Biomedical subjects

N de Jonge

Publications and source records attributed to N de Jonge.

45 records · Page 3Linked to original sources

PubMedDate not supplied

Time-resolved immunofluorometric assay (TR-IFMA) for the detection of the schistosome circulating anodic antigen.

We report the development of a time-resolved immunofluorometric assay (TR-IFMA) for the quantitative determination of the schistosome circulating anodic antigen (CAA). A mouse monoclonal antibody (line 120-1B10-A), recognizing a repetitive epitope on CAA, was used as both antigen-capture antibody and as Europium-labelled antigen-detecting antibody. The lower detection limit of the assay was 20 pg of trichloroacetic acid soluble fraction of adult worm antigen (AWA-TCA) per ml, with a nearly linear measuring range from 20 pg to 130 ng AWA-TCA per ml. The TR-IFMA was compared with an enzyme-linked immunosorbent assay (ELISA), in which the same monoclonal antibody was used as antigen-capture antibody and as alkaline phosphatase-conjugated antibody. The lower detection limit of the TR-IFMA was tenfold lower than that of the ELISA, while the linear range of the TR-IFMA exceeded that of the ELISA one hundred-fold. Serum samples of 80 Burundese individuals infected with Schistosoma mansoni (egg counts ranging from 4 to 2583 eggs per gram of faeces) were tested in both assays. Antigen concentrations in serum of individuals infected with S. mansoni ranged from 0-500 ng AWA-TCA per ml. The correlation between antigen levels measured by TR-IFMA and ELISA was good: Spearman's p = 0.92. Whereas in the ELISA the samples had to be titrated, the wide linear range of the TR-IFMA allowed the assay to be performed at a single serum dilution, at which an exact estimation of the antigen concentration was possible.

Adolescent↗

PubMedDate not supplied

Circulating anodic antigen levels in serum before and after chemotherapy with praziquantel in schistosomiasis mansoni.

The kinetics of serum levels of circulating anodic antigen (CAA) of Schistosoma mansoni were studied in patients with intestinal schistosomiasis before and after treatment with praziquantel. Day to day fluctuation in faecal egg excretion was compared with fluctuation in antigen level in 20 patients by serum and stool examination on 3 consecutive days before treatment. Antigen levels - calculated either as absorbance value of undiluted serum or as titre - showed less fluctuation than the number of eggs per gram of faeces determined by stool examinations based on single or duplicate 25 mg Kato smears. Compared with a placebo control group of 11 individuals, there was a significant reduction in CAA level in serum of 10 patients treated with praziquantel (40 mg/kg), 10 weeks after treatment. A similar decrease in serum CAA level was observed in a group of 46 patients treated with praziquantel, 6 weeks after treatment. In both groups, patients who remained seropositive after treatment still excreted eggs in their faeces. The kinetics of the antigen decrease were studied in more detail in 20 patients in hospital. Within 10 d after treatment with a double dose of 40 mg praziquantel per kg body weight, the antigen level fell to less than 10% of the original serum level, with a CAA half-life of approximately 2 d.

Animals↗

PubMedDate not supplied

Detection of the schistosome circulating cathodic antigen by enzyme immunoassay using biotinylated monoclonal antibodies.

We have developed an enzyme immunoassay (ELISA) for the quantification of the schistosome circulating cathodic antigen (CCA), a glycoprotein associated with the syncitium lining the gut of the parasite. A mouse monoclonal antibody of IgG3 isotype was used as coating (antigen-capture) antibody, while a biotinylated mouse monoclonal IgM was used as second (antigen-detecting) antibody. Streptavidin-alkaline phosphatase was used as enzyme label. The lower detection limit of the assay was 1.0 ng of the trichloroacetic acid soluble fraction of adult worm antigen (AWA-TCA) per ml, which corresponds to approximately 0.2 ng CCA per ml. The ELISA showed a linear range from 1.0 to 62.5 ng AWA-TCA per ml. Serum and urine samples of 16 individuals infected with Schistosoma mansoni (egg counts ranging from 5 to 4820 eggs per gram of faeces) were tested in the assay. Antigen titres ranged from less than 4-8192. This assay represents a considerable advantage in diagnosis of Schistosoma infections as it allows the detection and quantification of CCA in serum and urine in even lightly infected individuals.

Animals↗

PubMedDate not supplied

Quantitative detection of schistosomal circulating anodic antigen by a magnetic bead antigen capture enzyme-linked immunosorbent assay (MBAC-EIA) before and after mass chemotherapy.

The magnetic bead antigen capture enzyme-linked immunosorbent assay (MBAC-EIA) has been applied to detect schistosomal circulating anodic antigen (CAA) in pre- and post-treatment sera from 55 individuals in a Schistosoma mansoni control project in the Blue Nile valley of western Ethiopia. The amounts of CAA detected by this assay were positively correlated with the numbers of eggs per gram of faeces (epg). A significant reduction in CAA levels as measured by the MBAC-EIA was observed after mass chemotherapy. The sensitivity was 88-89% in clinically significant cases excreting more than 100 epg. In light infections, however, the sensitivity was lower. None of 32 uninfected Norwegian blood donors or 12 Ethiopian immigrants to Norway were positive. The specificity was thus estimated to be 100%. The test is rapid (1-2 h) and simple to perform without sophisticated equipment and could therefore, with slight modification, be used as a reliable method of diagnosis at field level in endemic areas undergoing mass chemotherapy campaigns or population surveys.

Animals↗

PubMedDate not supplied

Quantitative determination of circulating anodic and cathodic antigens in serum and urine of individuals infected with Schistosoma intercalatum.

Circulating anodic and cathodic Schistosoma antigens (CAA and CCA) have been determined by enzyme immunoassays in serum and urine of 60 individuals infected with S. intercalatum in Equatorial Guinea. The median egg output was 29 eggs/g of faeces (range 3-840). The egg output strongly correlated with concentrations of serum CAA (p = 0.47) and urine CAA (p = 0.42) (P < 0.001 for both); the later 2 quantities were also correlated with each other (p = 0.44, P < 0.001). All except 3 infected individuals had detectable amounts of serum CAA and/or urine CCA, a sensitivity of 95% for these 2 tests combined. Urine CAA was detected in 43% of patients. Serum CCA was detected in all infected individuals; however, no significant correlation was obtained between serum CCA levels and egg output in the stools of individual patients. This is the first study to demonstrate CCA in specimens of patients infected with S. intercalatum. The detection of CCA in urine is a new, non-invasive diagnostic method for S. intercalatum infection.

Adolescent↗

PubMedDate not supplied

Field emission from individual multiwalled carbon nanotubes prepared in an electron microscope.

Individual multiwalled carbon nanotube field emitters were prepared in a scanning electron microscope. The angular current density, energy spectra, and the emission stability of the field-emitted electrons were measured. An estimate of the electron source brightness was extracted from the measurements. The results show that carbon nanotubes are promising candidates to replace existing sources in high-resolution electron beam instruments.

Journal Article↗

PubMedDate not supplied

Ventricular fibrillation during acute rejection after heart transplantation.

The case of a 46-year-old patient who underwent orthotopic heart transplantation for treatment of end-stage heart failure as a result of ischemic heart disease is reported. Four months after transplantation a grade II rejection episode was complicated by ventricular fibrillation. Lidocaine and procainamide intravenously did not effectively prevent recurrence. An increase of antirejection therapy in combination with flecainide acetate effectively prevented further episodes of ventricular fibrillation. This case demonstrates that recurrent ventricular fibrillation can be a complication of acute rejection.

Electrocardiography↗

PubMedDate not supplied

Cytoimmunologic monitoring as an adjunct in monitoring rejection after heart transplantation: results of a 6-year follow-up in heart transplant recipients.

The cytoimmunologic monitoring assay has been proposed as a useful noninvasive technique in the diagnosis of rejection and infection after heart transplantation. In this study, we have analyzed the diagnostic usefulness of cytoimmunologic monitoring in 73 patients after heart transplantation. For individual patients, the follow-up varied between 2 and 78 months. Data were related to histopathologic characteristics of the endomyocardial biopsy. Significantly different cytoimmunologic monitoring results were not observed between groups according to endomyocardial biopsy histopathologic evaluation. The diagnostic usefulness of cytoimmunologic monitoring depended on the cutoff value applied. With higher cutoff values, the sensitivity decreased and the specificity and predictive value increased. For the previously reported cutoff value of 5%, the sensitivity was 0.29, the specificity was 0.73, and the predictive value was 0.66. Values of sensitivity, specificity, and predictive value were similar when only the first acute rejection was taken into account, or when only data on the first 4 weeks and the first 6 months after transplantation were considered. In calculating the diagnostic usefulness of the sensitivity, specificity, and predictive values were observed. We concluded that cytoimmunologic monitoring has a limited value for diagnosing acute rejection after heart transplantation.

Acute Disease↗

PubMedDate not supplied

Cytotoxic T lymphocytes infiltrating the human cardiac allograft show a restriction in T-cell receptor V beta gene usage: a study on serial biopsy and blood specimens.

T lymphocytes were propagated in vitro from endomyocardial biopsy specimens that were obtained weekly from four patients during the first 2 to 3 months after heart transplantation. The culture was performed in the presence of recombinant interleukin-2 and interleukin-4, with or without mitogen, in which especially CD8+ donor-specific cytotoxic T cells expanded. These cells, presumably reflecting an in vivo activated population, could even be cultured from biopsy specimens without histopathologic signs of rejection. A preferential expression of T cell receptor V beta gene families was found in these T-cell lines. This finding is in contrast with the heterogenous expression in peripheral blood T cells of the same patient. The restriction in V beta gene family expression was substantiated in the evaluation of clones obtained from two cell lines. Among 17 donor-specific cytotoxic T-cell clones derived from one cell line, only four V beta gene families were expressed. All five clones from the other cell line used the V beta 8 family. Some clones expressing a distinct V beta gene family used the same V-D-J junction sequence, indicative of their origin from the same precursor. With the use of oligonucleotide probes complementary to clone-specific V-D-J junction sequences, four of five clones were detected not only in the parent T-cell line but also in T-cell lines derived from biopsy specimens with rejection reactions taken 1 week earlier and 2 weeks later and in blood cells taken before and 0.5, 3, and 6 months after transplantation; these clones were not detected in blood cells harvested 12 months after transplantation. This study showed a restricted usage of the V beta gene families by activated donor-specific cytotoxic T lymphocytes in the heart transplant.

Antigens, CD↗