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M van der Weide

Publications and source records attributed to M van der Weide.

17 recordsLinked to original sources
PubMed2000

Molecular characterisation of the Theileria buffeli/orientalis group.

Benign bovine Theileria parasites known as either Theileria buffeli, Theileria orientalis or Theileria sergenti are classified on basis of their morphology, vector specificity, pathogenicity and 18S small subunit ribosomal RNA or major piroplasm protein (MPSP) sequences. Since most isolates have been characterized on only some of these criteria and the existing confusion in nomenclature, an analysis was performed on eight different isolates to combine 18S rRNA data with MPSP data and the results were compared with available biological parameters. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach for both genes was used in combination with reverse line blot hybridisation for the 18S rRNA gene. Both MPSP and 18S rRNA genes were cloned and sequenced from parasites displaying aberrant MPSP RFLP profiles. Phylogeny based on published and determined 18S rRNA and MPSP sequences did correlate within the same isolate but there was no obvious correlation between molecular and biological data. Based on these findings, we suggest that the appropriate name for all these parasites is Theileria buffeli. A more specific nomenclature should be assigned when new molecular markers may become available.

Animals↗
PubMed1999

Simultaneous detection of bovine Theileria and Babesia species by reverse line blot hybridization.

A reverse line blot (RLB) assay was developed for the identification of cattle carrying different species of Theileria and Babesia simultaneously. We included Theileria annulata, T. parva, T. mutans, T. taurotragi, and T. velifera in the assay, as well as parasites belonging to the T. sergenti-T. buffeli-T. orientalis group. The Babesia species included were Babesia bovis, B. bigemina, and B. divergens. The assay employs one set of primers for specific amplification of the rRNA gene V4 hypervariable regions of all Theileria and Babesia species. PCR products obtained from blood samples were hybridized to a membrane onto which nine species-specific oligonucleotides were covalently linked. Cross-reactions were not observed between any of the tested species. No DNA sequences from Bos taurus or other hemoparasites (Trypanosoma species, Cowdria ruminantium, Anaplasma marginale, and Ehrlichia species) were amplified. The sensitivity of the assay was determined at 0.000001% parasitemia, enabling detection of the carrier state of most parasites. Mixed DNAs from five different parasites were correctly identified. Moreover, blood samples from cattle experimentally infected with two different parasites reacted only with the corresponding species-specific oligonucleotides. Finally, RLB was used to screen blood samples collected from carrier cattle in two regions of Spain. T. annulata, T. orientalis, and B. bigemina were identified in these samples. In conclusion, the RLB is a versatile technique for simultaneous detection of all bovine tick-borne protozoan parasites. We recommend its use for integrated epidemiological monitoring of tick-borne disease, since RLB can also be used for screening ticks and can easily be expanded to include additional hemoparasite species.

Animals↗
PubMed1997

Detection of Theileria annulata by the PCR in ticks (Acari:Ixodidae) collected from cattle in Mauritania.

We report on the detection of Theileria annulata in infected Hyalomma ticks by the PCR using primers derived from the gene encoding the 30 kDa major merozoite surface antigen (TamsI-1). No inhibition of the PCR was observed and as little as 0.1 pg of parasite DNA, corresponding to 12 sporozoites, could be detected in non-infected tick DNA samples, spiked with T. annulata genomic DNA. Hyalomma dromedarii ticks, fed on a calf experimentally infected with T. annulata, were used to validate the PCR further. The infection rate in the adult ticks, fed as nymphs during the febrile reaction, was high (62%), dropped to zero for 1 day in tick batches that engorged after treatment with Butalex and increased to 30% 2 days later and 38% of the ticks acquired the infection after feeding as nymphs during a carrier state piroplasm parasitaemia of less than 0.1%. As an internal control, 16S tick rDNA sequences could be amplified from T. annulata-negative tick samples. Finally, 202 adult ticks from Mauritania, collected from zebu cattle carrying low levels of Theileria piroplasms, were tested by the PCR. Thirty-eight out of 52 (73%) and 17 out of 30 (57%) H. dromedarii from the Gorgol and Trarza regions, respectively and two out of 30 (7%) Hyalomma marginatum rufipes from the Gorgol region were positive. Hyalomma marginatum rufipes, Rhipicephalus evertsi evertsi and Rhipicephalus guilhoni from the Trarza region were negative. These findings confirm that H. dromedarii is the main vector of T. annulata in Mauritania and that the PCR is a useful method of determining the infection rates in ticks collected from cattle carrying low levels of T. annulata piroplasms.

Animals↗
PubMed1996

Expression of genes encoding two major Theileria annulata merozoite surface antigens in Escherichia coli and a Salmonella typhimurium aroA vaccine strain.

The genes, Tams1-1 and Tams1-2, encoding the 30-and 32-kDa major merozoite surface antigens of Theileria annulata (Ta), have recently been cloned and characterized. Both genes encode a protein of 281 amino acids (aa) containing a putative hydrophobic N-terminal signal peptide. Another hydrophobic stretch is predicted at the C terminus which probably functions to anchor the protein in the membrane of the merozoite and piroplasm. Here, we report the successful expression of both Tams1-1 and Tams1-2 in Escherichia coli (Ec) using gene fragments lacking both hydrophobic domains. Attempts to produce high amounts of the entire recombinant (re-) protein, or a fragment containing the N terminus only, were unsuccessful. This is presumably due to the toxicity of these re-proteins. The internal part of both genes was also expressed in Salmonella typhimurium (St) aroA vaccine strain SL3261. We employed a dual-plasmid expression system based on an invertible promoter and selected the most stable St construct in vitro using liquid cultures and a macrophage-like cell line. The re-Tams1-1 protein produced in Ec, as well as in St, was recognized by monoclonal antibody (mAb) 5E1 specific to the 30-kDa protein. Both re-Tams1-1 and re-Tams1-2 were recognized by Ta immune calf serum.

Animals↗
PubMed1995

Detection of Theileria annulata in blood samples of carrier cattle by PCR.

We report the detection of Theileria annulata, the causative agent of tropical theileriosis, by PCR in blood samples obtained from carrier cattle. The assay employs primers specific for the gene encoding the 30-kDa major merozoite surface antigen of T. annulata. A 721-bp fragment was amplified from blood samples taken monthly from calves experimentally infected with one of four different stocks of T. annulata originating in either Mauritania, Portugal, Spain, or Turkey. At the end of the experiment, five animals carried the infection for 12 months and two animals remained infected for 15 months. DNAs from six other Theileria species, T. parva, T. mutans, T. sergenti, T. buffeli, T. velifera, and T. taurotragi, were not amplified. Moreover, DNAs from four other hemoparasites (Anaplasma centrale, Anaplasma marginale, Babesia bovis, and Babesia bigemina) were also not amplified. As a control, primers derived from the small subunit rRNA gene of Theileria spp. amplified a 1.1-kb DNA fragment from all Theileria species examined but not from the other four hemoparasites. As few as two to three parasites per microliter of infected blood in a 50-microliters sample volume were detected by Southern or microplate hybridization with a T. annulata-specific cDNA probe. In addition, 92 field samples obtained from cattle in Spain were tested; 22% were positive in blood smears, 40% were positive by immunofluorescent antibody test, and 75% were positive for T. annulata by PCR. The method provides a useful diagnostic tool for detecting T. annulata carrier cattle.

Animals↗
PubMed1988

Myelodysplastic syndromes: analysis of morphological features related to the FAB-classification.

In a retrospective study of 96 patients with a myelodysplastic syndrome, the reproducibility of the French-American-British (FAB) classification was determined. Morphological abnormalities in peripheral blood and bone marrow were studied. Slides were reviewed by 3 examiners. All 3 observers agreed on morphological classification in 61% of cases, pairs of 2 in 64, 76 and 76%. The final diagnosis was refractory anaemia (RA) in 7 patients, acquired sideroblastic anaemia (AISA) in 2, chronic myelomonocytic leukaemia (CMML) in 31, refractory anaemia with excess of blasts (RAEB) in 34 and RAEB in transformation (RAEB-t) in 22. Dyserythropoiesis, dysgranulopoiesis and dysmegakaryopoiesis were found in all FAB subgroups. Dyserythropoiesis was significantly more frequently encountered in RAEB than in RAEB-t and CMML.

Adolescent↗
PubMed1988

Myelodysplastic syndromes: analysis of clinical and prognostic features in 96 patients.

In a retrospective study of 96 patients with a myelodysplastic syndrome the FAB classification, Bournemouth score and other parameters were correlated with leukaemic transformation and survival. Diagnosis was refractory anaemia (RA) in 7 patients, acquired idiopathic sideroblastic anaemia (AISA) in 2, chronic myelomonocytic leukaemia (CMML) in 31, refractory anaemia with excess of blasts (RAEB) in 34 and RAEB in transformation (RAEB-t) in 22. Median survival for all patients was 37 weeks (RA and AISA 103, CMML 67, RAEB 35, RAEB-t 27). Scoring according to the Bournemouth criteria showed significant differences in survival between groups A, B and C. Of the separate variables, only percentage of bone marrow blasts and haemoglobin level were prognostically significant. A modified scoring system based upon these two variables was even more discriminative. It proved to be particularly useful in CMML, a subtype with a wide range of survival times. Leukaemic transformation was seen in 39% (RA and AISA 0%, CMML 30%, RAEB 39%, RAEB-t 75%).

Bone Marrow↗
PubMed1988

Motility of leukaemic cells in acute leukaemia related to tumour mass, maturation and FAB classification.

In a group of 56 patients with acute leukaemia, the relation between leukaemic cell motility and peripheral leukaemic cell count, degree of organomegaly, maturation and FAB classification was investigated. Cell motility was studied by means of directly observed motility and scoring of handmirror cells and anti-HLA-capping. The percentage of moving cells in the peripheral blood was higher than in the bone marrow. A positive correlation was found between the percentage of moving cells in the peripheral blood and the peripheral leukaemic cell count. In acute myeloid leukaemia, the percentage of moving cells in the bone marrow and the degree of organomegaly were higher in the monoblastic groups than in the myeloblastic groups. No correlation was found between directly observed motility, handmirror cells and capping. Leukaemic cell motility can play a role in the egress of leukaemic cells from the bone marrow, resulting in a higher tumour mass, thereby influencing prognosis.

Acute Disease↗
PubMed1987

Relation between leukaemic cell count and degree of maturation in acute myeloid leukaemia.

In acute myeloid leukaemia the peripheral leukocyte count is known to be a prognostic factor. The preserved capacity of leukaemic cells to mature has also been suggested to be one. In a series of 179 cases of adult acute myeloid leukaemia peripheral leukaemic cell count and degree of maturation were found to be inversely correlated. As the degree of maturation of leukaemic cells in peripheral blood was lower than that in bone marrow in the majority of cases, blast cells appear to be released more easily from the marrow than cells that have matured to some extent in the direction of the larger promyelocytic or promonocytic cell type. In a series of 35 cases we found peripheral blast cells to be smaller than those in bone marrow. Moreover, central blast cell diameter and peripheral leukaemic cell count were inversely correlated. Therefore, leukaemic cell size or some factor related to it may contribute to the preferential egress of small immature cells from the marrow. Differences in proliferative activity could not account for the inverse correlation between degree of maturation and leukaemic cell count.

Adult↗
PubMed1985

Maturation changes in relapsing acute myeloid leukaemia.

Smears of peripheral blood and bone marrow from 17 patients with acute myeloid leukaemia in relapse were compared with smears made at presentation. We found a change of more than 10 in Maturation Index (MI) in the bone marrow smears of 14 out of 17 patients (82%). Decreases and increases were equally represented. In 5 cases the changes caused assignment to another FAB-group.

Adult↗
PubMed1980

Two patients with recurrent pneumonias in one lung.

Case histories are described of two young patients, both known to have recurrent infections of one pulmonary lobe. Further investigations (especially aortography) disclosed the cause in both to be an intrapulmonary sequestration. Surgical intervention made both patients symptom-free. The aetiology, clinical and investigational findings as well as therapy are discussed. The need for further investigations in patients with recurring infections of one pulmonary lobe is stressed.

Adolescent↗