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W Gassmann

Publications and source records attributed to W Gassmann.

At least 37 records · Page 2Linked to original sources
PubMed1996

The abnormal eosinophils are part of the leukemic cell population in acute myelomonocytic leukemia with abnormal eosinophils (AML M4Eo) and carry the pericentric inversion 16: a combination of May-Grünwald-Giemsa staining and fluorescence in situ hybridization.

The French-American-British subtype acute myelomonocytic leukemia with abnormal eosinophils (FAB AML M4Eo) with pericentric inversion of chromosome 16 is cytomorphologically defined by a myelomonoblastic blast population and abnormal eosinophils. Until now, it remained an open question whether these abnormal eosinophils are part of the malignant clone or an epiphenomenon. We analyzed five cases of AML M4Eo with inv(16) and combined May-Grünwald-Giemsa staining with fluorescence in situ hybridization using yeast artificial chromosome clone 854E2, which spans the inv(16) breakpoint on 16p. In the case of inv(16), three instead of the normal two hybridization signals can be observed both on metaphase spreads and in interphase cells. With this approach, we were able to show inversion 16 in abnormal eosinophils and, therefore, identified them as a part of the leukemic cell population.

Adult↗
PubMed1996

Improved outcome in adult B-cell acute lymphoblastic leukemia.

A total of 68 adult patients with B-cell acute lymphoblastic leukemia (B-ALL) were treated in three consecutive adult multicenter ALL studies. The diagnosis of B-ALL was confirmed by L3 morphology and/or by surface immunoglobulin (Slg) expression with > 25% blast cell infiltration in the bone marrow (BM). They were characterized by male predominance (78%) and a median age of 34 years (15 to 65 y) with only 9% adolescents (15 to 20 y), but 28% elderly patients (50 to 65 y). The patients received either a conventional (N = 9) ALL treatment regimen (ALL study 01/81) or protocols adapted from childhood B-ALL with six short, intensive 5-day cycles, alternately A and B. In study B-NHL83 (N = 24) cycle A consisted of fractionated doses of cyclophosphamide 200 mg/m2 for 5 days, intermediate-dose methotrexate (IdM) 500 mg/m2 (24 hours), in addition to cytarabine (AraC), teniposide (VM26) and prednisone. Cycle B was similar except that AraC and VM26 were replaced by doxorubicin. Major changes in study B-NHL86 (N = 35) were replacement of cyclophosphamide by ifosphamide 800 mg/m2 for 5 days, an increase of IdM to high-dose, 1,500 mg/m2 (HdM) and the addition of vincristine. A cytoreductive pretreatment with cyclophosphamide 200 mg/m2, and prednisone 60 mg/m2, each for 5 days was recommended in study B-NHL83 for patients with high white blood cell (WBC) count (> 2,500/m2) or large tumor burden and was obligatory for all patients in study B-NHL86. Central nervous system (CNS) prophylaxis/treatment consisted of intrathecal methotrexate (MTX) therapy, later extended to the triple combination of MTX, AraC, and dexamethasone, and a CNS irradiation (24 Gy) after the second cycle. Compared with the ALL 01/81 study where all the patients died, results obtained with the pediatric protocols B-NHL83 and B-NHL86 were greatly improved. The complete remission (CR) rates increased from 44% to 63% and 74%, the probability of leukemia free survival (LFS) from 0% to 50% and 71% (P = .04), and the overall survival rates from 0% to 49% and 51% (P = .001). Toxicity, mostly hematotoxicity and mucositis, was severe but manageable. In both studies B-NHL83 and B-NHL86, almost all relapses occurred within 1 year. The time to relapse was different for BM, 92 days, and for isolated CNS and combined BM and CNS relapses, 190 days (P = .08). The overall CNS relapses changed from 50% to 57% and 17%, most probably attributable to the high-dose MTX and the triple intrathecal therapy. LFS in studies B-NHL83 and B-NHL86 was significantly influenced by the initial WBC count < or > 50,000/microL, LFS 71% versus 29% (P = .003) and hemoglobin value > or < 8 g/dL, LFS 67% versus 27% (P = .02). Initial CNS involvement had no adverse impact on the outcome. Elderly B-ALL patients (> 50 years) also benefited from this treatment with a CR rate of 56% and a LFS of 56%. It is concluded that this short intensive therapy with six cycles is effective in adult B-ALL. HdM and fractionated higher doses of cyclophosphamide or ifosphamide seem the two major components of treatment.

Adolescent↗
PubMed1996

Secondary acute leukaemias with 11q23 rearrangement: clinical, cytogenetic, FISH and FICTION studies.

Three patients with secondary acute leukaemia after treatment with topoisomerase II inhibitor agents are described. Two patients had acute myeloid leukaemia (AML). FAB M5a, one had pro-B-acute lymphoblastic leukaemia (ALL). The interval between initiation of chemotherapy and the onset of secondary acute leukaemia was 19-20 months. 11q23 rearrangements were detected in all cases. They were due to translocations t(11;19) (q23;p13.3), t(11;16)(q23;p13) and t(4;11)(q21;q23), respectively. Fluorescence in situ hybridization (FISH) with Yeast Artificial Chromosome (YAC) probe 13HH4 spanning the ALL-1 gene on 11q23 confirmed that in each case the ALL-1 gene had been disrupted by the translocations. The study underlined the relationship between the development of secondary acute leukaemias with 11q23 rearrangement and previous chemotherapy with topisomerase II inhibitor agents. So far, however, only six adult patients with secondary ALL with t(4;11) after treatment with topoisomerase II inhibitor agents have been reported. All with t(4;11) mostly occurs in infants or young children. Our patient received epirubicin continuously for >19 months. This indicates that both myeloid and lymphoid leukaemias with involvement of the ALL-1 gene can be induced by exogenous agents, especially topoisomerase II inhibitors. Thus they may have a common biological background. This hypothesis was substantiated by means of combined immunophenotyping and FISH (FICTION). In the case of AML M5a with t(11;19), the tumour cells with ALL-1 rearrangement expressed CD34. Moreover, the pro-B-ALL with t(4;11) was CD34 positive. These findings suggest that the cell of origin of secondary AML and ALL with 11q23 rearrangement is an immature haemopoietic progenitor cell.

Acute Disease↗
PubMed1996

Glass slide smears are a suitable source for RT-PCR-based analysis of chromosomal aberrations in leukaemias.

The polymerase chain reaction (PCR) is a well-established method to detect cytogenetic abnormalities. The handling of fresh specimens is difficult, therefore a method to use smears of blood or bone marrow as a source would be advantageous. Furthermore, such a technique would give the opportunity to investigate retrospectively bone marrow smears in leukaemias without cytogenetic results. The aim of the present study was to investigate the influence of staining procedures and laboratory handling of smears. We chose CML cases as a model. We demonstrated that smears are a suitable source for PCR without loss of information caused by previous routine laboratory handling.

Base Sequence↗
PubMed1996

Graft-versus-leukaemia activity can be predicted by natural cytotoxicity against leukaemia cells.

We have investigated graft-versus-leukaemia (GVL) effects after allogeneic bone marrow transplantation (BMT), using three murine leukaemia models, A20 (B lymphocytic), WEHI-3 (myelomonocytic) and PU5-1R (myeloid). Injection of leukaemia cells in a high number (10(6) cells) into syngeneic Balb/c mice (H-2d) invariably led to death with a median survival time of 22 d (A20), 18 d (WEHI-3) and 45 d (PU5-1R). A lower tumour load of A20 (5 x 10(5) cells) was used in some experiments resulting in a leukaemic death rate of 94%. Lethal total-body irradiation followed by syngeneic BMT prolonged survival (P<0.05) for animals bearing the leukaemia A20 and WEHI-3 but was unsuccessful for animals injected with cells from the monocytic leukaemia PU5-1R. Graft-versus-host (GVH)-nonreactive marrow of (C57 x Balb/c)F1 mice (H2bxd) exerted a significant GVL-effect with reduced relapse rate and improved survival in mice receiving the leukaemia cell line A20. In animals with low tumour load a significant reduction of the relapse rate from 82% following syngeneic BMT to 47% following allogeneic, GVH-nonreactive BMT could be achieved. Depletion of natural killer (NK) cells from the GVL-reactive semi-allogenic bone marrow graft enhances the relapse rate of the leukaemia A20 to 65%. In mice bearing the leukaemias WEHI-3 or PU5-1R allogeneic GVH-nonreactive BMT did not improve survival compared to syngeneic BMT. Transplantation of GVH-reactive bone marrow from DBA mice (MHC identical to Balb/c, minor difference) caused only a limited and insignificant reduction of relapse rate for animals with the leukaemia A20. These in vivo data are in close correlation with in vitro natural killer cell (NK) activity of the donor strains against the respective leukaemia targets. Depletion of NK cells from the GVL-reactive (C57 x Balb/c)F1 bone marrow resulted in a significant loss of GVL activity. We conclude that NK cells are involved in graft-versus-leukaemia effects independent of graft-versus-host disease (GVHD).

Animals↗
PubMed1996

Prognostic significance of additional chromosome abnormalities in adult patients with Philadelphia chromosome positive acute lymphoblastic leukaemia.

The clinical and biological significance of additional chromosome aberrations was investigated in a large series of 66 adult patients with Philadelphia (Ph) chromosome positive acute lymphoblastic leukaemia (ALL). Additional chromosome changes were observed in 71% of the cases. 9p abnormalities were identified in 26%, and monosomy 7 as well as hyperdiploid karyotypes 50 were both found in 17% of cases. 9p anomalies were characterized by a low complete remission (CR) rate (58%) and an extremely short median remission duration (MRD: 100 d). In patients with monosomy 7, the poor treatment outcome was confirmed (CR rate 55%: MRD 113 d). In contrast, all patients with hyperdiploid karyotypes 50 achieved CR, and the overall survival was superior to all other Ph-positive ALL patients except those without additional chromosome aberrations. Exclusive rearrangement of the minor breakpoint cluster region of the BCR gene and lack of coexpression of myeloid-associated antigens in cases with 9p anomalies as well as a high frequency of rearrangements of the major breakpoint cluster region of the BCR gene in patients with monosomy 7 (89%) further substantiated that additional chromosome aberrations may characterize distinct subgroups of Ph-positive ALL. Moreover, the necessity of the complementing use of chromosome banding analyses, polymerase chain reaction (PCR) assays, and fluorescence in situ hybridizations in the accurate identification of Ph-positive patients has become evident due to variant Ph translocations in 3%, and negative PCR assays in 4% of the cases.

Adolescent↗
PubMed1996

Acute myeloid leukemia with translocation (8;21). Cytomorphology, dysplasia and prognostic factors in 41 cases. AML Cooperative Group and ECOG.

The translocation t(8;21) is one of the most common structural aberrations in acute myeloid leukemia (AML). Excellent response rates and a better relapse-free survival have been described. We analyzed specific morphologic and cytochemical features including dysplasia and other prognostic factors in 41 patients with AML and t(8;21) who underwent aggressive chemotherapy in two national cooperative group studies. Five patients were classified as AML M1 and 36 as AML M2 according to the FAB criteria. Auer rods were detected in 28 patients (68%), however in only 16 patients were they "thin and elongated" as has been described as typical for t(8;21). The presence or absence of Auer rods did not appear to be associated with disease-free survival in this sample. Dysgranulopoiesis was detected in 31/41 patients (90%); five of these patients additionally had dyserythropoiesis (12%). In six cases (15%), dysmegakaryopoiesis was seen in combination with dysgranulopoiesis. Only one patient had trilineage dysplasia. Dysplastic features had no influence on prognosis. Additional cytogenetic abnormalities were detected in 24/41 patients. Twelve male (48%) and four female (25%) had a loss of a sex chromosome. This was correlated with a better disease-free survival (p = 0.039). The complete remission rate (CR) to chemotherapy was 90%. The early death rate was 10%. Disease-free survival of the complete responders was 60% at two years with no relapses observed in ten patients with 2-6 years of follow up. This favorable disease-free survival was observed with a variety of post-induction regimens and t(8;21) had been detected as an independent factor for good prognosis. The need for very intensive therapy, such as bone marrow transplantation, is unanswered at this time.

Adult↗
PubMed1996

High lytic activity against human leukemia cells after activation of allogeneic NK cells by IL-12 and IL-2.

IL-12 is a novel cytokine with interesting features regarding its potential usefulness in peripheral blood stem cell transplantation and leukemia immunotherapy. We used cryopreserved leukemia cells of 18 patients with acute myelogenous (n= 14) or lymphocytic (n= 4) leukemia to investigate the effect of IL-12, alone or in combination with IL-2, on the cytolytic activity of NK cells against human leukemia targets. Effector cells were peripheral blood mononuclear cells from healthy donors which were depleted from CD3+ T cells by immunomagnetic separation. CD3-negative effector cells (mainly CD56+ NK cells) were treated for 24 h with various concentrations of IL-2 (100 U/ml to 1000 U/ml) and IL-12 (1 U/ml to 100 U/ml). Cytotoxicity was measured in a 4 h 51Cr-release assay. Whereas a two-fold enhancement of cytotoxic activity was observed after incubation with optimal doses of IL-2 or IL-12, the combination of both cytokines (500 U/ml IL-2, 100 U/ml IL-12) increased the lytic activity more than six-fold. This effect was accompanied by increased expression of cellular adhesion molecules (CD2, CD18) and CD25 on CD56+ effector cells. Of 18 leukemias investigated, five were completely resistant to lysis by effector cells activated with IL-2 or IL-12 alone. In three of these five cases, however, high cytolytic activity was observed after coincubation with IL-2 and IL-12. In comparison to allogeneic NK cells, autologous cells of three patients in remission demonstrated significantly lower cytotoxic activity. No killing of nonmalignant cells (PHA blasts) by allogeneic NK cells was observed. Our data demonstrate that IL-12 can enhance or even induce MHC-unrestricted cytotoxicity of IL-2-activated allogeneic natural killer cells. Since IL-12 has also been shown to have stem-cell mobilizing capacities, it could be used for the recruitment of both stem cells and antileukemic effector cells in the context of peripheral blood stem cell transplantation.

Animals↗
PubMed1995

Sodium-driven potassium uptake by the plant potassium transporter HKT1 and mutations conferring salt tolerance.

Sodium (Na+) at high millimolar concentrations in soils is toxic to most higher plants and severely reduces agricultural production worldwide. However, the molecular mechanisms for plant Na+ uptake remain unknown. Here, the wheat root high-affinity potassium (K+) uptake transporter HKT1 was shown to function as a high-affinity K(+)-Na+ cotransporter. High-affinity K+ uptake was activated by micromolar Na+ concentrations; moreover, high-affinity Na+ uptake was activated by K+ (half-activation constant, 2.8 microM K+). However, at physiologically detrimental concentrations of Na+, K+ accumulation mediated by HKT1 was blocked and low-affinity Na+ uptake occurred (Michaelis constant, approximately 16 mM Na+), which correlated to Na+ toxicity in plants. Point mutations in the sixth putative transmembrane domain of HKT1 that increase Na+ tolerance were isolated with the use of yeast as a screening system. Na+ uptake and Na+ inhibition of K+ accumulation indicate a possible role for HKT1 in physiological Na+ toxicity in plants.

Animals↗
PubMed1995

Identification of strong modifications in cation selectivity in an Arabidopsis inward rectifying potassium channel by mutant selection in yeast.

The Arabidopsis thaliana cDNA, KAT1, encodes a hyperpolarization-activated K+ channel. In the present study, we utilized a combination of random site-directed mutagenesis, genetic screening in a potassium uptake-deficient yeast strain, and electrophysiological analysis in Xenopus oocytes to identify strong modifications in cation selectivity of the inward rectifying K+ channel KAT1. Threonine at position 256 was replaced by 11 other amino acid residues. Six of these mutated KAT1 cDNAs complemented a K+ uptake-deficient yeast strain at low concentrations of potassium. Among these, two mutants (T256D and T256G) showed a sensitivity of yeast growth toward high ammonium concentrations and a dramatic increase in current amplitudes of rubidium and ammonium ions relative to K+ by 39-72-fold. These single site mutations gave rise to Rb+- and NH4(+)-selective channels with Rb+ and NH4+ currents that were approximately 10-13-fold greater in amplitude than K+ currents, whereas the NH4+ to K+ current amplitude ratio of wild type KAT1 was 0.28. This strong conversion in cation specificity without loss of general selectivity exceeds those reported for other mutations in the pore domain of voltage-dependent K+ channels. Yeast growth was greatly impaired by sodium in two other mutants at this site (T256E and T256Q), which were blocked by millimolar sodium (K1/2 = 1.1 mM for T256E), although the wild type channel was not blocked by 110 mM sodium. Interestingly, the ability of yeast to grow in the presence of toxic cations correlated to biophysical properties of KAT1 mutants, illustrating the potential for qualitative K+ channel mutant selection in yeast. These data suggest that the size of the side chain of the amino acid at position 256 in KAT1 is important for enabling cation permeation and that this site plays a crucial role in determining the cation selectivity of hyperpolarization-activated potassium channels.

Amino Acid Sequence↗
PubMed1995

AML M1 and M2 with eosinophilia and AML M4Eo: diagnostic and clinical aspects.

AML with eosinophilia belongs to the morphologic cytogenetic entity M1/M2 t(8;21) with the involvement of the genes AML1/ETO. These eosinophils differ only slightly from normal eosinophils with one rare exception i.e. Auer rods in eosinophils which has only been found on peroxidase staining: This subtype belongs to the good prognosis group of AML. AML with inv(16) (mostly M4Eo) per se is a morphologic-cytogenetic entity with inv(16),--rarely t(16;16), and the genes MYL 11/CBF beta involved. The eosinophils show special abnormalities. AML with inv(16) also belongs to the good prognosis group of AML.

Bone Marrow↗
PubMed1995

Acute megakaryoblastic leukemia.

In 1985 acute megakaryoblastic leukemia was included in the FAB classification system of hematological neoplasias with the designation of AML M7. It occurs in all age groups with two peaks in distribution. The one is in adults and the other in children 1 to 3 years of age especially in those with Down's syndrome. The diagnosis of AML M7 requires more than 30% of the nucleated bone marrow cells being megakaryoblasts. The more common types of AML MO-M6 have to be excluded by morphological and cytochemical analysis whereas immunology is needed to exclude ALL. The megakaryocytic nature of the leukemia has to be proven by ultrastructural demonstration of platelet peroxidase or by immunological demonstration of CD61, CD42, CD41 on the surface of the leukemic blasts. Megakaryocytic/megakaryoblastic leukemias show a wide morphologic spectrum. In some instance small cells dominate, clearly showing megakaryocytic differentiation with scant amounts of cytoplasm and with nuclei showing dense chromatin. On the other hand, there are cases with larger cells resembling ALL-L2 blasts with moderate amounts of rather basophilic cytoplasm which in some instances contain azurophilic granules. Cytoplasmic blebs and protrusions are the most prominent feature of many cases. The nuclei of these cells are round with more finely reticulated chromatin and with prominent nucleoli. The megakaryoblastic nature of these cells can be suggested by morphology. However, according to our experience there are cases of c-ALL with the very same morphologic picture. Consequently, immunologic phenotyping of these cases is necessary in any instance. Cytochemistry is of limited diagnostic value in megakaryoblastic leukemias. Usually it is used to exclude the more common types of leukemia.

Adult↗
PubMed1995

Leukemia-specific allogeneic donor T cells: quantification by limiting dilution assay.

Allogeneic T cells are capable of discriminating between leukemia cells and non-malignant hematopoetic cells. This has been concluded from clinical BMT data and demonstrated by in vitro experiments. We analyzed the frequency and specificity of leukemia-reactive T cells from syngeneic and allogeneic blood donors by limiting dilution assays for interleukin-2-producing (TH1) and cytotoxic (CTLp) T cells. Target cells were leukemia blasts obtained from a patient with common ALL. Control targets were generated by EBV transformation. Effector cells were generated from the peripheral blood of the patient in remission, from his syngeneic brother and from eight healthy, HLA-mismatched volunteers. The effector cells were stimulated with leukemia cells and interleukin-2. Neither the patient nor his brother were able to generate anti-leukemic CTLp or TH1. The HLA-mismatched allogeneic donors displayed anti-leukemic CTLp frequencies with a range from 0 to 68 million. TH1 cells with anti-leukemic specificity were not detectable. We conclude that there are great inter-individual differences in the GVL potential of fully allogeneic peripheral T lymphocytes. It is possible to identify T cell lines with reactivity against leukemia blasts and non-reactivity against normal hematological cells from the same individual. These cell lines are potential effector cells for immunotherapy of human leukemia.

Blood Donors↗
PubMed1994

Morphology and cytochemistry of acute lymphoblastic leukaemia.

ALL is characterized by small to medium sized leukaemic blasts with a rather low grade of cell-to-cell variability. The nucleocytoplasmic ratio is high with just a small cytoplasmic rim in many cases. The cytoplasm tends to be moderately basophilic. Usually, though not in each instance, it is agranular and free of vacuoles. The chromatin is more condensed than in AML and the nucleoli tend to be indistinct. The FAB classification of haematological malignancies separates ALL into three categories: ALL L1, L2, and L3. However, just the identification of the L3 variant is of major importance. The L3 cells are medium sized to large and are characterized by intensely basophilic and moderately abundant cytoplasm with prominent cytoplasmic vacuolation in the bone marrow but not necessarily in the peripheral blood. According to our experience there is a high but not universal correlation of the L3 phenotype as defined by morphology with the immunologically defined B-ALL with surface expression of immunoglobulins. Until recently, acute leukaemias proving negative for all cytochemical tests especially for the PAS reaction and for the focal type of acid phosphatase, were termed 'acute undifferentiated leukaemia' (AUL). However, this morphological/cytochemical diagnosis may be confused with the immunological diagnosis of unclassifiable leukaemia. Since almost any of these cases can be recognized as ALL or AML by immunology, the term AUL should be reserved for cases which can be classified neither by morphology/cytochemistry nor by immunology. The morphological and cytochemical distinction of ALL from poorly differentiated AML remains a problem, especially if the FAB criteria for distinguishing ALL from AML by cytochemistry (3% of the blasts positive for peroxidase) are applied rigidly. A small but significant percentage of poorly differentiated leukaemias have less than 3% of the blasts positive for peroxidase and the myeloid nature of the leukaemia can be identified by cytochemistry. The absence of blasts being positive for peroxidase is no reliable indicator for the lymphatic nature of a leukaemia, even if the PAS reaction is typical for ALL. The morphological diagnosis of ALL needs confirmation by immunology in each instance.

Adult↗
PubMed1994

Influence of donor lymphocytes on the incidence of primary graft failure after allogeneic bone marrow transplantation in a murine model.

We used a murine model to determine the impact of donor lymphocyte subsets on the incidence of primary marrow graft failure after transplantation of lymphocyte-depleted bone marrow. After lethal irradiation with 7.5 Gy, Balb/c mice received 1 x 10(5) to 4 x 10(7) GvH-nonreactive (C57 x Balb)F1 or GvH-reactive C57Bl/6 marrow cells. Pretreatment with anti-Thy-1.2, anti-CD4/CD8, anti-asialo-GM1 or L-leucyl-L-leucine methyl ester (Leu-Leu-OMe) was employed to eliminate T lymphocytes and/or natural killer cells. Primary graft failure was defined as death with neutrophils < 0.5 x 10(9)/l. To assess long-term chimaerism, the percentage of H-2b-positive spleen cells was determined. Pretreatment with anti-Thy-1.2, anti-CD4/CD8 or Leu-Leu-OMe successfully eliminated GvHR-induced mortality. Graft failure rates gradually declined from 88% after transplantation of 1 x 10(5) cells to 0% after transplantation of 4 x 10(7) C57Bl/6 cells. The incidence of graft failure, however, was not altered by T-cell depletion, provided that the unspecific loss of marrow cells was compensated for. After transplantation of GvH-nonreactive (C57 x Balb)F1 bone marrow, neither ex-vivo treatment with anti-Thy-1.2 and anti-asialo GM1 nor addition of 1 x 10(7) donor thymocytes to the allograft significantly influenced engraftment. The data obtained in our animal model suggest that the total number of marrow cells is of critical importance for successful marrow engraftment and not the presence or absence of T cells, NK cells or GvHR.

Animals↗