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排序方式: 共有351条查询结果,搜索用时 15 毫秒
1.
Terje K. Steigen Truls Myrmel Kirsti Forsdahl Terje S. Larsen 《Molecular and cellular biochemistry》1992,116(1-2):47-52
Myocardial cell vulnerability to phospholipase C (PC-PLC) attack was investigated in three different preparations of rat myocardial cells: triacylglycerol (TG)-loaded, hypothermic/rewarmed and energy depleted myocytes. The attack by PC-PLC was evaluated as PC-PLC induced glycerol output due to the combined action of phospholipase C and intracellular lipases. PC-PLC induced glycerol output was significantly higher (p < 0.05) in all three myocyte preparations, compared to their respective controls. Cell morphology (% rod shaped myocytes) of TG-loaded or hypothermic/rewarmed myocytes was not different from their controls, whereas energy depleted myocytes almost exclusively were rounded up, due to hypercontraction of the myofilaments. Hypothermic/rewarmed and energy depleted myocytes showed a significantly higher release of lactate dehydrogenase (LDH), compared to their controls although the difference was much more pronounced in the latter. Finally, the cellular contents of ATP were maintained both in TG-loaded and hypothermic rewarmed myocytes, while energy depleted myocytes contained only about 25% of the normal ATP level. These results demonstrate that attack from exogenously added phospholipases can occur, not only in seriously damaged cardiac myocytes, but in myocytes with a more subtle damage as well. (Mol Cell Biochem 116: 47–52, 1992) 相似文献
2.
Peter A. Lando Gunnar Hedlund Mikael Dohlsten Terje Kalland 《Cancer immunology, immunotherapy : CII》1991,33(4):231-237
Summary Activation of lymphocytes by interleukin-2 (IL-2) induces lymphokine-activated killer (LAK) cells that show promising effects on tumour growth in clinical trials. We examined the effect of the superantigen staphylococcal enterotoxin A (SEA) on anti-tumour activity of freshly prepared human lymphocytes. Picomolar amounts of SEA rapidly induced cytotoxic activity against K562 and Raji cells as well as some natural-killer(NK)-resistant tumour cell lines. Cytotoxic activity was not dependent on target cell expression of either major histocompatibility complex (MHC) class I or II antigens as shown using mutated cell lines. Cell-sorting experiments showed that the activity was expressed by NK (CD5–CD56+) as well as T (CD5+) cells, although the former contained the majority of cytotoxic activity. NK cells could not be directly activated by SEA. In contrast, SEA activated purified T cells to the same extent as in bulk cultures. It is suggested that SEA activation of NK cells is secondary to that brought about by lymphokines produced by T cells. Activation of LAK cells with SEA was comparable in magnitude as well as target cell spectrum to that of IL-2. In addition to the LAK-like cytotoxic activity induced by SEA, a superimposed cytotoxicity towards target cells expressing MHC class II antigens coated with SEA was observed. This staphylococcal-enterotoxin-dependent cell-mediated cytotoxicity (SDCC) was exclusively mediated by T cells. It is well established that MHC class II antigens function as receptors for staphylococcal enterotoxins on mammalian cells and that the complex between MHC class II antigen and — SEA apparently functions as a target structure for activated T cells with target cell lysis as a consequence. Activation of T lymphocytes with IL-2 also resulted in the capability to mediate SDCC. Staphylococcal enterotoxins represent a novel way of inducing anti-tumour activity in human lymphocytes, which could be of value in therapeutic applications. 相似文献
3.
Terje H. Larsen 《The Histochemical journal》1988,20(2):69-74
Summary In the present investigation atrial natriuretic peptide (ANP) was localized in striated myocytes of the venae cavae and the pulmonary veins in the rat by the use of immunohistochemical and immunocytochemical staining techniques. ANP was stored in granules which appeared to be morphologically similar to the atrial specific granules (ASG) of the atria. In general, the amount of ASG in the great thoracic veins was less than observed in the atria, and the specific granules appeared to be more evenly distributed throughout the sarcoplasm. However, the presence of ANP-containing specific granules in the venae cavae and the pulmonary veins may suggest participation of these veins in the production and secretion of the hormone. 相似文献
4.
The carbon assimilation pathways of Methylococcus capsulatus, Pseudomonas methanica and Methylosinus trichosporium (OB3B) during growth on methane 总被引:8,自引:2,他引:6
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d-arabino-3-Hexulose 6-phosphate was prepared by condensation of formaldehyde with ribulose 5-phosphate in the presence of 3-hexulose phosphate synthase from methane-grown Methylococcus capsulatus. The 3-hexulose phosphate was unstable in solutions of pH greater than 3, giving a mixture of products in which, after dephosphorylation, allulose and fructose were detected. A complete conversion of d-ribulose 5-phosphate and formaldehyde into d-fructose 6-phosphate was demonstrated in the presence of 3-hexulose phosphate synthase and phospho-3-hexuloisomerase (prepared from methane-grown M. capsulatus). d-Allulose 6-phosphate was prepared from d-allose by way of d-allose 6-phosphate. No evidence was found for its metabolism by extracts of M. capsulatus, thus eliminating it as an intermediate in the carbon assimilation process of this organism. A survey was made of the enzymes involved in the regeneration of pentose phosphate during C(1) assimilation via a modified pentose phosphate cycle. On the basis of the presence of the necessary enzymes, two alternative routes for cleavage of fructose 6-phosphate are suggested, one route involves fructose diphosphate aldolase and the other 6-phospho-2-keto-3-deoxygluconate aldolase. A detailed formulation of the complete ribulose monophosphate cycle of formaldehyde fixation is presented. The energy requirements for carbon assimilation by this cycle are compared with those for the serine pathway and the ribulose diphosphate cycle of carbon dioxide fixation. A cyclic scheme for oxidation of formaldehyde via 6-phosphogluconate is suggested. 相似文献
5.
Terje H. Larsen Henrik S. Huitfeldt Ole Myking Thorvald Sætersdal 《Cell and tissue research》1993,272(2):201-210
A close spatial relationship between specific granules containing atrial natriuretic factor (ANF) and microtubules was demonstrated in primary cultures of neonatal rat cardiac myocytes. For the detection of specific granules and microtubules, the myocytes were double immunolabelled with antibodies against -ANF and -tubulin and examined by conventional fluorescence or laser scanning confocal microscopy. In addition, the ultrastructural distribution of specific granules was demonstrated by electron microscopy. In the atrial myocytes, ANF was stored in numerous specific granules that were mainly localized in the perinuclear sarcoplasm. In the ventricular myocytes, however, a minority of the cells (10%) exhibited limited ANF immunoreactivity after 4 days in culture. Microtubules were present throughout the sarcoplasm of the myocytes. They were most densely packed in the perinuclear regions. Depolymerization of the microtubules with nocodazole was followed by dispersal of ANF immunostaining both in the atrial myocytes and in the ventricular myocytes exhibiting ANF immunoreactivity. When the microtubules were allowed to recover, the perinuclear distribution of specific granules, as seen in non-treated myocytes, reappeared. Measurements of secreted immunoreactive ANF by radioimmunoassay revealed that the secretion of ANF from atrial myocytes into the medium was significantly reduced following nocodazole treatment, whereas a similar decrease in secretion from ventricular myocytes was not observed. These findings indicate that ANF-containing specific granules are closely associated with microtubules within the myocytes. It is suggested that secretion of ANF from the atrial myocytes, in contrast to the ventricular myocytes, is microtubule-dependent. 相似文献
6.
Terje Kalland Mikael Dohlsten Lars Abrahmsén Gunnar Hedlund Per Björk Peter A. Lando Anette Sundstedt Eva Åkerblom Peter Lind 《Cell biochemistry and biophysics》1993,22(1-3):147-164
The bacterial superantigen staphylococcal enterotoxin A (SEA) is an extremely potent activator of T lymphocytes when presented on MHC class II antigens. In order to induce T lymphocytes to reject a tumor, we substituted the specificity of SEA for MHC class II molecules with specificity for tumor cells by combining SEA with a MAb recognizing colon carcinomas. Chemical conjugates or recombinant fusion proteins of the MAb C215 and SEA retained excellent antigen binding properties whereas the binding to MHC class II was markedly reduced. The hybrid proteins directed SEA responsive T cells to tumors with specificity determined by the specificity of the MAb. Significant tumor cell killing was obtained at picomolar concentrations of the hybrid proteins and was the result of direct cell mediated by cytotoxicity as well as production of tumoricidal cytokines by T cells. Targeting of superantigens represents a novel approach to specific immunomodulation and deserves further study as a potential therapy for malignant disease. 相似文献
7.
Crustacean plankton in Høylandet 总被引:4,自引:3,他引:1
Crustacean plankton was studied in 12 lakes in theHøylandet area in 1986–87. Basic lake characteristicsare elevation 134–415 m, surface area 9–530 ha, pH 5.9–7.1,conductivity (25 °C) 12–40 µS cm-1 andSecchi depth 4–9 m. Number ofspecies present varied between 3 and 11. Populationnumbers between 4000 and 400 000 per m2 andbiomasses were within the range 30 to1800 mg m-2 dry weight. Cladocera dominated overCopepoda in lakes with allopatric brown trout (Salmo trutta L.), on the contrary to lakes also populatedby Arctic charr (Salvelinus alpinus (L.)). Thesevariations are caused by differences in elevation,lake morphometry, water quality, fish predation andthe general distribution of the species. The largestlakes at lowest elevation were richest in species. Theacid sensitive genus Daphnia was represented by 3species. The lakes Storgrønningen (530 ha) andRøyrtjønna (27 ha) were sampled monthly in theice-free seasons of 1986–89, and Storgrønningen moreintensively from June to November in 1987 and 1988. The same6 species of Cladocera and 5 of Copepoda were presentin both lakes. Their life cycles were traditional orknown from several other Scandinavian lakes. Meanseasonal biomasses were of the range600–750 mg m-2. At the species level, there wereconsiderable variations between years inStorgrønningen and particularly in Røyrtjønna. Noeffects of human impacts on the crustacean planktonwere found. The Høylandet lakes are representative forScandinavian oligotrophic to almost ultra-oligotrophiclakes. Storgrønningen is well qualified as a referencesystem. The between year variations in Røyrtjønna areso extreme, that any human impact could only be traced at alevel causing the extinction of species. 相似文献
8.
The species composition of aquatic insects in theboreal stream, Skiftesåa, was investigated usingemergence traps, Malaise traps and kick samples. Atleast 13 Ephemeroptera, 16 Plecoptera, 25 Trichopteraand 120 Chironomidae species were recorded. This faunais representative for non-polluted, northern streams.The production of macrobenthos was estimated to beonly about 1 g dry weight per year and m2,possibly due to the fluctuating flow of water. 相似文献
9.
Mikael Dohlsten Peter A. Lando Per Björk Lars Abrahmsén Lennart Ohlsson Peter Lind Terje Kalland 《Cancer immunology, immunotherapy : CII》1995,41(3):162-168
T lymphocytes generally fail to recognize human colon carcinomas, suggesting that the tumour is beyond reach of immunotherapy. Bacterial superantigens are the most potent known activators of human T lymphocytes and induce T cell cytotoxicity and cytokine production. In order to develop a T-cell-based therapy for colon cancer, the superantigen staphylococcal enterotoxin A (SEA) was given tumour reactivity by genetic fusion with a Fab fragment of the monoclonal antibody C242 reacting with human colon carcinomas. The C242Fab-SEA fusion protein targeted SEA-reactive T cells against MHC-class-II-negative human colon carcinoma cells in vitro at nanomolar concentrations. Treatment of disseminated human colon carcinomas growing in humanized SCID mice resulted in marked inhibition of tumour growth and the apparent cure of the animals. Therapeutic efficiency was dependent on the tumour specificity of the fusion protein and human T cells. Immunohistochemistry demonstrated massive infiltration of human T cells in C242Fab-SEA-treated tumours. The results merit further evaluation of C242Fab-SEA fusion proteins as immunotherapy in patients suffering from colon carcinoma. 相似文献
10.
One series of 12 rats was exposed to X-irradiation (1500 R) of the stomach 19 days before implantation of Walker tumour cells in the gastric mucosa, and the frequency of tumour take and the extent of tumour growth after 10 days were compared with a second series with the same tumour implantation, but without X-ray exposure. In a third series simple gastric ulcers without tumour were produced by clamping the gastric wall with a heated (80 degrees) surgical needle holder, and the animals were killed 5-7 day later. All the rats were given injections of vinblastine sulfate 3 hours and of 3H-TDR 1 hour before sacrifice. In viewfields with diameter 180 mu the vinblastine-arrested mitoses and labelled cells on the tumour side of the tumour/mucosa border were calculated as percentages of all tumour cells. In the mucosa the total number of proliferating cells was counted at various distances from the border of the tumour or ulcer. No clear differences in the frequency of tumour take and the extent of tumour growth were found between the X-irradiated and the normal rat stomachs, and it is concluded that the X-ray exposure 3 weeks prior to tumour implantation did not reduce the normal mucosal resistance to tumour growth. The percentage of arrested mitoses and labelled cells in the tumour decreased one view field away from the mucosal border, and the number of proliferating cells in the mucosa bordering on the tumours showed a gradual fall with increasing distance up to 0.8-1.0 mm from the tumour border; within these distances, however, the numbers were much higher than at corresponding distances from edges of the ulcers. The Walker tumour thus seems to stimulate cell proliferation in mucosa to a much greater extent than a simple ulcer does. The causes of this phenomenon and the possible roles of "chalones" or "anti-chalones" are discussed. 相似文献