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Biomedical subjects

R Koch

Publications and source records attributed to R Koch.

421 records · Page 24Linked to original sources
PubMedDate not supplied

Chromogranin A: an additional tumor marker for postoperative recurrence and metastases of medullary thyroid carcinomas?

In this study, plasma concentrations of chromogranin A, calcitonin and carcinoembryonic antigen (CEA) were measured in 40 healthy volunteers as well as in 129 patients with recurrences and/or metastases of neuroendocrine tumors and of medullary thyroid carcinomas (MTCs). A double antibody assay was employed using polyclonal rabbit antibodies to a C-terminal fragment of the protein for detection of human chromogranin A. Using ROC analysis, a cutoff at 22 U/l chromogranin A was calculated. In patients with neuroendocrine tumours, much higher serum concentrations of chromogranin A than for patients with MTC (80% vs. 46%) were measured. The following sensitivities were found: chromogranin A; 46%, calcitonin 100%, CEA 52%. Furthermore, the mean values of chromogranin A concentrations correlated with the tumour mass and/or number of metastases in MTC and neuroendocrine tumours. Evaluation of follow-up studies remains to be completed; however, preliminary results showed similarities regarding the behaviour of chromogranin A and calcitonin. Despite the findings of this study, the observations could not confirm chromogranin A as a reliable marker for metastazing or recurrent MTC.

Biomarkers, Tumor↗
PubMedDate not supplied

Studies on the mechanism of action of the antiparkinsonian drugs memantine and amantadine: no evidence for direct dopaminomimetic or antimuscarinic properties.

The effects of the antiparkinsonian drugs amantadine and memantine and of the noncompetitive NMDA receptor antagonist MK-801 were studied in the model of the electrically evoked release of [3H]dopamine and [3H]acetylcholine in slices of the rabbit caudate nucleus in vitro. In the [3H]dopamine release model, high concentrations (> 10 microM) of the drugs investigated showed a marked increase in spontaneous 3H-efflux, with the following order of potency: memantine > MK-801 > amantadine. The spontaneous 3H-efflux induced by 50 microM memantine was diminished by pargyline (10 microM), but was insensitive to the presence of tetrodotoxin (0.3 microM), or nomifensine (1 microM), or to the omission of Ca2+ in the superfusion medium; in the absence of nomifensine it consisted mainly of 3H-metabolites of dopamine. The latter findings indicate that the memantine-induced spontaneous 3H-efflux is unrelated to the firing of striatal interneurons but point to a direct releasing effect of memantine on dopaminergic storage granules. On the other hand, the electrically evoked release of [3H]dopamine seemed to be unaffected by memantine, was only slightly reduced by amantadine but significantly inhibited by MK-801. In the model of the electrically evoked release of [3H]acetylcholine, only MK-801 (> 50 microM) showed significant inhibitory effects, both on spontaneous and evoked overflow of [3H]acetylcholine; the effects of memantine and amantadine were negligible. Since only high concentrations of amantadine and memantine (exceeding those which, according to the literature, may be reached in vivo) showed effects in the present in vitro dopamine and acetylcholine release models, it is concluded that the clinical efficacy of these antiparkinsonian drugs is most probably unrelated to an enhancement of dopaminergic transmission as suggested from earlier in vitro and in vivo findings. The higher activity of MK-801 in the present model and the recent observation that both memantine and amantadine bind--although with lower affinity--to an MK-801 binding site in the NMDA receptor-linked ion channel, suggest a possible involvement of striatal NMDA receptors in the antiparkinsonian effects of these drugs.

Acetylcholine↗
PubMedDate not supplied

Loss of BRCA2 correlates with reduced long-term survival of sporadic breast cancer patients.

BACKGROUND: The present study was undertaken to analyze the prognostic value of loss of heterozygosity (LOH) at 13q12-13, 17q21 and 17p13, harboring BRCA2, BRCA1 and p53 to predict the clinical course of sporadic breast cancer patients. MATERIALS AND METHODS: LOH analysis was performed by PCR amplification of genomic DNA using nine microsatellite markers. Fifty-three sporadic breast cancer patients were followed clinically for a median of 55 months. Disease-free and overall survival was documented as the endpoint for statistical evaluation. RESULTS: Patients presenting with LOH in their tumor samples at at least one of the loci examined were found to have a reduced overall survival time compared to those retaining heterozygosity (61% versus 48%). Focusing on the three target regions, patients with LOH at the BRCA2 locus died earlier compared to patients retaining heterozygosity (69% versus 50%) and, in addition, BRCA2 LOH-positive patients showed a shorter metastasis-free interval (30 versus 37 months). In a multivariate analysis, LOH at the 13q12-13 locus was found to be a significant predictor for reduced long-term survival (risk ratio 2.33, 95% C.I., 1.0-5.3; p<0.05) and earlier metastases manifestation (risk ratio 2.32, 95% C.I., 1.0-5.3, p<0.05). CONCLUSION: Allelic loss at the BRCA2 locus may be of use as a negative predictor for metastases-free and overall survival.

Adult↗
PubMedDate not supplied

Simultaneous immunohistochemical and biochemical hormone receptor assessment in breast cancer provides complementary prognostic information.

The prognostic value of the biochemical and the immunohistochemical assessment of estrogen- and progesterone receptor (ER, PR) status was tested in 111 breast cancer patients, mostly focusing on whether the results reveal complementary prognostic information. The biochemical receptor analysis was performed on snap-frozen tumor tissue using a standard protocol (ER-DCC, PR-DCC). The immunohistochemical staining was done on 4 microns thick paraffin sections and was evaluated semiquantitatively (ER-IHC, PR-IHC) and immunohistometrically by means of image analysis (ERMEAN, PRMEAN). 74% of the ER-DCC and 50% of the PR-DCC assays were interpreted as positive. The positivity rates of the immunohistochemical reactions ranged between 78% and 81% for ER and between 66% and 82% for PR, depending on the interpretation mode. The concordance rate for the DCC method was 68%, and ranged between 77% and 85% for the immunohistochemical results on paraffin sections. ER-DCC and PR-DCC showed a better survival for receptor-positive patients; however, this tendency was only statistically significant for the PR-DCC (p = 0.0294). Patients with immunohistochemically determined ER- or PR-positivity revealed a significantly better survival than receptor-negative patients, the effect being stronger for the progesterone receptor (ER: p = 0.0253, PR: p = 0.0005). Combining the different methods and receptors in a multivariate analysis, we observed that a) ER and PR reveal complementary prognostic information to each other after immunohistochemical determination (p < or = 0.0018) and that, b) complementary prognostic information was also obtainable by comparing the biochemical and the immunohistochemical PR-analysis (p < or = 0.0084); slightly more significant results were obtained for ERMEAN and PRMEAN compared to ER-IHC and PR-IHC. Considering the lymph node status and a combined receptor analysis (PR-DCC, ERMEAN, PRMEAN) as the two strongest prognosticators in multivariate Cox models, the combined receptor analysis was able to discover for each of the three groups of NO- and N1-patients different survival probabilities (p < 0.0001). In conclusion, the ER-DCC appears to be dispensable in all patients. In lymph node-negative patients, the PR-DCC has no outstanding merit, indicating that the neccessity of this method is also controversial. In priamry tumors of lymph node-positive patients, however, all three remaining types of receptor analysis should be evaluated for their therapeutic implications.

Breast Neoplasms↗