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Biomedical subjects

R Hilger

Publications and source records attributed to R Hilger.

At least 19 recordsLinked to original sources
PubMed2002

Ex vivo stimulation of renal transport of the cytostatic drugs methotrexate, cisplatin, topotecan (Hycamtin) and raltitrexed (Tomudex) by dexamethasone, T3 and EGF in intact human and rat kidney tissue and in human renal cell carcinoma.

Previous experiments have shown that both in vivo and in vitro pre-treatment with various hormones increases the renal transport capacity for weak organic acids, such as PAH, in rats. The aim of the present study was to test whether or not accumulation of the anticancer drugs methotrexate (MTX), cisplatin (CP), raltitrexed (Tomudex) and topotecan (Hycamtin) can be increased in intact, healthy rat and human renal cortical slices and in human renal cell carcinoma (RCC). Intact, healthy human tissue was obtained from tumour bearing kidneys of patients suffering from RCC. Experiments were intended as a new approach to overcome so-called multidrug resistance. Kidney tissue slices were incubated for 24 h in William's medium E containing various concentrations of dexamethasone, T(3), or EGF. Thereafter slices were placed in anticancer drug containing Cross-Taggart medium and the drug uptake into kidney tissue was measured for 2 h. In intact rat and human renal tissue slices, the uptake of p-aminohippurate (PAH = reference substance) increased significantly after incubation in dexamethasone containing medium (134% and 156%, respectively). There were no stimulating effects of either T(3) or EGF on PAH accumulation. On the other hand, only the accumulation of MTX, but not of CP, raltitrexed or topotecan, was significantly enhanced after hormone pre-treatment both in intact renal tissue and in RCC. A stimulation of renal PAH accumulation can be performed ex vivo, as reported previously, both in intact rat and human renal cortical slices and in RCC. Discrepancies between the effects of dexamethasone and T(3) or EGF indicate different modes of action of these substances at the cellular level. Unfortunately, with the exception of MTX, the uptake of anticancer drugs can not be stimulated effectively ex vivo in human RCC tissue by the substances used. Evidently the transport of these anticancer drugs out of the kidney cells is more effective than their uptake.

Animals↗
PubMed2001

High-dose chemotherapy with peripheral blood stem cell transplantation for patients with advanced ovarian cancer.

PURPOSE: We report the results of high-dose chemotherapy (HDC) with peripheral blood stem cell transplantation in twenty-one patients with primarily advanced or relapsed ovarian cancer. METHODS: Twenty-five women underwent stem cell collection, and 21 were finally treated with different regimens of HDC containing cyclophosphamide, etoposide, carboplatin, and treosulfan. The patients received cyclophosphamide +/- cisplatin and cisplatin + paclitaxel, respectively, followed by G-CSF (n = 24) or GM-CSF (n = 1) for stem cell mobilization. RESULTS: A mean of 7.2 +/- 6.1 x 10(6) CD34+ cells per kg bw were collected. Thirteen patients received double transplants and one patient received a triple transplant. The median age was 47 years (range 24-61 years) and the mean number of prior regimens was three (range 1-8). Engraftment occurred on time in all patients and there was one treatment-related death resulting in an overall mortality rate of 4.8% among the 21 patients treated with HDC. The response rate was 72% (48% CR, 24% PR) and the mean time to progression and overall survival after HDC were 7 and 32 months, respectively. CONCLUSION: HDC could be performed safely in patients with advanced ovarian cancer. However, even with a high response rate, the duration of response is short, warranting new treatment approaches to further improve the outcome of this population of patients with unfavorable prognosis.

Adult↗
PubMed1996

Constitutive overexpression of the cytidine deaminase gene confers resistance to cytosine arabinoside in vitro.

In search of potential therapeutic targets for enhancing the cellular detoxification of cytosine-arabinoside (ara-C), we transfected the human CDD cDNA gene into murine fibroblast cells and examined the effect of increased CDD expression on the cellular resistance to ara-C. Several cell lines were established which consistently demonstrated a 2.5-3.0-fold increase in cellular CDD activity and exhibited an up to 3.0-3.5-fold increase in the IC50 value of ara-C with regard to inhibition of cell proliferation or DNA synthesis, respectively. In the absence of ara-C, these cells maintained unaltered morphology and growth characteristics as compared with parental cells and mock-transfected controls. In addition, we examined the CDD and dCK activity in hematopoietic cells and found CD34+ hematopoietic progenitor cells to reveal a low ratio of CDD/dCK activity. Together, these data suggest that constitutive overexpression of the CDD gene correlates with increased ara-C resistance and thus may prove useful in considering attempts to attenuate ara-C-induced toxicity on hematopoietic progenitor cells.

Adult↗
PubMed1991

Modulation of leukotriene formation by cellular composition and exogenous leukotriene A4.

We investigated the interactions of exogenous leukotriene A4 (LTA4) with isolated cells in the presence or absence of cellular stimuli. The majority of isolated cells are able to transform exogenous LTA4 into LTB4 as well as LTC4. In eosinophils, LTA4 induced 15-hydroxy-eicosatetranoic acid formation and was converted into LTB4. The Ca-ionophore-induced generation of LTB4 from polymorphonuclear leukocytes or from the cell fraction containing lymphocytes, monocytes and basophils was significantly suppressed with LTA4 while the formation of LTC4 was increased. Conversely, the Na-fluoride- and fMLP-induced generation of LTB4 was significantly increased. Our results suggest that the stimulus and the cellular composition determine the pattern of the generated inflammatory mediators.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
PubMed1988

Leukotriene generation and metabolism in isolated human lung macrophages.

We studied the generation and metabolism of leukotrienes (LTs) in human lung macrophages obtained from lung tissue of patients with central bronchial carcinoma. By counterflow centrifugation macrophages were enriched with a purity of more than 95-100%. A time and dose dependent generation of LTB4 and LTC4 was determined by specific radioimmunoassays after stimulation with the Ca-ionophore and anti-IgE. The amount of LTB4 exceeded the amount of LTC4. The concentrations of leukotrienes in the macrophage fraction amounted to 4.3 +/- 2.2 ng LTB4 and 0.6 +/- 0.05 ng LTC4/1 x 10(7) cells after 5 min of incubation with the Ca-ionophore. The LTB4 levels decreased to 3.0 +/- 0.6 ng after 60 min indicating the metabolism of the generated LTB4 by human lung macrophages. This was confirmed by incubation of the cells with exogenously added [3H]LTB4. LTB4 was converted into unpolar products as was identified by thin-layer chromatography and high-performance liquid chromatography; a comparison with the fibroblast cell line L929 which is known to convert LTB4 into the dihydro-LTB4 metabolite (5,12-dihydroxyeicosatrienoic acid) indicates that human lung macrophages use the same pathway of metabolization. Biological inactivation as determined by chemotaxis and cross-reaction with the LTB4 antiserum correlates with the degree of LTB4 metabolism. Moreover, the macrophages convert LTC4 into LTD4 and LTE4 by the enzymatic activity of the gamma-glutamyltranspeptidase and dipeptidase. Our data emphasize that the human alveolar macrophage not only produces arachidonic acid metabolites but modulates the local inflammatory potential by its metabolizing capacity for leukotrienes.

Antibodies, Anti-Idiotypic↗