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1.
Sci Adv ; 5(12): eaay0044, 2019 12.
Article de Anglais | MEDLINE | ID: mdl-31840070

RÉSUMÉ

An immense demand in biomedical imaging is to develop efficient photoluminescent probes with high biocompatibility and quantum yield, as well as multiphoton absorption performance to improve penetration depth and spatial resolution. Here, iron selenide (FeSe) quantum dots (QDs) are reported to meet these criteria. The synthesized QDs exhibit two- and three-photon excitation property at 800- and 1080-nm wavelengths and high quantum yield (ca. 40%), which are suitable for second-window imaging. To verify their biosuitability, poly(ethylene glycol)-conjugated QDs were linked with human epidermal growth factor receptor 2 (HER2) antibodies for in vitro/in vivo two-photon imaging in HER2-overexpressed MCF7 cells and a xenograft breast tumor model in mice. Imaging was successfully carried out at a depth of up to 500 µm from the skin using a nonlinear femtosecond laser at an excitation wavelength of 800 nm. These findings may open up a way to apply biocompatible FeSe QDs to multiphoton cancer imaging.


Sujet(s)
Tumeurs du sein/imagerie diagnostique , Acides carboxyliques/pharmacologie , Fer/pharmacologie , Composés organiques du sélénium/pharmacologie , Récepteur ErbB-2/isolement et purification , Animaux , Tumeurs du sein/anatomopathologie , Acides carboxyliques/composition chimique , Femelle , Colorants fluorescents/composition chimique , Colorants fluorescents/pharmacologie , Hétérogreffes , Humains , Fer/composition chimique , Cellules MCF-7 , Souris , Imagerie moléculaire , Composés organiques du sélénium/composition chimique , Boîtes quantiques/composition chimique , Récepteur ErbB-2/génétique
3.
Biol Signals ; 1(1): 23-33, 1992.
Article de Anglais | MEDLINE | ID: mdl-1307725

RÉSUMÉ

Studies of intracellular signal transduction are facilitated by the use of permeabilized cell systems, which permit the ready manipulation of the cytosol. These model systems have helped to define the roles that small solutes, particularly Ca2+ and nucleotides, play in stimulus-response coupling. In circumstances where the full depletion of intracellular ATP contents is required, some investigators have resorted to prior treatment with metabolic toxins, with the expectation that the role of ATP in signal transduction could then be more unambiguously studied. However, in the work reported here, we found that treatment with 2-deoxyglucose (2-DOG) irreversibly altered the cells: when poisoned human neutrophils were then permeabilized, the cells failed to degranulate well in response to Ca2+, and their sensitivity to Ca2+ could not be recovered by the readdition of ATP. Inhibition of secretion by 2-DOG was most pronounced when low concentrations of Ca2+ were used as the stimulus. Preincubation of the cells with only 1 mM 2-DOG for 10 min at 37 degrees C (prior to washing and permeabilizing the cells) was sufficient for maximal inhibition. Even without preincubation, high concentrations of 2-DOG directly inhibited secretion. The refractory nature of poisoned cells was not restored by the presence of Mg2+ and/or ATP. The protein kinase C agonist phorbol myristate acetate also did not restore sensitivity of secretion to Ca2+. Addition of ATP and/or GTP to the permeabilization medium (to maximize penetration of the nucleotides) failed to restore sensitivity; tracer studies demonstrated that these conditions were adequate for repletion of the nucleotide pool. These data indicate that human neutrophils poisoned with 2-DOG were irreversibly altered, such that restoration of the putative deficiency (ATP) was without effect. Experiments in which such preincubation measures are employed should be viewed with caution.


Sujet(s)
Adénosine triphosphate/métabolisme , Désoxyglucose/pharmacologie , Granulocytes neutrophiles/métabolisme , Adulte , Calcium/métabolisme , Dégranulation cellulaire/effets des médicaments et des substances chimiques , Perméabilité des membranes cellulaires , Électrophysiologie , Humains , Cinétique , Granulocytes neutrophiles/cytologie , Granulocytes neutrophiles/effets des médicaments et des substances chimiques , Transduction du signal
4.
Biochem J ; 279 ( Pt 3): 657-64, 1991 Nov 01.
Article de Anglais | MEDLINE | ID: mdl-1953659

RÉSUMÉ

It is generally believed that G-proteins play stimulatory roles on cell activation. In contrast, we found that guanosine 5'-[gamma-thio]triphosphate (GTP[S]) was a potent inhibitor of Ca(2+)-induced secretion from specific granules (as monitored by vitamin B-12-binding protein). GTP[S] inhibition of specific-granule release occurred in the presence or absence of adenine nucleotides, required Mg2+ (1-3 mM), and was half-maximal at 30 microM-GTP[S]. The dual stimulatory and inhibitory effects of GTP[S] could be readily observed and differentiated when degranulation was monitored over a range of Ca2+ concentrations. Inhibition of specific-granule release by GTP[S] was observed at low Ca2+ concentrations and resulted from shifting the Ca2+ dose-response curves to the right. In contrast, GTP[S] promoted azurophil-granule secretion at relatively high concentrations of Ca2+ and appeared to be due to a general enhancement at all Ca2+ concentrations. A series of hydrolysable and non-hydrolysable nucleotides did not mimic GTP[S] or block its action. Inhibition by GTP[S] occurred in cells which were sensitized with a protein kinase C agonist, suggesting that inhibition of secretion took place distal to this enzyme. However, the inhibitory effects of GTP[S] on specific-granule secretion were reversed by cytochalasin D, which prevents new microfilament formation; this compound also enhanced the stimulation of azurophil-granule release by GTP[S]. We also found that GTP[S] greatly increased the F-actin content of permeabilized neutrophils, whereas Ca2+ (to a lesser extent) decreased F-actin. These data are consistent with the hypothesis that at least two G-proteins are involved in regulating secretion: one which has been previously described as stimulating Ca(2+)-induced secretion (particularly from azurophil granules) and a second, possibly involved in promoting microfilament assembly, which inhibits the discharge of specific granules.


Sujet(s)
Guanosine 5'-O-(3-thiotriphosphate)/pharmacologie , Granulocytes neutrophiles/métabolisme , Actines/composition chimique , Adulte , Calcium/physiologie , Toxine cholérique/pharmacologie , Cytochalasine D/pharmacologie , Granulations cytoplasmiques/effets des médicaments et des substances chimiques , Granulations cytoplasmiques/métabolisme , Stimulation électrique , Protéines G/physiologie , Humains , Magnésium/physiologie , Granulocytes neutrophiles/effets des médicaments et des substances chimiques , 12-Myristate-13-acétate de phorbol/pharmacologie , Facteurs de virulence des Bordetella/pharmacologie
5.
Singapore Med J ; 11(4): 208-9, 1970 Dec.
Article de Anglais | MEDLINE | ID: mdl-5511854
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