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Biomedical subjects

C Kasper

Publications and source records attributed to C Kasper.

At least 19 recordsLinked to original sources
PubMed2005

Impact of early NK cell recovery on development of GvHD and CMV reactivation in dose-reduced regimen prior to allogeneic PBSCT.

Dose-reduced allogeneic peripheral blood stem cell transplantation (PBSCT) is a therapeutic approach for patients with haematological malignancies who are not eligible for conventional allogeneic PBSCT. We analysed early development of lymphocyte subpopulations and the occurrence of cytomegalovirus (CMV) reactivation and acute graft-versus-host reaction (GvHD) in patients undergoing the protocol according to Slavin vs conventionally treated patients. Lymphocyte status prior to conditioning and at day +30 after allogeneic PBSCT was determined in 24 out of 51 patients who received conventional allogeneic PBSCT (eg cyclophosphamide plus total body irradiation) and compared with 27 patients being treated according to the Slavin protocol (fludarabine, busulphan and ATG). There is a significant delay in CD4 (T helper) cell development and consecutive lower CD4/CD8 ratios and a better reconstitution of CD8 (T cytotoxic) and NK (natural killer) cells after the Slavin protocol. Patients undergoing this protocol and no, or only grade I, acute GvHD show an even better NK cell reconstitution compared to patients with grade II-IV GvHD. A low CD4/CD8 ratio represents a CMV risk factor only in conventionally treated patients with grade 0-I GvHD, while after preparative regimen according to the Slavin protocol, the NK/CD8 ratio might be a marker for the prediction of CMV reactivation in addition to CMV risk status.

Adult↗
PubMed2004

Combined standard graft-versus-host disease (GvHD) prophylaxis with mycophenolate mofetil (MMF) in allogeneic peripheral blood stem cell transplantation from unrelated donors.

In this open single-centre phase II study, MMF was added on day +10 after allogeneic transplantation to standard immunosuppressive prophylaxis consisting of cyclosporine and methotrexate to decrease the incidence of GvHD. In all, 30 patients aged 20-59 years with advanced haematological malignancies received an unmanipulated blood-stem-cell graft (median of 8.5 x 10(6) CD34(+) and 349 x 10(6) CD3(+) cells per bodyweight) from matched unrelated (n=26), or mismatched donors (n=4). Prior to transplantation, 13 patients underwent fractionated total body irradiation and cyclophosphamide, one patient additional etoposide. In all, 16 patients received reduced conditioning of fludarabin, busulfan, and antithymocyte globulin. All patients engrafted in a median of 12 days, and 19 developed acute GvHD>/=II, including two patients with GvHD III and three with GvHD IV. Subsequently, nine patients developed limited and two patients extensive chronic GvHD. With a median follow-up of 28 months, the overall survival is 53.3% and disease-free survival 50%, respectively. Only two deaths were due to GvHD IV. Out of 13 patients, 10 being CMV IgG positive became positive for pp65. In conclusion, this MMF schedule seems to be safe and feasible in the prophylaxis of severe acute GvHD for high-risk patients, restricted by an increased risk for reactivating CMV in seropositive patients.

Adult↗
PubMed2003

In vitro comparison of complementary interactions between synthetic linear/branched oligo/poly-L-lysines and tissue plasminogen activator by means of high-performance monolithic-disk affinity chromatography.

The recently discovered serine protease called tissue plasminogen activator (t-PA) enables efficient dissolution of blood clots. t-PA works by converting plasminogen into its active form, plasmin, dissolving the major component of blood clots, fibrin. The activation of plasminogen by t-PA is enhanced by the presence of fibrin, and this is probably due to the fact that both plasminogen and t-PA possess high affinity binding sites for fibrin. Besides fibrin, fibrin monomers and some fibrin(ogen) degradation products, certain synthetic polymers (for instance, poly-L-lysines) can provide the same stimulation of plasminogen activation. The recently developed high-performance monolithic-disk chromatography, HPMDC, could become the most convenient way to study biological pairs of interest. The inherent speed of HPMDC isolation facilitates the recovery of a biologically active product, since the exposure to putative denaturing influences, such as solvents or temperature, is reduced. The better mass transfer mechanism (convection rather than diffusion) allows to consider only the biospecific reaction as time limiting. The step-by-step modeling of hypothetical affinity pairs between t-PA and different types of oligo/polymer forms of linear and branched lysine derivatives obtained both by initiated polycondensation and solid-phase peptide synthesis using HPMDC seemed to be possible and a quite useful tool. The results of quantitative evaluation of such affinity interactions were compared with those established for natural affinity counterparts to t-PA (monoclonal antibodies, plasminogen, fibrinogen). The role of steric structure of lysine ligands was observed and analyzed. The results allowing to make the practical choice of affinity systems will be used for development of fast and efficient analytical and preparative methods for the downstream processes of recombinant production of this valuable enzyme.

Animals↗
PubMed2003

Multi parameter in vitro testing of ratjadone using flow cytometry.

Ratjadone, isolated from the myxobacterium Sorangium cellulosum, belongs to the family of so-called orphan ligands, which includes leptomycin, callystatin and other compounds. In previous screening tests, ratjadone revealed a growth inhibitory effect against bacteria, yeast and human cancer cells. Following these first results, ratjadone was tested on several human tumour cell lines (Jurkat, HepG2, U87-MG) and, as a control, on a non-tumour cell line (RLC18) for its mode of action. The cell analysis was carried out by flow cytometry. This comprised cell density measurements, live-dead analysis, cell-cycle analysis and detection of apoptosis. First experiments confirmed the growth inhibitory effect on any chosen tumour cell line. Following these results a dose effect relationship was monitored, confirming the high effectiveness of ratjadone against cell growth at nanomolar concentration. Cell cycle analysis has shown that ratjadone intervenes in the cell cycle by arresting the cells in G1-phase. Biological testing of additional ratjadone derivatives with changed configuration and stereochemistry, identified the pharmacophoric site of the molecule.

Antineoplastic Agents↗
PubMed2002

GluR2 ligand-binding core complexes: importance of the isoxazolol moiety and 5-substituent for the binding mode of AMPA-type agonists.

X-ray structures of the GluR2 ligand-binding core in complex with (S)-Des-Me-AMPA and in the presence and absence of zinc ions have been determined. (S)-Des-Me-AMPA, which is devoid of a substituent in the 5-position of the isoxazolol ring, only has limited interactions with the partly hydrophobic pocket of the ligand-binding site, and adopts an AMPA-like binding mode. The structures, in comparison with other agonist complex structures, disclose the relative importance of the isoxazolol ring and of the substituent in the 5-position for the mode of binding. A relationship appears to exist between the extent of interaction of the ligand with the hydrophobic pocket and the affinity of the ligand.

Animals↗
PubMed2002

Recombinant human erythropoietin in combined treatment with granulocyte- or granulocyte-macrophage colony-stimulating factor in patients with myelodysplastic syndromes.

PURPOSE: Myelodysplastic syndromes (MDS) are a heterogeneous group of hemopoietic progenitor cell disorders, and patients with MDS regularly develop anemia and frequently become transfusion-dependent. Treatment with erythropoietin (EPO) has been tried to correct anemia with only limited success with response rates ranging from 16% to 25%. However, it is becoming evident that the generally rather low response rate of EPO in patients with MDS will be improved by the combination of EPO with either G-CSF or GM-CSF. METHOD: Here, we analyzed the results from the literature (six papers and one abstract using EPO plus G-CSF, and seven papers using EPO plus GM-CSF). RESULTS: Among all trials the cytokine dose and schedule varied, and the response criteria were not uniform. The average response rate for improving anemia was 41% in 207 patients treated with EPO and G-CSF, and 26% in 154 patients treated with EPO and GM-CSF. There were higher response rates for refractory anemia (RA) (45%), ringed sideroblasts (RARS) (47%), and excess of blasts (RAEB) (38%) compared with blasts in transformation (RAEBT) (17%) for the treatment with EPO plus G-CSF. The corresponding response rates for treatment with EPO plus GM-CSF were 30% (RA), 29% (RARS), 16% (RAEB), and 0% (RAEBT), respectively. Prolonged administration even showed a higher increment in the response rates. CONCLUSION: In conclusion, the combination of EPO with G-CSF is probably superior to EPO plus GM-CSF. There seems to be a positive correlation between the duration of cytokine treatment and response rates, and higher response rates in early MDS stages compared to advanced entities. However, controlled studies are mandatory to evaluate the role of the combined cytokine treatment in patients with MDS.

Anemia↗
PubMed2001

Flow cytometry in biotechnology.

Flow cytometry is a general method for rapidly analyzing large numbers of cells individually using light-scattering, fluorescence, and absorbence measurements. The power of this method lies both in the wide range of cellular parameters that can be determined and in the ability to obtain information on how these parameters are distributed in the cell population. Flow cytometric assays have been developed to determine both cellular characteristics such as size, membrane potential, and intracellular pH, and the levels of cellular components such as DNA, protein, surface receptors, and calcium. Measurements that reveal the distribution of these parameters in cell populations are important for biotechnology, because they better describe the population than the average values obtained from traditional techniques. This Mini-Review provides an overview of the principles of flow cytometry, with descriptions of methods used to measure various cellular parameters and examples of the application of flow cytometry in biotechnology. Finally, a discussion of the challenges and limitations of the method is presented along with a future outlook.

Animals↗
PubMed2001

Recombinant human erythropoietin in the treatment of anemic patients with hematological malignancies.

Patients with malignant diseases frequently develop anemia. An alternative to blood transfusions is the application of recombinant human erythropoietin. Several nonrandomized and prospective, placebo-controlled studies have demonstrated the effect and safety of erythropoietin in patients with hematological malignancies, particularly in patients with multiple myeloma and low- to intermediate-grade non-Hodgkin's lymphoma. However, in patients with myelodysplastic syndromes, the rather low response rate of erythropoietin is overcome by the combination of erythropoietin with granulocyte colony-stimulating factor. A significant acceleration of the reconstitution of erythropoiesis has been reported in allogeneic, but not in autologous bone marrow transplantation. Especially in large open-label, multicenter studies, a statistically and clinically significant improvement in quality of life independent from chemotherapeutic response or tumor type has been demonstrated. A number of simple algorithms have been proposed using the pretreatment serum erythropoietin level, transfusion requirements, and early changes in hematological parameters.

Anemia↗
PubMed2000

Factor IX mutations in South Africans and African Americans are compatible with primarily endogenous influences upon recent germline mutations.

Similar patterns of germline mutations in the factor IX gene (F9) have been observed in certain geographically and racially diverse populations. Germline mutation data have not been available from any region of Africa or from the Black race. Analysis of mutation data for Blacks is of interest, since this race has a high frequency of polymorphism compared to other races. This high frequency has been interpreted as evidence for the "out of Africa" hypothesis for the origin of humans, but it is possible that Blacks have a higher mutation rate due to genetic differences or environmental exposures. We report 26 independent mutations that were detected in patients of mixed races with hemophilia B from South Africa. The pattern of mutation in patients from this African country was similar to that of U.S. Caucasians. In addition, 22 independent mutation were detected in African American patients. The patterns of independent germline mutation in 22 African Americans (and in a combination 34 North American and African Blacks) is similar to that of U.S. Caucasians. Neither genetic differences between the Black and Caucasian races nor environmental and cultural differences between South Africa and the U.S. alter the germline pattern of mutation observed in F9. Hum Mutat 16:372, 2000.

Black People↗
PubMed2000

Structural basis of cell-cell adhesion by NCAM.

The neural cell adhesion molecule NCAM, a member of the immunoglobulin superfamily, mediates cell-cell recognition and adhesion via a homophilic interaction. NCAM plays a key role during development and regeneration of the nervous system and is involved in synaptic plasticity associated with memory and learning. The 1.85 A crystal structure of the two N-terminal extracellular domains of NCAM reported here provides a structural basis for the homophilic interaction. The molecular packing of the two-domain structure reveals a cross shaped antiparallel dimer, and provides fundamental insight into trans-cellular recognition mediated by NCAM.

Amino Acid Sequence↗
PubMed2000

Biological effects of stroma-derived factor-1 alpha on normal and CML CD34+ haemopoietic cells.

We compared the biological effects of the CXC chemokine SDF-1alpha on immunomagnetically purified CD34+ cells isolated from human normal bone marrow (NBM), leukapheresis products (LP) and patients with chronic myeloid leukaemia (CML). LP CD34+ cells showed a significantly stronger migration response to SDF-1alpha (100 ng/ml) than CD34+ cells isolated from the peripheral blood (PB) of CML patients (P < 0.05). The chemotactic response to SDF-1alpha was also reduced in CML BM CD34+ cells in comparison to NBM CD34+ cells but the observed differences were not statistically significant. In analogy to normal CD34+ cells circulating CML PB CD34+ cells were less responsive to SDF-1alpha than their BM counterparts (P < 0.05). Furthermore, SDF-1alpha elicited similar concentration-dependent growth suppressive effects on normal and CML CD34+ cells (P > 0.05) in colony-forming cell assays. We then demonstrated that SDF-1alpha triggers intracellular calcium increases in CD34+ cells and there were no differences in the time course and dose response characteristics of normal and CML CD34+ cells. The reduced migration response to SDF-1alpha in CML CD34+ cells was not due to a down-regulation of the SDF-1alpha receptor CXCR-4 as flow cytometric analysis revealed similar CXCR-4 expression levels on NBM, LP, CML PB and CML BM CD34+ cells (P > 0.05). Finally, no differences in the modulation of CXCR-4 levels in response to SDF-1alpha and serum were observed in CML and normal CD34+ cells. Our data suggest that the impaired chemotactic response of CML CD34+ cells to SDF-1alpha is not caused by a lack or complete uncoupling of CXCR-4, but may be due to an intracellular signalling defect downstream of the receptor.

Antigens, CD19↗
PubMed2000

Perfusion-contraction mismatch with coronary microvascular obstruction: role of inflammation.

A close relationship exists between regional myocardial blood flow (RMBF) and function during acute coronary inflow restriction (perfusion-contraction matching). However, the relationship of flow and function during coronary microvascular obstruction is unknown. In 12 anesthetized dogs, the left circumflex coronary artery was perfused from an extracorporeal circuit. After control measurements, 3,000 microspheres (42 micrometer diameter) per milliliter per minute inflow were injected to cause a microembolism (ME, n = 6). With unchanged systemic hemodynamics and RMBF, posterior systolic wall thickening (PWT) decreased from 19.8 +/- 1.9% SD at control to 13.3 +/- 4.0, 10.3 +/- 3.8, and 6.9 +/- 4.7% (P < 0.05 vs. control) at 1, 4, and 8 h, respectively. For comparison, inflow was progressively reduced to match PWT to that of the ME group at 1, 4, and 8 h (stenosis, STE, n = 6). RMBF in the STE group was reduced in proportion to PWT. Infarct size was not different among groups (6.5 +/- 4.5 vs. 3.4 +/- 3.2%). However, the number of leukocytes infiltrating the area at risk was significantly greater in the ME group than in the STE group. Coronary microembolization results in perfusion-contraction mismatch and is associated with an inflammatory response.

Anesthesia↗
PubMed1999

High performance flow injection analysis of recombinant protein G.

Chromatographic discs were investigated for their potential to substitute for the hitherto used cartridges in heterogeneous flow injection analysis. Originally designed for fast high performance liquid chromatography (HPLC) of biopolymers, the discs combine reliability with speed and resolution. This together with their price and their long-standing time made them attractive for use in flow injection analysis. The base material of the discs is a glycidyl methacrylate-co-ethylene dimethacrylate (GMA-EDMA) co-polymer. The epoxy groups inherent to this base structure can be used for immobilization purposes. In this first demonstration, antibodies were immobilized and the resulting affinity discs used for the fast analysis (< 5 min) of protein G from cell lysate of recombinant Escherichia coli. A linear calibration curve over several orders of magnitude as well as excellent reproducibility and correlation with data produced by conventional protein assay were obtained.

Chromatography↗
PubMed1999

Splenic rupture in a patient with acute myeloid leukemia undergoing peripheral blood stem cell transplantation.

Splenic rupture is a rare but well-recognized complication of hematological malignancies. Here, we present the case of a 22-year-old woman with the diagnosis of acute myeloid leukemia who was undergoing peripheral blood stem cell transplantation. On day + 10 she developed a hypovolemic shock due to rupture of her spleen and went to emergency laparotomy. This is the first report of splenic rupture during peripheral blood stem cell transplantation.

Adult↗
PubMed1999

Characterisation of the differential response of normal and CML haemopoietic progenitor cells to macrophage inflammatory protein-1alpha.

The clonogenic cells of chronic myeloid leukaemia (CML), unlike normal haemopoietic colony forming cells (CFC), are resistant to the growth inhibitory effects of the chemokine, macrophage inflammatory protein-1alpha (MIP-1alpha). Here, we tested the hypothesis that MIP-1alpha protects normal, but not CML, CFC from the cytotoxic effects of the cell-cycle active drug cytosine arabinoside (Ara-C). Using a 24-h Ara-C protection assay we showed that MIP-1alpha confers protection to normal CFC but also sensitizes CML CFC to Ara-C. The differential MIP-1alpha responsiveness was not due to a down-regulation of MIP-1alpha receptors on CML CD34+ cells as flow cytometric analysis showed similar binding of a biotinylated MIP-1alpha molecule to normal and CML CD34+ cells. Flow cytometric analysis of the MIP-1alpha receptor subtype CCR-5 revealed comparable CCR-5 expression levels on normal and CML CD34+ cells. Furthermore, culture of CD34+ cells for 10 h in the presence of TNF-alpha resulted in an increased MIP-1alpha receptor expression on both normal and CML CD34+ cells. Our data suggest that the unresponsiveness of CML CFC to the growth inhibitory effect of MIP-1alpha is not caused by a lack of MIP-1alpha receptor or total uncoupling of the MIP-1alpha responsiveness but may be due to an intracellular signalling defect downstream of the receptors.

Adolescent↗
PubMed1999

Content of long-term culture-initiating cells, clonogenic progenitors and CD34 cells in apheresis harvests of normal donors for allogeneic transplantation, and in patients with acute myeloid leukaemia or multiple myeloma.

Using a limiting dilution assay the frequency of long-term culture-initiating cells (LTC-IC) in the apheresis products following mobilization by granulocyte-colony stimulating factor (G-CSP) with or without chemotherapy from 14 normal donors (ND) for allogeneic bone marrow transplantation, 16 patients with multiple myeloma (MM) and 15 patients with acute myeloid leukaemia (AML), where the aphereses were intended for autologous transplantation, were compared. The estimated median incidences of LTC-IC in the first apheresis products from ND, MM and AML were 1/3289, 1/1775 and 1/13075 mononuclear cells (MNC) respectively. The patients with AML had a significantly lower incidence compared with the other two groups (P < 0.0001). There was a positive correlation between the incidence of LTC-IC and the number of CD34+ cells, the number of GM-CFC, and the number of BFU-E. The positive association with GM-CFC or BFU-E was weaker. In these experiments the percentage of CD34+ cells was the best predictor for the frequency of LTC-IC in the peripheral blood progenitor cells (PBPC). In eight cases of MM the LTC-IC assay was performed for both the first and second harvest. All cases had a lower LTC-IC frequency in the second harvest compared with the first, an average of 23% (13-42%, 95% confidence interval) and this reduction was statistically significant (P<0 001); CD34+ cells were also lower (P< 0.001).

Acute Disease↗
PubMed1999

Expression, crystallization and preliminary X-ray analysis of the two amino-terminal Ig domains of the neural cell adhesion molecule (NCAM).

The two amino-terminal Ig domains of the rat neural cell adhesion molecule, NCAM, have been expressed in the yeast strain Pichia pastoris. The double domain consisting of 191 amino acids was overexpressed, purified and crystallized. The crystals belong to the monoclinic space group P2(1), with unit-cell parameters a = 47.1, b = 122.5, c = 72.9 A and beta = 98.3 degrees. Assuming there are four double domains per asymmetric unit, V(m) is estimated to be 2.41 A(3) Da(-1) and the solvent content to be 42.3%. A native data set has been collected from a single flash-frozen crystal to 1.85 A resolution.

Animals↗