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Andreas Neubauer

Publications and source records attributed to Andreas Neubauer.

34 records · Page 2Linked to original sources
PubMed2005

Interferon alpha and T-cell responses in chronic myeloid leukemia.

Chronic myelogenous leukemia (CML) was the first human malignancy where a consistent chromosomal abnormality, the BCR-ABL translocation, was identified as the causative genetic aberration. There is a mounting body of evidence suggesting that CML cells are particularly good targets for immunological surveillance mechanisms, the most intriguing being the curative effect of allogeneic donor lymphocyte infusion given in relapsed disease after allogeneic bone marrow transplantation. Likewise, interferon alpha (IFN alpha), which has long been considered as the standard conservative therapy in CML, may exert its life-prolonging effect by activating immunological effector functions. This review will focus on the recent advances in the understanding of the contribution of IFN alpha in eliciting T-cell responses against self-antigens in CML.

Humans↗
PubMed2005

Distinct gene expression profile of human mesenchymal stem cells in comparison to skin fibroblasts employing cDNA microarray analysis of 9600 genes.

Broad differentiation capacity has been described for mesenchymal stem cells (MSC) from human bone marrow. We sought to identify genes associated with the immature state and pluripotency of this cell type. To prove the pluripotent state of the MSC, differentiation into osteocytes, adipocytes, and chondrocytes was performed in vitro. In contrast, normal skin cells did not harbor these differentiation abilities. We compared the expression profile of human bone marrow MSC with cDNA from one primary human skin cell line as control, using a cDNA chip providing 9600 genes. The identity of all relevant genes was confirmed by direct sequencing. Data of gene array expression were corroborated employing quantitative PCR analysis. About 80 genes were differently expressed more than threefold in MSC compared to mature skin fibroblasts. Interestingly, primary human MSC were found to upregulate a number of genes important for embryogenesis such as distal-less homeo box 5, Eyes absent homolog 2, inhibitor of DNA binding 3, and LIM protein. In contrast, mesenchymal lineage genes were downregulated in MSC in comparison to skin cells. We also detected expression of some genes involved in neural development, indicating the broad differentiation capabilities of MSC. We conclude that human mesenchymal stem cells harbor an expression profile distinct from mature skin fibroblast, and genes associated with developmental processes and stem cell function are highly expressed in adult mesenchymal stem cells.

Bone Marrow Cells↗
PubMed2004

Ongoing monoclonal B-cell proliferation is not common in gastric B-cell lymphoma after combined radiochemotherapy.

PURPOSE: Gastric marginal-zone B-cell lymphoma (MZBCL) of the mucosa-associated lymphoid tissue (MALT) is associated with chronic Helicobacter pylori gastritis. Stable complete remission (CR) can be induced by H pylori eradication. Whether this is paralleled by cure of the lymphoma remains unclear. Persisting monoclonal bands for immunoglobulin heavy chain variable region (VH) representing the lymphoma clone have been described in up to 50% of patients in CR. This retrospective study investigated whether this phenomenon also occurs after radiochemotherapy. PATIENTS AND METHODS: Biopsy samples of 20 patients receiving chemotherapy with cyclophosphamide, doxorubicin, vincristine, and prednisone and irradiation were analyzed before and after therapy. Study patients had Ann Arbor stage I/II primary gastric cancer, including four cases of MZBCL of MALT type, 12 cases of diffuse large-cell lymphomas (DLCL), and four cases of mixed MALT type/DLCL. Polymerase chain reaction (PCR) for VH rearrangement was performed. Monoclonal PCR products were cloned and sequenced. RESULTS: Fourteen of 20 patients had a monoclonal or oligoclonal band distribution at diagnosis converted into polyclonal pattern after radiochemotherapy. Of the remaining six patients, two were lost to follow-up. One patient did not respond and died of progressive disease. PCR in this patient showed persistent B-cell clonality. In three patients, the initial PCR showed a polyclonal pattern and thus could not be evaluated during follow-up. CONCLUSION: In contrast with H pylori eradication alone, radiochemotherapy results in clearing of monoclonal cells during follow-up. This may result in better elimination of residual lymphoma cells. Further study is needed to determine whether this translates into lower risk of relapse.

Adult↗
PubMed2004

Confocal fluorescence detection expanded to UV excitation: the first continuous fluorimetric assay of human steroid sulfatase in nanoliter volume.

Steroid sulfatase is an enzyme that currently enjoys considerable interest as a potential drug target in the treatment of estrogen- and androgen-dependent diseases, in particular breast cancer. We have purified human steroid sulfatase to apparent homogeneity from recombinant Chinese hamster ovary cells, and we established an assay with a new fluorogenic substrate, 3,4-benzocoumarin-7-O-sulfate (1). Substrate 1 features a K(m) value of 22.5 microM, which is close to the value for the natural substrate dehydroepiandrosterone sulfate (26 microM) and much lower than the K(m) values of other synthetic substrates (276-736 microM). Importantly, the cleavage of substrate 1 can be monitored continuously during the enzymatic cleavage, since a change in fluorescence intensity is detectable at the pH where the enzyme is active; in contrast, all other synthetic substrates described so far require alkalization to reveal a measurable absorbance or fluorescence signal. The adaptation of the assay to the 96-well format allows continuous monitoring of multiple wells in a microplate fluorescence reader. Applications of the assay for the determination of IC(50) and K(i) values of novel steroid sulfatase inhibitors are presented. Most importantly the assay was transferred to the nanoscale format (1-microl assay volume) in 2080-well plates with confocal fluorescence detection. This miniaturization will permit screening with a minimum throughput of 20000 compounds per day. The system presented demonstrates that the confocal detection platform used for nanoscreening can be successfully adapted to assays for which conventional ultraviolet dyes like coumarins are necessary. This strongly broadens the application range of confocal readers in drug screening.

Algorithms↗
PubMed2003

Interferon consensus sequence binding protein (ICSBP; IRF-8) antagonizes BCR/ABL and down-regulates bcl-2.

BCR/ABL is the causative genetic aberration in chronic myelogenous leukemia (CML). Mice lacking expression of the interferon (IFN) consensus sequence binding protein (ICSBP), an IFN gamma-inducible transcription factor of the interferon regulatory factor (IRF) family, develop a disease similar to human CML. Mounting evidence suggests a role for ICSBP in the pathogenesis of CML. However, the underlying mechanisms are largely unknown. By stable and conditional expression of ICSBP in wild-type and BCR/ABL-transformed 32D cells (32D/wt and 32D/BA), we found that ICSBP inhibited BCR/ABL-mediated leukemogenesis in vivo. Moreover, ICSBP also overrode BCR/ABL-mediated morphology changes, chemotherapy, and imatinib resistance, as well as BCR/ABL-induced repression of differentiation. Some of these ICSBP effects may be explained in part by an ICSBP-mediated repression of bcl-2, a major antiapoptotic target of BCR/ABL, on transcriptional and protein level. Using reporter gene assays and electrophoretic mobility shift assays we identified that the bcl-2 promoter activity was inhibited by ICSBP by way of a fragment containing 2 characteristic ICSBP-responsive elements. An inverse correlation between ICSBP and bcl-2 expression was confirmed in vivo. Collectively, our findings suggest that ICSBP antagonizes BCR/ABL by down-regulation of bcl-2 and implicates a central role for ICSBP in the pathogenesis of CML, as well as a therapeutic target to overcome drug resistance in bcl-2-dependent tumors.

Animals↗
PubMed2003

Analysis of Tikhonov regularization for function approximation by neural networks.

This paper is devoted to the convergence and stability analysis of Tikhonov regularization for function approximation by a class of feed-forward neural networks with one hidden layer and linear output layer. We investigate two frequently used approaches, namely regularization by output smoothing and regularization by weight decay, as well as a combination of both methods to combine their advantages. We show that in all cases stable approximations are obtained converging to the approximated function in a desired Sobolev space as the noise in the data tends to zero (in the weaker L(2)-norm) if the regularization parameter and the number of units in the network are chosen appropriately. Under additional smoothness assumptions we are able to show convergence rates results in terms of the noise level and the number of units in the network. In addition, we show how the theoretical results can be applied to the important classes of perceptrons with one hidden layer and to translation networks. Finally, the performance of the different approaches is compared in some numerical examples.

Algorithms↗
PubMed2003

Bacterial contamination of ex vivo processed PBPC products under clean room conditions.

BACKGROUND: Patients undergoing high-dose radio- and/or chemotherapy and autologous or allogeneic PBPC transplantation are at high risk for infections owing to profound immunosuppression. In this study, the rate of microbial contamination of ex vivo processed PBPC products was analyzed, comparing preparation under clean room conditions to standard laboratory conditions. STUDY DESIGN AND METHODS: After implementation of good manufacturing practice conditions in the two participating institutions, the microbial contamination rate of 366 PBPC harvests from 198 patients was determined under certified clean room conditions (Group A) from 2000 until 2002. To investigate influence of improved environmental conditions along with other parameters, this set of samples was compared with a historical control set of 1413 PBPC products, which have been processed ex vivo under a clean bench in a regular laboratory room and were harvested from 626 patients (Group B) from 1989 until 2000. RESULTS: In Group B microbial contamination was found in 74 PBPC products (5.2%) from 57 patients. In Group A microbial growth was detected in 3 leukapheresis products (0.8%) from 3 patients. After exclusion of PBPC products, which were probably contaminated before manipulation, statistical analysis showed a significant difference (chi2= 10.339; p < 0.001). CONCLUSION: These data suggest an impact of clean room conditions on the bacterial contamination rate of PBPC products. To identify confounding variables, variables like technique of leukapheresis, culture methodology, and microbial colonization of central venous catheters were taken into account. Further variables might be identified in following studies.

Bacteria↗
PubMed2003

B-cell monoclonality is associated with lymphoid follicles in gastritis.

The gold standard for diagnosis of gastric MALT lymphoma is histopathology. Polymerase chain reaction-based assays to detect the expansion of monoclonal B cells have also been used to corroborate the diagnosis. However, there are conflicting data on monoclonal B-cell expansion in gastritis. We asked about its frequency in graded gastritis cases. Lymphocytic infiltration in gastric biopsies was graded according to Wotherspoon in 129 cases. The histologic diagnosis ranged from normal gastric mucosa to suspicious for gastric MALT lymphoma. To search for a monoclonal B-cell population, a semi-nested polymerase chain reaction strategy was used for amplification of rearranged VDJ sequences of the immunoglobulin heavy chain gene. Of 106 evaluable samples, 18 were found to be monoclonal. The detection of a monoclonal B-cell population was strongly associated with the presence of lymphoid follicles. In cases with lymphoid follicles, detection of monoclonality was independent of Wotherspoon grading; there is no significant difference between cases being suspicious for lymphoma and those not. We found B-cell monoclonality to be a more frequent than expected finding in gastritis and to be strongly associated with the presence of lymphoid follicles; thus, its presence is of little significance in patient management.

B-Lymphocytes↗
PubMed2003

Normal intrinsic Th1/Th2 balance in patients with chronic phase chronic myeloid leukemia not treated with interferon-alpha or imatinib.

BACKGROUND AND OBJECTIVES: CD4+ T helper cells are an integral part of effective immune responses against various malignancies; however in tumor-bearing patients they are frequently functionally unresponsive. T helper cells of patients with chronic myeloid leukemia (CML), analyzed as part of mononuclear cell fractions, show a loss of signaling molecules, a compromised Th1 cytokine production and a shift towards a non-productive Th2 state. The underlying mechanism is unknown and may involve intrinsic T cell defects as well as indirect effects mediated by leukemia or antigen-presenting cells. The purpose of the present study was to analyze the intrinsic cytokine-producing capacity of purified CML T helper cells in the absence of other cell types. DESIGN AND METHODS: Untouched CD4+ T cells with a purity of more than 90% were isolated from 10 patients with Ph+ chronic phase CML on maintenance treatment with hydroxyurea. The cells were isolated by density gradient centrifugation followed by immunomagnetic depletion of leukemia and accessory cells. The ex vivo cytokine-producing capacity of CML T helper cells in response to polyclonal stimulation with anti-CD3 and anti-CD28 was then compared to that of cells purified from matched healthy volunteers. RESULTS: T helper cells purified from CML patients produced comparable amounts of the Th1 cytokines interleukin (IL)-2 and interferon (IFN)-g as cells purified from healthy volunteers. Likewise, no difference between CML and control T helper cells was found with respect to the Th2 cytokines, IL-4 and IL-13, as well as the immunomodulatory cytokine, IL-10. INTERPRETATION AND CONCLUSIONS: In the absence of leukemia and accessory cells, the intrinsic cytokine-producing capacity of CML T helper cells is normal. A Th2 shift was not detected, and the predominant presence of an IL-10-producing, immunosuppressive T helper cell subset could be excluded.

Adult↗
PubMed2002

Interferon-alpha, but not the ABL-kinase inhibitor imatinib (STI571), induces expression of myeloblastin and a specific T-cell response in chronic myeloid leukemia.

Chronic myeloid leukemia (CML) is a clonal disease of hematopoietic stem cells caused by a reciprocal translocation of the long arms of chromosomes 9 and 22. In human leukocyte antigen A*0201(+) (HLA-A*0201(+)) individuals, response after interferon-alpha (IFN-alpha) was shown to be associated with the emergence of CML-specific cytotoxic T cells that recognize PR-1, a myeloblastin (MBN)-derived nonapeptide. In contrast, imatinib potently induces remissions from CML by specific inhibition of the ABL tyrosine kinase. Here, we explored molecular regulations associated with CML responses under different treatment forms using cDNA-array. Expression of MBN was found to be down-regulated in remission under imatinib therapy (0 of 7 MBN(+) patients). In contrast, MBN transcription was readily detectable in the peripheral blood in 8 of 8 tested IFN-alpha patients in complete remission (P =.0002). IFN-alpha-dependent MBN transcription was confirmed in vitro by stimulation of peripheral blood mononuclear cells (PBMCs) with IFN-alpha and by IFN-alpha-mediated activation of the MBN promoter in reporter gene assays. Finally, with the use of HLA-A*0201-restricted, MBN-specific tetrameric complexes, it was demonstrated that all of 4 IFN-alpha-treated patients (100%), but only 2 of 11 imatinib patients (19%), in complete hematological or cytogenetic remission developed MBN-specific cytotoxic T cells (P =.011). Together, the induction of MBN expression by IFN-alpha, but not imatinib, may contribute to the specific ability of IFN-alpha to induce an MBN-specific T-cell response in CML patients. This also implies that the character of remissions achieved with either drug may not be equivalent and therefore a therapy modality combining IFN-alpha and imatinib may be most effective.

Benzamides↗
PubMed2002

Analysis of FLT3-activating mutations in 979 patients with acute myelogenous leukemia: association with FAB subtypes and identification of subgroups with poor prognosis.

Constitutive activation of the FLT3 receptor tyrosine kinase, either by internal tandem duplication (ITD) of the juxtamembrane region or by point mutations in the second tyrosine kinase domain (TKD), has been described in patients with acute myelogenous leukemia (AML). We analyzed the prevalence and the potential prognostic impact of FLT3 mutations in 979 AML patients. Results were correlated with cytogenetic data and the clinical response. FLT3-ITD mutations were found in 20.4% and FLT3-TKD mutations in 7.7% of the patients. Each mutation was associated with similar clinical characteristics and was more prevalent in patients with normal karyotype. Significantly more FLT3 aberrations were found in patients with FAB M5, and fewer were found in patients with FAB M2 and M6. Although less frequent in patients with cytogenetic aberrations, FLT3-ITDs were found in 13 of 42 patients with t(15;17) and in 9 of 10 patients with t(6;9). The prevalence of the ITD allele on the DNA level was heterogeneous, ranging from faint mutant bands in some patients to predominant mutant bands in others. Based on quantitative analysis, the mutant-wild-type (wt) ratio ranged from 0.03 to 32.56 (median, 0.78). Patients with a high mutant/wt ratio (ie, greater than 0.78) had significantly shorter overall and disease-free survival, whereas survival in patients with ratios below 0.78 did not differ from those without FLT3 aberrations. Multivariate analysis confirmed a high mutant/wt ratio to be a strong independent prognostic factor. Taken together, these data confirm that FLT mutations represent a common alteration in adult AML. Constitutive activation may be associated with monocytoid differentiation. A high mutant/wt ratio in ITD-positive patients appears to have a major impact on the prognostic relevance.

Adult↗
PubMed2002

[Fatal bleeding complications caused by Evans syndrome (autoimmune thrombocytopenia and hemolytic anemia) and type II autoimmune hepatitis in a 56-year-old patient].

BACKGROUND: Autoimmune hepatitis is a rare form of hepatitis of nonviral origin. Two main subentities have been described. The classical lupoid hepatitis (type I) is characterized by hypergammaglobulinemia and the presence of lupus erythematosus cells due to antinuclear antibodies. Autoimmune hepatitis type II, which is associated with antiliver/kidney microsomal antibodies type 1 (LKM 1) shows a more aggressive clinical course than autoimmune hepatitis type I and is frequently (41% of cases) associated with other immunologic diseases. CASE REPORT: In the present study we report a case of autoimmune hepatitis Type II, associated with autoimmune thrombocytopenia and hemolytic anemia, in a 56-year-old patient. The patient's death was caused by a fatal association of a failing coagulation system due to liver dysfunction and a severe autoimmune thrombocytopenia. The aggressive course of the thrombocytopenia even after splenectomy demonstrated that the splenic enlargement due to the portal hypertension was only a minor factor in the destruction of the thrombocytes. Interestingly, some findings of this case such as the advanced age, the presence of anti-smooth muscle antibodies and HLA-DR4 are usually associated with autoimmune hepatitis type I. CONCLUSION: The findings of this case indicate that concomitant autoimmune diseases can worsen the prognosis of autoimmune hepatitis. Prednisolone and azathioprine might not be sufficient to treat aggressive forms of autoimmune hepatitis. Immunosuppressive regimens administered to recipients after organ transplantation might be used as a therapy of autoimmune hepatitis in multicenter clinical trials.

Anemia, Hemolytic, Autoimmune↗
PubMed2002

T(11;18) is a marker for all stage gastric MALT lymphomas that will not respond to H. pylori eradication.

BACKGROUND & AIMS: Eradication of Helicobacter pylori leads to cure of gastric mucosa-associated lymphoid tissue (MALT) lymphoma in 75% of localized cases. However, prolonged follow-up is necessary to determine whether a lymphoma responds to therapy. In a small series of cases, we showed that t(11;18)(q21;q21)-positive MALT lymphomas failed to respond to H. pylori eradication. The present study aimed to verify this finding in a large cohort and confirm whether the translocation predicts the response of stage I(E) tumors, for which clinical staging has little prognostic value. METHODS: A total of 111 patients with H. pylori-positive gastric MALT lymphoma treated with antibiotics were studied. Clinical staging was undertaken before therapy. The response of lymphoma to H. pylori eradication was determined by histologic examination of gastric biopsy specimens. Diagnostic biopsy specimens were analyzed for t(11;18)(q21;q21) by reverse-transcription polymerase chain reaction of the API2-MALT1 transcript. RESULTS: Forty-seven of the 48 patients who showed complete regression had lymphoma at stage I(E), whereas 43 of the 63 nonresponsive cases were at stage I(E) and the remaining cases at stage II(E) or above. t(11;18)(q21;q21) was detected in 2 of 48 complete-regression cases, and these positive cases showed relapse of lymphoma in the absence of H. pylori reinfection. In contrast, the translocation was present in 42 of the 63 nonresponsive cases, including 26 of 43 (60%) at stage I(E). CONCLUSIONS: t(11;18)(q21;q21)-positive gastric MALT lymphomas, including those at stage I(E), do not respond to H. pylori eradication. Detection of the translocation should help the clinical management of patients with gastric MALT lymphoma.

Adult↗
PubMed2002

Intensified double induction therapy with high dose mitoxantrone, etoposide, m-amsacrine and high dose ara-C for elderly acute myeloid leukemia patients aged 61-65 years.

BACKGROUND AND OBJECTIVES: Treatment outcome in elderly patients with acute myeloid leukemia (AML) is still disappointing. However, some trials showed that increasing the dosage of anthracyclines within induction therapy improved treatment outcome substantially. We, therefore, tried to escalate induction therapy further in a group of young elderly AML patients. DESIGN AND METHODS: In a multicenter trial 33 patients aged 61-65 years with de novo or secondary AML were treated with double induction therapy including high dose mitoxantrone, etoposide and ara-C (MAV) in the first course and m-amsacrine together with high dose ara-C (MAMAC) in the second course. Treatment results were compared to those in 39 AML patients older than 65 years receiving conventional double induction therapy including daunorubicin and ara-C (DA I and DA II) within the same time period. RESULTS: Compared to results achieved with conventional induction therapy, intensified double induction therapy did not significantly improve CR rates, overall or disease-free survival. Hematologic toxicity was not different between the two groups, but non-hematologic toxicity was significantly higher with MAV/MAMAC. This was mainly due to gastro-intestinal or liver toxicity. The rate of early mortality (death within the first 12 weeks) was 42% in the group receiving intensified therapy and 18% in that given conventional induction therapy (p=0.04). INTERPRETATION AND CONCLUSION: Intensification of double induction therapy using high dose mitoxantrone and high dose ara-C in AML patients aged 61-65 years did not lead to improved treatment outcome and conferred an unacceptable early death rate due to high non-hematologic toxicity. Risk-adapted or alternative treatment strategies are needed to improve treatment outcome in these young elderly AML patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗