Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 9 de 9
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Plant Mol Biol ; 39(1): 75-82, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-10080710

RESUMO

Developmentally regulated GTP-binding proteins (DRGs) from animals and fungi are highly conserved but have no known function. Here we characterize DRGs from pea (PsDRG) and Arabidopsis (AtDRG). Amino acid sequences of AtDRG and PsDRG were 90% identical to each other and about 65% identical to human DRG. Genomic Southern blotting indicated that AtDRG and PsDRG probably are single-copy genes. PsDRG mRNA accumulated preferentially in growing organs (root apices, growing axillary buds and elongating stems) compared with their non-growing counterparts. At DRG mRNA was relatively abundant in Arabidopsis leaves, stems and siliques, less abundant in flowers and flower buds, and barely detectable in roots. Histone mRNAs are known to accumulate predominantly during S phase of the cell cycle and are markers for proliferating cells. The patterns of histone H2A mRNA accumulation in pea and Arabidopsis organs were very similar to those of DRG mRNAs. An antiserum raised against a PsDRG N-terminal fusion protein recognized 43 and 45 kDa proteins. PsDRG proteins were more abundant in growing pea roots and stems than in non-growing organs, but they were equally abundant in growing and dormant axillary buds. After differential centrifugation, PsDRG proteins were found primarily in the microsomal (150,000 x g pellet) and soluble (150,000 x g supernatant) cell fractions.


Assuntos
Arabidopsis/química , Proteínas de Ligação ao GTP/química , Pisum sativum/química , Sequência de Aminoácidos , DNA Complementar/química , DNA de Plantas/química , Eletroforese em Gel de Poliacrilamida , Proteínas de Ligação ao GTP/genética , Humanos , Dados de Sequência Molecular , RNA Mensageiro/análise , Homologia de Sequência de Aminoácidos
2.
Planta ; 205(4): 547-52, 1998 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9684359

RESUMO

Pea (Pisum sativum L. cv. Alaska) axillary buds can be stimulated to cycle between dormant and growing states. Dormant buds synthesize unique proteins and are as metabolically active as growing buds. Two cDNAs, PsDRM1 and PsDRM2, were isolated from a dormant bud library. The deduced amino acid sequence of PsDRM1 (111 residues) is 75% identical to that of an auxin-repressed strawberry clone. PsDRM2 encodes a putative protein containing 129 residues, which includes 11 repeats of the sequence [G]-GGGY[H][N] (the bracketed residues may be absent). PsDRM2 is related to cold- and ABA-stimulated clones from alfalfa. Decapitating the terminal bud rapidly stimulates dormant axillary buds to begin growing. The abundance of PsDRM1 mRNA in axillary buds declines 20-fold within 6 h of decapitation; it quickly reaccumulates when buds become dormant again. The level of PsDRM2 mRNA is about three fold lower in growing buds than in dormant buds. Expression of PsDRM1 is enhanced in other non-growing organs (roots >> root apices; fully-elongated stems > elongating stems), and thus is an excellent "dormancy" marker. In contrast, PsDRM2 expression is not dormancy-associated in other organs.


Assuntos
Regulação da Expressão Gênica de Plantas , Genes de Plantas , Pisum sativum/genética , Proteínas de Plantas/genética , Sequência de Aminoácidos , Dados de Sequência Molecular , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos
3.
Plant Mol Biol ; 29(2): 255-65, 1995 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-7579177

RESUMO

Accumulation patterns of mRNAs corresponding to histones H2A and H4, ribosomal protein genes rpL27 and rpL34, MAP kinase, cdc2 kinase and cyclin B were analyzed during growth-dormancy cycles in pea (Pisum sativum cv. Alaska) axillary buds. The level of each of these mRNAs was low in dormant buds on intact plants, increased when buds were stimulated to grow by decapitating the terminal bud, decreased when buds ceased growing and became dormant, and then increased when buds began to grow again. Flow cytometry was used to determine nuclear DNA content during these developmental transitions. Dormant buds contain G1 and G2 nuclei (about 3:1 ratio), but only low levels of S phase nuclei. It is hypothesized that cells in dormant buds are arrested at three points in the cell cycle, in mid-G1, at the G1/S boundary and near the S/G2 boundary. Based on the accumulation of histone H2A and H4 mRNAs, which are markers for S phase, cells arrested at the G1/S boundary enter S within one hour of decapitation. The presence of a cell population arrested in mid-G1 is indicated by a second peak of histone mRNA accumulation 6 h after the first peak. Based on the accumulation of cyclin B mRNA, a marker for late G2 and mitosis, cells arrested at G1/S begin to divide between 12 and 18 h after decapitation. A small increase in the level of cyclin B mRNA at 6 h after decapitation may represent mitosis of the cells that has been arrested near the S/G2 boundary. Accumulation of MAP kinase, cdc2 kinase, rpL27 and rpL34 mRNAs are correlated with cell proliferation but not with a particular phase of the cell cycle.


Assuntos
Ciclo Celular , Pisum sativum/crescimento & desenvolvimento , Caules de Planta/crescimento & desenvolvimento , Sequência de Aminoácidos , Northern Blotting , Proteína Quinase CDC2/genética , Proteínas Quinases Dependentes de Cálcio-Calmodulina/genética , Separação Celular , Clonagem Molecular , DNA Complementar/genética , DNA de Plantas/análise , Citometria de Fluxo , Histonas/genética , Dados de Sequência Molecular , Pisum sativum/citologia , Pisum sativum/genética , Caules de Planta/citologia , Caules de Planta/genética , RNA Mensageiro/análise , Proteínas Ribossômicas/genética
5.
Cancer Res ; 53(15): 3518-23, 1993 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-8339257

RESUMO

The combination of N-(phosphonacetyl)-L-aspartate, 6-methylmercaptopurine, and 6-aminonicotinamide has been shown to be an effective antineoplastic regimen and also to enhance the effects of other chemotherapeutic agents. The mechanism of action of this combination of drugs is not known definitively, but one possible mechanism is biochemical modulation of energy metabolism and inhibition of production of tumor ATP. Tumor-bearing mice were treated with N-(phosphonacetyl)-L-aspartate, followed 17 h later by 6-methylmercaptopurine and 6-aminonicotinamide. 31P nuclear magnetic resonance spectroscopic studies demonstrated a significant depletion of high energy phosphates at 10 h post-6-methylmercaptopurine and 6-aminonicotinamide. The addition of radiation at this time was shown to induce a significantly longer tumor growth delay and a greater number of regressions (including durable complete regressions) than either chemotherapy or radiation alone. The combination of chemotherapy and radiation was found to be supra-additive compared to the antineoplastic effects of either modality administered separately, without a measurable increase in host toxicity.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Experimentais/terapia , 6-Aminonicotinamida/administração & dosagem , Animais , Ácido Aspártico/administração & dosagem , Ácido Aspártico/análogos & derivados , Terapia Combinada , Feminino , Mercaptopurina/administração & dosagem , Mercaptopurina/análogos & derivados , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos DBA , Transplante de Neoplasias , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/radioterapia , Ácido Fosfonoacéticos/administração & dosagem , Ácido Fosfonoacéticos/análogos & derivados
6.
Cancer Res ; 52(17): 4620-7, 1992 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-1511430

RESUMO

Hypoxia is considered to be a major cause of tumor radioresistance. Reoxygenation of previously hypoxic areas after a priming dose of radiation is associated with an increase in tumor radiosensitivity. In a study of a hypoxic mammary carcinoma, 31P nuclear magnetic resonance spectra showed statistically significant increases in metabolite ratios (phosphocreatine/Pi and nucleotide triphosphate/Pi) after 65 and 32 Gy. The maximum changes in metabolite ratios after 32 Gy occurred at 48 h, although significant changes were detected at 24 h. A corresponding increase in the mean tumor pO2 (polarographic microelectrode measurements) and a decrease in hypoxic cell fraction [changes in paired (clamped versus unclamped) tumor control dose for 50% of tumors] were also shown to occur 48 h after a priming dose of 32 Gy. A significant increase in the mean tumor pO2, phosphocreatine/Pi, and nucleotide triphosphate/Pi, compared to initial values, was noted at 24, 48, and 96 h post 65-Gy radiation. An increase in the downfield component of the phosphomonoester peak relative to the upfield component (phosphoethanolamine), is also noted after doses of 65 and 32 Gy. These are likely to be due to cell kill and/or decreased cell proliferation. In this tumor model, 31P nuclear magnetic resonance spectroscopic changes postradiation are temporally coincident with and may be indicative of tumor reoxygenation as measured by the tumor control dose for 50% of tumors and oxygen-sensitive microelectrodes.


Assuntos
Metabolismo Energético/efeitos da radiação , Neoplasias Mamárias Experimentais/radioterapia , Oxigênio/metabolismo , Animais , Relação Dose-Resposta à Radiação , Hipóxia/metabolismo , Espectroscopia de Ressonância Magnética , Fosfocreatina/metabolismo , Fosforilcolina/metabolismo , Ratos , Fatores de Tempo
7.
J Magn Reson Imaging ; 2(3): 335-40, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1627869

RESUMO

Assessing tumor response to chemotherapy in the liver has always been difficult. Most investigators estimate tumor volume as either a product of the two perpendicular diameters of a tumor nodule, or, in animal studies, simply count surface tumor nodules. The authors evaluated magnetic resonance (MR) imaging as a technique for determining absolute tumor volume in the liver in an animal model. Specifically, histologic volumetric and MR imaging measurements of tumor and liver volumes were quantitatively compared over a wide range of tumor burdens in a rat model of hepatic metastasis of a colorectal carcinoma. Twenty-three rats were imaged, with two different section thicknesses used in each animal. Both section thicknesses showed highly significant correlations between MR and histologic measurements for both tumor and liver volumes (P less than .001). MR imaging may be useful for noninvasively quantifying tumor burden and temporal response of metastatic disease in the liver to novel antineoplastic regimens.


Assuntos
Adenocarcinoma/secundário , Neoplasias Hepáticas/secundário , Imageamento por Ressonância Magnética , Adenocarcinoma/diagnóstico , Adenocarcinoma/patologia , Animais , Neoplasias Hepáticas/diagnóstico , Neoplasias Hepáticas/patologia , Transplante de Neoplasias , Ratos
8.
Magn Reson Med ; 19(1): 113-23, 1991 May.
Artigo em Inglês | MEDLINE | ID: mdl-2046526

RESUMO

We have used in vivo 19F NMR spectroscopy to study the metabolism of 5-fluorouracil (FUra) in tumors with and without pretreatment with methotrexate (MTX). Using the CD8F1 murine mammary tumor as an in vivo model, we observed signals from FUra, alpha-fluoro-beta-alanine (F beta ALA), alpha-fluoro-beta-ureidopropionic acid (FUPA), and 5-fluorouracil-nucleotides (FUN) after intravenous or intraperitoneal injection of 150 mg/kg FUra. Formation of FUN was increased about 1.7-fold in CD8F1 tumor with methotrexate pretreatment as determined by acid extraction and HPLC analysis. A comparison of in vivo NMR spectra from FUra and sequential MTX + FUra-treated tumors showed a significantly higher ratio of the FUN signal to the initial total 19F signal in the MTX + FUra-treated tumors (p less than 0.001) for animals receiving FUra either intravenously or intraperitoneally. In addition, tumors treated with MTX + FUra had significantly longer time durations during which FUN was detected, independent of the mode of administration. These experiments indicate that in vivo 19F NMR spectroscopy can be used to noninvasively monitor alterations of 5-fluorouracil metabolism that occur with administration of modulating agents such as methotrexate. Further studies, in both murine tumor models and patients, are indicated to determine if these results can be correlated with tumor response.


Assuntos
Fluoruracila/metabolismo , Espectroscopia de Ressonância Magnética , Neoplasias Mamárias Experimentais/tratamento farmacológico , Metotrexato/uso terapêutico , Animais , Feminino , Fluoruracila/uso terapêutico , Masculino , Camundongos , Pré-Medicação
9.
Cancer Res ; 50(22): 7252-6, 1990 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-2121332

RESUMO

Numerous agents have been studied in attempts to sensitize radioresistant hypoxic tumor cells. We have investigated the effect of Fluosol-DA plus carbogen (95% oxygen and 5% CO2) on the sensitivity of a radioresistant mammary carcinoma in C3H/He mice and also on tumor metabolism by 31P nuclear magnetic resonance spectroscopy. Statistically significant increases in phosphocreatine/Pi were noted for small- (150-350 mm3) and medium- (351-650 mm3) sized tumors treated with Fluosol-DA plus carbogen. Small tumors were shown to undergo significant radiosensitization in the presence of Fluosol-DA plus carbogen and medium-sized tumors showed a lesser degree of radiosensitization. Large tumors (greater than 900 mm3) showed no effect. Fluosol-DA or carbogen alone had no effects on animals with any tumor volume, as monitored by significant changes in radiosensitivity or nuclear magnetic resonance parameters. An approximately linear relationship was found between the decrease in the values for radiation dose which yields 50% tumor control and the increase in phosphocreatine/Pi, with a correlation of r = -0.93. 31P nuclear magnetic resonance spectroscopy may be useful for monitoring changes in radiosensitivity induced by agents which alter tumor oxygenation and subsequent metabolic status.


Assuntos
Fluorocarbonos/farmacologia , Radiossensibilizantes/farmacologia , Animais , Dióxido de Carbono/farmacologia , Relação Dose-Resposta à Radiação , Combinação de Medicamentos , Concentração de Íons de Hidrogênio , Derivados de Hidroxietil Amido , Espectroscopia de Ressonância Magnética , Masculino , Camundongos , Camundongos Endogâmicos C3H , Nucleotídeos/metabolismo , Oxigênio/farmacologia , Fosfocreatina/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...