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Biomedical subjects

N de Vries

Publications and source records attributed to N de Vries.

At least 55 records · Page 3Linked to original sources
PubMed1993

Correlation between antibodies to Cowdria ruminantium (rickettsiales) in cattle and the distribution of Amblyomma vector ticks in Zimbabwe.

Cowdriosis, caused by Cowdria ruminantium, is transmitted by Amblyomma ticks, which are widely distributed in Zimbabwe. To assess the distribution of this disease in Zimbabwe, cattle either exposed to Amblyomma ticks or maintained in areas free from these ticks were tested for antibodies to Cowdria. A total of 324 sera were tested using competitive ELISA and the indirect fluorescent antibody test (IFAT). At diptanks in Amblyomma-infested areas 52% (n = 95) and 26% (n = 47) of sera were positive by cELISA and IFAT, respectively. At diptanks in Amblyomma-free areas 11% (n = 125) and 10% (n = 134) of sera were positive by cELISA and IFAT, respectively. The results were significantly different between Amblyomma-infested and tick-free areas (chi 2 = 24.73, P < or = 0.005 for IFAT and chi 2 = 57.53, P < or = 0.005 for cELISA). High background readings in field sera, possibly due to cross-reactive antibodies to Ehrlichia spp., complicated the determination of a realistic cut-off point, especially in cELISA. On the basis of the distribution of Amblyomma ticks, currently a large part of Zimbabwe can be considered endemic for the disease.

Animals↗
PubMed1993

The value of twice yearly bronchoscopy in the work-up and follow-up of patients with laryngeal cancer.

The aim of this retrospective study was to investigate the usefulness and feasibility of twice-yearly bronchoscopy and sputum cytology in patients with laryngeal cancer. In 170 selected patients, 500 (both initial and during follow-up) bronchoscopies were performed. There was a maximum follow-up of 34 months. 5 (2.8%) male patients developed lung cancer. In only 2 of them was the diagnosis based on bronchoscopy alone. After treatment with curative intent, both patients developed a recurrent lung carcinoma. According to most patients' experience, regular bronchoscopy is unpleasant. It is concluded that twice-yearly bronchoscopy and sputum cytology in patients with laryngeal cancer is not useful as a routine procedure. At present, chemoprevention of second primary tumours seems the most promising adjunctive treatment modality.

Adult↗
PubMed1993

HLA-DR1 and rheumatoid arthritis in Israeli Jews: sequencing reveals that DRB1*0102 is the predominant HLA-DR1 subtype.

Rheumatoid arthritis (RA) is associated with the HLA-DR4 cellular subtypes Dw4 and Dw14 in Caucasians, with Dw15 in Japanese, and possibly with HLA-DR1 in Israeli Jews. Sequencing studies in Caucasians have shown that these molecules share a common amino acid sequence in the third hypervariable region of the DR molecule (AA 67-74: LLEQRRAA or LLEQKRAA), suggesting that this sequence is primarily associated with RA. An important argument in favor of this shared-epitope hypothesis has been the reported association between DR1 and RA in Israeli Jews. However, a later report did not confirm this association, and cellular typing showed that Israeli DR1 consists of three or more subtypes, suggesting that new subtypes might be present. Since no sequencing data on Israeli HLA-DR1 genes have been reported, we sequenced the first domain (AA 10-91) of the DRB1 gene in 12 DR1-positive Israeli RA patients, 5 healthy controls and a homozygous typing cell (HTC), defining the major Jewish cellular HLA-DR1 subtype. DRB1*0102 (DR1 Dw20) was found in 8 RA patients, 3 controls and the HTC "LVA". DRB1*0101 (DR1 Dw1) was found in 4 RA patients and 2 controls. No other DR1 subtypes were encountered. In all 20 DR1 haplotypes, the DRB1*0101 or 0102 allele was associated with DQA1*0101 and DQB1*0501, being identical to the Caucasian DR1 haplotypes. Thus, at the sequence level, we found no basis for the reported extensive cellular heterogeneity of DR1 in the Israeli population.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1993

A T cell receptor beta chain variable region polymorphism associated with radiographic progression in rheumatoid arthritis.

OBJECTIVE: In rheumatoid arthritis (RA) genetic factors influence susceptibility to disease and progression. Identifying these genetic factors may give more insight into the aetiology and pathogenesis of this disease. Furthermore, if these genetic markers can predict progression in an early stage of disease, timely institution of more aggressive treatment in patients with a bad prognosis may help to prevent joint damage. Several studies have shown that HLA-DRB1 alleles are associated with RA, whereas others have indicated that genes not linked to the HLA complex are also involved. Candidates for such genes are the T cell receptor (TCR) alpha/beta genes. METHODS: The association of a polymorphism in a TCR beta chain variable region gene (TCR-V beta 8) with both risk for RA and radiographic progression of joint disease was analysed after a three year follow up. A cohort of 118 white patients with a duration of disease shorter than one year at entry, and 110 white controls were typed for this (BamHI) TCR-V beta 8 polymorphism. RESULTS: The distribution of the two alleles, 2.0 and 23.0 kb, was identical in patients and controls. Radiographic progression (modified Sharp method) after a three year follow up, studied in 111 patients, was significantly less in the group possessing the 2.0 kb allele (p = 0.03). CONCLUSION: This does not confirm the reported association of the (BamHI) TCR-V beta 8 2.0 kb allele with RA. By contrast with previous findings in smaller studies, in the present study this 2.0 kb allele was protective against radiographic progression. Because well known prognostic variables in RA were corrected for, the findings indicate that the TCR-V beta 8 polymorphism studied is a new prognostic marker for this disease.

Alleles↗
PubMed1993

The immunodominant 32-kilodalton protein of Cowdria ruminantium is conserved within the genus Ehrlichia.

Serological tests for cowdriosis are hampered by cross-reacting antibodies from animals suspected to be infected with Ehrlichia species. We have monitored infections with Ehrlichia bovis, E. ovina, E. canis and E. phagocytophila in experimental animals by competitive ELISA, Western blotting and immunofluorescence using Cowdria-infected endothelial cell culture antigens. Cross-reactions due to Ehrlichia antibodies could be attributed to the recognition of epitopes on the immunodominant Cr32 Cowdria protein. This was especially true for E. canis and E. ovina, much less for E. bovis, but not at all for E. phagocytophila. In addition, strong cross-reactivity between Cowdria and antibodies to E. Chaffeenis were demonstrated. These findings are in agreement with the phylogenetic relationships, recently reported by van Vliet et al. in 1992, between Cowdria and other members of the tribe Ehrlichieae, which showed Cowdria to be closely related to E. canis and also to E. chaffeensis. Although the tests used in this study remain valuable tools under laboratory conditions, their specificity requires improvement. It is suggested to study recombinant Cowdria antigens for the development of second generation serological tests for cowdriosis.

Animals↗
PubMed1992

Complications of endoscopic sinus surgery.

Endoscopic sinus surgery has become popular during recent years. We report the complications of endoscopic sinus surgery in 593 patients in whom 1235 sides were operated on. Forty-five patients had complications, in three of whom they were systemic. The remaining 42 patients had complications on 52 (4.2%) sides; these complications were mostly minor. In 0.3% of the sides operated on, potentially serious complications, such as orbital hematoma or cerebrospinal fluid leak, were seen. None of these patients developed loss of vision or meningitis. Absence of the middle turbinate is a risk factor for developing complications. We conclude that endoscopic sinus surgery is a safe procedure in experienced hands.

Adolescent↗
PubMed1992

Autoantibodies against constituents of neutrophils in the diagnosis and treatment of (isolated) subglottic stenosis.

Six patients had a subglottic stenosis either as a presenting symptom or as a manifestation of a systemic disease. All patients had in common the presence of circulating autoantibodies against constituents of neutrophils on indirect immunofluorescence. Cytoplasmic and perinuclear staining patterns were recognized. Such autoantibodies have been reported in Wegener's granulomatosis, microscopic polyarteritis, (idiopathic) glomerulonephritis, and Churg-Strauss syndrome. However, only one of the six patients fulfilled the criteria for these conditions. Because a positive test for autoantibodies against constituents of neutrophils is rare in other conditions and because other diseases had been excluded, we suggest that this places subglottic stenosis within the spectrum of necrotizing (granulomatous) vasculitis. The consequences for therapy are discussed.

Adolescent↗
PubMed1992

Second primary tumours in laryngeal cancer.

Second primary tumours develop in 3.8-20.5% of patients with laryngeal cancer. 2.2-15.3% of those occur in the upper aerodigestive tract, 1.1-12% in the lungs. More second tumours occur in supraglottic than in glottic cancer and more in males than in females. Both tobacco and alcohol are important risk factors. Second primary tumours usually carry a bad prognosis. Two approaches are possible to combat the problem: early detection and (chemo-)prevention. The largest chemoprevention study in head and neck cancer patients is EUROSCAN. Preliminary data of the study will be presented.

Acetylcysteine↗
PubMed1991

Circulating anti-neutrophil cytoplasmic autoantibodies in subglottic stenosis: a useful aid in diagnosing vasculitis in this condition?

Five patients with subglottic stenosis, occurring either as a presenting symptom or as a manifestation in the course of a systemic disease, are described. Indirect immunofluorescence revealed the presence of circulating autoantibodies against both cytoplasmic and perinuclear constituents of neutrophils in all five. Antibodies directed against a 29 kDa antigen of the azurophilic granules (two patients), against myeloperoxidase (one patient), and against both the 29 kDa antigen and myeloperoxidase (one patient) were found by enzyme-linked immunosorbent assay. These autoantibodies have previously been found in patients with Wegener's granulomatosis, microscopic polyarteritis, (idiopathic) glomerulonephritis and Churg-Strauss syndrome. However, only one of these five patients fulfilled the criteria for these conditions. Since these autoantibodies are seldom observed in other conditions, and other diseases had been excluded by careful evaluation, we suggest that their presence places subglottic stenosis within the spectrum of necrotizing (granulomatous) vasculitis. Whether immunosuppressive therapy is always warranted in patients with subglottic stenosis and circulating anti-neutrophil cytoplasmic antibodies is a matter of debate.

Adolescent↗