Search PubMed⌕ Search

Biomedical subjects

A Dekker

Publications and source records attributed to A Dekker.

At least 19 recordsLinked to original sources
PubMed2003

The foot-and-mouth disease epidemic in The Netherlands in 2001.

An outbreak of foot-and-mouth disease (FMD) in Great Britain was reported on 21 February 2001, followed by an outbreak of FMD in The Netherlands a month later. This Dutch index outbreak occurred on a mixed, veal-calf/dairy-goat farm in Oene, in the central part of The Netherlands. The most-likely route of infection was the import of Irish veal-calves to this Dutch herd via an FMD-contaminated staging point in France. With hindsight, more herds seemed to be infected by the time the index outbreak was confirmed. The regular EU control measures were implemented, in combination with pre-emptive culling of herds within 1km of each outbreak. Nevertheless, more outbreaks of FMD occurred. Most of the virus infections on those farms were "neighborhood infections". Because the situation seemed out of control locally and the destruction capacity became insufficient, it was decided to implement an emergency vaccination strategy for all biungulates in a large area around Oene to stop further spread of the virus. All susceptible animals on approximately 1800 farms in this area were vaccinated. All farms subsequently were depopulated, starting from 2 weeks after vaccination. In total, 26 outbreaks were detected (the last outbreak on 22 April 2001). In total, approximately 260,000 animals were killed.

Animals↗
PubMed2002

A decision-tree to optimise control measures during the early stage of a foot-and-mouth disease epidemic.

A decision-tree was developed to support decision making on control measures during the first days after the declaration of an outbreak of foot-and-mouth disease (FMD). The objective of the tree was to minimise direct costs and export losses of FMD epidemics under several scenarios based on livestock and herd density in the outbreak region, the possibility of airborne spread, and the time between first infection and first detection. The starting point of the tree was an epidemiological model based on a deterministic susceptible-infectious-recovered approach. The effect of four control strategies on FMD dynamics was modelled. In addition to the standard control strategy of stamping out and culling of high-risk contact herds, strategies involving ring culling within 1 km of an infected herd, ring-vaccination within 1 km of an infected herd, and ring-vaccination within 3 km of an infected herd were assessed. An economic model converted outbreak and control effects of farming and processing operations into estimates of direct costs and export losses. Ring-vaccination is the economically optimal control strategy for densely populated livestock areas whereas ring culling is the economically optimal control strategy for sparsely populated livestock areas.

Animal Husbandry↗
PubMed2002

Isotype specific ELISAs to detect antibodies against swine vesicular disease virus and their use in epidemiology.

Isotype specific ELISAs to detect antibodies against swine vesicular disease, which may help to estimate the moment of infection, were developed and validated on sera from pigs experimentally infected with four different isolates of swine vesicular disease virus. Virus specific IgM antibodies could be detected from days 3-49 and occasionally up to day 91 after infection. IgG1 antibodies were first detected at day 8 and IgG2 at day 11. IgA antibodies coincided with IgG1 antibodies, but antibody titres varied widely. From the results obtained with the sera from the experimentally infected pigs, we calculated the day at which 50% of the pigs had become positive (D50). A D50 of 5, 4, 12, 12 and 24 days was calculated, respectively, for the appearance of antibodies in the virus neutralization test, the IgM, total IgG, IgG1 and IgG2 ELISA. A D50 of 49 days was calculated for the disappearance of IgM antibodies. The isotype specific ELISAs proved to be valuable tools to study the epidemiology of the disease.

Animals↗
PubMed2002

Lessons from the foot and mouth disease outbreak in The Netherlands in 2001.

The Netherlands had recently developed a new strategy for the eradication of foot and mouth disease (FMD). When FMD was confirmed in Great Britain and France, recent imports of susceptible animals from these countries were traced and preventive measures were taken. On 21 March 2001, FMD was confirmed in The Netherlands. The disease was introduced by calves which became infected at a staging post in Mayenne, France, where infected sheep from Great Britain were present. A total of 26 farms were infected. Emergency vaccination of all susceptible animals was applied. Suppressive vaccination was chosen, implying that all vaccinated animals had to be slaughtered. Ring vaccination of all susceptible animals within 2 km of an infected herd was the standard procedure. However, in the 'Noord Veluwe', vaccination had to be applied to a larger area. The last affected farm was confirmed on 22 April 2001. Emergency vaccination contained the FMD infection rapidly. The last vaccinated animal was slaughtered on 25 May 2001. Many farmers were not convinced that the killing of their healthy, vaccinated animals was justified and tried to prevent the culling, but without success. Politicians and the public at large are now strongly opposed to the large-scale slaughter of vaccinated animals should a future outbreak of FMD occur. The Office International des Epizooties (OIE: World organisation for animal health) should incorporate control of vaccinated animals with non-structural protein (NSP) tests in the chapter on FMD in the International Animal Health Code.

Animals↗
PubMed2001

Cidofovir for cytomegalovirus infection and disease in allogeneic stem cell transplant recipients. The Infectious Diseases Working Party of the European Group for Blood and Marrow Transplantation.

A retrospective study was performed to collect information regarding efficacy and toxicity of cidofovir (CDV) in allogeneic stem cell transplant patients. Data were available on 82 patients. The indications for therapy were cytomegalovirus (CMV) disease in 20 patients, primary preemptive therapy in 24 patients, and secondary preemptive therapy in 38 patients. Of the patients, 47 had received previous antiviral therapy with ganciclovir, foscarnet, or both drugs. The dosage of CDV was 1 to 5 mg/kg per week followed by maintenance every other week in some patients. The duration of therapy ranged from 1 to 134 days (median, 22 days). All patients received probenecid and prehydration. Ten of 20 (50%) patients who were treated for CMV disease (9 of 16 with pneumonia) responded to CDV therapy, as did 25 of 38 (66%) patients who had failed or relapsed after previous preemptive therapy and 15 of 24 (62%) patients in whom CDV was used as the primary preemptive therapy. Of the patients, 21 (25.6%) developed renal toxicity that remained after cessation of therapy in 12 patients. Fifteen patients developed other toxicities that were potentially due to CDV or the concomitantly given probenecid. No toxicity was seen in 45 (61.6%) patients. Cidofovir can be considered as second-line therapy in patients with CMV disease failing previous antiviral therapy. However, additional studies are needed before CDV can be recommended for preemptive therapy.

Adolescent↗
PubMed2001

Respiratory virus infections after stem cell transplantation: a prospective study from the Infectious Diseases Working Party of the European Group for Blood and Marrow Transplantation.

Community-acquired respiratory virus infections are a cause of mortality after stem cell transplantation (SCT). A prospective study was performed at 37 centers to determine their frequency and importance. Additional cases were also collected to allow the analysis of risk factors for severe infection. Forty episodes were collected in the prospective study and 53 additional episodes through subsequent case collection. The frequency of documented respiratory virus infections was 3.5% among 819 allogeneic and 0.4% among 1154 autologous SCT patients transplanted during the study period. The frequency of lower respiratory tract infections (LRTI) was 2.1% among allogeneic and 0.2% among autologous SCT patients. The mortality within 28 days from diagnosis of a respiratory viral infection was 1.1% among allogeneic SCT while no autologous SCT patient died. The deaths of five patients (0.6%) were directly attributed to a respiratory virus infection (three RSV; two influenza A). On multivariate analysis, lymphocytopenia increased the risk for LRTI (P = 0.008). Lymphocytopenia was also a significant risk factor for LRTI in patients with RSV infections. The overall mortality in RSV infection was 30.4% and the direct RSV-associated mortality was 17.4%. For influenza A virus infection, the corresponding percentages were 23.0% and 15.3%. This prospective study supports the fact that community-acquired respiratory virus infections cause transplant-related mortality after SCT.

Adolescent↗
PubMed2001

Detection of photoacoustic transients originating from microstructures in optically diffuse media such as biological tissue.

The generation and detection of broadband photoacoustic (PA) transients may be used for on-axis monitoring or for imaging of optically different structures in the interior of diffuse bodies such as biological tissue. Various piezoelectric sensors are characterized and compared in terms of sensitivity, depth response, and directivity with respect to spherical broadband acoustic pulses. The influence on the sensor output of acoustic interference and refraction of the PA transients at the sample-sensor interface is discussed. Ring detectors are suitable for deep on-axis detection thanks to their strong directional sensitivity, and small disk sensors are most suited for 3-D imaging of microstructures such as the (micro)vascular system. Voltage and charge preamplification schemes are compared in terms of the signal-to-noise ratio (SNR). In all cases, the preamplifier noise turns out to be the limiting factor for the sensitivity. Based on experimental data, for several sensor types and optical wavelengths, the theoretical detectability of PA signals generated by blood-like absorbers in biological tissue is discussed.

Acoustics↗
PubMed2000

Singleton reactors in the diagnosis of swine vesicular disease: the role of coxsackievirus B5.

Swine vesicular disease virus (SVDV) and Coxsackie B5 virus (CVB5) are closely related viruses that can infect swine and man and give rise to cross-reacting serum antibodies. It is, therefore, possible that SVD antibodies found in serologic screenings of pigs are induced by CVB5. Single positive animals found in screening programmes are generally referred to as singleton reactors (SR). To determine whether SR in SVDV screenings are induced by CVB5 infection, virus neutralisation tests (VNTs) and radioimmunoprecipitation assays (RIPA) were carried out on sera of SR, sera of pigs experimentally infected with SVDV, and sera from pigs vaccinated with CVB5 isolates. The SR sera reacted repeatedly positive in the SVDV UKG/27/72 VNT, but reacted differently in three other VNTs (SVDV NET/1/92, CVB5A, and CVB5B). The VNT titres obtained with the SR sera revealed a correlation between both SVDV strains, and also between both CVB5 stains, but no correlation was found between SVD and CVB5 VNT titres. Sera of experimentally infected (SVDV) or vaccinated (CVB5) pigs showed titres in all four neutralisation tests. In the RIPA, the reaction patterns of the SR sera varied considerably with all four antigens used, in contrast to sera from pigs experimentally infected with SVDV that reacted with all antigens used, and sera from pigs vaccinated with CVB5 that reacted only with CVB5 antigens. The results presented in this paper show that neither CVB5 nor SVDV infections are the only cause of the SR phenomenon. Testing for CVB5 specific antibodies can reduce the number of SR sera in the serodiagnosis of SVDV.

Animals↗
PubMed2000

Chimeric swine vesicular disease viruses produced by fusion PCR: a new method for epitope mapping.

A new method of epitope mapping based on chimeric swine vesicular disease (SVD) viruses produced by fusion PCR (polymerase chain reaction). Seven out of 16 neutralising and non-neutralising newly produced monoclonal antibodies (MAbs) discriminated between SVD isolate ITL/1/66 and NET/1/92. Using fusion PCR eight chimeric viruses were produced containing different supplementary pieces of the P1 region of both parent strains. Using these chimeric viruses we were able to map the epitope regions recognised by these seven neutralising and non-neutralising Mabs. This new method, using chimeric viruses produced by fusion PCR, is particularly valuable for the epitope mapping of non-neutralising MAbs.

Animals↗
PubMed2000

Dose-finding study of valspodar (PSC 833) with daunorubicin and cytarabine to reverse multidrug resistance in elderly patients with previously untreated acute myeloid leukemia.

INTRODUCTION: This trial was designed to determine the maximum tolerated dose of intravenous daunorubicin (DNR) in combination with valspodar and to test the feasibility of P-glycoprotein modulation using valspodar in elderly patients with previously untreated acute myelogenous leukemia receiving standard induction chemotherapy. METHODS: Patients > or =60 years of age with previously untreated AML received valspodar (10 mg/kg/24 h by continuous intravenous infusion [CIV] on days 1-4 with a 2-mg/kg loading dose on day 1) in conjunction with two cycles of induction chemotherapy consisting of cytarabine (200 mg/m(2) CIV on days 1-7), and DNR (35 mg/m(2) [cohort 1] or 45 mg/m(2) [cohort 2] on days 1-3, intravenous bolus). Patients were assessed for dose-limiting toxicities (DLT), response rate, event-free and overall survival, and pharmacokinetics of valspodar and DNR. RESULTS: Valspodar was well tolerated at the lower DNR dose level (ie, 35 mg/m(2)) resulting in a 21% rate of DLT and only three toxic deaths. Treatment-related mortality was unacceptably high at the 45 mg/m(2) DNR dose level. The complete response rate was 49% overall and similar in both cohorts. The median overall survival of patients was 333 days in cohort 1 compared to 98 days in cohort 2. At baseline, 70% of assessable patients were P-glycoprotein positive. CONCLUSION: Substantial inhibition of P-glycoprotein activity can be achieved in this patient population at clinically tolerable doses of valspodar and DNR. The maximum tolerated dose of DNR was established as 35 mg/m(2). This regimen is being further evaluated in phase III trials.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Swine vesicular disease, studies on pathogenesis, diagnosis, and epizootiology: a review.

Swine vesicular disease (SVD) is a contagious viral disease of swine. It causes vesicular lesions indistinguishable from those observed of foot-and-mouth disease. Infection with SVD virus (SVDV) can lead to viraemia within 1 day and can produce clinical signs 2 days after a pig has come into contact with infected pigs or a virus-contaminated environment. Virus can be detected 3.5 hours after infection using immunohistochemistry. In these in vitro studies, this technique was superior to in-situ hybridization. In SVDV-infected tissues, however, more infected cells were positive using in-situ hybridization, and these were already seen 4.5 hours after infection. For serological diagnosis of SVD several new enzyme-linked immunosorbent assays (ELISA's) have been developed. The newest ELISAs, based on monoclonal antibodies, are superior to the previous tests. The new tests produce fewer less false-negative results and enable large-scale serological screening. In screening programmes a small percentage of false positive reactors have been detected. The cause of these false-positive reactions has not been identified, though infections with human Coxsackie B5 virus can be excluded.

Animals↗
PubMed2000

Construction of a full-length infectious cDNA clone of swine vesicular disease virus strain NET/1/92 and analysis of new antigenic variants derived from it.

The Dutch swine vesicular disease virus (SVDV) isolate NET/1/92 was one of the first isolates belonging to a new SVDV antigenic group. This strain was completely sequenced and was shown to have 93% similarity with the UKG/27/72 isolate. To enable antigenicity, replication, maturation and pathogenicity studies of NET/1/92, an infectious full-length cDNA clone, designated pSVD146, was prepared. The in vitro and in vivo biological properties of the virus derived from pSVD146 were studied by analysing antigenicity, plaque morphology, growth curves and virulence in pigs. The epitopes of newly prepared monoclonal antibodies were roughly mapped by fusion-PCR. Fine mapping of epitopes at the amino acid level was achieved by introducing single amino acid mutations in pSVD146. Two new amino acids important in epitope formation were located in VP1; one was mapped in the C-terminal end and the second is thought to be located in the H-I loop. Growth curve and plaque sizes in vitro were similar between virus derived from pSVD146 and the parent wild-type virus. In virulence studies in pigs, the lesions score, neutralization titres and the seroconversion rates were comparable between virus derived from pSVD146 and the parent strain. Since virus derived from pSVD146 had the same biological properties as the parent strain NET/1/92, the full-length infectious cDNA clone pSVD146 will be very useful in studies of the antigenicity, virulence, pathogenesis, maturation and replication of SVDV.

Amino Acid Sequence↗
PubMed1999

[Foot-and-mouth disease: clinical aspects, epizootiology and diagnosis].

A description of the clinical signs, differential diagnosis, epizootiology and laboratory diagnosis of foot-and-mouth disease in ruminants and pigs is given. Clinical signs are most easily recognised in cattle and pigs. Sheep and goats with foot-and-mouth disease do not show distinct clinical signs and can easily be missed. Clinical diagnosis by the veterinary practitioner is very important in case of an outbreak of foot-and-mouth disease.

Animals↗
PubMed1999

[Foot-and-mouth disease of cattle is not a zoonosis].

In 1997 there was an outbreak of foot-and-mouth disease (FMD) among cattle in Turkey. People visiting that country were warned against importing animal products into the Netherlands. This had nothing to do with hazards to human health, as FMD virus is not a zoonotic virus, but with the risk of spread of the disease to livestock in the Netherlands, notably to cattle and pigs. A disease with similar clinical symptoms in pigs is swine vesicular disease (SVD), which is not a zoonosis either. FMD virus is an aphtovirus, SVD virus is an enterovirus. Hand-foot-and-mouth disease in humans is caused by other enteroviruses, i.e. Coxsackie virus and enterovirus 71.

Animals↗
PubMed1999

Production of recombinant human type I procollagen homotrimer in the mammary gland of transgenic mice.

The large scale production of recombinant collagen for use in biomaterials requires an efficient expression system capable of processing a large (> 400 Kd) multisubunit protein requiring post-translational modifications. To investigate whether the mammary gland of transgenic animals fulfills these requirements, transgenic mice were generated containing the alpha S1-casein mammary gland-specific promoter operatively linked to 37 Kb of the human alpha 1(I) procollagen structural gene and 3' flanking region. The frequency of transgenic lines established was 12%. High levels of soluble triple helical homotrimeric [(alpha 1)3] type I procollagen were detected (up to 8 mg/ml) exclusively in the milk of six out of 9 lines of lactating transgenic mice. The transgene-derived human procollagen chains underwent efficient assembly into a triple helical structure. Although proline or lysine hydroxylation has never been described for any milk protein, procollagen was detected with these post-translational modifications. The procollagen was stable in milk; minimal degradation was observed. These results show that the mammary gland is capable of expressing a large procollagen gene construct, efficiently assembling the individual polypeptide chains into a stable triple helix, and secreting the intact molecule into the milk.

Amino Acids↗