Biomedical subjects

R Porschen

Publications and source records attributed to R Porschen.

94 records · Page 6Linked to original sources

PubMedDate not supplied

The prognostic value of S-phase fraction in preoperative radiotherapy of rectal cancer.

The aim of this study was to analyze the flow cytometric S-phase fraction (SPF) in rectal tumors before and after preoperative radiotherapy (15x2 Gy) and to compare the findings to the clinical outcome. Archival specimens from 84 cases, treated from 1980 to 1988 with S-phase data and complete follow-up were reviewed. There was no significant correlation between SPF and clinicopathological factors. The median SPF for the 26 diploid tumors before irradiation was 6.6%+/-3.1, compared to a significantly higher median for the 58 preirradiated aneuploid tumors (20.3%+/-6.1; p<0.0001). With a median follow-up of 6 years, there was a significant difference in the number of recurrences for aneuploid tumors with a pretreatment SPF < and >20.3 (51.7% vs. 20.7%; p=0.029), which also led to a significant difference in recurrence-free survival (p=0.05). For diploid tumors, a reduction in the percentage of cells in S-phase after radiation resulted in a borderline significant lower number of recurrences (p=0.06). It is concluded that pretreatment S-phase measurements may be of predictive value especially for aneuploid tumors. An alteration in SPF after radiotherapy may also be helpful in predicting outcome and planning therapy.

Adult↗

PubMedDate not supplied

Telomerase activity in long-standing ulcerative colitis.

Telomerase activity is frequently associated with neoplasia. It is a ribonucleoprotein capable of replacing telomeric DNA sequences that are lost at each cell division. Neoplastic progression in chronic ulcerative colitis is characterized by the development of epithelial dysplasia which is accompanied by genetic alterations. Therefore we tested telomerase activity in 128 biopsy samples of four colectomy specimens with long-standing ulcerative pancolitis by using the Telomerase PCR ELISA System. In three patients with multiple dysplastic or carcinomatous lesions, telomerase activity was detected in 22 samples with a regional association to dysplastic or carcinomatous areas. 15 of the samples with telomerase activity (68%) were found in dysplastic/carcinomatous samples or in the direct vicinity of dysplastic areas, 4 (18%), 2 positions (about 4 cm) and the remaining three (14%) not more than 3 positions away from such areas. In the fourth patient, resected because of clinical deterioration despite medical treatment and who had no dysplastic lesions, no telomerase activity was detected. These results show that telomerase activity might be used as a complementary marker to histology for the identification of patients with ulcerative colitis who are at an increased risk for neoplastic progression.

Biomarkers, Tumor↗

PubMedDate not supplied

Antiproliferative effect of tyrosine kinase inhibitors in epidermal growth factor-stimulated growth of human gastric cancer cells.

AGS human gastric cancer cells were characterized to possess EGF receptors. Scatchard analysis revealed a half saturation constant of 0.6 nM and 9000 receptors per cell. Exogenously added EGF stimulated gastric cancer cell growth in a dose-dependent manner with a maximum effect of +38% at 10 nM EGF. Inhibition of the EGFR-associated tyrosine kinase by genistein and the tyrphostins RG-13022, RG-14620 and RG-50864 resulted in a dose-dependent growth inhibition with half maximal inhibition at 10 microM, 7 microM and 23 microM, respectively. EGF mediated growth stimulation was dose-dependently reversed by coincubation with genistein. At genistein concentrations exceeding 6 microM serum-stimulated growth of AGS cancer cells was also inhibited. We conclude that EGF is an important growth factor for AGS gastric cancer cells. Inhibition of the EGFR-associated tyrosine kinase seems to be an effective antiproliferative principle in EGFR-positive human gastric cancer cells.

Adenocarcinoma↗

PubMedDate not supplied

Tumor vascularization and prognosis in squamous cell carcinomas of the esophagus.

Quantification of tumor vascularization has recently been shown to be a parameter of potential prognostic significance in various types of malignant tumors. To determine the prognostic value of tumor vascularization in esophageal cancer, tumor samples from 150 patients with squamous cell carcinoma of the esophagus and 10 samples of normal esophageal mucosa were stained immunohistochemically with the monoclonal antibody QBEND/10 (CD34), which recognises endothelial cells. Using light microscopy, the number of microvessels was counted in the areas with the highest microvessel density (MVD). The microvessel density was significantly higher in the normal esophageal mucosa (mean: 130/mm2) than in the tumor samples (mean: 69/mm2, p = 0.0001). Correlation of the MVD in the tumor tissue with other prognostic factors showed significantly lower microvessel counts in tumors with lymphatic-vessel invasion (p = 0.0076) and in high pT-stages (p = 0.0081). No significant correlation was found between the MVD and pN stage, tumor size, tumor grade, blood-vessel invasion and proliferative activity. In the univariate survival analysis no significant differences were found between poorly vascularized tumors and highly vascularized tumors. A Cox proportional hazard regression selected the parameters lymphatic-vessel invasion (p = 0.0001), pT stage (p = 0.0034) and pN stage (p = 0.0256) but not MVD as independent prognostic variables.

Age Factors↗