Publications by authors named "Voeten J"

The discovery of levodopa in the late 60 s of twentieth century was a 'golden moment' for people with Parkinson's disease (PD). Unfortunately, clinical experience showed that some symptoms escaped from symptomatic control, and long-term complications developed. Back then, neurologists coined the term "honeymoon period" for the early phase of uncomplicated response to levodopa, and it continues to be used in scientific literature.

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Parkinson’s disease (PD) is a neurodegenerative condition, characterized by motor, non-motor disability, and a reduced quality of life. Stimulated by a question raised by a person with PD, we posted an orienting survey on social media, asking whether there is possibly any “silver lining” (an upside) to having PD. Most respondents identified one or more positive changes, mainly a new focus in life, better coping skills, new activities, healthier lifestyle, and improved relationships with relatives and friends.

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Live attenuated influenza vaccines (LAIV) offer significant advantages over subunit or split inactivated vaccines to mitigate an eventual influenza pandemic, including simpler manufacturing processes and more cross-protective immune responses. Using an established reverse genetics (rg) system for wild-type (wt) A/Leningrad/134/1957 and cold-adapted (ca) A/Leningrad/134/17/1957 (Len17) master donor virus (MDV), we produced and characterized three rg H5N1 reassortant viruses carrying modified HA and intact NA genes from either A/Vietnam/1203/2004 (H5N1, VN1203, clade 1) or A/Egypt/321/2007 (H5N1, EG321, clade 2) virus. A mouse model of infection was used to determine the infectivity and tissue tropism of the parental wt viruses compared to the ca master donor viruses as well as the H5N1 reassortants.

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The cold-adapted, temperature sensitive and attenuated influenza master donor viruses A/Leningrad/134/17/57 (H2N2) and B/USSR/ 60/69 were used to generate the vaccine viruses to be included in live attenuated influenza vaccine. These vaccine viruses typically are 6:2 reassortant viruses containing the surface antigens hemagglutinin and neuraminidase of current wild type influenza A and influenza B viruses with the gene segments encoding the internal viral proteins, and conferring the cold-adapted, temperature sensitive and attenuated phenotype, being inherited from the master donor viruses. The 6:2 reassortant viruses were selected from co-infections between master donor virus and wild type viruses that theoretically may yield as many as 256 combinations of gene segments and thus 256 genetically different viruses.

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Continued H5N1 virus infection in humans highlights the need for vaccine strategies that provide cross-clade protection against this rapidly evolving virus. We report a comparative evaluation in ferrets of the immunogenicity and cross-protective efficacy of isogenic mammalian cell-grown, live attenuated influenza vaccine (LAIV) and adjuvanted, whole-virus, inactivated influenza vaccine (IIV), produced from a clade 1 H5N1 6:2 reassortant vaccine candidate (caVN1203-Len17rg) based on the cold-adapted A/Leningrad/134/17/57 (H2N2) master donor virus. Two doses of LAIV or IIV provided complete protection against lethal homologous H5N1 virus challenge and a reduction in virus shedding and disease severity after heterologous clade 2.

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Aim: To identify the genes that are responsible for attenuation of donor viruses for live influenza vaccine. MATERIALS AND METHODS. Analysis of phenotypical properties of reassortants of wild type A and B influenza viruses with A/Leningrad/134/17/57 (H2N2) (A17) and B/USSR/60/69 (B60) master donor viruses was performed by comparison of their capability to grow at different temperatures in chicken eggs or/and MDCK cells.

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Trivalent live attenuated influenza vaccines whose type A components are based on cold-adapted A/Leningrad/134/17/57 (H2N2) (caLen17) master donor virus (MDV) have been successfully used in Russia for decades to control influenza. The vaccine virus comprises hemagglutinin and neuraminidase genes from the circulating viruses and the remaining six genes from the MDV. The latter confer temperature-sensitive (ts) and attenuated (att) phenotypes.

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Demonstration of the absence of neurovirulent properties of reassortant viruses contained in live attenuated influenza vaccine (LAIV) is a regulatory requirement. A mouse model was used to detect neurovirulent properties of the cold-adapted, temperature-sensitive and attenuated influenza master donor viruses (MDVs) A/Leningrad/134/17/57 (H2N2) and B/USSR/60/69 and derived reassortant influenza viruses. A/NWS/33 (H1N1), which is known to be neurovirulent in mice, was used as a positive control.

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The cold-adapted (ca) and temperature-sensitive (ts) influenza master donor virus (MDV) B/USSR/60/69 was derived from its wild-type parental virus after successive passages in eggs at 32 degrees C and 25 degrees C. This strain is currently in use for preparing reassortant influenza B vaccine viruses which are used in the Russian trivalent live attenuated influenza vaccine. Vaccine viruses are obtained by classical reassortment of MDV and a currently circulating wild-type virus.

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Myoelectric recordings from the gastrointestinal (GI) tract in conscious animals have been limited in duration and site. Recently, we have implanted 24 electrodes and obtained electrograms from these sites simultaneously (200 Hz sampling rate; 1.1 MB/min data stream).

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Real-time analysis of gene expression in experimental tumor models represents a major tool to document disease biology and evaluate disease treatment. However, monitoring gene regulation in vivo still is an emerging field, and thus far it has not been linked to long-term tumor growth and disease outcome. In this report, we describe the development and validation of a fluorescence-based gene expression model driven by the promoter of the cyclin-dependent kinase inhibitor p21waf1,cip1.

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Myoelectric recordings from the intestines in conscious animals have been limited to a few electrode sites with relatively large inter-electrode distances. The aim of this project was to increase the number of recording sites to allow high-resolution reconstruction of the propagation of myoelectrical signals. Sets of six unipolar electrodes, positioned in a 3x2 array, were constructed.

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In the present paper, an in vitro model was established in which the interaction between influenza virus-specific CD8+ T cells and human airway epithelial cells can be studied. To this end, the human lung epithelial cell line A549 was transduced with the HLA-A*0201 gene. This MHC class I allele is involved in the presentation of the immunodominant M158-66 cytotoxic T lymphocyte (CTL) epitope of the influenza A virus matrix protein.

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CD8+ cytotoxic T lymphocytes (CTLs) contribute to the control of viral infections by recognizing peptides of viral proteins presented by MHC class I molecules on infected cells. Some viruses have developed strategies to evade recognition by CTL. One of these strategies involves antigenic variation in CTL epitopes as described for viruses chronically infecting their host like EBV, HIV, HBV and HCV.

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In general, exogenous proteins are processed by antigen-presenting cells in the endosomes for major histocompatibility complex (MHC) class II presentation to CD4+ T cells, while proteins synthesized endogenously are processed in the cytoplasm for MHC class I presentation to CD8+ T cells. However, it is recognized that exogenous proteins can be processed for MHC class I presentation also, and evidence in favour of alternatives to the conventional MHC class I processing and presentation pathway is accumulating. Here, we show that exogenous recombinant influenza A virus nucleoprotein (rNP) is processed for MHC class I presentation to CD8+ cytotoxic T lymphocytes (CTL) by EBV-transformed, B-lymphoblastoid cell lines (B-LCL).

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The gene encoding the influenza virus A matrix (MA) protein was cloned into the bacterial expression vector pMalC with and without the sequence encoding the transmembrane region of the haemagglutinin (HA). With the resulting recombinant proteins, immune stimulating complexes (ISCOM) were prepared. The MA protein with the hydrophobic anchor region (rMAHA) associated more efficiently with ISCOM than the unmodified MA protein (rMA).

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Viruses exploit different strategies to escape immune surveillance, including the introduction of mutations in cytotoxic T-lymphocyte (CTL) epitopes. The sequence of these epitopes is critical for their binding to major histocompatibility complex (MHC) class I molecules and recognition by specific CTLs, both of which interactions may be lost by mutation. Sequence analysis of the nucleoprotein gene of influenza A viruses (H3N2) isolated in The Netherlands from 1989 to 1999 revealed two independent amino acid mutations at the anchor residue of the HLA-B27-specific CTL epitope SRYWAIRTR (383 to 391).

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The replacement of embryonated chicken eggs by tissue culture cells for the production of influenza vaccines is likely to take place in the near future. Vaccines have already been produced in Madin Darby Canine Kidney (MDCK) cells (Brands et al, in this issue) and extensively tested in phase III trials in humans (Palache et al, in this issue) and it seems a matter of time before such vaccines will become available. For this reason, the generation of high-growth reassortants of influenza A virus strains in MDCK cells has been examined.

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In the present study reassortant influenza A viruses of both the H1N1 and H3N2 type were generated in Madin Darby Canine Kidney cells grown in the absence of fetal bovine serum (MDCK-SF1 cells). To this end, MDCK-SF1 cells were simultaneously infected with one of the high-growth laboratory strains A/Puerto Rico/8/34 (H1N1) or A/Hong Kong/2/68 (H3N2) and recent H3N2 and H1N1 vaccine strains, respectively. Reassortant viruses obtained from these mixed infections were genetically characterized by RT-PCR and restriction enzyme analysis and their growth properties were compared to those of the corresponding field strains.

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The nucleoprotein genes of influenza virus A/Netherlands/018/94 (H3N2) and influenza virus B/Harbin/7/94 were cloned into the bacterial expression vector pMalC to yield highly purified recombinant influenza virus A and B nucleoproteins. With these recombinant influenza nucleoproteins, enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of influenza virus A- and B-specific immunoglobulin A (IgA) and IgG serum antibodies. Serum samples were collected at consecutive time points after the onset of clinical symptoms from patients with confirmed influenza virus A or B infections.

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A new, non-invasive method for measuring reserpine-induced tremor in rodents is described here. The test procedure is based on the piezo-electric principle and was evaluated using the tremorogenic compound reserpine and the stereotypies-inducing drug apomorphine. Whereas for reserpine an orderly and dose-related increase in activity was observed, no such effect was detected with apomorphine.

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Previous results showed that plasmids containing one of the eight putative origins (ori's) of Autographa californica nuclear polyhedrosis virus (AcMNPV) are replicated after transfection into Spodoptera frugiperda cells if essential trans-acting factors are supplied by AcMNPV infection (Kool et al., Virology, 192, 94-101, 1993a; Kool et al., J.

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Seven putative origins of DNA replication (oris) were identified and located on the genome of Autographa californica multiple nucleocapsid nuclear polyhedrosis virus (AcMNPV), when an improved infection-dependent replication assay was used. A threefold higher yield of amplified plasmid was achieved when an m.o.

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