摘要:

AbstractTransport of 2,4‐dinitrophenyl‐S‐glutathione (DNP‐SG) and a fluorescent glutathione S‐conjugate, bimane‐S‐glutathione (B‐SG) was studied in the baker's yeasts (S. cerevisiae). Both conjugates were exported from the cells; the transport was inhibited by fluoride and vanadate like in mammalian cells. B‐SG was also found to be accumulated in the vacuoles. The transport rate of DNP‐SG outside the cell was higher in a vacuolar‐deficient strain. A significant ATP‐dependent uptake of (3H)‐DNP‐SG by vacuoles was found. These results indicate thatS. cerevisiaetransport glutathione S‐conjugates both outside th

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0035

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractUsing anin vitromodel for cell transformation, the relationship between specific chromosomal aberration and phenotypic changes was studied at different passages of Rat‐2 cell line. A marker chromosome resulting from a translocation [t(2;7)] was found to be associated with focus formation in soft agar. Conversely, the loss of this marker chromosome was found to be associated with phenotypic reversion. These results suggest an association of this marker chromosome with phenotypic transformation for the Rat‐cell l

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0036

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe regulatory effects of the combined treatment of tumour necrosis factorα (TNFα), interleukin‐1α (IL‐1α) and interferonα(IFNα) on the growth and differentiation of Daudi lymphoma cells were investigated. By means of anti‐BrdU monoclonal antibodies and [3H‐thymidine] incorporation a reduced proliferation rate was shown both through a combi‐nation of TNFα with either IL‐1α or IFNα and, above all, through simultaneous treatment with the three cytokines. In parallel, the degree of differentiation was evaluated via morphological criteria and detection of Fc receptors (FcR) and appeared higher after treatment with the three cytokines. Our results provide evidence of the increased sensitivity of this cell line to this combined treatment supporting the existence of a synergistic interaction in inducing the antiproliferative and dif

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0037

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractHormonal imprinting takes place at the first encounter of the hormone and receptor, and results in a changed binding capacity and reaction of the cell and its progeny generations. The imprinting effect of three amino acids and their oligopeptides is studied using fluorescent‐labelled peptides. Glycine and lysine could provoke positive imprinting (increased binding in the progeny generations) for their own peptides, but alanine could not. Mostly positive imprinting was provoked by glycine and lysine peptides for their own peptides of different chain length. The optimal chain length provoking self‐imprinting was four for glycine, two for lysine and three for alanine. Except in this case, alanine was neutral or provoked mostly negative imprinting. After reaching the optimal chain length, there is a decline in binding. Evolutionary conclusions are discus

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0038

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe interaction of NO and O−2free radicals generated from PMA (phorbol myristate acetate)‐stimulated PMN (polymorphonuclear leukocytes) was studied by a nitroxide spin trap, DMPO (5,5‐dimethyl‐1‐pyrroline‐1‐oxide). It was found that addition of L‐arginine to the system would significantly decrease the trapped O−2by DMPO and addition of NG‐monomethyl‐arginine (NGMA) would significantly increase the trapped O−2by DMPO. It was proved that the formation of ONOO−by the reaction of NO and O−2was the main reason for the decrease of trapped O−2in the experiment with xanthine/xanthine oxidase and irradiation of riboflavin systems. The yield of NO during this process was calculated. The generation dynamic of NO was studied by a luminol‐dependent chemiluminescence technique and it was found that after stimulation of PMN by PMA, there would be an immediate, significant chemi‐luminescence, which came mainly from the active oxygen free radicals generated by PMN. If L‐arginine was added to this system, the chemiluminescence would increase about 100‐fold, but NGMA inhibited the increase of the chemiluminescence. Ten minutes after addition of L‐arginine, this increase did not change, the chemiluminescence peak decreased gradually, but the half life increased. The ESR and chemiluminescence properties of NO and ONOO−synth

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0039

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractA part of sperm glycosidase activities was detected as detergent‐insoluble after sequential extractions with Triton X‐100. Sixty per cent of total β‐glucuronidase activity was found in the detergent‐insoluble fraction. This portion of β‐glucuronidase was resistant to extractions in the presence of 1mKCl, chaotropic agents, colchicine or cytochalasine B, being only partially solubilized by 3mKCl or DNAse I treatment. Results demonstrate that β‐glucuronidase is tightly associated to the Triton X‐100 re

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0040

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractCisplatin reportedly plays an important role as a chemical modulator in enhancing the chemotherapeutic effects of 5‐fluorouracil on tumour cells. The aim of the present study was to test the synergistic cytotoxicity of cisplatin and 5‐fluorouracil in 5‐fluorouracil‐resistant (C6) and ‐sensitive (9L) rat brain tumour cell lines. Survival fractions, determined using colony‐formation assays, were compared following 5‐fluorouracil treatment, with and without cisplatin. The presence of cisplatin (1–10μm) enhanced cytotoxicity by more than three times compared with 5‐fluorouracil alone in 5‐fluorouracil‐resistant C6 cells, whereas no enhancement effects were noted in 9L cells. These results suggest that a cisplatin‐fluorouracil‐based regimen may be promising in the treatment of 5‐fluorour

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0041

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractGlutamine requirements are increased during injury, in particular to sustain the needs of rapidly growing cells. This includes fibroblasts involved in wound healing. α‐Ketoglutarate (α‐KG) has been proved to be a potent precursor of glutamine. However, little is known about the process of its cell uptake. Since this first step could be crucial in α‐KG metabolism, we have characterized α‐ketoglutarate uptake in fibroblasts. Total uptake of α‐ketoglutarate was linear up to 1mmol and temperature independent. Rate of uptake was independent of the presence of Na+in the medium. Competition studies with another ketoacid demonstrated the non‐specificity of α‐ketoglutarate uptake. In addition, 4‐hydroxy‐α‐cyanocinnamate, a known inhibitor of anion transport, was ineffective on α‐ketoglutarate uptake. Taken as a whole, these data provide evidence that α‐ketoglutarate uptake in fibroblast occurs by an unmediated diffusion process. This suggests that α‐ketoglutarate uptake is not the controlling step in fibroblasts, i.e. only the availability of extracellular α‐ketoglutarate. This could be an advantage since during injury, cell membrane depolarization and dissipation of Na+gradie

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0042

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractUsing the binding of heterologous, rhodamine phalloidin‐labelled F‐actinin vitro, two F‐actin binding proteins were identified in protein extracts from the green algaChara corallinaafter fractionation by anion exchange chromatography. The first protein, a putative myosin, released laterally bound F‐actin at ATP‐concentrations as low as 1μm; equivalent concentrations of ADP were not effective. Binding of F‐actin was inhibited by the sulfhydryl‐alkylating agent N‐ethylmaleimide (NEM). Binding of F‐actin was also abolished by a monoclonal anti‐myosin (J14) previously used for immunodetection and immunolocalization in internodal cells (Groliget al., 1988,Eur J Cell Biol47: 22–31). Immunoblotting with J14 detected a 110kDa polypeptide only in those protein fractions that had revealed ATP‐sensitive binding of F‐actin. The putative myosin bound with mediocre affinity to immobilized calmodulin and free Ca2+‐concentration made no difference to this binding affinity. In contrast to the putative myosin, the second, less abundant protein revealed ATP‐insensitive and end‐wise binding to the microfilament and was not recogn

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0043

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractGelatinase B has been thought to be a key enzyme for degradation of extracellular matrix in tumour invasion and metastasis. In this study, we examined the effect of acidic culture medium (pH5.9) on the expression of gelatinase B mRNA in mouse metastatic melanoma cell line (B16‐F10). Using reverse transcription‐polymerase chain reaction (RT‐PCR) analysis, we found that gelatinase B was induced by the acidic culture medium at 24h, and then gradually diminished to 72h. By gelatin zymographic analysis, gelatinase B was first detected at 24h, continued to increase and then reached a plateau at around 48h. These results suggest that the induction of gelatinase B secretion by acidic culture medium occurs as a result of the gene expre

ISSN:1065-6995    

DOI:10.1006/cbir.1996.0044

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY