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991.
Eliška Rybníčková 《Folia Geobotanica》1982,17(1):99-100
Additional C-14 dates to the pollen diagrams from the Zbudovská blata marshes (see Rybní?ková, Rybní?ek et Jankovská 1975) are published. The dates support the previous hypothesis of a stratigraphic hiatus for the middle Holocene era. 相似文献
992.
Eliška Rybníčková 《Folia Geobotanica》1966,1(1):289-310
The paper presents the results of pollen analyses of samples collected from two peat localities in the Orlické hory mountains in Czechoslovakia. Appended pollen diagrams depict the vegetation and its changes in the Older and Younger Subatlantic period. The paper suggests the probable proportional representation of the principal woody plants in the area and, on the basis of pollen analyses, reconstructs the forest covers of the Orlické hory, especially of their upper regions. The author has foundFagus to have predominated among woody plants in the area (even in the upper regions) in the Older Subatlantic. From the 16th or 17th century onward it was gradually replaced byPicea. This change was primarily due to human activity (cutting down of the beeches). The composition of foot-hill forests, as far as it is reflected in the diagrams, is discussed. The pollen diagrams also testify to agricultural activity by man in the wide surroundings of the Orlické hory. 相似文献
993.
Transgenic Mice With Elevated Level of CuZnSOD Are Highly Susceptible to Malaria Infection 总被引:1,自引:0,他引:1
Jacob Golenser Mira Peled-Kamar Eli Schwartz Ilanit Friedman Yoram Groner Yaakov Pollack 《Free radical biology & medicine》1998,24(9):1504-1510
Copper/zinc superoxide dismutase (CuZnSOD) catalyses the conversion of O2•− into H2O2. Constitutive overexpression of CuZnSOD in cells and animals creates an indigenous oxidative stress that predisposes them to added insults. In this study, we used transgenic CuZnSOD (Tg-CuZnSOD) mice with elevated levels of CuZnSOD to determine whether overexpression of CuZnSOD affected the susceptibility of these mice to plasmodium infection. Acute malaria is associated with oxidative stress, mediated by redox-active iron released from the infected RBC. Two independently derived Tg-CuZnSOD lines showed higher sensitivity than control mice to infection by Plasmodium berghei (P. berghei), reflected by an earlier onset and increased rate of mortality. Nevertheless, while Tg-CuZnSOD mice were more vulnerable than control mice, the levels of parasitemia were comparable in both strains. Moreover, treatment of infected red blood cells (RBC) with oxidative stress inducers, such as ascorbate or paraquat, reduced the viability of parasites equally in both transgenic and control RBC. This further confirms that increased CuZnSOD does not support plasmodia development. The data are consistent with the possibility that the combination of increased redox-active iron and elevated H2O2 in the plasmodium-infected Tg-CuZnSOD mice, led to an enhanced Fenton’s reaction-mediated HO• production, and the resulting oxidative injury renders the transgenic mice more vulnerable to parasite infection. 相似文献
994.
The in vitro human serum albumin binding characteristics of the enantiomers of the major metabolites of warfarin [6-hydroxywarfarin (6-HW), 7-hydroxywarfarin (7-HW), (S)-warfarin alcohols [(S,S)- and (S,R)-WA], and (R,S)-warfarin alcohol [(R,S)-WA]] have been studied, using a stereospecific HPLC assay. Warfarin metabolites are less bound both within plasma and a 40 g/liter solution of human serum albumin than the enantiomers of warfarin. The reduced warfarin metabolites have a lower fraction unbound [1.33% for (S,R)-WA, 2.09% for (S,S)-WA, and 1.04% for (R,S)-WA] than hydroxylated metabolites [3.24% for (R)-6-HW, 4.26% (S)-6-HW, 4.49% for (R)-7-HW and 4.27% for (S)-7-HW] to HSA. Phenylbutazone produced a concentration-dependent increase in the unbound fraction of all metabolites. It was possible to predict the unbound fraction of warfarin metabolites based on the unbound fraction of warfarin enantiomers. © 1993 Wiley-Liss, Inc. 相似文献
995.
Helge Rootwelt Janice Chou William A. Gahl Ruud Berger Turgay Coşkun Else Brodtkorb Eli Anne Kvittingen 《Human genetics》1994,93(6):615-619
Hereditary tyrosinemia type 1, due to a deficiency of fumarylacetoacetase (FAH), is characterized by progressive liver damage and renal tubular dysfunction and may occur in an acute or a chronic form. An Ala 134 to Asp (GCT to GAT) transition was found in one Turkish and two Norwegian patients with chronic tyrosinemia. SphI digestion of polymerase chain reaction (PCR) amplified genomic DNA identified the mutation and showed that the patients were heterozygous. All these patients had immunoreactive FAH protein in fibroblasts. Another Norwegian patient with chronic disease, without FAH immunoreactive material in fibroblasts, had a Pro 342 to Leu mutation (CCG to CTG). This mutation was identified by MspI digestion of PCR amplified genomic DNA, and the patient was heterozygous. Northern blotting showed FAH mRNA of normal size and amounts in all patients. Site directed mutagenesis and translation in a rabbit reticulocyte lysate demonstrated that both mutations abolished FAH activity. 相似文献
996.
Ca2+ inhibits guanine nucleotide-activated phospholipase D in neural-derived NG108-15 cells. 下载免费PDF全文
We have investigated the regulation of phospholipase D (PLD) activity by guanine nucleotides and Ca2+ in cells of the NG108-15 neuroblastoma X glioma line that were permeabilized with digitonin. The nonhydrolyzable GTP analogue guanosine-5'-O-(3-thiotriphosphate) (GTP gamma S) caused a nearly sixfold increase (EC50 = 3 microM) in production of [3H]phosphatidylethanol (specific product of the PLD transphosphatidylation reaction). Other GTP analogues were less effective than GTP gamma S, and guanosine-5'-O-(2-thiodiphosphate) inhibited PLD activation by GTP gamma S. Both basal and GTP gamma S-stimulated PLD activities were potentiated by MgATP and Mg2+. Adenosine-5'-O-(3-thiotriphosphate) and ADP also potentiated the effect of GTP gamma S, but non-phosphorylating analogues of ATP had no such effect. The activation of PLD by GTP gamma S did not require Ca2+ and was independent of free Ca2+ ions up to a concentration of 100 nM (resting intracellular concentration). Higher Ca2+ concentrations (greater than or equal to 1 microM) completely inhibited PLD activation by GTP gamma S. It is concluded that elevated intracellular Ca2+ concentrations may negatively modulate PLD activation by a guanine nucleotide-binding protein, thus affecting receptor-PLD coupling in neural-derived cells. 相似文献
997.
998.
999.
Eli Kedar Revital Ben-Aziz Eyal Epstein Benny Leshem 《Cancer immunology, immunotherapy : CII》1989,29(1):74-78
Summary The antitumor effect of interleukin-2 (IL-2), alone and in combination with cyclophosphamide was assessed in mice with established sarcoma (MCA 105, H-2b), carcinoma (M109, H-2d) and T lymphoma (PIR-2, H-2b). Whereas administration of IL-2 alone (5×104–10×104 U, i.p. twice daily, for 4–8 consecutive days) prolonged the survival of mice with the solid neoplasms, it enhanced tumor growth and decreased survival of mice with the lymphoma. In the PIR-2 lymphoma, no IL-2 receptor (TAC) could be detected, nor could we demonstrate IL-2 tumor growth stimulation in vitro. A synergistic therapeutic effect was achieved in mice with the solid tumors, but not in mice with the lymphoma, only when IL-2 was given 1–4 days after cyclophosphamide (100–200 mg/kg). Conversely, administration of IL-2 1–4 days prior to cyclophosphamide resulted, in all three tumor systems, in enhanced tumor growth and in decreased survival as compared with mice receiving cyclophosphamide alone. Similarly, treatment with IL-2 both before and after cyclophosphamide was less efficacious than a single course of IL-2 given after-wards. It is concluded that for maximal therapeutic efficacy, IL-2 should be administered following chemotherapy, and that certain tumors may respond adversely to IL-2 treatment. 相似文献
1000.