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R Van Velthoven

Publications and source records attributed to R Van Velthoven.

At least 19 recordsLinked to original sources
PubMed2006

Construct validity of the chicken model in the simulation of laparoscopic radical prostatectomy suture.

BACKGROUND AND PURPOSE: For a simulation to be valid, it has to be close to reality, correlate with the performance in a real case, and be able to discriminate between individuals with different degrees of experience. We explored the construct validity (ability to discriminate between experienced and inexperienced subjects) of a simulation for the urethrovesical anastomosis during laparoscopic radical prostatectomy (LRP). MATERIALS AND METHODS: Dead chickens were used. After partial emptying of the corporal cavity, an 18F catheter was placed through the esophagus to the stomach. In the Pelvic Trainer, a laparoscopic section of the esophago-glandular-stomach junction and a suture between the two edges were performed in the same fashion as for a urethrovesical suture in LRP. Five subjects with different levels of experience in laparoscopy, ranging from nil to more than 250 LRPs, tested two types of suture. One-way ANOVA was used to detect differences in suturing time among the operators. A multiple comparison test was used to detect specific differences between operators. RESULTS: Although suturing time had a strong negative correlation with the operator's experience, significant statistical differences in suturing time were found only between the least experienced operator and the other ones. Qualitative differences in the suture were found among operators. CONCLUSION: This simulation correlates well with the laparoscopic (LRP) subject's experience. It can discriminate between inexperienced and experienced subjects, exhibiting moderate construct validity, but failed to reflect the different levels of experience among the most experienced subjects.

Animals↗
PubMed2000

Processing of some antigens by the standard proteasome but not by the immunoproteasome results in poor presentation by dendritic cells.

By stimulating human lymphocytes with an autologous renal carcinoma, we obtained CTL recognizing an antigen derived from a novel, ubiquitous protein. The CTL failed to lyse autologous EBV-transformed B cells, even though the latter express the protein. This is due to the presence in these cells of immunoproteasomes, which, unlike standard proteasomes, cannot produce the antigenic peptide. We show that dendritic cells also carry immunoproteasomes and fail to present this antigen. This may explain why the relevant CTL escape thymic deletion and are not regularly activated in the periphery. Lack of cleavage by the immunoproteasome was also observed for melanoma differentiation antigen Melan-A26-35/HLA-A2, currently used for antitumoral vaccination. For immunization with such antigens, proteins should be less suitable than peptides, which do not require proteasome digestion in dendritic cells.

Antigen Presentation↗
PubMed1997

PSA evolution: a prognostic factor during treatment of advanced prostatic carcinoma with total androgen blockade. Data from a Belgian multicentric study of 546 patients.

OBJECTIVES: To study the prognostic value of the prostate-specific antigen (PSA) response and its relationship with other initial prognostic factors during the treatment of advanced prostatic carcinoma with total androgen blockade. METHODS: Five hundred forty-six patients with advanced loco-regional (M0) or distant metastatic (M1) prostatic carcinoma treated with flutamide combined with either orchiectomy or LHRH analogues were included in this analysis. Initial patients characteristics and the PSA response were evaluated in relation to progression-free survival using a univariate and multivariate (Cox regression) analysis. RESULTS: The following prognostic factors were indicative of a decrease in progression-free survival: the absence of PSA normalization (< 4 ng/ml) after 3 or 6 months, M1 stage, high G grade, ECOG performance status > 1, presence of pain and absence of dysuria. In M1 patients the combination of PSA normalization after 3 or 6 months with initial G grade and ECOG performance status had the strongest predictive value. CONCLUSIONS: This study demonstrates that PSA normalization after 3 or 6 months along with initial tumor stage, grade and health status of the patient are the most important prognostic factors related to progression-free survival in the hormonal treatment of advanced prostatic carcinoma.

Aged↗
PubMed1996

Differential histochemical peanut agglutinin stain in benign and malignant human prostate tumors: relationship with prostatic specific antigen immunostain and nuclear DNA content.

The histochemical binding pattern of the peanut (Arachis hypogaea) lectin (PNA) was quantitatively described by means of computer-assisted microscope analysis in 28 benign prostatic hyperplasias (BPH), 15 prostatic intraepithelial neoplasias (PIN), and 119 prostatic adenocarcinomas. PNA exhibits nonimmune but selective binding to glycoproteins with beta-D-galactosyl(1,3)-N-acetyl-D-galactosamine residues. We also investigated whether a relationship existed between the number of histochemical-related PNA acceptors and the histochemical prostate-specific antigen (PSA) stain intensity, and between the number of PNA receptors and DNA ploidy level. The results show that neoplastic prostate tissues and high-grade intraepithelial prostatic neoplasias (PIN2_3) exhibit a significantly higher number of PNA acceptors than benign prostatic hyperplasias and low (PIN1) grade prostatic intraepithelial neoplasias. A statistically significant correlation was observed between the number of histochemically related PNA acceptors and PSA immunostain intensity. Lastly, diploid prostatic tumors, whether benign or malignant, exhibited a significantly higher number of PNA acceptors than aneuploid ones. These results suggest that PNA acceptors play an important role in the biology of prostate tumors.

Adenocarcinoma↗
PubMed1996

Tolerability and safety of flutamide in monotherapy, with orchiectomy or with LHRH-a in advanced prostate cancer patients. A Belgian multicenter study of 905 patients.

OBJECTIVE: In a multicenter study, 905 patients with newly diagnosed advanced prostate cancer treated with flutamide were followed for safety and side effects. METHODS: Flutamide was administered in monotherapy (75 patients (8%)) or as part of total androgen blockade (TAB groups): the latter group had orchiectomy (196 patients (22%)) or an LHRH (634 patients (70%)). RESULTS: The incidence of gastrointestinal complaints such as loss of appetite, vomiting/nausea and diarrhea (+/- 15%) was similar in the TAB and the monotherapy groups. Eighteen patients (2%) were withdrawn because of severe diarrhea. Hot flushes was the most frequently reported adverse event in TAB groups (40% of patients), leading to withdrawal in 4 patients (0.4%). Breast tenderness occurred most frequently in the monotherapy group (49%) and was reported as severe in 7% of the patients. Only 0.8% of the patients were withdrawn because of liver function changes. No unexpected potentially dangerous adverse events were reported. CONCLUSION: Flutamide alone or in combination therapy appears to be safe and well tolerated.

Appetite↗
PubMed1990

Computerized morphonuclear cell image analyses of malignant disease in bladder tissues.

We analyzed the relationship between several morphonuclear parameters related to nuclear size, densitometry (deoxyribonucleic acid content and ploidy) and the chromatin pattern versus the histopathological grading of 46 bladder cancer samples graded according to the World Health Organization classification. We used a SAMBA 200 cell image processor with software allowing for the discrimination of 15 different parameters on Feulgen-stained imprint smears. In addition, we set up preliminary data banks that enable objective and reproducible grading of unknown cases. This approach must be validated in a large series of cases to create an expert system for bladder malignancy diagnosis.

Cell Division↗