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1.
R Foa M T Fierro M Giovarelli P Lusso G Benetton M Bonferroni G Forni 《Blood cells》1987,12(2):399-412
Several phenotypic and functional defects have been described within the residual T-lymphocyte population of patients with B-cell chronic lymphocytic leukemia (B-CLL), particularly in those in the more advanced stages of the disease. In this study, we review these abnormalities and discuss their possible effects on the course of the illness. Particular emphasis is devoted to the role of interleukin 2 (IL-2) in B-CLL. Evidence is provided that the IL-2 released by B-CLL T-lymphocytes may be utilized by the neoplastic B-cell clone that expresses the IL-2 receptor and that decreased availability of IL-2 may play a contributory role in some of the T-cell defects encountered in B-CLL. 相似文献
2.
The Ultrastructure of a Cyanophage Attack on Anabaena variabilis 总被引:2,自引:0,他引:2
Cyanophages multiplying on the nitrogen fixing blue-green alga Anabaena variabilis Kütz. were revealed by electron microscopy. Severe ultrastructural changes have been observed in the vegetative cells, whereas the heterocysts appeared resistant to the cyanophage. A lytic cycle was observed from adsorption to lysis. 相似文献
3.
4.
Phorbol myristate acetate-induced down-modulation of CD4 is dependent on calmodulin and intracellular calcium 总被引:1,自引:0,他引:1
M Bigby P Wang J F Fierro M S Sy 《Journal of immunology (Baltimore, Md. : 1950)》1990,144(8):3111-3116
PMA causes rapid down-modulation of CD4 molecules on murine immature thymocytes, human PBL, and CD4-positive human tumor cell lines, but not on murine peripheral lymphocytes. The mechanisms of phorbol ester-induced down modulation of CD4 molecules, however, have not been elucidated. To determine how PMA down-modulates CD4 expression by T lymphocytes, we studied the ability of inhibitors of protein kinase C, calmodulin, actin, and tubulin to block PMA-induced modulation of CD4 in several murine and human cell types. We also tested the ability of intracellular and extracellular calcium chelators to block CD4 internalization. There was marked variability in the degree of PMA-induced down-modulation of CD4 among various cell types. The effects of PMA on CD4 expression were greater for murine thymocytes, for human PBL, and for the human lymphoblastic leukemia cell line, MOLT-3, than for any of the other cell types studied. The protein kinase C inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine, blocked phosphorylation but not internalization of CD4 molecules induced by PMA. Therefore, phosphorylation of CD4 molecules by protein kinase C is not required for the internalization of the molecules. Internalization was blocked by both inhibitors of calmodulin, N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide, and trifluoperazine. PMA-induced internalization of CD4 was blocked by Quin-2 AM, which chelates intracellular calcium. EGTA, which chelates extracellular calcium, did not block internalization. Inhibitors of actin or tubulin did not block internalization. These results suggest that PMA-induced modulation of CD4 can occur in the absence of phosphorylation of the CD4 molecules and is calmodulin and intracellular calcium dependent. 相似文献
5.
F. Fierro E. Montenegro S. Gutiérrez J. F. Martín 《Applied microbiology and biotechnology》1996,44(5):597-604
The organization of the genes of the penicillin cluster has been studied in three different mutants of P. chrysogenum impaired in penicillin biosynthesis. The three blocked mutants (derived from the parental strain P. chrysogenum Bb-1) lacked the genes pcbAB, pcbC and penDE of the penicillin biosynthetic pathway and were unable to form isopenicillin N synthase and isopenicillin N acyltransferase. All strains were identified as P. chrysogenum derivatives by fingerprinting analysis with (GTG)n as a probe. The borders of the deleted region were cloned and sequenced, showing the same junction point in the three mutants. The deleted DNA region was found to be identical to that described in P. chrysogenum npe10. The frequent deletion of the pen gene cluster at this point may indicate that this cluster is located in an unstable genetic region, flanked by hot spots of recombination, that is easily lost by mutagen-induced recombination. 相似文献
6.
An increase in nitric oxide produced by rat peritoneal neutrophils is not involved in cell apoptosis
Fierro IM Barja-Fidalgo C Canedo RM Cunha FQ Ferreira SH 《Mediators of inflammation》1995,4(3):222-228
Polymorphonuclear neutrophils (PMN) obtained from carrageenin-stimulated peritoneal cavities of rats, but not blood PMN, spontaneously produced nitric oxide (NO) when incubated in vitro. Incubation of the cells with the NO synthase inhibitors, L-imino-ethyl-L-ornithine (L-NIO) or N(G)-monomethyl-L-arginine (L-NMMA), inhibited NO production. This inhibition could be reversed by L-arginine. Incubation of PMN with lipopolysaccharide (LPS) failed to enhance NO production. Pretreatment of the rats with dexamethasone (DEXA) prior to carrageenin injection or incubation of PMN with the glucocorticoid in vitro partially inhibited the spontaneous release of NO. On the other hand, when PMN obtained from DEXA pretreated rats were incubated in vitro with DEXA, NO synthase activity and hence NO generation were almost abolished. A similar inhibition was also observed following the addition of L-NIO or cycloheximide to cultures of carrageenin-elicited PMN. The NO production by PMN did not appear to be related to cell viability or apoptosis. Indeed, neither the blockade of NO generation by L-NIO nor the incubation of the neutrophils with a NO donor, S-nitroso-acetylpenicillamine (SNAP) modified the pattern of LDH release or DNA fragmentation. In summary, it appears that PMN migration triggers a continuous NO synthesis, and that NO produced by these cells is not related to their apoptosis. 相似文献
7.
Hans-Börje Jansson Angelica von Hofsten Claes von Mecklenburg 《Antonie van Leeuwenhoek》1984,50(4):321-327
The obligate endoparasitic fungus Meria coniospora lives its entire vegetative life within infected nematodes. Conidia of M. coniospora infect the nematode Panagrellus redivivus mainly in the mouth region. The infection, starting with adhesion of conidia to the nematode surface, growth of trophic hyphae, production of conidiophores and conidia, was followed using light, scanning and transmission electron microscopy.This work was supported by grants from the Swedish Natural Science Research Council. 相似文献
8.
C Giovannini M Sellini L Marchesi A Fierro F Massimiani 《Bollettino della Società italiana di biologia sperimentale》1979,55(24):2544-2549
The behaviour of plasma cortisol levels was studied in fifteen overweight subjects with comparison to normal subjects. In eight subjects the insulin hypoglycemic test was performed before and after medication with reserpine (4mg/24HR); the other seven subjects were tested with LVP before and after treatment with reserpine. In both cases, premedication with reserpine significantly reduce the cortisolemic response. This behaviour is similar to the response observed in normal subjects. 相似文献
9.
Calmodulin, as a major intracellular calcium-binding protein, regulates many Ca(2+)-dependent enzymes and plays an important role in a wide spectrum of cellular functions of the eukaryotes. Interaction between calmodulin and human lactoferrin, a 78 kDa protein with antibacterial properties, was found in the presence of Ca2+ using (i) a method for the detection of calmodulin binding proteins with biotinylated calmodulin, (ii) affinity chromatography on an agarose-calmodulin column with subsequent detection by an enzyme-linked immunosorbent assay (ELISA). The binding of calmodulin to lactoferrin blocked the ability of lactoferrin to agglutinate Micrococcus lysodeikticus. 相似文献
10.