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Biomedical subjects

A Dekker

Publications and source records attributed to A Dekker.

At least 55 records · Page 3Linked to original sources
PubMed1997

Detection of early infection of swine vesicular disease virus in porcine cells and skin sections. A comparison of immunohistochemistry and in-situ hybridization.

Sensitive methods are required to study the early pathogenesis of swine vesicular diseases (SVD). Therefore, two new methods, immunohistochemistry (IHC) and in-situ hybridization (ISH), were developed and tested for their specificity and sensitivity. With these methods the SVD virus (SVDV) infection in cytospins of primary porcine kidney cells and in frozen skin sections was investigated. Both IHC and the ISH showed a specific cytoplasmic staining, but the IHC detected more infected cells than the ISH. Furthermore, both IHC and ISH were able to detect SVDV in skin sections 4.5 h after infection. It is concluded that IHC is the most suitable and simplest method to identify cells and tissues that support the initial replication of swine vesicular disease virus. However, IHC can only be applied to frozen sections, whereas ISH can also be used in paraformaldehyde-fixed tissues.

Animals↗
PubMed1996

[Insight in SVD epidemiology. Specimen collection Regulation Farm Surveillance Animal Diseases].

Periodic (4-monthly) surveillance of pig herds for antibodies against swine vesicular disease (SVD) is obligatory in the Netherlands since 1993. Samples should be collected "at random' in as many compartments as possible, with a maximum of one pig per pen. This prerequisite for a sensitive surveillance will be elucidated using four examples of SVD outbreaks in the Netherlands.

Animal Husbandry↗
PubMed1996

Needle biopsy of the adrenal gland: retrospective review of 54 cases.

A retrospective review of 54 cases of adrenal gland needle biopsy in 53 patients is presented. The cases included 43 fine-needle aspirations (FNA), six core-needle biopsies, and five cases in which both types of needle biopsy were done. Clinical or histologic follow-up was available in 28 of the 36 specimens deemed adequate for evaluation. Metastatic malignancies represented the largest group of cases (19), with lung being the most common primary site (8). The series included four cases of metastatic hepatocellular carcinoma. Probable adrenocortical adenoma was the next most common diagnosis (12 cases). Cases causing diagnostic confusion included a case of metastatic well-differentiated hepatocellular carcinoma which was initially confused with an adrenocortical adenoma and a probable adrenocortical adenoma which was mistaken for a metastatic small round cell malignancy. (This case is unproved because of lack of clinical or histologic follow-up). By evaluating only those cases with histologic confirmation or clinical follow-up greater than one year, the sensitivity of needle biopsy for the presence of malignancy was 95% and the specificity was 100%. The cytologic findings are described with attention to the potential problem of confusing primary adrenocortical neoplasms with metastases from hepatocellular carcinoma.

Adenoma↗
PubMed1996

Prevalence of foot-and-mouth disease antibodies in dairy herds in The Netherlands four years after vaccination.

A total of 298 serum samples were collected from Dutch cattle born in 1988 or before, and examined in the virus neutralisation test for antibodies against foot-and-mouth disease virus types A10 Holland. O BFS, and C1Detmold. All the cattle had been vaccinated at least twice during the annual vaccination programme, which stopped in 1991. Antibody titres equal to or higher than the titre at which 95 per cent of the cattle would be expected to be protected against challenge, were found in 57 to 73 per cent of the younger age groups, and in 100 per cent of the older animals. Since the animals tested constituted only 10.5 per cent of the total cattle population on the farms tested, it is concluded that should the virus be introduced, foot-and-mouth disease would be detected as easily in the Netherlands as in a country with no history of vaccination.

Animals↗
PubMed1995

[Swine vesicular disease: threat or challenge for Dutch pig farming?].

Swine vesicular disease (SVD) caused problems in 1993 when it was detected in Dutch pigs in Italy. As a result, the EC took measures against the export of live pigs. In all cases the animals had been retained at an Italian abattoir or farm for three days or more, which is longer than the minimum incubation time. Extensive clinical inspections and serological testing on the farms from where the pigs originated revealed no evidence of SVD infection. Serological testing for SVD of over 1.5 million blood samples collected from herds within the framework of export- and herd certification, and the testing of slaughter sows and slaughter boars (EC directive), was negative as well. In view of these results it has to be assumed that the Dutch pig population is free from SVD and that the pigs were infected in Italy. However, a complaint from Italy in 1994 led to the detection of two SVD virus-contaminated export collection centres. If the existing regulations on the cleansing and disinfection of the transport chains are stringently enforced and implementation of the rules is continuously supervised, then it may be expected that the problems have been overcome.

Animals↗
PubMed1995

Validation of a screening liquid phase blocking ELISA for swine vesicular disease.

A direct liquid-phase blocking ELISA (LPBE) was developed for serological examination of swine vesicular disease (SVD). The sensitivity and specificity of the test were assessed on 272 and 365 sera collected on two farms where an outbreak had occurred. The specificity of the direct LPBE was higher than the specificity of the indirect LPBE. The European Community reference serum for SVD (RS 01-04-93), which has been adopted as the threshold for SVD serological examination in the European Community, had a mean titre of 2.19 in the neutralisation test. At a cut-off level of 2.0 in the neutralisation test, the sensitivity of the direct LPBE (screening at 1:432 final dilution) on the two farms was 90% and 99%, respectively. Based on these results, the screening dilution of the direct LPBE was adjusted to 1:160 final dilution, to obtain a sensitivity > or = 98% on both farms. Regression analyses showed a good correlation between the virus neutralisation test and the direct LPBE (r = 0.87). Compared to the indirect LPBE described before, the direct LPBE correlates better with the neutralisation test, has a higher specificity, and is more rapid. Because sera are tested in only one dilution, the test is highly suitable for the examination of large numbers of serum samples.

Animals↗
PubMed1995

Pathogenesis of swine vesicular disease after exposure of pigs to an infected environment.

The pathogenesis of swine vesicular disease (SVD) has been studied following a natural route of infection. In two experiments groups of ten and eight pigs respectively were introduced into a stable contaminated with SVD virus. At various intervals after stable exposure, pigs were killed and the amount of virus was determined in serum, vesicles (if present), spleen, kidney, and in seven lymph glands representing various parts of the body. One day after the pigs were introduced into the stable, five out of eight pigs were viraemic and virus could be isolated from various tissues. At 2 d after introduction, three out of four pigs killed had vesicular lesions on the feet. The tonsils of all pigs killed between 1 to 7 d after introduction into the stable were virologically positive. Four days after introduction 50% of the pigs were serologically positive and at 7 d all pigs had developed an antibody response. This study shows that contact with a SVD virus contaminated environment can be equally as infectious as injection, or direct contact with SVD infected pigs, causing a rapid spread of the disease. Because the tonsil was shown to be highly efficient in trapping and growing circulating virus, we recommend that in addition to serological examination, virus isolation from pig tonsils should be used to study the epidemiology of SVD on farms where the infection is present.

Animals↗
PubMed1995

Six antigenic groups within the genus pestivirus as identified by cross neutralization assays.

Antigenic differences between pestivirus isolates of ruminant and porcine origin were characterized by neutralization assays. First, six different clusters of pestiviruses were identified by clustering cross-neutralization results of 13 pestivirus strains tested against 23 sera. Cluster I consisted of four strains of bovine viral diarrhoea virus (BVDV) of bovine origin and two BVDV isolates of porcine origin. Cluster II consisted of one sheep isolate and two porcine BDV isolates. Cluster III consisted of one classical swine fever virus strain and cluster IV, V, and VI each consisted of one strain isolated from a giraffe, a deer, and a pig. After the clusters were identified, one-way neutralization tests were used to test a total of 45 pestivirus isolates. Although the same six groups were found, results of some individual strains differed from previous cross-neutralization results and the results obtained by typing with monoclonal antibodies. The discrepancy between one way neutralization tests and cross-neutralisation tests is demonstrated clearly by recalculation of the cross-neutralization results without the classical swine fever sera. We conclude that neutralization tests are only suitable to characterize antigenic differences when virus strains are tested in a cross-neutralization test.

Animals↗
PubMed1995

[In vitro and in vivo studies of a temporary absorbable dressing].

The major advantage of biodegradable synthetic wound dressings compared to other synthetic materials and biological tissue derivatives is avoidance of the necessity to change the dressing. The copolymer films used in this study were made of lactic and caproic acid. They pose no problems concerning immunology or transmission of diseases. Moreover, the substances released by degradation may possibly influence the process of wound healing. The material proved to be non-toxic and was used successfully as a carrier for cell culture with keratinocytes. The permeability for bacteria is determined by degradation. Evaluation of the bacteriological studies indicates secure protection against secondary contamination of the films for at least 15 days, however. Concerning application, dressing properties, wound healing and wound retraction, no disadvantages were found in comparison with the results of the competition's film Opsite. Based on these findings, the films are now used in a clinical study as a wound dressing for split-skin donor sites.

Animals↗
PubMed1994

Adsorption, degradation and leaching of pirimicarb in orchard soils.

This paper shows the results of experiments (adsorption, degradation and mobility) carried out to investigate the risk of pirimicarb leaching to groundwater, after its application to integrated fruit growing systems. Soil batches were collected from experimental fruit farms in Numansdorp and Zeewolde (The Netherlands). The distribution coefficients and the degradation rate coefficients for Numansdorp and Zeewolde soils, respectively, show a higher adsorption and degradation rate in the Zeewolde soil than in the Numansdorp soil. By leaching of pirimicarb in two soil columns, it was found that pirimicard mobility is lower in the Zeewolde soil columns than in the Numansdorp ones but, in both cases, it is much lower than it would be expected from their adsorption coefficients. Pirimicarb is detected in the first effluents, however, the highest concentration remained in the upper 10 cm of the soil columns. A computation model simulating uniform water flow and instantaneous adsorption desorption equilibrium is not suitable to describe the leaching of pirimicarb in structured loamy soils at relatively high water flow-rates.

Adsorption↗
PubMed1994

Ultrasonically guided fine-needle aspiration biopsy of portal vein thrombosis: a cytomorphological study of 14 patients.

Portal vein tumor thrombosis is an important and consistent prognostic indicator in hepatocellular carcinoma. We reviewed 14 cases of ultrasonically guided fine-needle aspiration biopsy (FNAB) of the portal vein. All the patients had clinical evidence of portal vein thrombosis (PVT). Twelve of these patients had a preliminary diagnosis of hepatocellular carcinoma while the remaining two, initially, had a clinical diagnosis of end-stage liver disease. The mean age of the patients was 60 years. An average of 1.7 passes per case was made. No clinical complications were encountered. The cytomorphologic features of the aspirated materials were reviewed. Twelve of the 14 cases (85.7%) were judged neoplastic or thought to have probable neoplastic involvement of the portal vein while two were clearly benign. The cell block was found to be the most useful in diagnosis. We conclude that FNAB of the portal vein is a feasible method in evaluating PVT, especially in patients already known to have hepatocellular carcinoma.

Aged↗
PubMed1994

Fluid shear induced endothelial cell detachment from glass--influence of adhesion time and shear stress.

In this study, human umbilical vein and human saphenous vein endothelial cells were seeded on glass and exposed to fluid shear in a parallel-plate flow chamber. Cell retention, morphology and migration were studied as a function of shear stress and of adhesion time prior to exposure to shear. Three-hour and 24-h adhesion times gave rise to comparable cell retention values after 2 h of flow for both cell types. Cell retention decreased from 85 to 20% as shear stress increased from 88 to 264 dynes cm-2 (8.8 to 26 Pa). Mean spreading areas decreased after the onset of flow, but subsequently stabilized to plateau values, which were smaller at higher shear stresses. Shape factors increased faster to higher values as cells were exposed to higher shear stresses, without any obvious preference in orientation of the cells with respect to the direction of flow. Migration was unidirectional with flow and linear with time. Migration was faster for cells which had adhered for 24 h than for cells which had adhered for 3 h and was accompanied by the presence of fibrillar structures left behind on the surface upstream of migrating cells. It is concluded that after 3 h adhesion to glass, cells have adhered with an adhesion strength that does not substantially increase during the next 21 h. However, during this time changes in cell-substratum interactions seem to occur judging by the differences in, e.g., migration rates.

Blood Vessel Prosthesis↗
PubMed1994

Induction of estrogen independence of ZR-75-1 human breast cancer cells by epigenetic alterations.

Antagonists of steroid hormones are clinically important in the management of breast cancer. However, the duration of response is limited due to the development of hormone-independent tumors in virtually all cases. In an attempt to obtain insight into the mechanisms underlying antiestrogen resistance, the consequences of epigenetic changes in gene expression were studied in vitro. Estrogen-dependent ZR-75-1 human breast cancer cells were treated with 5-azacytidine, an inhibitor of DNA methylation, and cultured in the absence of estradiol or in the presence of antiestrogens. Estrogen-independent cell colonies developed within 3 weeks at high frequency in 5-azacytidine-treated cultures (0.7 x 10(-3), in contrast to control cultures (< or = 10(-8). The derived cells (ZR/AZA) were resistant to 4-hydroxytamoxifen and ICI 164,384, independent of the selection protocol, but had lost the ability to grow anchorage-independent. Whereas expression of estrogen receptor, progesterone receptor, and pS2 were down-regulated, expression of epidermal growth factor (EGF) receptor and HER2/neu were increased in ZR/AZA cells. In contrast to the stable altered expression patterns of estrogen receptor and EGF receptor, transient keratin 7 expression was observed. Transforming growth factor-alpha mRNA was identified in ZR-75-1 cells and ZR/AZA cells and EGF-like peptides were secreted in the culture medium. Proliferation of ZR/AZA cells could be partially inhibited with an EGF receptor-blocking antibody. Presence of both growth factor receptors and possible ligands suggests the development of an autocrine growth mechanism. Our data show that epigenetic alterations of gene expression result in rapid progression of breast cancer cells to hormone independence.

Azacitidine↗
PubMed1994

Prostatic sequestration of Cryptococcus neoformans in immunocompromised persons treated for cryptococcal meningoencephalitis.

We report a case of a patient with acquired immune deficiency syndrome who was successfully treated for cryptococcal meningoencephalitis with amphotericin B and 5-flucytosine. He died from other sequelae of acquired immune deficiency syndrome two years later. An autopsy revealed prominent cryptococcal prostatitis. Cryptococci were neither found in the central nervous system nor in other anatomic sites. The autopsy files yielded seven other cases of men with a history of cryptococcal meningoencephalitis. The possibility that the prostate sequesters Cryptococcus neoformans thereby contributing to systemic relapse is explored. The qualify as a sequestration, cyptococci must be cultured from the prostate, or from a midstream voided specimen after prostatic massage, and the prostate must be the only focus of infection.

AIDS-Related Opportunistic Infections↗
PubMed1993

Induction of antiestrogen resistance in human breast cancer cells by random insertional mutagenesis using defective retroviruses: identification of bcar-1, a common integration site.

Duration of response to antiestrogen therapy in metastatic breast cancer is limited due to the development of antiestrogen-resistant tumors. The mechanisms involved are not understood but could originate from (epi)genetic alterations within the tumor cells. We have applied in vitro random insertional mutagenesis with replication defective retroviruses to identify those genes playing a key role in development of antiestrogen resistance in human breast cancer cells. Eighty antiestrogen-resistant cell clones were isolated from 7 x 10(8) estrogen-dependent ZR-75-1 cells, mass-infected with defective retroviruses and subjected to 4-OH-tamoxifen selection. Integration site-specific DNA probes were made by inverse polymerase chain reaction techniques and used to search for common integration sites. Six cell clones were identified with retroviral genome integrations in the same orientation in a single locus, designated breast cancer antiestrogen resistance locus-1 (bcar-1). These bcar-1 cell clones had lost estrogen receptor expression and had become estrogen independent. Our results strongly suggest that alteration of the bcar-1 locus is responsible for development of antiestrogen resistance in human breast cancer cells in vitro. In addition, we have shown that in vitro insertional mutagenesis using defective retroviruses can be applied for gene tagging in human cells.

Autoradiography↗
PubMed1992

Hemoperitoneum in the setting of metastatic cancer to the liver. A report of two cases with review of the literature.

Two cases of hemoperitoneum occurring as a result of hepatic rupture due to metastatic neoplasms are presented. They represent examples of a striking and devastating but fortunately uncommon entity. The variety of primary neoplastic sites is diverse. Several possible mechanisms have been put forward to explain the event of hepatic rupture itself. Finally, it is important to note the uniformly poor survival rates following hepatic rupture despite therapy.

Adenocarcinoma↗
PubMed1991

Improved adhesion and proliferation of human endothelial cells on polyethylene precoated with monoclonal antibodies directed against cell membrane antigens and extracellular matrix proteins.

Endothelial cell seeding may improve the patency of synthetic vascular grafts provided that platelet reactivity of nonendothelialized sites is not increased. We have investigated if surface-adsorbed monoclonal antibodies directed against endothelial cell membrane proteins and against extracellular matrix proteins promote the adhesion and proliferation of cultured human endothelial cells, without causing platelet deposition at non-endothelialized sites. Adhesion of endothelial cells onto polyethylene coated with monoclonal antibodies directed against endothelial cell-specific membrane antigens, integrin receptors and glycoprotein CD31 was equal to or higher than adhesion onto fibronectin-coated polyethylene. Endothelial cells did not proliferate on these surface-adsorbed antibodies. However, pre-coating of polyethylene with mixtures of endothelial cell-specific monoclonal antibodies and monoclonal antibodies directed against fibronectin or von Willebrand factor, resulted in relatively high adhesion and optimal proliferation. Platelet reactivity of the polyethylene surface was found to significantly increase after adsorption of fibronectin, endothelial cell-specific monoclonal antibody or its Fc fragments. In contrast, adsorption of F(ab')2 fragments of endothelial cell-specific monoclonal antibody did not promote platelet deposition. Therefore, it is concluded that coating of vascular graft materials with mixtures of F(ab')2 fragments of monoclonal antibodies specifically directed against endothelial cells and against extracellular matrix proteins may be an effective way to both promote the growth of seeded endothelial cells and limit platelet-graft interaction.

Adsorption↗