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Biomedical subjects

E Holler

Publications and source records attributed to E Holler.

At least 127 records · Page 7Linked to original sources
PubMed1991

Immunological characterization of canine hematopoietic progenitor cells.

Canine hematopoietic progenitor cells were characterized by separation with monoclonal antibodies. Depleted and enriched fractions were studied for growth of CFU-GM in semisolid agar and for repopulating capacity of lethally irradiated dogs. CFU growth was not reduced by depletion of marrow using monoclonal antibodies F 3-20-7 (anti-dog Thy-1), MT606 (anti-human CD 6), and IOT2a (anti-human DR). CFU growth was variable following treatment with the anti-canine T-cell antibody MdT-P 1 and immunomagnetic bead separation. It was regularly enriched when MdT-P 1 treatment was followed by immunorosetting with staphylococcal protein A-loaded sheep red blood cells and density gradient separation. Lethally irradiated dogs were reconstituted by autologous marrow depleted of MdT-P 1-positive cells using immunorosetting and density gradient centrifugation, whereas immunomagnetic bead-depleted marrow was ineffective. Fluorescence-activated cell sorting showed enrichment of hematopoietic progenitor cells in the weakly MdT-P 1-positive fraction.

Animals↗
PubMed1991

Functional characterization of canine lymphocyte subsets.

Functional characterization of subsets of T lymphocytes is essential for transplantation studies in dogs, as it is in other species. We studied the function of T cells separated by two mouse monoclonal antibodies recognizing complementary subsets--an antibody directed to canine T cells (MdT-P1) with an up-regulating function, and an antibody directed to human CD 8 (MT811) that cross-reacts with down-regulating canine T cells. Immunorosetting with sheep red blood cells and Percoll gradient allowed us to study depleted and enriched fractions. Their function was tested in mixed lymphocyte culture (MLC), cell-mediated cytotoxicity (CML), and coculture with B cells in a hemolytic plaque assay (PFC). In MLC, MdT-P1-positive cells showed a high proliferative response, and MT811-positive cells responded poorly to allogeneic cells. Vice versa, MT811- negative cells responded strongly, and MdT-P1-negative cells were poor responders but strong stimulators. Effector cells of CML were separated following 8 days of culture and prior to mixing with target cells. Enriched and depleted fractions with either antibody showed low cytotoxic activity as compared with unseparated cells. When added to unseparated effector cells MT 811-positive cells suppressed cytotoxicity. B cells were obtained by rosetting with staphylococcal protein A (SPA). Their immunoglobulin production was studied following 6 days of culture stimulated by pokeweed mitogen in a reverse hemolytic plaque assay. Again, MT 811-positive cells added to the culture suppressed, and MT 811-negative cells enhanced immunoglobulin production. In conclusion, immunorosetting with two monoclonal antibodies allowed us to distinguish subpopulations of canine T cells with up-regulating (helper/inducer) from those with down-regulating (suppressor) activity.

Animals↗
PubMed1991

Low incidence of transplant-related complications in patients with chronic release of tumor necrosis factor-alpha before admission to bone marrow transplantation: a clinical correlate of cytokine desensitization?

To investigate the role of tumor necrosis factor-alpha (TNF-alpha) released by activated macrophages, sequential serum samples of 120 patients undergoing bone marrow transplantation (BMT) were analyzed by enzyme-linked immunosorbent assay. De novo increases in serum TNF-alpha levels were correlated with the development of acute endothelial complications as well as acute graft-versus-host disease. In addition, the analysis of time courses revealed a different capacity of TNF-alpha regulation at various phases of BMT. While patients with acute TNF-alpha release in the first 2 weeks of BMT had a significantly enhanced incidence of complications, a subgroup of 9 patients with chronic asymptomatic release of TNF-alpha before admission to BMT was observed. These patients were protected from complications in the course of the first 6 months of BMT. Our observations indicate the occurrence of desensitization for TNF-alpha, as it is also reported after repeated injections of TNF-alpha or endotoxin in experimental models.

Adolescent↗
PubMed1991

Inhibition of Escherichia coli DNA polymerase I catalysed DNA polymerization by trans-imidazolium-bisimidazoletetrachlororuthenate(III).

The tumor-inhibiting metal complex trans-imidazolium-bisimidazoletetrachlororuthenate(III) (ICR) reacts with DNA and inhibits template-primer properties for DNA synthesis catalysed by Escherichia coli DNA polymerase I. The reaction with DNA depends on the aging (half-life 6.8 h) of the aqueous solution containing ICR. The kinetics of the reaction with DNA are reminiscent of those for cisplatin.

DNA Polymerase I↗
PubMed1991

Treatment of aGVHD with OKT3: clinical outcome and side-effects associated with release of TNF alpha.

Monoclonal antibodies are increasingly used for treatment of acute graft-versus-host disease (aGVHD) in bone marrow transplantation. We treated seven patients with steroid resistant aGVHD with the monoclonal anti-T cell antibody OKT3. Though five patients showed improvement of aGVHD, only two became long-term survivors. OKT3 treatment was accompanied by deterioration of microangiopathy and prolonged increase of tumor-necrosis-factor alpha serum levels indicating activation of monocytes/macrophages in vivo, as this was not observed in a control group of patients receiving anti-T cell globulin. These findings may be related to immunostimulatory activity reported for OKT3 in vitro. Strategies interfering with cytokine release should improve clinical results of OKT3 treatment.

Acute Disease↗
PubMed1990

Donor leukocyte transfusions for treatment of recurrent chronic myelogenous leukemia in marrow transplant patients.

Three patients with hematologic relapse after bone marrow transplantation for chronic myelogenous leukemia were treated with interferon alpha and transfusion of viable donor buffy coat. All had complete hematologic and cytogenetic remission, which persisted 32 to 91 weeks after treatment. In two patients graft-versus-host disease developed and was treated by immunosuppression. These results are an example of adoptive immunotherapy without cytoreductive chemotherapy or radiotherapy in human chimeras.

Adult↗
PubMed1990

Escherichia coli DNA polymerase I: inherent exonuclease activities differentiate between monofunctional and bifunctional adducts of DNA and cis- or trans-diamminedichloroplatinum(II). An exonuclease investigation of the kinetics of the adduct formation.

[3H]dGMP-3'-labelled, activated salmon testis DNA and [32P]dGMP-5'-labelled open circular M13 DNA were reacted with cis-diamminedichloroplatinum(II), cis-diamminechloroaquaplatinum(II), cis-diamminediaquaplatinum(II) or trans-diamminechloroaquaplatinum(II). The reaction was arrested after arbitrary times by adjustment to slightly alkaline solution conditions. The platinum-containing DNA was digested with Escherichia coli DNA polymerase I. The progress of nucleotide release was measured by acid precipitation of undigested DNA. Solubilized nucleotides and adducts were analyzed by HPLC. The 3'-5'-exonuclease activity liberated single-coordinated dGMP-platinum(II) adducts from both cis- and trans-platinum(II) treated salmon testis DNA and a small fraction of adducts of cis-platinum(II) that coordinated two molecules of dGMP. The bisadduct was derived from non-neighboring guanine residues probably located at or close to 3'-termini. This nuclease activity neither cut between nor after neighboring guanine residues crosslinked by cis-platinum(II). No bisadduct was liberated for trans-platinum(II). The 5'-3'-exonuclease activity did not liberate any nucleotide adducts from cis-platinum(II)-treated DNa. However, it removed single-coordinated guanine adducts of trans-diamminedichloroplatinum(II). From the kinetics of the appearance of dGMP monoadducts and the inhibition of digestion, a reaction scheme is formulated for the reaction of platinum(II) complexes with DNA that confirms and extends the previously published one [W. Schaller, H. Reisner & E. Holler (1987) Biochemistry 26, 943-950]. The longevity of the dGMP monoadduct intermediate is discussed in the context of the efficiency of cis-diamminedichloroplatinum(II) as an antitumor drug.

Animals↗
PubMed1990

Increased serum levels of tumor necrosis factor alpha precede major complications of bone marrow transplantation.

Acute graft-versus-host disease, interstitial pneumonitis, endothelial leakage syndrome, and veno-occlusive disease are major complications of bone marrow transplantation. Though several new regimens for prophylaxis and treatment of these syndromes have been introduced, the overall incidence has been only slightly reduced over the last few years. We retrospectively analyzed tumor necrosis factor alpha (TNF alpha) serum levels between day -8 and day 100 after bone marrow transplantation in 56 patients transplanted in our unit for a variety of hematological diseases. In 34 patients with uneventful courses, mean TNF alpha levels rose to a maximum of 76 +/- 29 pg/mL. In contrast, 22 patients with major transplant related complications showed mean increases of TNF alpha of 492 +/- 235 pg/mL (P less than .0001). Increases of TNF alpha occurred before interstitial pneumonitis and severe acute graft-versus-host disease with a latency of 25 to 54 days. Early complications such as endothelial leakage syndrome and veno-occlusive disease were closely associated with increases of TNF alpha serum levels. Our study suggests two pathways of TNF alpha release: activation of host macrophages and stimulation of donor cells in the course of acute graft-versus-host disease. Cytokine monitoring should be helpful for prediction and earlier treatment of major transplant related complications.

Adolescent↗
PubMed1990

Structure-function analysis of mononucleotides and short oligonucleotides in the priming of enzymatic DNA synthesis.

The reversed-phase chromatography technique was employed in the measurement of DNA synthesis at the primers d(pT)n, r(pU)n, d(pA)n, and r(pA)n (n = 1-16) in the presence of template poly(dA) or poly(dT). DNA synthesis was catalyzed by Escherichia coli DNA polymerase I Klenow fragment, Physarum polycephalum DNA polymerase beta-like, P. polycephalum DNA polymerase alpha, and human placenta DNA polymerase alpha. Values of Km and Vmax were measured as functions of the primer chain lengths. It was found that all mononucleotides and small oligonucleotides served as primers of DNA synthesis. Values of the logarithm of both Km and Vmax increased linearly until primers had attained a chain length of 9-12 nucleotides, where a break was observed. The incremental as well as the absolute values of Km were interpreted in terms of free binding energies. These together with other data indicate that the 3'-ultimate nucleotide of the primer contributes a decisive amount of free energy of binding to DNA polymerase both from the nucleoside and from the phosphate moiety. The incremental increase is due to a complementary interaction between bases of primer and template buried in the binding cleft of the polymerase. It is also the ultimate nucleotide that determines whether the ribonucleotide or the deoxyribonucleotide is an efficient primer. It is of interest that the major results seem preserved for all four DNA polymerases. An energetic model for the binding of the template-primer was proposed and compared with available crystallographic data.

Base Sequence↗
PubMed1990

Dose rate and fractionation of total body irradiation in dogs: short and long term effects.

Variations of regimens of total body irradiation (TBI) were investigated in the dog as a preclinical model for bone marrow transplantation. Inactivation of hemopoietic precursor cells (CFU-GM) was studied following irradiation of marrow in vitro, following TBI at sublethal doses in vivo and following autologous transplantation of marrow obtained after sublethal TBI. Inactivation and recovery of CFU-GM as well as restoration of hemopoiesis following autologous transplantation was independent of the dose rate, but nadirs of blood counts were lower following sublethal TBI with the higher dose rate. Acute non-hemopoietic toxicity of TBI depended on the dose, the dose rate and the total treatment time and not on the fractionation regimen. At a total dose of 25 Gy acute mortality was prevented by prophylactic administration of oral, non-absorbable antibiotics. Late mortality was due to degenerative and autoimmune-like disorders with or without infections and to malignant tumors. Evaluation of long-term survival is still preliminary, since surviving dogs of two groups (10 Gy as single dose, 25 Gy as hyperfractionated TBI) have not yet reached the median survival time of their group. So far, long-term survival depended on the total dose (p = 0.05) and, possibly, the fractionation regimen (p = 0.12). The latency period until development of malignant tumors was influenced by the total doses given in the same treatment time (p = 0.05) and by the total treatment time for equal doses (p = 0.04). It was concluded that TBI at a low dose rate may give the best therapeutic ratio of inactivation of hemopoietic precursor cells to acute toxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Platinum incorporation and differential effects of cis- and trans-diamminedichloroplatinum(II) on the growth of mouse leukemia P388/D1.

The parallel effects of cis-diamminedichloroplatinum(II) (1 microM) or trans-diamminedichloroplatinum(II) (20 microM) on the growth of mouse leukemia P388/D1 in culture, on the cellular content of protein/DNA, on the average cell volume, and on the distribution in different phases of the cell cycle were measured over a period of 70 h and compared with the amount of platinum residing in the cells. Despite different concentrations in the culture medium, similar amounts of cis- and trans-diamminedichloroplatinum(II) were incorporated. The platinum content of cells passed through an early concentration maximum in the millimolar range and decreased during prolonged times of incubation. Effects of cis-diamminedichloroplatinum(II) were marked and irreversible whereas those of trans-diamminedichloroplatinum(II) were small and transient. Proliferation was inhibited, while synthesis of protein and DNA continued almost unaffected. Cells were arrested in G2-phase of the cell cycle, and their volume increased correspondingly. The results suggested an inhibition of mitotic events, rather than of DNA replication, that caused cell arrest.

Animals↗
PubMed1989

An unusual polyanion from Physarum polycephalum that inhibits homologous DNA polymerase alpha in vitro.

From extracts of microplasmodia of Physarum polycephalum and their culture medium, an unusual substance was isolated which inhibited homologous DNA polymerase alpha of this slime mold but not beta-like DNA polymerase and not heterologous DNA polymerases. Analysis, especially NMR spectroscopy, revealed the major component to be an anionic polyester of L-malic acid and the inhibition to be due to poly(L-malate) in binding reversibly to DNA polymerase alpha. The mode of inhibition is competitive with substrate DNA and follows an inhibition constant Ki = 10 ng/mL. Inhibition is reversed in the presence of spermine, spermidine, poly(ethylene imine), and calf thymus histone H1. According to its ester nature, the inhibitor is slightly labile at neutral and instable at acid and alkaline conditions. Its largest size corresponds to a molecular mass of 40-50 kDa, but the bulk of the material after purification has lower molecular masses. The inhibitory activity depends on the polymer size and has a minimal size requirement.

Binding Sites↗
PubMed1989

Microangiopathy in patients on cyclosporine prophylaxis who developed acute graft-versus-host disease after HLA-identical bone marrow transplantation.

Severe microangiopathy has been reported as a rare complication of cyclosporine A (CsA) prophylaxis in allogeneic bone marrow transplantation (BMT). We found morphological and biochemical changes indicative of generalized endothelial damage in 49 of 66 allogeneic marrow graft recipients receiving cyclosporine, but none in 11 patients treated with methotrexate for prophylaxis of graft-v-host disease (GVHD). Changes occurred after engraftment of bone marrow and consisted of intravascular hemolysis with red cell fragmentation and de novo thrombocytopenia. They were preceded by a decrease in activated partial thromboplastin time and fibrinogen indicating activation of coagulation. Endothelial damage as the central lesion of microangiopathy was confirmed by a simultaneous increase of factor VIII related antigen. Severe microangiopathy was observed in ten patients and was fatal in seven. Risk factor analysis revealed a highly significant association of microangiopathy with severity of acute GVHD (aGVHD) (P less than .001) and use of CsA prophylaxis (P less than .001). Our data suggest endothelial damage as a result of cellular activation and subsequent release of cytokines in the course of a aGVHD, which is not inhibited by CsA prophylaxis.

Adult↗
PubMed1989

Investigations on the antiproliferative effects of amino acid antagonists targeting for aminoacyl-tRNA synthetases. Part I--The antibacterial effect.

Amino acid antagonists with proven or potentially inhibitory activities on aminoacyl-tRNA synthetases were tested for their antiproliferative effect against E. coli B. The compounds 4- and 6-fluoro-tryptophan, 5-methyltryptophan, selenocystine and beta-(2-thienyl)alanine gave strong growth inhibition in minimal medium, which disappeared after addition of structurally related natural amino acids or in an enriched broth. The inhibitory effect on amino-acyl-tRNA synthetases and the minimal inhibitory concentration for growth inhibition in minimal medium could not be correlated.

Amino Acids↗