Background: One of the strategies to promote the quality of palliative care in non-specialised settings is the appointment of palliative care nurse champions. It is unclear what the most effective model to implement the concept of nurse champions is and little is known about palliative care nurse champions' own views on their role and responsibilities. This paper aims to describe views of palliative care nurse champions in hospitals and home care on their role, responsibilities and added value.

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Background: Advance care planning (ACP) can help to enhance the care of patients with limited life expectancy. Despite physicians' key role in ACP, the ways in which physicians estimate and communicate prognosis can be improved.

Aim: To determine how physicians in different care settings self-assess their performance in estimating and communicating prognosis to patients in palliative care, and how they perceive their communication with other physicians about patients' poor prognosis.

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The limited protective immunity induced by acellular pertussis vaccines demands development of novel vaccines that induce broader and longer-lived immunity. In this study, we investigated the protective capacity of outer membrane vesicle pertussis vaccines (omvPV) with different antigenic composition in mice to gain insight into which antigens contribute to protection. We showed that total depletion of virulence factors ((-) mode) in omvPV led to diminished protection despite the presence of high antibody levels.

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Background: When patients receiving palliative care are transferred between care settings, adequate collaboration and information exchange between health care professionals is necessary to ensure continuity, efficiency and safety of care. Several studies identified deficits in communication and information exchange between care settings. Aim of this study was to get insight in the quality of collaboration and information exchange in palliative care from the perspectives of nurses.

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Nucleotide skew analysis is a versatile method to study the nucleotide composition of RNA/DNA molecules, in particular to reveal characteristic sequence signatures. For instance, skew analysis of the nucleotide bias of several viral RNA genomes indicated that it is enriched in the unpaired, single-stranded genome regions, thus creating an even more striking virus-specific signature. The comparison of skew graphs for many virus isolates or families is difficult, time-consuming, and nonquantitative.

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Background: With the increasing incidence of births of very preterm very-low-birth-weight infants, there is a demand for echocardiographic reference values of cardiac dimensions.

Objectives: The aim of this study was to provide reference values of cardiac valve annulus diameters in a cohort of extremely preterm very-low-birth-weight neonates and to correlate these with patient characteristics.

Methods: Valve diameters of 376 infants of < 32 weeks' gestation and with a birth weight of ≤2,000 g were measured using 2-dimensional echocardiography.

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Background: The worlds of a physician and a jazz musician seem entirely different. Various studies, however, relating the concepts behind jazz music to medical practice and education, have been published. The aim of this essayistic review is to summarize previously described concepts behind jazz music and its required artistic skills that could be translated to medicine, encouraging doctors, medical students and medical educators to see their professional environment from a different perspective.

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Mucosal immunity is often required for protection against respiratory pathogens but the underlying cellular and molecular mechanisms of induction remain poorly understood. Here, systems vaccinology was used to identify immune signatures after pulmonary or subcutaneous immunization of mice with pertussis outer membrane vesicles. Pulmonary immunization led to improved protection, exclusively induced mucosal immunoglobulin A (IgA) and T helper type 17 (Th17) responses, and in addition evoked elevated systemic immunoglobulin G (IgG) antibody levels, IgG-producing plasma cells, memory B cells, and Th17 cells.

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Physicochemical and immunochemical assays were applied to substantiate the relation between upstream processing and the quality of whole-cell pertussis vaccines. Bordetella pertussis bacteria were cultured on a chemically defined medium using a continuous cultivation process in stirred tank reactors to obtain uniform protein expression. Continuous culture favors the consistent production of proteins known as virulence factors.

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Outer Membrane Vesicles (OMVs) are gaining attention as vaccine candidates. The successful expression of heterologous antigens in OMVs, with the OMV functioning both as adjuvant and delivery vehicle, has greatly enhanced their vaccine potential. Since there are indications that surface exposed antigens might induce a superior immune response, targeting of heterologous antigens to the OMV surface is of special interest.

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The current resurgence of whooping cough is alarming, and improved pertussis vaccines are thought to offer a solution. Outer membrane vesicle vaccines (omvPV) are potential vaccine candidates, but omvPV-induced humoral responses have not yet been characterized in detail. The purpose of this study was to determine the antigen composition of omvPV and to elucidate the immunogenicity of the individual antigens.

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Despite high vaccination coverage rates, pertussis continues to be a global concern, with increased incidence widely noted. The current pertussis epidemiologic situation has been mainly attributed to waning immunity and pathogen adaptation. To improve the disease control, a new generation of vaccines capable to overcome those weaknesses associated to the current vaccines need to be developed.

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Bordetella pertussis (B. pertussis) is the causative agent of whooping cough, which is a highly contagious disease in the human respiratory tract. Despite vaccination since the 1950s, pertussis remains the most prevalent vaccine-preventable disease in developed countries.

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An improved whole cell pertussis vaccine, designated as Plow, which is low in endotoxicity due to a chemical extraction of lipo-oligosaccharide (LOS) from the outer membrane, was evaluated for safety, immunogenicity and potency, comparatively to a traditional whole cell pertussis vaccine. Current whole cell pertussis vaccines are effective but contain large quantities of endotoxin and consequently display local and systemic adverse reactions after administration. Endotoxin is highly inflammatory and contributes considerably to the reactogenicity as well as the potency of these vaccines.

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Pertussis has recently re-emerged in well-vaccinated populations most likely due to a combination of pathogen adaptation and waning of vaccine-induced pertussis immunity. Changes in genomic content of the etiologic agent, Bordetella pertussis, observed in the postvaccination era can have a bearing on the efficacy of vaccines currently in use. Moreover, protective immune responses in vaccinees wane gradually depending on their originally induced size and breadth, and memory responses may not be as regularly boosted by circulating strains as was the case in the prevaccination era.

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Fever has been reported as the most common adverse event after vaccination in infants and children. For this reason it is important that, prior to clinical testing of a new vaccine, change in body temperature following vaccination is tested carefully in nonclinical animal studies. Since both the timing and the height of the temperature peak after vaccination may differ from vaccine to vaccine, it is important that the time point for body temperature measurement should be chosen on a case-by-case basis with sufficient knowledge of the specific vaccine.

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In an effort to devise a safer and effective pertussis acelullar vaccine, outer membrane vesicles (OMVs) were engineered to decrease their endotoxicity. The pagL gene from Bordetella bronchiseptica, which encodes a lipid A 3-deacylase, was expressed in Bordetella pertussis strain Tohama I. The resulting OMVs, designated OMVs(BpPagL), contain tetra- instead of penta-acylated LOS, in addition to pertussis surface immunogens such as pertactin and pertussis toxin, as the wild type OMVs.

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This work describes the development of an animal-component free medium (IPT-AFM) that allows an optimal growth of Vero cells, an adherent cell line used for the production of viral vaccines. Statistical experimental design was applied to identify crucial nutrients that affect cell growth. Using Medium 199 or MEM as a basal medium, a serum-free medium (SFM) referred as IPT-SFM that only enclosed transferrin as a component of animal origin was developed at first.

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Vero cells growth and rabies production in IPT-AF medium, a property animal-component-free medium are described in this work. Kinetics of cell growth and rabies virus (strain LP 2061) production were first conducted in spinner flasks. Over eight independent experiments, Vero cell growth in IPT-AF medium, on 2 g/l Cytodex 1 was consistent.

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