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1.
J Chem Phys ; 156(24): 244116, 2022 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-35778104

RESUMO

A method to calculate the autoionization width from a discretized pseudo-spectrum is proposed. This method relies on an analytic continuation of Green's function within the Fano-Feshbach formalism. The pseudo-spectrum is obtained at the multireference configuration interaction level in a square-integrable basis set, commonly found in quantum chemistry software. Few states around the desired resonance are needed to perform the analytic continuation. This method was applied to atomic (He and Ne) and molecular (HF and benzene) systems, and the results for the autoionization width show good agreement with the available theoretical and experimental values.

2.
J Chem Phys ; 155(19): 194110, 2021 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-34800958

RESUMO

A method for calculating the generalized oscillator strengths (GOSs) and differential cross section (DCS) with vibration and rotation resolution is presented. The importance of accounting for the rotational contribution is to be emphasized since it has not previously been considered in GOS calculations. Although largely neglected due to its small effect on various properties, the rotational resolution proved to be fundamental in the study of certain phenomena, such as the interference between rotational states in a molecule. As the general goal of this work is to obtain theoretical values comparable to high resolution experiments, special care was taken on the calculation of the electronic part of the scattering amplitude, particularly in what concerns the choice of the atomic basis set. Accordingly, even-tempered basis sets have proved to lead to good results. The helium atom was taken as a model system for this aspect of the problem. Then, GOS and DCS, for explicit vibrational and rotational transitions, were calculated for hydrogen and nitrogen molecules. For higher accuracy, a non-Franck-Condon approach was used to obtain transitions involving vibrational states. The resultant values have shown good agreement with the available experimental data.

3.
J Chem Phys ; 150(17): 174116, 2019 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-31067880

RESUMO

Transition energies and generalized oscillator strengths (GOSs) for transitions up to 6.3 eV of carbon disulfide were calculated at the multireference configuration interaction level. It is shown that the consideration of the vibronic coupling mechanism is essential to establish not only a quantitative but also a qualitative profile of the GOS, as a function of the momentum transferred, for the dipole forbidden transitions (Σg+1→1Σu - and Σg+1→1Δu). For the dipole allowed Σg +→Σu + transition, the calculated GOS is in good agreement with the available experimental data.

4.
J Phys Chem A ; 122(51): 9755-9760, 2018 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-30520626

RESUMO

The photofragmentation dynamics of 1,1,1,2-tetrafluoroethane (R134a) with photon energies from 12 eV up to 320 eV, surrounding the C 1s edge is discussed. The ionic moieties were measured in coincidence with the ejected electrons (PEPICO mode), and detected as a function of the photon energy. Around the C K core edge, the fragmentation profiles are examined regarding the site specific excitation of the CH2FCF3 molecule. In the present case, site-selectivity is favored by the distinct chemical environments surrounding both C atoms. NEXAFS spectrum at the C 1s edge simulation has been obtained at the TDDFT level and excited state geometry optimization calculations have been performed at the inner-shell multiconfigurational self-consistent field level. Our observations indicate that the C(H2F) 1s excitation to a highly repulsive potential expels a fluorine atom leaving the heavier radical fragment C2F3H2* which relaxes to the fundamental state of the ion C2F3H2+. On the other hand, the excitation from the C(F3) 1s carbon to a repulsive state in the C-C bond, leads to a C-C bond cleavage, explaining the observed site specific fragmentation.

5.
J Chem Phys ; 149(5): 054303, 2018 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-30089389

RESUMO

Autoionization spectra of CH2Cl2 and CD2Cl2 molecules after Cl 2p excitation are studied. The two molecular and atomic Auger transitions are examined and assigned. The contribution of atomic Auger transitions is lower in the deuterated molecule. In addition, to support the presence of the ultrafast dissociation mechanism in the dichloromethane molecule, a series of high-level ab initio quantum mechanical calculations were performed at multiconfigurational self-consistent field (MCSCF) and multireference configuration interaction (MRCI) levels of theory. Minimum energy pathways for the dissociation of the dichloromethane molecule have been calculated by taking into account the spin-orbit splitting between the singlet and triplet transitions in the Cl 2p edge.

6.
J Phys Chem A ; 121(22): 4233-4241, 2017 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-28514147

RESUMO

The dynamics of the photofragmentation pathways of tetrachloroethylene with photon energies from 15 up to 250 eV encompassing the Cl 2p edge is presented. In order to distinguish the fragmentation channels, the ionic fragments were separated according to their mass-to-charge ratio, measured in coincidence with the photoelectrons, and collected as a function of the incident photon energy. Distinct minima or maxima are found in the partial ion yield in the region between 40 and 50 eV. These features are believed to be associated with the Cooper minimum which results from a molecular orbital with a strong atomic 3p subshell character. In the shallow core region, some fragmentation patterns are considered in terms of fast fragmentation of the C2Cl4 molecule, despite the heavy mass of its fragments. In the present case, the fast fragmentation is favored by the very strong antibonding character of the LUMO, understandable in the frame of the core equivalent model for halogen-containing molecules. In addition, ab initio calculations were performed to obtain states at the Cl 2p edge. Singlet and triplet states at the Cl 2p edge of the C2Cl4 molecule, corresponding to the Cl(2p → 9b1u*) and Cl(2p → 8b2u*) transitions, were calculated in order to form a basis set of molecular states from which the spin-orbit splitting can be inferred. Multiconfigurational self-consistent field (MCSCF) calculation followed by multireference configuration interaction (MRCI) was the method chosen to establish a set of singlet and triplet states at the 2p excitation edge in addition to the ground state.

7.
J Phys Chem A ; 120(34): 6728-37, 2016 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-27523328

RESUMO

The center of mass kinetic energy release distribution (KERD) spectra of selected ionic fragments, formed through dissociative single and double photoionization of CH2Cl2 at photon energies around the Cl 2p edge, were extracted from the shape and width of the experimentally obtained time-of-flight (TOF) distributions. The KERD spectra exhibit either smooth profiles or structures, depending on the moiety and photon energy. In general, the heavier the ionic fragments, the lower their average KERDs are. In contrast, the light H(+) fragments are observed with kinetic energies centered around 4.5-5.5 eV, depending on the photon energy. It was observed that the change in the photon energy involves a change in the KERDs, indicating different processes or transitions taking place in the breakup process. In the particular case of double ionization with the ejection of two charged fragments, the KERDs present have characteristics compatible with the Coulombic fragmentation model. Intending to interpret the experimental data, singlet and triplet states at Cl 2p edge of the CH2Cl2 molecule, corresponding to the Cl (2p → 10a1*) and Cl (2p → 4b1*) transitions, were calculated at multiconfigurational self-consistent field (MCSCF) level and multireference configuration interaction (MRCI). These states were selected to form the spin-orbit coupling matrix elements, which after diagonalization result in a spin-orbit manifold. Minimum energy pathways for dissociation of the molecule were additionally calculated aiming to give support to the presence of the ultrafast dissociation mechanism in the molecular breakup.

8.
J Chem Phys ; 144(11): 114305, 2016 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-27004874

RESUMO

Plant volatiles are emitted by plants in response to several forms of stress, including interaction with energetic photons. In the present work, we discuss the interaction of extreme UV and soft X-ray photons with a plant volatile, vanillin. The single and double (multiple) ionization of the vanillin molecule have been studied for the first time using time-of-flight mass spectrometry and VUV and soft X-ray photons (synchrotron radiation, at 12.0 eV, 21.2 eV, 130 eV, 310 eV, 531 eV, and 550 eV). At 12.0 and 21.2 eV, only singly charged species are observed and the parent ion, C8H8O3 (+), is the dominant species. Energy differences for some selected fragments were calculated theoretically in this energy region. At 130 eV, direct double and triple ionization of the valence electrons may occur. The fragmentation increases and CHO(+) becomes one of the main cations in the mass spectrum. The molecular ion is still the dominant species, but other fragments, such as C6H5O(+), begin to present similar intensities. At 310 eV, C 1s electrons may be ionized and Auger processes give rise to dissociative doubly ionized cations. Ionization around the O 1s edge has been studied both at the 531 eV resonance and above the ionization edge. Resonant and normal Auger processes play a significant role in each case and a large fragmentation of the molecule is observed at both photon energies, with intense fragments such as CHO(+) and CH3 (+) being clearly observed. A near edge X-ray absorption fine structure spectrum of the vanillin molecule was obtained around the O 1s ionization threshold. In addition, the fragmentation of vanillin has also been studied using a fast beam of electrons (800 eV), for the sake of comparison.


Assuntos
Benzaldeídos/efeitos da radiação , Compostos Orgânicos Voláteis/efeitos da radiação , Benzaldeídos/química , Espectrometria de Massas , Modelos Químicos , Fótons , Espectrofotometria , Raios Ultravioleta , Compostos Orgânicos Voláteis/química , Raios X
9.
J Chem Phys ; 136(14): 144307, 2012 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-22502518

RESUMO

Electronic excitation and ionic dissociation of dimethylsulfide (DMS) and dimethyldisulfide (DMDS) have been studied around the S 2p edge using synchrotron radiation and time-of-flight mass spectrometry techniques. Mass spectra were obtained for both molecules, below, on and above the well defined resonances observed in the S 2p photoabsorption spectrum and centered at approximately 166 eV photon energy. Ab initio IS-CASSCF calculations were performed for a better understanding of the photoabsorption spectra. Similar calculations were also performed for the H(2)S molecule, in order to establish a bench mark. For both molecules, a higher fragmentation degree is observed with increasing photon energy. In the DMDS case, selective fragmentation was observed in the formation of the [CH(n)S](+) ions at the first S 2p resonance (corresponding to excitation to a σ*SS state) and in the formation of the [S(2)](+) and [S](+) ions at the third S 2p resonance (corresponding to excitation to a σ*CS state). Previously unreported doubly charged ([S](2+), [CH(3)](2+)) are observed for DMS and DMDS.


Assuntos
Dissulfetos/química , Elétrons , Sulfetos/química , Absorção , Espectrometria de Massas , Modelos Moleculares , Conformação Molecular , Teoria Quântica
10.
Plant Dis ; 95(3): 354, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30743527

RESUMO

Yellow stunt, an emerging disease of tobacco (Nicotiana tabacum), has become increasingly prevalent in tobacco-growing regions in southern Brazil. Major symptoms are moderate to severe stunting, yellowing of leaves, severe wilting, darkened roots, necrosis of stem tissue directly above the soil line, and plant death. Phytophthora glovera was first proposed in 1999 as the primary causal agent of yellow stunt (1), but since then, there has been no data or completion of Koch's postulates to support this. Fifty-six isolates of fungi and fungus-like organisms were obtained from stem and root samples of tobacco plants with typical symptoms of yellow stunt in the Brazilian States of Rio Grande do Sul, Santa Catarina, and Paraná during the growing seasons of 2004/05 to 2006/07. They were identified to species level by analysis of the morphological characteristics (2) and sequence of rDNA internal transcribed spacer regions 1 and 2 (ITS1 and ITS2) (3). The isolates were identified as Pythium dissotocum (29), Fusarium oxysporum (10), P. graminicola (5), Rhizoctonia solani (4), F. solani (3), P. ultimum (3), P. deliense (1), and P. inflatum (1). The ITS sequences of the 29 isolates identified as P. dissotocum were identical. The nucleotide sequence of one isolate, LFM27/2005, has been deposited in GenBank (GQ495982). Analysis of ITS sequences alone was not sufficient to differentiate this isolate from other species in the Pythium subclade B2, such as P. coloratum, P. lutarium, P. marinum, or P. diclinum. However, the combination of morphological and cultural characteristics (2) and sequence data support our identification of LFM27/2005 and similar isolates as P. dissotocum. Colonies of LFM27/2005 on cornmeal agar had filamentous sporangia and formed slightly inflated, dendroid structures. Zoospores formed at 5°C. Daily growth rate on potato carrot agar was 13 mm at 25°C. The oogonia (22 µm in diameter) were nonornamented and either intercalary or terminal. Antheridia, commonly 1 to 2 per oogonium, were sessile, born on unbranched stalks, and either monoclinous or diclinous. Aplerotic or nearly plerotic oospores measured 20 µm in diameter with a smooth wall 2.5 µm thick. Pathogenicity tests for each pathogen were performed in a greenhouse at ~24°C in pots filled with pine bark substrate infested with inoculum at the time Burley tobacco plants showed five expanded leaves. Each test consisted of five plants and was repeated three times. Inoculum for one to three isolates representative of each pathogen was prepared by growing 2-month-old cultures at 28°C in the dark for 7 days on potato dextrose agar medium overlaid with three sterile oat kernels. Noninfested oat kernels were used for control plants. Forty days after inoculation, only plants inoculated with isolates of P. dissotocum exhibited all symptoms associated with yellow stunt. P. inflatum and R. solani did not induce yellow stunt symptoms and the others induced only wilting and root rot. P. dissotocum was recovered from an inoculated, symptomatic plant, fulfilling Koch's postulates. Its morphology was identical to isolates obtained from original field samples. The results demonstrate the association of isolates of P. dissotocum with tobacco yellow stunt in Brazil. References: (1) H. D. Shew et al. Phytopathology (Abstr.) 89(suppl):S72, 1999. (2) A. J. van der Plaats-Niterink. Stud. Mycol. 21:1, 1981. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

11.
Phytomedicine ; 15(10): 882-5, 2008 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18304791

RESUMO

The dichloromethane and n-butanol extracts obtained from fresh bulbs of Hippeastrum vittatum (Amaryllidaceae), collected in Southern Brazil, were evaluated for their cytotoxic activity in vitro against five human cell lines (HT29 colon adenocarcinoma, H460 non-small cell lung carcinoma, RXF393 renal cell carcinoma, MCF7 breast cancer, and OVCAR3 epithelial ovarian cancer), using the sulphorhodamine B assay. Both extracts showed potential antiproliferative activity. From CH(2)Cl(2) fraction, three alkaloids were isolated: lycorine, vittatine and montanine. The two last compounds were submitted to the antiproliferative assay and the highest level of cytotoxicity was found for the alkaloid montanine.


Assuntos
Alcaloides/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Liliaceae/química , Extratos Vegetais/farmacologia , Alcaloides/química , Antineoplásicos Fitogênicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Extratos Vegetais/química
12.
J Phys Chem A ; 109(12): 2836-9, 2005 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-16833598

RESUMO

The photodissociation of formic acid at 248 and 193 nm was investigated by classical trajectory and RRKM calculations using an interpolated potential energy surface, iteratively constructed using the B3LYP/aug-cc-pVDZ level of calculation. Several sampling schemes in the ground electronic state were employed to explore the possibility of conformational memory in formic acid. The CO/CO2 branching ratios obtained from trajectories initiated at the cis and at the trans conformers are almost identical to each other and in very good accordance with the RRKM results. In addition, when a specific initial excitation that simulates more rigorously the internal conversion process is used, the calculated branching ratio does not vary with respect to those obtained from cis and trans initializations. This result is at odds with the idea of conformational memory in the ground state proposed recently for the interpretation of the experimental results. It was also found that the calculated CO vibrational distributions after dissociation of the parent molecule at 248 nm are in agreement with the experimental available data.

13.
Oncologist ; 7(1): 17-33, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-11854544

RESUMO

A large body of evidence suggests that the abnormal phenotype of neoplastic astrocytes, including their excessive proliferation rate and high propensity to invade surrounding tissues, results from mutations in critical genes involved in key cellular events. These genetic alterations can affect cell-surface-associated receptors, elements of signaling pathways, or components of the cell cycle clock, conferring a gain or a loss of relevant metabolic functions of the cells. The understanding of such phenomena may allow the development of more efficacious forms of cancer treatment. Examples are therapies specifically directed against overexpressed epidermal growth factor receptor, hyperactive Ras, excessively stimulated Raf-1, overproduced ornithine decarboxylase, or aberrantly activated cyclin-dependent kinases. The applicability of some of these approaches is now being assessed in patients suffering from primary malignant central nervous system tumors that are not amenable to current therapeutic modalities. Another potentially useful therapeutic strategy against such tumors involves the inhibition of hyperactive or overexpressed protein kinase C (PKC). This strategy is justified by the decrease in cell proliferation and invasion following inhibition of the activity of this enzyme observed in preclinical glioma models. Thus, interference with PKC activity may represent a novel form of experimental cancer treatment that may simultaneously restrain the hyperproliferative state and the invasive capacity of high-grade malignant gliomas without inducing the expected toxicity of classical cytotoxic agents. Of note, the experimental use of PKC-inhibiting agents in patients with refractory high-grade malignant gliomas has indeed led to some clinical responses. The present paper reviews the current status of the biochemistry and molecular biology of PKC, as well as the possibilities for developing novel anti-PKC-based therapies for central nervous system malignancies.


Assuntos
Antineoplásicos/uso terapêutico , Inibidores Enzimáticos/uso terapêutico , Glioma/tratamento farmacológico , Proteínas de Neoplasias/antagonistas & inibidores , Proteína Quinase C/antagonistas & inibidores , Esfingosina/análogos & derivados , Adolescente , Adulto , Apoptose/efeitos dos fármacos , Briostatinas , Divisão Celular , Criança , Pré-Escolar , Ativação Enzimática , Humanos , Lactente , Lactonas/uso terapêutico , Macrolídeos , Mutação , Naftalenos/uso terapêutico , Invasividade Neoplásica , Proteínas de Neoplasias/fisiologia , Fenótipo , Proteína Quinase C/fisiologia , Esfingosina/uso terapêutico , Estaurosporina/uso terapêutico
14.
Curr Opin Pharmacol ; 1(4): 364-9, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11710734

RESUMO

Many pharmaceutical agents have been discovered by screening natural products from plants, animals, marine organisms and microorganisms. Vincristine, irinotecan, etoposide and paclitaxel are examples of plant-derived compounds that are being employed in cancer treatment, and dactinomycin, bleomycin and doxorubicin are anticancer agents derived from microbial sources. Citarabine is an example of an anticancer agent originating from a marine source. Other agents originating from marine sources are bryostatin-1, aplidine, dolastatin 10 and ET-743, which have recently entered phase I and II clinical trials.


Assuntos
Antineoplásicos Fitogênicos/uso terapêutico , Antineoplásicos/uso terapêutico , Produtos Biológicos/uso terapêutico , Neoplasias/tratamento farmacológico , Animais , Bactérias/química , Fungos/química , Humanos , Toxinas Marinhas/uso terapêutico
15.
Oncologist ; 5(3): 185-98, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10884497

RESUMO

Throughout medical history, plant products have been shown to be valuable sources of novel anti-cancer drugs. Examples are the VINCA: alkaloids, the taxanes, and the camptothecins, derived from the Madagscan periwinkle plant Catharantus roseus, the Pacific yew Taxus brevifolia, and the Chinese tree Camptotheca acuminata, respectively. For this reason, the South-American Office for Anti-Cancer Drug Development has implemented a large-scale project of acquisition and testing of compounds isolated from South American medicinal plants. The species are selected on the basis of a potentially useful phytochemical composition by consulting ethnopharmacological, chemosystemic, and ecological information. The collected samples are dried and first extracted with an organic solvent, then with distilled water. These crude extracts are evaluated at a concentration of 50 microg/ml for antiproliferative activity against one cell line. Extracts that significantly inhibit the growth of the cells (>/=50%) at relatively low concentrations (

Assuntos
Antineoplásicos Fitogênicos , Etnofarmacologia , Plantas Medicinais , Antineoplásicos Fitogênicos/química , Brasil , Conservação dos Recursos Naturais , Ensaios de Seleção de Medicamentos Antitumorais , Humanos
16.
Braz J Med Biol Res ; 33(3): 287-93, 2000 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10719379

RESUMO

Chromatin proteins play a role in the organization and functions of DNA. Covalent modifications of nuclear proteins modulate their interactions with DNA sequences and are probably one of the multiple factors involved in the process of switch on/off transcriptionally active regions of DNA. Histones and high mobility group proteins (HMG) are subject to many covalent modifications that may modulate their capacity to bind to DNA. We investigated the changes induced in the phosphorylation pattern of cultured Wistar rat Sertoli cell histones and high mobility group protein subfamilies exposed to 7 microM retinol for up to 48 h. In each experiment, 6 h before the end of the retinol treatment each culture flask received 370 KBq/ml [32P]-phosphate. The histone and HMGs were isolated as previously described [Moreira et al. Medical Science Research (1994) 22: 783-784]. The total protein obtained by either method was quantified and electrophoresed as described by Spiker [Analytical Biochemistry (1980) 108: 263-265]. The gels were stained with Coomassie brilliant blue R-250 and the stained bands were cut and dissolved in 0.5 ml 30% H2O2 at 60oC for 12 h. The vials were chilled and 5.0 ml scintillation liquid was added. The radioactivity in each vial was determined with a liquid scintillation counter. Retinol treatment significantly changed the pattern of each subfamily of histone and high mobility group proteins.


Assuntos
Proteínas de Grupo de Alta Mobilidade/metabolismo , Histonas/metabolismo , Células de Sertoli/metabolismo , Vitamina A/farmacologia , Animais , Proteínas de Grupo de Alta Mobilidade/isolamento & purificação , Histonas/isolamento & purificação , Masculino , Fosforilação/efeitos dos fármacos , Ratos , Ratos Wistar
17.
Braz. j. med. biol. res ; 33(3): 287-93, Mar. 2000. tab, graf
Artigo em Inglês | LILACS | ID: lil-255047

RESUMO

Chromatin proteins play a role in the organization and functions of DNA. Covalent modifications of nuclear proteins modulate their interactions with DNA sequences and are probably one of the multiple factors involved in the process of switch on/off transcriptionally active regions of DNA. Histones and high mobility group proteins (HMG) are subject to many covalent modifications that may modulate their capacity to bind to DNA. We investigated the changes induced in the phosphorylation pattern of cultured Wistar rat Sertoli cell histones and high mobility group protein subfamilies exposed to 7 µM retinol for up to 48 h. In each experiment, 6 h before the end of the retinol treatment each culture flask received 370 KBq/ml [32P]-phosphate. The histone and HMGs were isolated as previously described [Moreira et al. Medical Science Research (1994) 22: 783-784]. The total protein obtained by either method was quantified and electrophoresed as described by Spiker [Analytical Biochemistry (1980) 108: 263-265]. The gels were stained with Coomassie brilliant blue R-250 and the stained bands were cut and dissolved in 0.5 ml 30 per cent H2O2 at 60oC for 12 h. The vials were chilled and 5.0 ml scintillation liquid was added. The radioactivity in each vial was determined with a liquid scintillation counter. Retinol treatment significantly changed the pattern of each subfamily of histone and high mobility group proteins.


Assuntos
Animais , Ratos , Proteínas de Grupo de Alta Mobilidade/metabolismo , Histonas/metabolismo , Células de Sertoli/metabolismo , Vitamina A/farmacologia , Proteínas de Grupo de Alta Mobilidade/isolamento & purificação , Histonas/isolamento & purificação , Fosforilação/efeitos dos fármacos , Ratos Wistar
18.
Pathobiology ; 68(3): 113-23, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11174068

RESUMO

We investigated the involvement of protein kinase C (PKC) in the in vitro invasiveness of the A-172, U-87 and U-373 human glioma cell lines, as well as the role of ornithine decarboxylase (ODC) and/or extracellular-signal-regulated kinase (ERK) in the actions of PKC. Thus, cells were treated under serum-free conditions with the PKC activator phorbol 12-myristate 13-acetate (PMA), or with the PKC inhibitors bisindolylmaleimide I (GF 109203X) or calphostin C in the absence or presence of the ODC inhibitor D,L-alpha-difluoromethylornithine (DFMO), and/or the mitogen-activated protein kinase/extracellular-signal-regulated kinase inhibitor 2'-amino-3'-methoxyflavone (PD 098059). Subsequently, cells were assessed for membrane-type 1 matrix metalloproteinase (MT1-MMP) mRNA contents, 72-kD latent, and 59/62-kD activated matrix metalloproteinase 2 (MMP-2) in conditioned media, as well as invasiveness. For these purposes, we used Northern blot analysis, gelatine zymography, and an in vitro filter invasion assay, respectively. Data were related to those found with untreated cells. PKC activity was 2- to 3-fold stimulated by PMA (100 nM for 30 min), and about 2-fold inhibited by calphostin C (40 nM for 2 h) or GF 109203X (5 microM for 20 min). This was accompanied by a similar increase or decrease, respectively, in MT1-MMP mRNA expression, 59/62-kD MMP-2 activity, and in vitro invasion. Inhibition of ODC activity (about 2-fold by 24 h DFMO 5 mM), ERK activation (almost completely by 20 min PD 098059 50 microM), or both these enzymes simultaneously led to a reduction by about half in levels of MT1-MMP mRNA, 59/62-kD MMP-2 activity, and invasion in untreated as well as PMA-stimulated cells. The use of these compounds did not significantly alter the inhibitory effects of GF 109203X or calphostin C. Modulation of PKC and/or ERK activity resulted in corresponding changes in ERK and/or ODC activities, but interference with ODC affected neither ERK nor PKC. Our data suggest a regulatory role for PKC, in co-operation with ERK and ODC, in glioma cell invasion, by modulation of MT1-MMP mRNA expression and MMP-2 activation.


Assuntos
Glioma/enzimologia , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Ornitina Descarboxilase/metabolismo , Proteína Quinase C/metabolismo , Meios de Cultivo Condicionados/metabolismo , Eflornitina/farmacologia , Flavonoides/farmacologia , Humanos , Indóis/farmacologia , Maleimidas/farmacologia , Metaloproteinase 2 da Matriz/genética , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinases da Matriz Associadas à Membrana , Metaloendopeptidases/genética , Metaloendopeptidases/metabolismo , Naftalenos/farmacologia , Invasividade Neoplásica , RNA Mensageiro/metabolismo , Acetato de Tetradecanoilforbol/farmacologia , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/enzimologia
19.
Eur J Cancer ; 35(5): 833-9, 1999 May.
Artigo em Inglês | MEDLINE | ID: mdl-10505046

RESUMO

We investigated the potential mechanisms of tamoxifen cytotoxicity in the U-373, U-138, and U-87 human glioblastoma cell lines, namely interference with protein kinase C (PKC) activity, the oestrogen receptor, and/or the production of transforming growth factor beta 1 (TGF-beta 1). We further examined the effects of tamoxifen on the cytotoxicity exerted by gamma-radiation, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), and etoposide in this cell line panel. Thus, the cells were treated for 4 days with tamoxifen, gamma-radiation, purified recombinant human TGF-beta 1 (rhTGF-beta 1), BCNU, or etoposide, either alone or at certain combinations. Cellular responses were evaluated with the sulphorhodamine B assay, as well as by multiple drug effect analysis, and related to PKC activities in particulate and cellular fractions; cellular oestrogen receptor contents; and the influence of rhTGF-beta 1 on cell growth. Tamoxifen inhibited cell proliferation as well as the phosphorylation capacity of the particulate, but not of the cytosolic fractions dose-dependently, at comparable kinetics, and at IC50 values of approximately 15 microM. At these concentrations, tamoxifen acted synergistically with gamma-radiation (4- to 6-fold) and additively with BCNU (approximately 2-fold), but did not affect etoposide cytotoxicity. The cells were negative to immunostaining for the oestrogen receptor, and rhRGF-beta 1 did not influence their growth up to 100 nm. Our data suggest that tamoxifen can sensitise cultured glioblastoma cells not to etoposide but to gamma-radiation and BCNU, possibly through interference with membrane PKC, supporting its evaluation in experimental protocols for primary malignant gliomas.


Assuntos
Antineoplásicos/uso terapêutico , Carmustina/uso terapêutico , Etoposídeo/uso terapêutico , Raios gama , Glioblastoma/tratamento farmacológico , Proteína Quinase C/antagonistas & inibidores , Tamoxifeno/uso terapêutico , Fator de Crescimento Transformador beta/farmacologia , Divisão Celular , Sinergismo Farmacológico , Humanos , Imuno-Histoquímica , Receptores de Estrogênio/metabolismo , Células Tumorais Cultivadas/efeitos dos fármacos , Células Tumorais Cultivadas/efeitos da radiação
20.
Arch Physiol Biochem ; 105(5): 473-7, 1997 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9439785

RESUMO

Sertoli cell preparations isolated from 15-day-old Wistar rats were cultured on two different substrates, i.e., plastic and a biomatrix isolated from seminiferous tubules of rat testis. Sertoli cells cultured on a biomatrix acquired a phenotype and morphology more characteristic of in vivo differentiated cells. In order to determine the influence of a biomatrix on the response of Sertoli cells to FSH, on the 7th day of culture, untreated cells, or cells pretreated for 12 h with FSH (1 microgram/ml), were incubated with [U-14C] leucine or [2-3H] mannose. Cells cultured on the biomatrix showed higher [U-14C] leucine and [2-3H] mannose incorporation into proteins and glycoproteins. FSH increased these activities in cells cultured on both substrates, although its stimulating effect was higher on cells cultured on the biomatrix. These results demonstrate that the biomatrix increases protein and glycoprotein synthesis and secretion, and also influences the response of Sertoli cells to FSH.


Assuntos
Matriz Extracelular/fisiologia , Hormônio Foliculoestimulante/metabolismo , Células de Sertoli/metabolismo , Animais , Células Cultivadas , Glicoproteínas/biossíntese , Leucina/metabolismo , Masculino , Manose/metabolismo , Plásticos , Biossíntese de Proteínas , Ratos , Ratos Wistar , Túbulos Seminíferos/citologia
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