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Biomedical subjects

M A de Jong

Publications and source records attributed to M A de Jong.

14 recordsLinked to original sources
PubMed2005

Closed system generation of dendritic cells from a single blood volume for clinical application in immunotherapy.

Dendritic cells (DC) used for clinical trials should be processed on a large scale conforming to current good manufacturing practice (cGMP) guidelines. The aim of this study was to develop a protocol for clinical grade generation of immature DC in a closed-system. Aphereses were performed with the Cobe Spectra continuous flow cell separator and material was derived from one volume of blood processed. Optimisation of a 3-phase collection autoPBSC technique significantly improved the quality of the initial mononuclear cell (MNC) product. Monocytes were then enriched from MNC by immunomagnetic depletion of CD19+ B cells and CD2+ T cells and partial depletion of NK cells using the Isolex 300I Magnetic cell selector. The quality of the initial mononuclear cell product was found to determine the outcome of monocyte enrichment. Enriched monocytes were cultured in Opticyte gas-permeable containers using CellGro serum-free medium supplemented with GM-CSF and IL-4 to generate immature DC. A seeding concentration of 1 x 10(6) was found optimal in terms of DC phenotype expression, monocyte percentage in culture, and cell viability. The differentiation pattern favours day 7 for harvest of immature DC. DC recovery, viability, as well as phenotype expression after cryopreservation of immature DC was considered in this study. DC were induced to maturation and evaluated in FACS analysis for phenotype expression and proliferation assays. Mature DC were able to generate an allogeneic T-cell response as well as an anti-CMV response as detected by proliferation assays. These data indicate that the described large-scale GMP-compatible system results in the generation of stable DC derived from one volume of blood processed, which are qualitatively and quantitatively sufficient for clinical application in immunotherapeutic protocols.

Adoptive Transfer↗
PubMed2003

Postoperative radiotherapy in squamous cell carcinoma of the oral cavity: the importance of the overall treatment time.

PURPOSE: To test the hypothesis that (1) the distinction between intermediate- and high-risk patients by clustering different prognostic factors results in a significant difference in treatment outcome and (2) a shorter interval between surgery and radiotherapy and shorter overall treatment times of radiation (OTTRT) result in higher rates of locoregional control (LRC). METHODS AND MATERIALS: Included were patients (n = 217) with previously untreated squamous cell carcinoma of the oral cavity treated with radical surgery and postoperative radiotherapy. Patients with extranodal spread or microscopic residual disease and patients with two or more other risk factors (i.e., N2b-N3, >1 nodal level involved, perineural growth, or stage T3-T4) were classified as high-risk patients. Patients with only one other risk factor were classified as intermediate risk. RESULTS: In the intermediate-risk group, the 3-year LRC was 87% as compared with 66% in the high-risk group (p = 0.0005). No association was found between interval and LRC. However, the OTTRT was significantly associated with LRC. The 3-year LRC was 87%, 75%, 69%, and 51% when the OTT was <6 weeks, 6-7 weeks, 7-8 weeks, and >8 weeks, respectively (p = 0.0004). The 3-year overall survival (OS) in the intermediate risk patients was 74% compared with 50% in the high-risk group (p = 0.0014). A significant association was also found between the OS and OTTRT. The OS increased from 50% when the OTTRT was >8 weeks to 74% when the OTT was <6 weeks (p = 0.006). Similar results were found with regard to the disease-free survival (DFS). In the multivariate analysis, both risk group and OTT were significantly associated with LRC, DFS, and OS. No significant interaction term was present between these two factors, which means that the OTT was of importance both for the high-risk and the intermediate-risk patients. CONCLUSION: In the subset of patients with carcinoma of the oral cavity, the classification of high- and intermediate-risk patients by clustering a number of prognostic factors provides important prognostic information regarding LRC, DFS, and OS. The OTT was the most important prognostic factor both in the high-risk and intermediate-risk patients. Reducing the OTT to 6 weeks or less is a rather simple measure to achieve a considerable improvement of the outcome of treatment in this category of patients.

Adult↗
PubMed2001

Resistance of activated human Th2 cells to NO-induced apoptosis is mediated by gamma-glutamyltranspeptidase.

Activation-induced death of inflammatory cells (AICD) has an important function in immune maintenance. Type 1 Th cells are known to be more susceptible to AICD than Th2 cells. In the current study we examined whether NO-induced apoptosis also preferentially eliminates Th1 cells over Th2 cells. Naive human Th lymphocytes (CD4(+)CD45RO(-)) were activated in vitro for 1 week in the presence of IL-12 plus anti-IL-4 or IL-4 plus anti-IL-12 to generate Th1- and Th2-polarized cultures respectively. Cultures were exposed to the NO donors Spermine-nonoate (Sper) and DPTA-nonoate to study NO-induced apoptosis. We found that NO preferentially induced apoptosis in Th1-polarized cells as demonstrated by Annexin staining in the presence of 10 microM Sper (70 +/- 16 versus 23 +/- 4.4% in Th2 cells P: < 0.01) and by DioC6 staining (38 +/- 10 versus 11 +/- 5% in Th2 cells, P: < 0.01). The mechanism of NO-induced apoptosis in Th1/Th2-polarized cells was distinct from AICD and Fas-induced apoptosis. Differential sensitivity between Th1- and Th2-polarized cultures originated at the level of intracellular glutathione (GSH) metabolism. GSH levels were higher in Th2 cells (1.6 +/- 0.2-fold Th1, P: < 0.01). High intracellular GSH in Th2-polarized cells did not account for reduced susceptibility to NO per se, since the inhibition of gamma-glutamyltrans-peptidase (gamma-GT), which is involved in GSH import, sensitized Th2 cells to NO-induced apoptosis without GSH depletion. Therefore, higher activity of gamma-GT in Th2 cells (2.1 +/- 0.4-fold Th1, P: < 0.001) specifically protects Th2 cells against NO-induced apoptosis. Preferential NO-induced elimination of human Th1 cells at sites of inflammation may thus select Th2 cells and contribute to immune deviation.

Apoptosis↗
PubMed2000

Clinical significance of anti-neutrophil cytoplasmic antibodies (ANCA) in autoimmune liver diseases.

BACKGROUND/AIMS: The clinical relevance of anti-neutrophil cytoplasmic antibodies (ANCA) in autoimmune liver disease is unclear. Defining the antigenic specificities of ANCA in these diseases may improve their clinical significance. METHODS: We studied the target antigens of ANCA in 88 patients with autoimmune hepatitis, 53 patients with primary biliary cirrhosis, and 55 patients with primary sclerosing cholangitis by indirect immunofluorescence, antigen-specific enzyme-linked immunosorbent assays, and immunodetection on Western blot, using an extract of whole neutrophils as a substrate. We related the data to clinical symptoms of autoimmune liver disease. RESULTS: By indirect immunofluorescence, ANCA were present in 74% of patients with autoimmune hepatitis, 26% of patients with primary biliary cirrhosis, and 60% of patients with primary sclerosing cholangitis. Major antigens were catalase, alpha-enolase, and lactoferrin. The presence of ANCA as detected by indirect immunofluorescence was associated with the occurrence of relapses in autoimmune hepatitis, with decreased liver synthesis function in primary biliary cirrhosis and in primary sclerosing cholangitis, and with increased cholestasis in primary sclerosing cholangitis. ANCA of defined specificities had only limited clinical relevance. CONCLUSIONS: ANCA as detected by indirect immunofluorescence seem associated with a more severe course of autoimmune liver disease. The target antigens for ANCA in these diseases include catalase, alpha-enolase, and lactoferrin. Assessment of the antigenic specificities of ANCA in autoimmune liver disease does not significantly contribute to their clinical significance.

Adolescent↗
PubMed1999

High dose thrombin time versus the activated clotting time during cardiopulmonary bypass.

In this study we compared the High Dose Thrombin Time (HiTT) with the Activated Clotting Time (ACT) during cardiopulmonary bypass (CPB) in non-aprotinin treated patients. On the advice of the HiTT test manufacturer each institution should perform comparative ACT/HiTT assays in the cardiac surgery population. In previous tests our target ACT value of 480 seconds corresponds with a mean HiTT value of 190 seconds. Our results showed that after heparinization (300-400 IU/kg body weight) 8 out of 20 patients did not reach the target ACT of 480 seconds, while the HiTT results in those 8 patients were higher than our target time of 190 seconds. Four heparin pretreated patients who received 400 IU/kg heparin, had relatively low ACT values (467 +/- 14 sec.) and high HiTT values (324 +/- 47 sec.). Before and during CPB there was a poor correlation between the HiTT and ACT (r = 0.38). The results of this study show that for the individual patient the target HiTT of 190 seconds is no guarantee for reaching an adequate ACT of 480 seconds. Although the HiTT may be a very useful assay for monitoring heparin effects during CPB, the determination of the target time can be a point of discussion. In contrast of the advice of the manufacturer we therefore suggest that comparative ACT/HiTT assay should be done in every individual patient to determine a safe target HiTT time, instead of the whole group of patients.

Adult↗
PubMed1994

Attitudes towards high-fat foods and their low-fat alternatives: reliability and relationship with fat intake.

Score on a scale of attitude towards the consumption of five high-fat foods and their low-fat alternatives was correlated with the energy percentage of fat in the diet across 419 subjects. Attitudes towards low-fat alternatives were more positive than towards high-fat foods. Mean energy percentage of fat in the diet was 38.8% (SD 7.1). The attitude scale explained 25% of the variance in percentage energy as fat. Test-retest reliability of the attitude scale (n = 25) was 0.92 (95% confidence limits 0.82 and 0.97). The reproducibility of energy percentage fat in the diet (n = 33) was 0.64 (95% confidence limits 0.38 and 0.81). Differences in attitude score were found between men and women, subjects following a dietary treatment and those who did not, and subjects with a fat intake according to the Dutch dietary guidelines and those who had not (p < 0.001). Fat intake (expressed as percentage of energy intake) differed between age groups (p < 0.05), and between subjects following a special diet and those who did not (p < 0.001). No difference in attitude score or energy percentage of fat was found for education level, occupation level, body mass index or household size. It is concluded that attitudes towards high-fat foods and their low-fat alternatives are useful in understanding fat intake.

Adolescent↗
PubMed1992

Proliferative lymphocyte responses to foot-and-mouth disease virus and three FMDV peptides after vaccination or immunization with these peptides in cattle.

We studied proliferative responses of bovine T lymphocytes to foot-and-mouth disease virus (FMDV) serotypes A, O and C as well as to three peptides including the two major B-cell epitopes of FMDV (VP1[141-156] and VP1[200-213]). Peripheral blood mononuclear cells (PBMC) from cattle previously vaccinated with monovalent vaccine responded to both homotypic and heterotypic virus strains. Of 14 FMDV-specific bovine T-cell clones, which were prepared from PBMC of an animal vaccinated with the trivalent vaccine, 11 reacted to each of the three serotypes A, O and C. This indicates that several T-cell epitopes might be conserved among these serotypes. PBMC from one of two cattle immunized with VP1[141-156]KLH, one of two cattle immunized with VP1[200-213]KLH and two of three cattle immunized with CC-VP1[200-213]-PPS-VP1[141-156]-PCG responded to the homotypic virus strain. After immunizations with VP1[200-213]KLH also heterotypic responses were found. Thus, it appears that these two B-cell sites include T-cell determinants that are recognized by some cattle. However, when proliferative responses of PBMC from an animal vaccinated with the trivalent vaccine were tested, no responses were found to VP1[141-156] and VP1[200-213], whereas the response was very poor to CC-VP1[200-213]-PPS-VP1[141-156]-PCG. These results suggest that these sequences do not represent dominant T-cell epitopes and/or that T-cell reactivity towards these synthetic peptides does not completely cover the T-cell reactivity towards the fragments present after processing of the whole virus.

Animals↗
PubMed1980

Correlation between size and age at different events in the cell division cycle of Escherichia coli.

The variability of (i) the B period between birth and initiation of chromosome replication, (ii) the U period between initiation of chromosome replication and initiation of cell constriction, and (iii) the interdivision period (tau) have been estimated for slowly growing Escherichia coli B/r F. Cultures synchronized by the membrane elution technique were pulse-labeled with [3H]thymidine or continuously labeled with [3H]thymine. After fixation, the pattern of deoxyribonucleic acid replication was analyzed by electron microscopic radioautography. Cell length was found to increase exponentially with age at two different slow growth rates. The coefficient of variation of the B period was estimated to be 60%, that of the U period was 29%, and that of the interdivision period was 12%. From these values and the coefficient of variation of length at different cell cycle events were calculated a negative correlation between the B and U period (r = -0.9) and a positive correlation between length at birth and cell separation (r = 0.6). Initiation of chromosome replication and cell constriction were strictly correlated both with respect to age (r = 0.7) and length (r = 0.8). On the other hand, length at initiation of chromosome replication was distantly correlated with age (r = 0.1) or length at birth (r = 0.3). This low correlation excludes a model in which chromosome initiation is controlled by a random event in the B period. It favors a model in which chromosome initiation occurs at a particular distributed size independent of cell division.

Cell Cycle↗
PubMed1977

Morphological analysis of the division cycle of two Escherichia coli substrains during slow growth.

Morphological parameters of the cell division cycle have been examined in Escherichia coli B/r A and K. Whereas the shape factor (length of newborn cell/width) of the two strains was the same at rapid growth (doubling time, tau, less than 60 min), with decreasing growth rate the dimensions of the two strains did change so that B/r A cells became more rounded and B/r K cells became more elongated. The process of visible cell constriction (T period) lasted longer in B/r A than in B/r K during slow growth, reaching at tau = 200 min values of 40 and 17 min, respectively. The time between termination of chromosome replication and cell division (D period) was found to be longer in B/r A than in B/r K. As a result, in either strain completion of chromosome replication seemed always to occur before initiation of cell constriction. Nucleoplasmic separation did not coincide with termination as during rapid growth but occurred in both strains within the T period, about 10 min before cell division.

Cell Division↗
PubMed1975

Hypnosis, stimulus preference and autonomic response.

We investigated whether stimuli consisting of beautiful and ugly colours as judged by human subjects elicit different autonomic response patterns. The autonomic functions recorded were heart rate (HR) respiration rate, skin conductance, number of GSFs (nGSR) and also eye movements, as an index of somatic activity. In order to obtain strong responses, i.e. to avoid inhibition of 'natural' responses by anxiety due to the laboratory setting, we made use of post-hypnotic suggestions regarding the nature of the stimuli the subjects were to expect. It appeared that for all but one autonomic function differences could be found between beautiful and ugly stimuli, in the sense that during the ugly stimuli more 'activation' occurred. The direction of HR change during the beauriful stimuli was opposite to those of the other functions. Effect of hypnosis on autonomic response could be substantiated for HR and nGSR. Apart from hypnosis it seems likely that the whole experimental set-up may have helped to reduce 'experimental anxiety'. One may conclude that response specificity for pleasant and unpleasant stimuli seems to exist.

Autonomic Nervous System↗