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W Eisterer

Publications and source records attributed to W Eisterer.

30 records · Page 2Linked to original sources
PubMed1995

Decreased potency of MDR-modulators under serum conditions determined by a functional assay.

A variety of agents are capable of overcoming P-glycoprotein-mediated multidrug resistance (MDR) in vitro. However, the clinical potential of these compounds is often limited due to high plasma protein binding. We compared the efficacy of several MDR-reversing compounds in serum-free culture medium and under serum conditions by means of a functional assay. Using flow cytometry the efflux of the fluorescent dye rhodamine 123 (Rh123) was measured from normal peripheral blood CD8+ T-lymphocytes which express low levels of P-glycoprotein. Inhibition of Rh123 efflux by R-verapamil, dexnigludipine-HCl, cyclosporin A, SDZ PSC833 and the protein kinase C (PKC) inhibitor CGP 41251 was determined in serum-free medium and in serum at concentrations from 0.1 to 50 mumol/l. With the exception of SDZ PSC833 all MDR modulators showed an insufficient or suboptimal modulation of P-glycoprotein under serum conditions at concentrations achievable in vivo. The highest potency under serum conditions demonstrated SDZ PSC833: even at a concentration of 0.5 mumol/l a sufficient inhibitory effect was observed. Subsequently this approach was applied to patients suffering from B-cell chronic lymphocytic leukaemia (B-CLL; n = 3) and acute myeloid leukaemia (AML; n = 2) which were positive in the Rh123 efflux assay. As for normal CD8+ T-lymphocytes, much higher drug concentrations were required under serum conditions to effectively inhibit Rh123 efflux from the leukaemic cells. Thus the interpretation of results of clinical 'modulator' trials should consider the decreased bioavailability of MDR-reversing agents.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Normal granulocyte function but impaired monocyte function in a patient with aplastic anemia.

Granulocytopenia is an invariable finding in aplastic anemia (AA) and bacterial infections are a frequent complication and major cause of death in patients suffering from this bone marrow disorder. Using well-established assays, we determined the chemotaxis of granulocytes and monocytes as well as the phagocytic capacity of monocytes and oxidative metabolism of granulocytes in a patient with aplastic anemia of unknown etiology. Our results indicate a normal granulocyte oxidative metabolism and granulocyte chemotaxis towards formyl-leucyl-methionyl-phenylalanine (fMLP), whereas monocyte chemotaxis and phagocytic capacity were markedly reduced in this patient.

Adult↗
PubMed1995

Identification of a favorable subgroup of patients with generalized immunocytomas by follicular dendritic cells.

In the present study, 89 patients with generalized immunocytoma were analyzed retrospectively for the prognostic influence of clinical features and of immunophenotype using bone marrow biopsies. Univariate analysis selected the following variables as significant for survival: age over 60 years (p = 0.021), Rai and Binet stage (p = 0.008 and 0.004, respectively), presence or absence of follicular dendritic cells (FDC, p = 0.036), presence or absence of anemia (p = 0.037). Multivariate regression analysis showed independent prognostic significance of age (p = 0.001), Rai stage (p = 0.003), and the presence of follicular dendritic cells (p = 0.010). Comparing CD5 positive and CD5 negative immunocytomas, no survival advantage for one of the two groups was seen. Presence of follicular dendritic cells clearly identified a favorable prognostic subgroup: of the 89 patients presented, only three of 18 (16.6%) with detectable FDC in bone marrow died within the observation period, as compared to 34 of 71 (52.1%) patients without FDC. Multivariate analysis emphasized the independent prognostic value of the presence of FDC. The high predictive capacity of follicular dendritic cells could add useful information to the commonly used Rai and Binet staging systems for immunocytoma.

Adult↗
PubMed1995

Low frequency of activity of P-glycoprotein (P-170) in acute lymphoblastic leukemia compared to acute myeloid leukemia.

The purpose of our investigations was to measure P-glycoprotein (P-170) activity in blast cells of 35 adults with acute myeloid leukemia (AML), and 24 children and adults with acute lymphoblastic leukemia (ALL) at time of diagnosis. Studies were based on a flow cytometric assay that detects efflux of the fluorescent dye rhodamine 123 (Rh123), which is transported from the cell by the P-170 pump. Dual-fluorescence staining with Rh123 and phycoerythrin-labeled monoclonal antibodies allowed selective measurement of Rh123 efflux in blast cells. Samples were scored positive when the fraction of blast cells showing Rh123 efflux exceeded 10% after a 120-min incubation. Activity of P-170 was observed in 19 (54%) of the 35 AML cases and was completely blocked in the presence of multidrug resistance inhibitors. Efflux activity was significantly higher in CD34-positive AML samples (p < 0.02). All AML patients with the FAB-subtype M5 (n = 5) lacked Rh123 pumping activity (p < 0.03). The complete remission rate in response to induction chemotherapy was significantly higher for Rh123-negative (11/13, 85%) than for Rh 123-positive AML patients (4/15, 27%) (p < 0.007). At a median follow-up of 9 months overall survival was significantly shorter for Rh123-positive than for Rh123-negative patients (p < 0.05). In contrast to AML, we could detect Rh123 efflux in only two (8%) out of 24 ALL cases. The immunological subtypes of these two positive cases was of B-ALL and pre-T-ALL. Bone marrow cryostat sections from 13 AML and five ALL patients were further analyzed for staining with monoclonal antibodies MM4.17 and JSB1. Ten of 13 AML and two of five ALL cases expressed the MDR protein. Our results indicate that there is a rather low frequency of P-170 pumping activity in ALL compared with AML. Further, functional activity of P-170 contributes to chemoresistance in de novo AML.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Treatment of relapsed and refractory acute myelogenous leukaemia with aclacinomycin A (ACA) and etoposide (VP-16).

Ten patients with refractory and relapsed acute myelogenous leukaemia (AML) and one patient with CML in blast crisis were treated with aclacinomycin A (ACA, 60 mg/m2/day for 5 days) and etoposide (VP-16, 100 mg/m2/day for 5 days) and analysed retrospectively. Of 11 patients, seven (63%) achieved an objective response including four CRs (36%). Most impressively, two patients experienced consecutive CRs (second, third, and fourth) following relapses. Only two patients (18%) were primary resistant with persisting leukaemia. In conclusion, the combination of ACA and VP-16 is an active regimen in refractory and relapsed AML with a toxicity comparable with other salvage regimens.

Aclarubicin↗
PubMed1994

Bone marrow lymphocyte subsets in myelodysplastic syndromes.

AIM: To examine lymphocyte subsets in patients with myelodysplastic syndromes (MDS); and to correlate immunohistological variables with prognosis. METHODS: Bone marrow trephine biopsy specimens from 65 patients with MDS were immunophenotyped using a panel of antibodies. A minimum of 1000 cells from representative areas of marrow sections were counted at light microscopy. The association between immunohistological variables and prognosis was assessed. RESULTS: Compared with normal control marrows (n = 23) no major abnormalities of T cells (CD3), T cell subsets (CD4, CD8, CD25, TCR gamma/delta) or natural killer cells (CD56, CD57) were seen in the 65 patients. In high risk MDS (RAEB, RAEB-t) 19% of the cases showed increased numbers of B lymphocytes compared with none in the low risk group (RA, RARS) (p < 0.0090). Only percentages of B cells above 3% significantly correlated with poor survival (p = 0.0121 for CD19, p = 0.046 for CD22). CONCLUSIONS: The deviations in T lymphocyte counts seen in peripheral blood and in bone marrow aspirates could not be verified in bone marrow biopsy specimens.

Adolescent↗
PubMed1994

[Functional detection of P-glycoprotein expressing cells with flow cytometry].

Classical multidrug resistance (MDR) is associated with the overexpression of a membrane glycoprotein termed P-glycoprotein (P-gp) that transports a variety of apparently unrelated anti-cancer drugs out of cells. Based on the fluorescent properties of the dye rhodamine 123 (Rh 123) we aimed to develop a functional flow cytometric assay for the detection of MDR-expressing cells. Using drug sensitive cell lines (KB-3-1) and MDR mutants (KB-8-5, KB-C1) experimental conditions were established enabling demonstration of significant differences in Rh 123 accumulation/efflux. Using two-colour flow cytometry we subsequently analysed 42 consecutive patients suffering from B-cell chronic lymphocytic leukemia (B-CLL). 34/42 (81%) cases showed a marked Rh 123 efflux which was completely abolished in the presence of the MDR inhibitor verapamil. The percentage of Rh 123 effluxing cells ranged from 10 to 70% with a median of 32%. In 26 cases extracted RNA was analysed by quantitative polymerase chain reaction to evaluate the expression of MDR 1 mRNA. In 25 of 26 (96%) cases MDR 1 mRNA was detectable. The levels of MDR 1 mRNA expression correlated well with the results of the Rh 123 efflux assay (r = 0.72; p < 0.0001). In addition, 37 cases of acute myeloid leukemia were analysed and demonstrated Rh 123 efflux in 18/37 (49%) cases. In this entity the percentage of Rh 123 effluxing cells ranged from 12 to 80% (median 45%). Additionally, we evaluated the Rh 123 efflux/retention in peripheral blood cells of healthy volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Activity of P-glycoprotein in B-cell chronic lymphocytic leukemia determined by a flow cytometric assay.

BACKGROUND: Chemoresistance in some hematologic malignancies has been associated with overexpression of P-glycoprotein, which is encoded by the MDR1 gene (also known as PGY1). However, inconsistencies in data on frequency and clinical relevance of multidrug resistance in B-cell chronic lymphocytic leukemia (B-CLL) may reflect a need for improved techniques to detect this overexpression. PURPOSE: Our purpose was to measure P-glycoprotein activity in peripheral blood cells of B-CLL patients and to analyze possible clinical correlations (disease duration, prior treatment, Rai disease stage, lymphocyte counts, and disease progression). METHODS: P-glycoprotein activity was assayed in peripheral blood cells of 42 consecutive B-CLL patients (22 treated and 20 untreated). We used dual fluorescence in a flow cytometric assay that detects efflux of the fluorescent dye rhodamine 123, which is transported from the cell by the P-glyprotein pump. Leukemia cells were costained with monoclonal antibody Leu12/CD19, and rhodamine 123 efflux was measured. Expression of MDR1 and MDR3 (also known as PGY3) messenger RNA (mRNA) was quantitatively evaluated by polymerase chain reaction (PCR) in 26 cases. RESULTS: Marked rhodamine 123 efflux was observed in 34 (81%) of the 42 cases and was abolished in the presence of multidrug resistance inhibitors. Rhodamine 123 efflux was not associated with Rai stage, lymphocyte counts, duration of disease, or disease progression. Although rhodamine 123-negative cases were about equally distributed among untreated and previously treated patients, the percentage of cells with rhodamine 123 efflux was significantly lower for untreated patients than for those treated with chemotherapy regimens including at least one multidrug resistance-associated drug. MDR1 mRNA was detected in 25 of 26 cases and MDR3 mRNA in all 26. MDR1 mRNA expression was significantly correlated with rhodamine 123 efflux, whereas MDR3 mRNA expression was not significantly correlated; MDR1 and MDR3 mRNA expression was not significantly associated with Rai stage, prior treatment, or disease progresssion. CONCLUSIONS: These findings suggest that P-glycoprotein overexpression in B-CLL is intrinsic rather than acquired and that P-glycoprotein activity is enhanced after exposure to multidrug resistance-associated drugs. This enhanced activity does not seem to be associated with more aggressive disease. Our results also indicate that an assay of P-glycoprotein function combined with PCR is suitable for clinical multidrug resistance screening. IMPLICATIONS: Additional studies are needed to determine whether functional activity of P-glycoprotein, measured by rhodamine 123 efflux, is directly related to clinical drug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

Oxidative burst of neutrophils in patients with rheumatoid arthritis: influence of various cytokines and medication.

OBJECTIVE: Toxic oxygen products are believed to be implicated in tissue damage in some complex-mediated diseases such as rheumatoid arthritis. In the present study we compared the superoxide (O2) production of polymorphonuclear leukocytes (PMNs) in 21 patients with rheumatoid arthritis (RA) with that of 9 healthy controls, examining the effect of different stimulants and cytokines on the oxidative burst (OB). Since many drugs used in the treatment of RA may alter O2 metabolism, the effects of antirheumatic medication were also studied. METHODS: Generation of superoxide anions was analysed by a flow cytometric method, using the fluorochrome dihydro-rhodamine. As stimulants for OB, we used N-formyl-methionyl-leucyl-phenylalanine (fMLP), which acts via a membrane receptor, and phorbol-myristate acetate (PMA), which acts in a membrane receptor-independent manner. As preactivating substances, TNF-alpha, G-CSF and GM-CSF were applied. RESULTS: In RA patients under treatment with antirheumatic medication, fMLP-induced OB (+/- cytokines) was significantly reduced, while O2 production after stimulation with PMA was similar compared to controls. GM-CSF showed the highest level of preactivation in controls, whereas in RA patients TNF-alpha proved to be most potent. In both controls and RA patients, a combination of GM-CSF or G-CSF with TNF-alpha further enhanced OB. No correlation between OB and clinical data or treatment could be established in RA patients. CONCLUSIONS: There is a reduced cytokine priming capacity for OB in RA patients under antirheumatic medication in spite of the presence of an intact enzyme system of OB. Antirheumatic medication combining multiple drugs capable of decreasing OB might effectively modulate oxidative metabolism.

Adult↗