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R Porschen

Publications and source records attributed to R Porschen.

At least 37 records · Page 2Linked to original sources
PubMed2001

[The role of oxaliplatin in the therapy for advanced colorectal carcinoma].

The role of oxaliplatin in the therapy for advanced colorectal carcinoma. Preclinical models and numerous phase I to III trials have demonstrated the efficacy of oxaliplatin (l-OHP) for colorectal carcinoma. In previously untreated patients, response rates with l-OHP plus 5-fluorouracil and leucovorin (5-FU/LV) have been shown to be more than twice as high as compared with 5-FU/LV alone, and progression-free intervals have been significantly increased. Nevertheless, overall-survival was similar in both treatment arms, that was possibly due to the cross-over-design of these studies. Moreover, the combination regimens with l-OHP and 5-FU/LV often have shown activity in 5-FU-resistant or 5-FU- refractory patients. Furthermore, treatment of previously unresectable liver metastases from colorectal carcinoma with l-OHP in combination with 5-FU/LV has provided promising results. Dose-limiting toxicity is a peripheral sensory neuropathy, that was found to be mostly completely reversible within a few months. Gastrointestinal toxicities have been demonstrated to be mild. Compared to other anticancer drugs currently used in the treatment for colorectal carcinoma, l-OHP not only shows a different mechanism of action but displays synergistic anti-tumor activity as well as minimal hematologic toxicity making this agent interesting for combination chemotherapy protocols. In conclusion, the development of l-OHP has essentially increased the therapeutical possibilities of treatment for colorectal carcinoma.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Comparison of flow cytometry and histology with mutational screening for p53 and Ki-ras mutations in surveillance of patients with long-standing ulcerative colitis.

BACKGROUND: We evaluate the usefulness of screening for p53 and Ki-ras mutations in comparison with histological and flow cytometric findings. METHODS: We analyzed 1486 biopsy samples from 769 locations of 83 patients with long-standing ulcerative colitis enrolled in a surveillance program by means of histology, flow cytometry and SSCP analysis. As a control we used 66 biopsy samples of 16 patients with irritable bowel disease. RESULTS: With respect to all biopsy samples analyzed, DNA aneuploidy was found in 32.5% (27/83) of patients, dysplasia in 22.9% (15/83), p53 in 21.7% (18/83) and Ki-ras mutations in 18.1% (15/83) of patients. None of these markers was found in our control group. In 7 out of 10 patients who displayed dysplastic findings during endoscopic surveillance p53 and / or Ki-ras mutations were present in at least one colonoscopy. Statistically significant associations were observed between dysplasia and DNA aneuploidy (P < 0.001), between dysplasia and p53 mutations (P = 0.05) and between dysplasia and p53 and/or Ki-ras mutations (P = 0.002). No significant associations were found between dysplasia and Ki-ras mutations alone. The results for the SSCP analysis showed a much broader variation than those for the flow cytometric analysis. CONCLUSIONS: These results show that screening for p53 and Ki-ras mutations can be a useful adjunct in surveillance of patients with long-standing ulcerative colitis.

Aneuploidy↗
PubMed2001

Comparative genomic hybridization analysis of chromosomal alterations in patients with long-standing ulcerative colitis.

Patients with ulcerative colitis (UC) are prone to develop colorectal cancer which is related to the duration and extent of the disease. One of the earliest events in tumor progression is the development of aneuploidy. Aneuploidy is correlated with the grade of dysplasia which serves as a common but not always reproducible marker for the prediction of UC associated formation of cancer. We analyzed 48 biopsy samples from 5 patients with long-standing ulcerative colitis by comparative genomic hybridization (CGH). The majority of these samples represented premalignant stages which are not well characterized at the molecular level as yet. We compared biopsy samples from different colon locations in regard to chromosomal alterations, dysplasia status and DNA index. Besides chromosomal changes occurring only in certain patients in restricted areas of the colon we also detected amplifications and deletions which were common in all persons throughout the colon. The stage of dysplasia seems to have no influence on the number and appearance of chromosomal changes. Amplifications in 2, 3, 6, 9, 11, 12 and 15 were found in almost all cases. In dysplastic samples chromosomal regions 3, 6 and 11 revealed gains of DNA. Deletions were detected within 8q, 15, 18q, 20p and 22q. The affected chromosomal regions may contain yet unknown oncogenes or tumor suppressor genes participating in UC associated carcinogenesis. The conspicuous regions found in the CGH experiments allow the selective and detailed characterization at a molecular level.

Chromosome Aberrations↗
PubMed2000

[Benign bile duct stenoses. Treatment with flexible metal wire stent or silicone prostheses (Yamakava) in nonresectable stenoses or high surgical risk cases].

INTRODUCTION: High benign biliary stenoses, which can occur as a complication of disease or surgery, may be difficult to correct by open surgery and may also carry a high risk. An alternative to surgery is the percutaneous implantation of a flexible metallic stent or silicon prosthesis at the affected site. METHODS: Twelve patients with benign biliary stenoses have been operated on in our department since March 1992, and the therapeutic success was reviewed in this study. RESULTS: Six received a Palmaz stent and six a silicon prosthesis, with a follow-up after completion of treatment of more than 7 years and more than 3 years, respectively. Fifty percent of the patients with a stent experienced no problems and 66% of the stents remained patent (including one requiring operative intervention to restore patency). No further surgery was necessary in any of the patients with a silicon prosthesis. CONCLUSION: When the advantages and disadvantages of the various procedures are considered, long-term splinting with a wide-lumened silicon prosthesis (Yamakava) appears to be a promising alternative to surgery for the treatment of benign biliary stenosis.

Adult↗
PubMed2000

Alteration of DNA ploidy status and cell proliferation induced by preoperative radiotherapy is a prognostic factor in rectal cancer.

To identify predictors of prognosis after preoperative radiotherapy, DNA ploidy and cell proliferation were investigated in 116 patients with rectal cancer. For flow cytometry, a nuclear suspension was prepared by pepsin digestion of paraffin samples of biopsies taken before preoperative radiotherapy (15 x 2 Gy) and also of the resected rectal tumors after radiotherapy. The median follow-up period was 6 years. The proportion of tumor necrosis was evaluated in histological sections before and after irradiation. There was a significant decrease (74 to 48%) in aneuploid tumors after radiation. Of 86 patients with aneuploid biopsies, 28 revealed no reduction in the proportion of aneuploid tumor cells [group AN(=/increase)], and 58 showed a reduction (mean 48.9%) or complete elimination of aneuploid tumor cells [group AN(decrease/psi)]. The incidence of local or distal failure was significantly reduced in the group AN(decrease/psi) (7.8%/20%), compared with the group AN (=/increase) (27%/54%) and the group of constant diploid tumors (n = 22; 13.6%/31.8 %; P = 0.034). There was a trend of decreased recurrence rate in diploid tumors with a reduced fraction of cells in S-phase after radiotherapy. Survival was significantly increased in group AN(decrease/psi) (P < 0.0001). In a multivariate regression analysis, variables of independent prognostic significance were increased proportion of necrosis after irradiation and DNA ploidy group and the postoperative tumor stage. These results suggest that alterations in tumor DNA ploidy and cell proliferation induced by preoperative radiotherapy might help to identify patients likely to benefit from preoperative radiation in rectal cancer.

Adenocarcinoma↗
PubMed1999

Influence of p53 status on prognosis in preoperatively irradiated rectal carcinoma.

BACKGROUND: Even when they are analogous in microscopic and macroscopic appearance, tumors vary in their response rates to radiotherapy. Cell culture and xenograft experiments with colorectal cell lines have demonstrated that wild-type p53 increases radiosensitivity. Hence, the authors investigated, in a well-defined population of patients treated at the same institution, whether p53 status was a prognostic factor in preoperatively irradiated rectal carcinoma patients. METHODS: The p53 status of rectal adenocarcinomas was examined immunohistochemically (with monoclonal antibody DO-1) in preirradiated biopsy samples (n = 100) and corresponding postirradiated resected specimens (n = 97). The mean follow-up was 73.2 months (median, 71.3 months; range, 4.3-157 months). Statistical analysis was performed using the SPSS program (SPSS, Chicago, IL). RESULTS: p53 protein expression was detected in 55 of 100 biopsy samples (> or = 5% nuclear staining). There was essentially no difference in p53 expression between biopsy samples and corresponding resected specimens (54 of 97 vs. 55 of 97). In univariate analysis, p53 immunoreactivity of biopsy samples did not correlate with age, gender, tumor location, TNM stage, pT category, pN category, or histologic grade. Unlike clinicopathologic variables, p53 expression did not have a statistically significant association with local recurrence free, disease free, or overall survival in either univariate (P = 0.91, 0.18, and 0.17, respectively) or multivariate analysis. CONCLUSIONS: In contrast to cell line studies, this immunohistochemical study demonstrates that p53 status is not useful as a prognostic marker in preoperatively irradiated rectal carcinoma.

Adenocarcinoma↗
PubMed1999

Differential expression of mucins and trefoil peptides in native epithelium, Barrett's metaplasia and squamous cell carcinoma of the oesophagus.

BACKGROUND AND AIMS: In humans, trefoil peptides (TFF peptides) and some mucins have been reported to be expressed in a cell-specific manner at mucosal surfaces of normal gastrointestinal tissues. Neoplastic conditions cause characteristic changes of these expression patterns. To study such patterns in Barrett's metaplasia and squamous cell carcinoma of the oesophagus (SCC), the distribution of MUC1, MUC2, MUC5AC and the three TFF peptides (TFF1, TFF2 and TFF3) was investigated. METHODS: In 40 archival samples of SCC and in 21 samples of Barret's metaplasia, expression of the three mucins and two TFF peptides (TFF1 and TFF2) was assessed by specific antibodies. Reverse transcriptase/polymerase chain reaction amplification (RT-PCR) was performed on frozen tissue samples from the 11 biopsies of SCC for the three TFF peptides. RESULTS: Immunohistochemical tests for MUC2 and TFF2 were negative both in samples of Barret's metaplasia and in SCC. MUC1 expression was detected in 57.5% of the tumour samples, while TFF1 and MUC5AC were found in 10% and 7.5% of the cases respectively. In Barrett's metaplasia MUC1 was detected in 90.5% of the cases and TFF1 and MUC5AC in all of them. RT-PCR analysis revealed a more complex pattern: TFF1 and TFF3 expressed the corresponding mRNA in all samples investigated; the third member, TFF2, was active in 45.5% of the carcinoma biopsies and not in the corresponding native tissue. CONCLUSIONS: This finding in oesophageal carcinoma contrasts with the situation found in normal and neoplastic stomach epithelium where TFF1 and TFF2 are found co-expressed and TFF3 remains silent. Interestingly, MUC1 is expressed in a significant proportion of SCC. Both in Barett's metaplasia and in SCC the expression of MUC5AC mirrors the TFF1 synthesis in intensity and spatial distribution.

Adult↗
PubMed1999

Diagnostic significance of nuclear p53 expression in the surveillance of Barrett's esophagus--a longitudinal study.

The efficacy of currently performed surveillance in patients with Barrett's esophagus (BE) is substantially compromised by shortcomings of dysplastic lesions as diagnostic markers. The aim of this study was to evaluate the possible role of p53 protein expression as complementary method in the diagnosis of neoplastic transformation in BE. A longitudinal study was performed. 41 patients were enrolled. The median time of surveillance was 46 months. 234 archival paraffin blocks containing a total of 627 biopsies were retrieved. p53 protein immunostaining by application of the monoclonal antibody DO-1 was performed. The results of immunohistochemistry were compared with the exact histopathological diagnosis and grading of dysplasia (no dysplasia, indefinite for dysplasia, low-grade dysplasia, high-grade dysplasia, carcinoma). In merely four of 206 nondysplastic mucosal sites p53 expression was found. However, p53 expression was detected with increasing frequency in sites indefinite for dysplasia (2/9), specimens with low-grade dysplasia (9/15), high-grade dysplasia (3/3) and the one with a carcinoma. This study shows a close association of nuclear p53 protein expression to the process of neoplastic transformation in Barrett's epithelium. However, it apparently does not precede the appearance of dysplasia significantly. Thus, nuclear p53 expression as detected by immunohistochemistry may serve to confirm a suspected diagnosis of dysplasia in BE.

Adenocarcinoma↗
PubMed1998

Hypermethylation of the p16INK4a promoter in colectomy specimens of patients with long-standing and extensive ulcerative colitis.

Functional inactivation of the p16INK4a gene has been reported to be involved in the development of a variety of human malignancies. Recent evidence shows that transcriptional silencing as a consequence of hypermethylation of CpG islands is the predominant mechanism of p16INK4a gene inactivation in sporadic colon cancer. This study sought to identify the significance of p16INK4a methylation in the colonic epithelium of patients with long-standing ulcerative colitis. A total of 89 tissue samples was retrieved from three colectomy specimens. A methylation-specific PCR assay was applied. The methylation status was compared with histological findings and the flow cytometrically determined DNA index. Hypermethylation of the p16INK4a promoter region was detected in 12.7% of samples that were negative for dysplasia. However, 70.0% of samples with dysplasia and all of the samples with carcinomatous lesions revealed hypermethylation. Hypermethylation of the p16INK4a gene promoter was detected already in 40% of specimens with lesions indefinite for dysplasia and in 13.7% of samples with exclusively diploid cell populations. These results suggest that hypermethylation of the p16INK4a promoter region is a frequent and early occurring event during the process of neoplastic progression in ulcerative colitis.

Colectomy↗
PubMed1998

Comparative analysis of histology, DNA content, p53 and Ki-ras mutations in colectomy specimens with long-standing ulcerative colitis.

Neoplastic progression in patients with chronic ulcerative colitis is characterized by the development of epithelial dysplasia, which is accompanied by genetic alterations. This study determined the time of onset of p53 and Ki-ras mutations as well as DNA aneuploidy during histological progression towards carcinoma. In all, 278 samples of 7 colectomy specimens were analyzed by flow cytometry, histology and single-strand conformation polymorphism analysis. Of the samples, 22% (61/278) were dysplastic and 43% (122/278) aneuploid, while 25% (71/278) showed p53 and 4% (11/278) Ki-ras mutations. The correlation between aneuploid status and p53 mutations varied among the patients. A strong correlation was noticed between histological progression from low-grade dysplasia to carcinoma and p53 mutations as well as DNA aneuploidy. Ki-ras mutations were found in 40% (2/5) of the carcinomatous samples. The correlation between p53 mutations and the histological status of the samples suggest the involvement of this genetic event in the development of colon cancer in patients with ulcerative colitis. In contrast to Ki-ras mutations, the appearance of p53 mutations is an early event. Therefore p53 analysis might be helpful in the classification of indefinite dysplasia and in the identification of patients at risk for cancer development. Further studies are necessary to detect the additional genetic alterations preceding the development of DNA aneuploidy.

Aneuploidy↗
PubMed1998

[Seeping gastrointestinal hemorrhage from telangiectasia in CREST syndrome].

A 55-year-old man with CREST syndrome had marked telangiectasias of the palms, the face and the gastrointestinal tract. The latter caused slow bleeding and anemia. The telangiectasias were definitely associated with the CREST syndrome. Iron substitution was sufficient therapy. If a need for further therapy should arise, endoscopic sclerotherapy could be employed. Gastrointestinal bleeding in the CREST syndrome is rarely described, probably because it is unrecognized or interpreted as hemorrhagic gastritis. The possibility of gastrointestinal telangiectasias and concomitant bleeding should be kept in mind in cases of CREST syndrome.

CREST Syndrome↗
PubMed1998

Hypermethylation of the CDKN2/p16 promoter during neoplastic progression in Barrett's esophagus.

BACKGROUND & AIMS: Inactivation of the CDKN2/p16(INK4A) tumor-suppressor gene is one of the most frequent genetic alterations in human malignancies. In esophageal adenocarcinomas, mutations of the p16 gene or homozygous deletions of the gene locus 9p21 are rare. This study investigated whether p16 promoter hypermethylation is an alternative mechanism for p16 gene inactivation during neoplastic progression in Barrett's esophagus. METHODS: A methylation-specific polymerase chain reaction protocol was applied. A total of 95 specimens from 14 patients with Barrett's esophagus were analyzed longitudinally. The p16 promoter status was compared with histomorphological findings. RESULTS: p16 promoter hypermethylation was detected in 9 of the 10 patients who had displayed dysplasia at some time during surveillance, whereas none of the patients who had not displayed dysplasia during surveillance had p16 promoter hypermethylation. p16 promoter hypermethylation was detected in 3% (2 of 67) of the samples without dysplasia, 60% (3 of 5) of the samples with lesions indefinite for dysplasia, 55.6% (10 of 18) of the specimens with low-grade dysplasia, and 75% (3 of 4) of the specimens with high-grade dysplasia. CONCLUSIONS: These data suggest that p16 promoter hypermethylation is a common mechanism of p16 gene inactivation during neoplastic progression in Barrett's esophagus.

Barrett Esophagus↗
PubMed1998

Examination of the prevalence and seasonal variation of intestinal microsporidiosis in the stools of persons with chronic diarrhea and human immunodeficiency virus infection.

The epidemiology of human microsporidiosis is poorly understood and environmental factors affecting transmission of the organism have not been fully elucidated. Temporal variation in the prevalence of microsporidia in the stool of patients with human immunodeficiency virus (HIV) infection and diarrhea was studied to evaluate the role of water-borne transmission. From January 1993 to December 1996, 8,439 stools from HIV-infected individuals were examined for microsporidia spores in southern California. Yearly positivity rates were 8.8% in 1993, 9.7% in 1994, 6.6% in 1995, and 2.9% in 1996. An analysis for linear trend showed a statistically significant decrease in stool positivity rates over time (chi2 = 81.9, P = 0.001). No significant seasonal variation in the prevalence of microsporidiosis was seen over that time period. These results suggest the constant presence of microsporidia in the environment, rather than a seasonal association with recreational water use or seasonal contamination of the water supply, and a real decrease in yearly prevalence of microsporidia related diarrhea. Factors related to a progressive decrease in prevalence are subjects of future investigation.

Animals↗