Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where D. H. J. Schamhart is active.

Publication


Featured researches published by D. H. J. Schamhart.


The Journal of Urology | 1996

Urinary Cytokines During Intravesical Bacillus Calmetteguerin Therapy for Superficial Bladder Cancer: Processing, Stability and Prognostic Value

Theo M. de Reijke; Elizabeth C. de Boer; Karl Heinz Kurth; D. H. J. Schamhart

PURPOSE An accurate prognostic indicator to identify nonresponding patients with superficial transitional cell carcinoma of the bladder at an early stage of intravesical bacillus Calmette-Guerin (BCG) therapy is urgently needed. MATERIALS AND METHODS The processing conditions and stability of several BCG induced urinary cytokines were analyzed, as was the possible correlation between these cytokines (indicating immune responsiveness to BCG) and bladder tumor recurrence. We studied 23 patients with superficial transitional cell carcinoma of the bladder. Monitoring was performed by serial collection of urine during the first 24 hours after each of the 6 consecutive weekly intravesical BCG instillations. Baseline pre-therapy cytokine levels were 3.9 +/- 4.7 pg./mumol creatinine for interleukin-6 and 0.1 +/- 0.2 pg./mumol creatinine for tumor necrosis factor-alpha (all measured by enzyme-linked immunosorbent assay). To investigate the correlation between interleukin-2 and bladder tumor recurrence, patients were stratified into 2 groups based on an early (6 months or less) or late (greater than 6 months) recurrent tumor. For each patient the highest cytokine value measured during the 6-week BCG treatment course was evaluated. RESULTS The results were positive if the level in urine exceeded 0.34 units interleukin-2 per mumol. creatinine. A significant correlation between urinary interleukin-2 and tumor recurrence was found (p = 0.003, 23 patients). Of the studied cytokines obtained from BCG treated patients, interleukin-1 beta, 2 and 6 but not tumor necrosis factor-alpha were stable in urine at 4C and 20C. At 37C all cytokines were unstable. Interferon-gamma could only be detected in immediately dialyzed urine and its occurrence correlated most with that of interleukin-2. Processing of urine by centrifugation to remove leukocytes immediately after collection was not required for reliable measurements of interleukins-2 and 6. Based on these results interleukins-2 and 6 were preferred for extensive monitoring of the BCG induced immune reaction. CONCLUSIONS Our study provides significant evidence for a correlation between urinary cytokine induction and clinical response following intravesical BCG therapy. Particularly, monitoring of interleukin-2 may have the potential for prognostic value provided that strict precautions regarding urine collection, such as maximal 2-hour sampling and immediate cooling, are taken.


Urology | 1998

Bladder Wash Cytology, Quantitative Cytology, and the Qualitative BTA Test in Patients with Superficial Bladder Cancer

H. Van Der Poel; M.R van Balken; D. H. J. Schamhart; P Peelen; Th de Reijke; F.M.J. Debruyne; Jack A. Schalken; J.A. Witjes

OBJECTIVES Two new methods for the detection of transitional tumor cells in bladder wash (karyometry: QUANTICYT) and voided urine material (BARD BTA test) were compared with bladder wash cytology for the prediction of histology and tumor recurrence. METHODS Bladder wash material and voided urine were sampled from 138 patients. Bladder wash karyometric (BWK) image analysis and the BTA test were applied. A subsequent urethrocystoscopy was performed and a bladder tumor, when present, was resected. Moreover, each patient was followed for tumor recurrence and progression. RESULTS Sensitivities for the detection of tumors were 34.4%, 44.8%, and 69.0% for the BTA test, bladder wash cytology (BWC), and BWK, respectively (BTA versus BWC, P = 0.64; BTA versus BWK, P = 0.0002; BWC versus BWK, P = 0.0001, using the McNemar test). Specificities for the different tests were 81.3%, 92.5%, and 72.5%, respectively (BTA versus BWC, P = 0.096; BTA versus BWK, P = 0.031; BWC versus BWK, P = 0.001, using the McNemar test). Combinations of tests did not result in better prediction of the presence of tumor. Sensitivity of carcinoma in situ for the three tests was 0 of 3, 3 of 3, and 3 of 3, respectively. Follow-up analysis after a negative cystoscopy revealed comparable predictive values for BWC and BWK. CONCLUSIONS The BTA test may be useful for patients with recurrent, low-grade papillary lesions. However, sensitivity for detection of these lesions, although higher than that for BWC, was only 42.9%. The highest specificity was found for BWC; however, this was accompanied by the lowest sensitivity of all three tests. The lower specificity of BWK was accompanied by a better prediction of tumor recurrence after a normal urethrocystoscopy. BWK is particularly sensitive for the recurrence of high-grade bladder lesions.


Urological Research | 1993

Cytokine production by the human bladder carcinoma cell line T24 in the presence of bacillus Calmette-Guerin (BCG)

T.M. De Reijke; P. C. N. Vos; E. de Boer; Rob F. M. Bevers; W. H. de Muinck Keizer; K.H. Kurth; D. H. J. Schamhart

SummaryThe study was initiated as an in vitro approach to the situation existing during intravesical bacillus Calmette-Guerin (BCG) instillation in patients with superficial bladder cancer. Cytokine secretion of a human bladder carcinoma cell line T24 treated with BCG was investigated. A 24-h treatment of T24 cells with BCG resulted in a tenfold higher secretion of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFα) when compared with T24 cells treated with Escherichia coli, Streptococcus faecalis or a cell wall preparation of Nocardia rubra (N-CWS). No secretion of IL-1β and IL-2 was detected. Pre-exposing T24 cells to BCG for various periods of time indicated that a minimum exposure time of 0.5–1 h was required to upregulate IL-6 and TNFα production. Extending the BCG pre-exposure time to 2 and 3 h further increased the rate of cytokine production. No significant difference was found, however, between the rate of secretion initiated after a 2-h or 3-h pre-exposure period. The amounts of these cytokines secreted in the presence of BCG-conditioned medium did not differ significantly from the constitutively secreted amounts, excluding an effect of products possibly secreted by BCG on the upregulation of IL-6 and TNFα. In addition, upregulation of cytokine production appeared to be dependent on the concentration of BCG. The results suggest that cytokines may be produced by urothelial tumor cells after intravesical instillation in patients with superficial bladder cancer, which may play a role in the mode of action of BCG.


The Journal of Urology | 1999

URINARY INTERLEUKIN-2 MONITORING DURING PROLONGED BACILLUS CALMETTE-GUERIN TREATMENT: CAN IT PREDICT THE OPTIMAL NUMBER OF INSTILLATIONS?

Theo M. de Reijke; Elizabeth C. de Boer; Karl Heinz Kurth; D. H. J. Schamhart

PURPOSE In patients with superficial bladder cancer treated with a first 6-week instillation course of bacillus Calmette-Guerin (BCG) the induction pattern of urinary interleukin (IL)-2 has been described, and the levels of urinary IL-2 were associated with the clinical response to BCG treatment. We evaluated urinary IL-2 kinetics in patients with recurrent superficial bladder tumor receiving a second or third 6-week BCG instillation course. To our knowledge there have been no studies of prolonged BCG treatment and urinary cytokine responses. MATERIALS AND METHODS Urinary IL-2 was determined in 12 patients with superficial transitional cell carcinoma of the bladder receiving a complete (6-week) second or third BCG instillation course and in 3 patients receiving 3 BCG instillations during a maintenance schedule at month 3. Urinary IL-2 was determined with an enzyme-linked immunosorbent assay using an oligoclonal system. RESULTS Of 12 patients 10 had a urinary IL-2 positive response during the subsequent BCG course and at week 1 urinary IL-2 was already increased. Comparing the urinary IL-2 kinetics observed during a second or third with a first course, urinary IL-2 tended to be higher during the first and lower during the last weeks. If the interval between subsequent courses was short (12 months or less) significantly higher urinary IL-2 levels at weeks 1 and 2, and a lower level at week 6 were observed. CONCLUSIONS During a repeat BCG instillation course urinary IL-2 reached a maximum at an earlier week, especially if the interval between the subsequent courses was short. Since an association between urinary IL-2 levels and response to BCG treatment during an induction course has been observed, these immunological data argue in favor of a limited number of instillations during prolonged BCG therapy which could reduce side effects as well as costs.


European Urology | 1998

The Bard® BTA Test: Its Mode of Action, Sensitivity and Specificity, Compared to Cytology of Voided Urine, in the Diagnosis of Superficial Bladder Cancer

D. H. J. Schamhart; T.M. De Reijke; H. Van Der Poel; J.A. Witjes; E. de Boer; K.H. Kurth; Jack A. Schalken

Objectives: Application of immunocytology directed against antigens of urothelial tumor cells or tumor-associated breakdown products intends to improve the sensitivity of the diagnosis of superficial transitional cell carcinoma (TCC) of the urinary bladder. In this study, the mode of action, sensitivity and specificity of the Bard® BTA test, detecting a tumor-associated release of a basement membrane complex, was addressed and compared with voided urine cytology (VUC). Results: Contrary to grade, a significant (p = 0.003) relationship between tumor stage and BTA test sensitivity was observed, being 23.8, 33.3 to 100% for Ta (n = 42), T1 (n = 6) to ≥T2 (n = 5), respectively. These data suggest an association between an increase of the BTA test sensitivity with an increase of basement membrane degradation or interruption. With regard to this mechanism, the BTA test may be of special importance for monitoring tumor progression or increase in tumor invasiveness. Detection of low-stage, low-grade tumors by noninvasive techniques remains a challenge. The sensitivity of the BTA test for the presence of TCC was 32.3%, while that of VUC was 17.7%, but in this study the difference was not statistically significant. Furthermore, the BTA test was not more effective in identifying the various tumor grades, stages or stage/grade groupings. However, dividing the patients in two groups of low risk (TaG1/TaG2) and high risk (TaG3 to ≥T2) leads to a significant (p = 0.008) increased sensitivity of the BTA test (27.3%) in detecting patients with low-risk tumors compared to VUC (3.0%). The specificity of the BTA test in patients with a history of TCC was 81.6%, while that of VUC was 98.9%. Conclusion: The sensitivity of the BTA test is at least equivalent to VUC and may be suited to monitor increase in stage in patients suffering from bladder carcinoma, but cannot replace cystoscopy in patients suspected for a bladder tumor.


Urological Research | 1992

BCG treatment and the importance of an inflammatory response.

D. H. J. Schamhart; K.H. Kurth; T.M. De Reijke; R. Vleeming

SummaryA prospective study was performed on patients with superficial bladder tumour treated with bacillus Calmette-Guérin (BCG). The kinetics of interleukin-6 (IL-6) titres were monitored in urine collected at regular intervals for 24 h during 14 BCG treatments, each consisting of six weekly intravesical instillations. IL-6 titres were quantified with an ELISA system and compared with a bioassay (biologically active IL-6) system. After instillation, urinary IL-6 titres transiently increased, reaching maximum levels between 2 and 6 h after instillation. IL-6 titres appeared to be significantly correlated with an increase of total cells retrieved by bladder washout 3 h after instillation. The kinetics of the weekly maximum biologically active IL-6 titres indicate that three types of BCG-induced response occur: an “early” response starting at the first instillation; a “late” response after the third instillation; or no IL-6 response. The “early” response appeared to be associated, but not strictly correlated, with an IL-2 response. The results suggest that the effectiveness of BCG treatment is determined by two processes, an inflammatory one, followed by a delayed type of hypersensitivity response.


European Urology | 2000

Urinary Cytokines Reflecting the Immunological Response in the Urinary Bladder to Biological Response Modifiers: Their Practical Use

D. H. J. Schamhart; Elizabeth C. de Boer; Theo M. de Reijke; K.H. Kurth

Background: Intravesical bacillus Calmette-Guérin (BCG) immunotherapy is currently the most effective treatment for superficial transitional cell carcinoma (TCC) of the urinary bladder. In recent years, the substantial number of patients not responding to BCG or experiencing considerable toxicities has stimulated studies addressing either the development of improved BCG treatment schedules or the exploration of the therapeutic value of a series of (novel) biological response modifiers, like interferons (IFNs), interleukin (IL) 2 and keyhole limpet hemocyanin. Although the actual mechanism by which BCG exerts its antitumor effect still needs detailed unraveling, current available knowledge suggests the induction of a T helper 1 (Th1) or Th1-like cytokine profile, represented by IL-2, IL-12 and IFN-γ, as essential in the development of a cell-mediated antitumor activity. Conclusions: In this review, it is argued that incorporation of urinary cytokine determinations, like IL-2 and possibly IL-12 and IFN-γ, may represent a valuable approach in the optimization and individualization of the BCG therapy and an early, initial evaluation of the potential efficacy of novel immunomodulating agents in the treatment of superficial TCC.


Cytometry | 1996

Double fluorescent flow cytometric assessment of bacterial internalization and binding by epithelial cells

Elizabeth C. de Boer; Rob F. M. Bevers; K.H. Kurth; D. H. J. Schamhart

This study describes a new flow cytometric method for assessment of phagocytosis of specific bacteria (bacillus Calmette-Guérin (BCG) and Escherichia coli) by bladder epithelial cells. The internalization assay consisted of labeling bacteria chemically with fluorescein isothiocyanate (FITC). Subsequent to incubation of fluoresceinated bacteria with internalizing cells, adherent nonphagocytosed bacteria were marked by two-step labeling using specific antibodies and phycoerythrin (PE)-conjugated antibodies. Double fluorescent FACS analysis differentiated between bacterial phagocytosis and adherence. The validity of the method was shown by inhibition of BCG phagocytosis at 4 degrees C by cytochalasin B, by removal of excess free bacteria, and by anti-BCG antibodies. BCG-phagocytizing and -nonphagocytizing cell lines were discriminated by applying this technique to a series of bladder carcinoma cell lines. There seemed to be a relationship between phagocytic capacity and grade of differentiation in these cell lines, which may have implications for topical BCG immunotherapy in superficial bladder cancer. In conclusion, a new, reliable, rapid, and relatively simple double fluorescent method is described for quantification of specific bacterial internalization by large numbers of (bladder) epithelial cells. This method should be generally applicable to the study of in vitro interaction between bacteria and different types of host cells.


Endocrinology | 1997

The role of interleukin-6 in the induction of hypercalcemia in renal cell carcinoma transplanted into nude mice.

Max Weissglas; D. H. J. Schamhart; Clemens W. G. M. Löwik; Socrates Papapoulos; Harry Theuns; K.H. Kurth

Hypercalcemia is a well known complication of renal cell carcinoma (RCC). As RCCs can produce IL-6, and IL-6 may stimulate bone resorption and cause mild hypercalcemia, we examined whether IL-6 is involved in renal cancer-associated hypercalcemia in vivo. Three human renal cell carcinoma tumor lines (RC-8, RC-9, and NC-65) growing in nude mice were studied. Tumors were implanted s.c., and parameters of bone metabolism and serum human IL-6 levels were determined in relation to tumor volume (TV). All three tumor lines secreted human IL-6, although in different quantities. The maximum level of IL-6 in RC-8 was 434 pg/ml (TV, 200 mm3), that in RC-9 was 81 pg/ml (TV, 1800 mm3), and that in NC-65 was 2368 pg/ml (TV, 1800 mm3). Hypercalcemia developed in RC-8 and RC-9 tumor-bearing animals, but not in NC-65-bearing animals. The hypercalcemia in both RC-8 and RC-9 tumor lines was associated with elevated levels of PTH-related peptide (PTHrP) and loss of trabecular bone volume. Serum calcium and phosphate concentrations showed an almost linear relationship with plasma PTHrP independently of the tumor line and serum IL-6 levels. No hypercalcemia occurred in the NC-65 animals, which had the highest levels of IL-6, but no detectable plasma PTHrP and PTHrP messenger RNA expression in the tumor. Administration of neutralizing antibodies to IL-6 to RC-8 animals normalized serum calcium concentrations and PTHrP values and induced a significant inhibition of tumor growth. No such effect on tumor growth of anti-IL-6 was seen in the other two tumor lines. The normalization of serum calcium in RC-8 mice is most likely attributed to the growth-inhibiting effect of anti-IL-6 on RC-8 tumor. We conclude that IL-6 secreted by RCC does not contribute directly to hypercalcemia, but may enhance hypercalcemia by stimulating the tumor growth of a subpopulation of PTHrP-secreting carcinomas.


Clinical Infectious Diseases | 2000

Immunostimulation in the urinary bladder by local application of Nocardia rubra cell-wall skeletons (Rubratin) and bacillus Calmette-Guérin as therapy for superficial bladder cancer : A comparative study

Elizabeth C. de Boer; Theo M. de Reijke; P. C. N. Vos; K.H. Kurth; D. H. J. Schamhart

Twelve patients with superficial bladder cancer were treated with intravesical instillations of Rubratin (ASTA Pharma AG, Frankfurt, Germany), a cell-wall preparation of Nocardia rubra. The objective was to compare the immunostimulating effect of Rubratin with that of bacillus Calmette-Guérin (BCG). Local immunostimulation was determined by cytokine induction in serially collected urine samples during the first 24 h after each instillation, leukocyte influx into the urine, and phenotypic analysis of the lymphocyte fraction. Levels of Rubratin-induced interleukin (IL)-1 beta, IL-6, and tumor necrosis factor-alpha were significantly elevated compared with pretherapy levels. Rubratin induced leukocyte influx into the urine. T-cell activation (IL-2 receptor and human leukocyte antigen-DR expression) can be induced, and CD4:CD8 cell ratios can be increased. All parameters indicated that Rubratin-induced immunostimulation was less than that associated with BCG. In conclusion, although local Rubratin-induced immunostimulation occurs in a limited number of patients, the amount of immunocompetent cells attracted to the bladder seems to be less than that associated with BCG therapy, thus resulting in lower levels of cytokine production (which may reflect less clinical efficacy).

Collaboration


Dive into the D. H. J. Schamhart's collaboration.

Top Co-Authors

Avatar

K.H. Kurth

University of Amsterdam

View shared research outputs
Top Co-Authors

Avatar

E. de Boer

University of Amsterdam

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

P. C. N. Vos

University of Amsterdam

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge