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W Fiedler

Publications and source records attributed to W Fiedler.

At least 91 records · Page 5Linked to original sources
PubMed1990

The IL-6 gene but not the IL-6 receptor gene is occasionally rearranged in patients with multiple myeloma.

Constitutive secretion of interleukin-6 (IL-6) has been proposed as a mechanism of transformation in multiple myeloma. We therefore studied 15 patients with this disease for rearrangements of the IL-6 and IL-6 receptor genes. Two patients with altered IL-6 genes were identified. Chromosome analysis revealed aberrations of chromosome 7, where the IL-6 gene resides, in only these two patients, but not in others without IL-6 rearrangements. In one of these patients, constitutive IL-6 m-RNA expression was observed. No alterations of IL-6 receptor genes were detected.

Base Sequence↗
PubMed1990

Mechanisms of growth factor expression in acute myeloid leukemia (AML).

To investigate possible mechanisms of growth factor expression in acute myeloid leukemia, genes for granulocyte macrophage colony-stimulating factor (GM-CSF) were analyzed by Southern blots in 20 patients, for M-CSF in 13, for interleukin-6 (IL-6) in 14, for IL-6 receptor in 14 and for G-CSF in five patients. Only in one patient a complex rearrangement of the G-CSF gene with possible amplification was noted indicating rarity of direct alterations of growth factor genes in acute myelogenous leukemia (AML). Spontaneous m-RNA expression for GM-CSF was found in only one of 20 patients, and for IL-6 in eight of 11 patients. In vitro incubation of AML cells of eight patients with recombinant tumor necrosis factor for 24 hr revealed induction of GM-CSF m-RNA expression in three cases and GM-CSF protein expression in two of them. These data suggest that spontaneous GM-CSF production occurs rarely in AML and that monokines, such as tumor necrosis factor, may induce GM-CSF in AML cells. Therefore, interactions of AML cells with normal or malignant accessory cells may be important for autocrine stimulation in AML. Our data suggest that ectopic growth factor secretion is not the primary cause of generating AML but may contribute to progression of the disease. Alternatively, AML may represent a heterogenous group of leukemias with different etiology but similar phenotype.

Blotting, Northern↗
PubMed1990

Developmental expression of the 43K and 58K postsynaptic membrane proteins and nicotinic acetylcholine receptors in Torpedo electrocytes.

The expression of the postsynaptic 43-kDa and 58-kDa proteins and actin during development of the Torpedo marmorata electric organ was compared to that of nicotinic acetylcholine receptors (AChRs). Western blot analysis demonstrates that AChRs and proteins of 43 kDa (43K protein) and 58 kDa (58K protein) are all present prior to synaptogenesis. Subsequently, levels of all 3 synaptic proteins increase dramatically during differentiation and innervation of electrocytes. In contrast, actin is present in relatively high concentrations at early times and decreases thereafter. The equimolar ratio of AChRs and the 43K protein found in the adult electric organ is established early in development. Furthermore, the AChR and 43K protein share a common postsynaptic localization in electrocytes following synapse formation. Aggregates of the AChR that form at the ventral pole of the oval-shaped electrocytes prior to innervation, however, show no detectable immunofluorescence staining with anti-43K monoclonal antibodies. Therefore, in some cases, aggregation of AChRs occurs without the 43K protein.

Actins↗
PubMed1990

Sequential studies on the role of mitoxantrone, high-dose cytarabine, and recombinant human granulocyte-macrophage colony-stimulating factor in the treatment of refractory non-Hodgkin's lymphoma.

Mitoxantrone (Novantrone, American Cyanamid Company; NO) and high-dose cytarabine (Ara-C; AC) have each been shown to be active in non-Hodgkin's lymphomas (NHL) in various studies. The studies reported here are sequential. The first study (NOAC I) combined high-dose cytarabine (3 g/m2/12 h as a 3 h infusion on day 1) with mitoxantrone (10 mg/m2/d on days 2 and 3). Of 31 patients with relapsed and refractory NHL, 7 achieved complete remission (CR) and 7, partial remission (PR). Myelosuppression was the major toxicity of this regimen. In the second study (NOAC II), the dosage of cytarabine was escalated to 3 g/m2/12 h on days 1 and 2 (4 doses) while mitoxantrone remained 10 mg/m2/d on days 2 and 3. The effects of recombinant human (rh) granulocyte-macrophage colony-stimulating factor (GM-CSF) were simultaneously studied. Twenty-three patients from five centers were treated with NOAC plus rhGM-CSF while 14 patients from four centers received NOAC II alone. A CR was achieved in 9 of 23 patients who received the additional rhGM-CSF and in 2 of 14 patients treated with NOAC alone. With rhGM-CSF, the median duration of severe neutropenia (less than 0.5/nL) after chemotherapy was 8 days versus a median of 13 days without rhGM-CSF, while the duration of severe thrombocytopenia (less than 20/nL) was not significantly different. The rates of infection and mucositis were 25% and 17%, respectively, with rhGM-CSF compared to 53% and 60% without rhGM-CSF. Thus, this last nonrandomized pilot study indicates that administration of rhGM-CSF reduces the duration of chemotherapy-induced cytopenia and the rate of mucositis. This growth factor does not appear to result in stimulation of lymphoma cells. At present, a controlled randomized trial is being conducted using NOAC II with rhGM-CSF or placebo to establish the definitive role of this growth factor in the treatment of NHL.

Adolescent↗
PubMed1988

Properties of Escherichia coli mutants lacking membrane-derived oligosaccharides.

Membrane-derived oligosaccharides (MDO) consist of branched substituted beta-glucan chains and are present in the periplasmic space of Escherichia coli and other gram-negative bacteria. A procedure for the isolation of mutants defective in MDO synthesis is described. Their phenotype was compared with a mdoA mutant previously identified, and they are mapped in the mdoA region. Mutants lacking MDO showed imparied chemotaxis on tryptone swarm plates, a reduced number of flagella, and an enhanced expression of the OmpC porin. Revertants able to form swarm rings again had regained the ability to synthesize MDO and showed the wild-type porin pattern. A second group of chemotactic revertants were mutated in the ompB gene region involved in osmoregulation, and they were still devoid of MDO. These findings provide evidence for a link between MDO biosynthesis and other functions of E. coli related to its adaptation to the environment.

Bacterial Outer Membrane Proteins↗
PubMed1988

Lysis induction of Escherichia coli by the cloned lysis protein of the phage MS2 depends on the presence of osmoregulatory membrane-derived oligosaccharides.

Expression of the cloned lysis protein of phage MS2, which is sufficient to lyse wild type Escherichia coli, does not cause lysis of mutants lacking the osmoregulatory membrane-derived oligosaccharides (MDO). The lysis gene product normally found in the membrane fraction was not stably inserted into the membranes of a mdoA mutant; rather degradation and release from the membrane occurred. Gentle plasmolysis of the MDO-lacking mutant clearly showed an increased periplasmic space as compared to wild type cells. It is concluded that the MDOs play an important role in maintaining a proper arrangement of inner and outer membrane, a prerequisite for a functional insertion of the MS2 lysis protein.

Bacteriolysis↗
PubMed1987

Development of the electromotor system of Torpedo marmorata: distribution of extracellular matrix and cytoskeletal components during acetylcholine receptor focalization.

A combination of direct fluorescence and indirect immunofluorescence microscopy has been used to compare the distribution of the acetylcholine receptor with the distribution of major cytoskeletal and extracellular matrix components during electrocyte differentiation in the electric organs of Torpedo marmorata. Laminin, fibronectin and extracellular matrix proteoglycan are always more extensively distributed around the differentiating cell than the acetylcholine receptor-rich patch that forms on the ventral surface of the cell. The distribution of acetylcholinesterase within the ventral surface of the differentiating electrocyte closely resembles the distribution of the acetylcholine receptor. Areas of apparently high acetylcholine receptor density within the ventrally forming acetylcholine receptor-rich patch are always areas of apparently high extracellular matrix proteoglycan density but are not always areas of high laminin or fibronectin density. Desmin levels appear to increase at the onset of differentiation and desmin initially accumulates in the ventral pole of each myotube as it begins to form an electrocyte. During differentiation F-actin-positive filament bundles are observed that extend from the nuclei down to the ventrally forming acetylcholine receptor-rich patch. Most filament bundles terminate in the acetylcholine receptor-rich region of the cell membrane. Electron-microscopic autoradiography suggests that the filament bundles attach to the membrane at sites where small acetylcholine receptor clusters are found. The results of this study suggest that, out of the four extracellular matrix components studied, only the distribution of acetylcholinesterase (which may be both matrix- and membrane-bound at this stage) closely parallels that of the acetylcholine receptor, and that F-actin filament bundles terminate in a region of the cell that is becoming an area of high acetylcholine receptor density.

Acetylcholinesterase↗
PubMed1987

T-cell activation defect in common variable immunodeficiency: restoration by phorbol myristate acetate (PMA) or allogeneic macrophages.

Common variable immunodeficiency (CVI) represents a group of familial and sporadic diseases characterized by a range of B-cell, T-cell, and macrophage defects. A defect in T-cell activation, involving reduced proliferation and IL-2 production after stimulation with OKT3 antibody, has been described previously. In the present study we found that these defects could be corrected in vitro by adding phorbol myristate acetate (PMA) to OKT3-stimulated peripheral blood mononuclear cells (PBMC) of 14 patients with CVI. PBMC of 6 out of 7 patients with CVI studied also exhibited a profound defect in IL-2 receptor expression when incubated with OKT3 antibody. IL-2 receptor expression after stimulation with PMA alone was normal, indicating that the OKT3- but not the PMA-induced pathway of IL-2 receptor expression was defective. On the RNA level, the genes for IL-2 and IL-2 receptor were expressed after stimulation with OKT3 antibody. IL-2 and IL-2 receptor gene expression were normal, indicating a possible post-transcriptional defect. To investigate whether the defect in T-cell activation was at the macrophage or the T-cell level, we prepared adherent cells and monocyte-depleted T cells (E+) from 3 patients with CVI and from normal blood donors. Incubating CVI E+ cells with normal adherent cells resulted in normal proliferation and IL-2 production in the presence of OKT3, whereas incubation of normal E+ cells with adherent cells from patients with CVI under the same conditions showed reduced IL-2 production and proliferation, suggesting the macrophage as the origin of the failure in T-cell activation in the patients with CVI studied. Inhibition by macrophage-secreted prostaglandins was excluded by failure to correct the IL-2 production and proliferation defects in the presence of indomethacin.

Adult↗
PubMed1986

An immunohistochemical study of synaptogenesis in the electric organ of Torpedo marmorata by use of antisera to vesicular and presynaptic plasma membrane components.

Synaptogenesis has been studied in the electric organ of embryonic Torpedo marmorata by use of two antisera directed against components of synaptic vesicles (anti-SV) and presynaptic plasma membranes (ap-anti-TSM), respectively. The anti-SV serum was previously shown to recognize a proteoglycan specific for synaptic vesicles. The ap-anti-TSM serum was raised to plasma membranes of synaptosomes derived from the electromotor nerve terminals and affinity-purified on electric-organ gangliosides. The vesicular antigen was first detectable at the 81-mm stage of development, which is 1-2 weeks earlier than the formation of morphologically mature presynaptic terminals, but is coincident with a rise in choline acetyltransferase levels and the ability of the electric organ to generate discharges. The gangliosidic antigen recognized by the ap-anti-TSM was first detectable on the ventral electrocyte surface at the 93-mm stage of development. This indicates that specific carbohydrate epitopes, not present on the growth cones, are expressed during maturation of the nerve terminal. The nerve terminal components recognized by these sera arose pari passu with neurite coverage of the ventral surface of the electrocyte, reaching a maximum in the adult. In contrast, postsynaptic aggregates of acetylcholine receptor, rendered visible with rhodamine-labeled alpha-bungarotoxin, arose previous to the presynaptic antigens, reaching a maximum surface density at 110 mm and then declining in the adult.

Animals↗
PubMed1986

A kinetic study of stimulus-induced vesicle recycling in electromotor nerve terminals using labile and stable vesicle markers.

The kinetics of recovery, by recycling electromotor synaptic vesicles, of the biophysical parameters of the reserve population has been studied in perfused blocks of electric organ of Torpedo marmorata prestimulated in vivo, followed by density gradient separation of the extracted vesicles in a zonal rotor using labile (acetylcholine and ATP) and stable (proteoglycan) vesicle markers. Stimulation in vivo at 0.15 Hz for 3.3 h depleted tissue acetylcholine much less than stimulation at 1 Hz for 1 h but nevertheless generated a much larger pool of recycled vesicles that recovered more slowly. At the lower rate of stimulation, recovery of the biophysical characteristics of the reserve population by the recycled vesicles, identified by their content of newly synthesized transmitter, was essentially complete by 8 h. The stable proteoglycan marker was immunochemically assayed and was bimodally distributed in the vesicle-containing portion of the density gradient even in experiments with unstimulated or recovered tissue. The second peak corresponded with that of newly synthesized transmitter and was thus identified as containing the recycled vesicles. Its normalized acetylcholine/proteoglycan ratio was lower than that of the first peak, which is consistent with earlier findings that recycled vesicles, before recovery, are only partially loaded with transmitter. However, as expected, the proportion of total vesicular proteoglycan and acetylcholine associated with the recycled vesicle fraction was very much lower in preparations derived from unstimulated or recovered tissue than in those from recently stimulated tissue.

Acetylcholine↗
PubMed1985

Characterization of an Escherichia coli mdoB mutant strain unable to transfer sn-1-phosphoglycerol to membrane-derived oligosaccharides.

A procedure for the isolation of mutants affected in components containing glycerol derived from phospholipids yielded two mutant strains that contain membrane-derived oligosaccharides (MDO) devoid of glycerol (Rotering, H., Fiedler, W., Rollinger, W., and Braun, V. (1984) FEMS Microbiol. Lett. 22, 61-68). MDO are found in the periplasmic space of Escherichia coli and other Gram-negative bacteria, and they may comprise up to 7% of the cells dry weight. The biosynthesis of MDO is osmoregulated (Kennedy, E. P. (1982) Proc. Natl. Acad. Sci. U. S. A. 79, 1092-1095) and linked to the metabolism of phospholipids (van Golde, L. M. G., Schulman, H., and Kennedy, E. P. (1973) Proc. Natl. Acad. Sci. U. S. A. 70, 1368-1372). This leads to substitution of MDO with sn-1-phosphoglycerol and phosphoethanolamine (Kennedy, E. P., Rumley, M. K., Schulman, P., and van Golde, L. M. G. (1976) J. Biol. Chem. 251, 4208-4213). MDO also contain succinate in O-ester linkage. We now report that one mutant strain lacks phosphoglycerol transferase I activity and thus is unable to transfer sn-1-phosphoglycerol residues from phosphatidylglycerol to MDO. The mdoB gene affected in this mutant has been located at 99.2 min on the E. coli chromosome. The ethanolamine content of MDO isolated from the mutant strain is elevated, whereas the number of succinate residues is not affected. The only phenotype of mdoB mutants we found is a dramatic reduction of the diglyceride content observed in dgk mdoB double mutants when the beta-glucoside arbutin is present in the growth medium.

Chromatography, DEAE-Cellulose↗
PubMed1985

The localization and rate of disappearance of a synaptic vesicle antigen following denervation.

A proteoglycan-specific antiserum has been used to monitor the effects of denervation in the electric organ of Torpedo marmorata. The antiserum was produced by injecting a highly purified synaptic vesicle fraction prepared from the electric organs of Torpedo marmorata. Following absorption the serum appears to be specific towards synaptic vesicles. The ultrastructural localization of the antigen determined by immuno-electron microscopy confirmed the specificity of the antiserum and showed that it did not cross-react with the proteoglycans of the basal lamina. The rate of disappearance of the vesicle proteoglycans following denervation was evaluated by means of the antiserum and was compared to the rate of disappearance of other vesicular and nerve terminal-associated markers. The results suggest that degeneration affects the vesicular constituents at varying rates resulting in a progressive disappearance of the entire functional capacity of the synaptic vesicles.

Acetylcholine↗
PubMed1985

Electron microscopic localization of calelectrin, a Mr 36 000 calcium-regulated protein, at the cholinergic electromotor synapse of Torpedo.

Calelectrin is a calcium-binding protein of Mr 36 000 which has previously been shown to be associated with membranes of the cholinergic synapse in a calcium-dependent manner. We report here that calelectrin was solubilized from the electric organ of Torpedo marmorata in the absence of calcium together with proteins of Mr 54 000 and Mr 15 000. In cholinergic nerve endings isolated from the electric organ only calelectrin was solubilized in a calcium-dependent manner. A specific antiserum to calelectrin was used to localize the antigen by immunofluorescence microscopy on sections of electric organ and showed that calelectrin is distributed throughout the postsynaptic cell. Calelectrin was also detected in axons and in the cell bodies of the cholinergic neurones where it was concentrated in discrete patches throughout the cells. Electric organ tissue was processed to localize calelectrin with the electron microscope using an immunoperoxidase method. The most intense staining was observed on the cytoplasmic face of the acetylcholine receptor-containing postsynaptic membrane and also associated with the intracellular filaments of the electrocyte. The intensity of staining associated with these structures could be greatly reduced by preincubating the tissue with calcium chelators. In nerve terminals calelectrin was associated with synaptic vesicles in a polarized fashion. Calelectrin was also found on the cytoplasmic face of the synaptosomal plasma membrane and associated with neurofilaments. No extracellular staining was ever observed. Our results strongly support our original hypothesis that calelectrin is a calcium-regulated component of intracellular structure associated both with membranes and filaments.

Animals↗