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1.
Rev Sci Instrum ; 89(12): 125115, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30599562

RESUMO

In this paper, we report the development of a novel technique in which the magnetoresistance of nanostructures is perturbatively measured by transversally modulating the DC magnetic field. It measures the electrical transport counterpart of the transverse magnetic AC-susceptibility. The technique was developed in a conventional four-probe configuration in which a small DC current flows through the sample and a small transverse AC-field perturbates the equilibrium position of the sample magnetization. Lock-in detection, in-phase with the AC-perturbation, is used to measure the voltage signal between the two inner electrodes of the four-probe station. We successfully demonstrated that this signal is proportional to the product of the first derivative of sample resistance with respect to the equilibrium position of the magnetization times the second derivative of the energy with respect to the equilibrium position of the magnetization. These dependences add new features to the technique investigated here that were not captured by the investigations previously reported on the same subject. To show the effective use of the technique, we discuss its application in measuring magnetic properties of thin magnetic films in the non-saturated regime.

2.
Braz. j. med. biol. res ; 51(1): e6822, 2018. tab, graf
Artigo em Inglês | LILACS | ID: biblio-889012

RESUMO

Cervical cancer is a public health problem and the molecular mechanisms underlying radioresistance are still poorly understood. Here, we evaluated the modulation of key molecules involved in cell proliferation, cell cycle and DNA repair in cervical cancer cell lines (CASKI and C33A) and in malignant tissues biopsied from 10 patients before and after radiotherapy. The expression patterns of epidermal growth factor receptor (EGFR), excision repair cross-complementation group 1 (ERCC1) and p53 were evaluated in cancer cell lines by quantitative PCR and western blotting, and in human malignant tissues by immunohistochemistry. The mutation status of TP53 gene was evaluated by direct sequencing. Among cell lines, absent or weak modulations of EGFR, ERCC1 and p53 were observed after exposure to 1.8 Gy. Conversely, increased expressions of p53 (5/10 patients; P=0.0239), ERCC1 (5/10 patients; P=0.0294) and EGFR (4/10 patients; P=0.1773) were observed in malignant tissues after radiotherapy with the same radiation dose. TP53 mutations were found only in one patient. Here we show that a single dose of radiotherapy induced EGFR, ERCC1 and p53 expression in malignant tissues from cervical cancer patients but not in cancer cell lines, highlighting the gap between in vitro and in vivo experimental models. Studies on larger patient cohorts are needed to allow an interpretation that an upregulation of p53, EGFR and ERCC1 may be part of a radioresistance mechanism.


Assuntos
Humanos , Feminino , Adulto , Pessoa de Meia-Idade , Idoso , Carcinoma de Células Escamosas/radioterapia , Neoplasias do Colo do Útero/radioterapia , Genes p53/efeitos da radiação , Genes erbB-1/efeitos da radiação , Proteínas de Ligação a DNA/efeitos da radiação , Endonucleases/efeitos da radiação , Imuno-Histoquímica , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Ensaio Tumoral de Célula-Tronco , Western Blotting , Estudos Prospectivos , Linhagem Celular Tumoral , Mutação
3.
Braz J Med Biol Res ; 51(1): e6822, 2017 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-29160417

RESUMO

Cervical cancer is a public health problem and the molecular mechanisms underlying radioresistance are still poorly understood. Here, we evaluated the modulation of key molecules involved in cell proliferation, cell cycle and DNA repair in cervical cancer cell lines (CASKI and C33A) and in malignant tissues biopsied from 10 patients before and after radiotherapy. The expression patterns of epidermal growth factor receptor (EGFR), excision repair cross-complementation group 1 (ERCC1) and p53 were evaluated in cancer cell lines by quantitative PCR and western blotting, and in human malignant tissues by immunohistochemistry. The mutation status of TP53 gene was evaluated by direct sequencing. Among cell lines, absent or weak modulations of EGFR, ERCC1 and p53 were observed after exposure to 1.8 Gy. Conversely, increased expressions of p53 (5/10 patients; P=0.0239), ERCC1 (5/10 patients; P=0.0294) and EGFR (4/10 patients; P=0.1773) were observed in malignant tissues after radiotherapy with the same radiation dose. TP53 mutations were found only in one patient. Here we show that a single dose of radiotherapy induced EGFR, ERCC1 and p53 expression in malignant tissues from cervical cancer patients but not in cancer cell lines, highlighting the gap between in vitro and in vivo experimental models. Studies on larger patient cohorts are needed to allow an interpretation that an upregulation of p53, EGFR and ERCC1 may be part of a radioresistance mechanism.


Assuntos
Carcinoma de Células Escamosas/radioterapia , Proteínas de Ligação a DNA/efeitos da radiação , Endonucleases/efeitos da radiação , Genes erbB-1/efeitos da radiação , Genes p53/efeitos da radiação , Neoplasias do Colo do Útero/radioterapia , Adulto , Idoso , Western Blotting , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos da radiação , Reparo do DNA/efeitos da radiação , Proteínas de Ligação a DNA/metabolismo , Relação Dose-Resposta à Radiação , Endonucleases/metabolismo , Receptores ErbB/metabolismo , Feminino , Expressão Gênica , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade , Mutação , Estudos Prospectivos , Reação em Cadeia da Polimerase em Tempo Real , Reprodutibilidade dos Testes , Resultado do Tratamento , Ensaio Tumoral de Célula-Tronco , Proteína Supressora de Tumor p53/metabolismo , Neoplasias do Colo do Útero/genética , Neoplasias do Colo do Útero/patologia
4.
Mutat Res ; 490(2): 141-58, 2001 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-11342240

RESUMO

The genotoxicity of river water and sediment including interstitial water was evaluated by microscreen phage-induction and Salmonella/microsome assays. Different processes used to fractionate the sediment sample were compared using solvents with different polarities. The results obtained for mutagenic activity using the Salmonella/microsome test were negative in the water and interstitial water samples analysed using the direct concentration method. The responses in the microscreen phage-induction assay showed the presence of genotoxic or indicative genotoxic activity for at least one water sample of each site analysed using the same concentration method. Similar results were obtained for interstitial water samples, i.e. absence of mutagenic activity in the Salmonella/microsome test and presence of genotoxic activity in the microscreen phage-induction assay. Metal contamination, as evidenced by the concentrations in stream sediments, may also help explain some of these genotoxic results. Stream sediment organic extracts showed frameshift mutagenic activity in the ether extract detected by Salmonella/microsome assay. The concentrates evaluated by microscreen phage-induction assay identified the action of organic compounds in the non-polar, medium polar and polar fractions. Thus, the microscreen phage-induction assay has proven to be a more appropriate methodology than the Salmonella/microsome test to analyse multiple pollutants in this ecosystem where both organic compounds and heavy metals are present.


Assuntos
Bacteriófago lambda/fisiologia , DNA Bacteriano/efeitos dos fármacos , Metais Pesados/toxicidade , Salmonella typhimurium/efeitos dos fármacos , Ativação Viral/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Poluição Química da Água/análise , Animais , Bacteriófago lambda/genética , Biotransformação , Brasil , DNA Bacteriano/genética , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/virologia , Água Doce , Genes Bacterianos/efeitos dos fármacos , Sedimentos Geológicos/química , Resíduos Industriais/análise , Lisogenia , Masculino , Metais Pesados/análise , Metais Pesados/isolamento & purificação , Microssomos Hepáticos/metabolismo , Testes de Mutagenicidade , Ratos , Ratos Sprague-Dawley , Resposta SOS em Genética , Salmonella typhimurium/genética , Solventes , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
5.
Exp Parasitol ; 97(1): 1-8, 2001 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11207108

RESUMO

An extracellular metalloproteinase from Crithidia guilhermei, a monoxenic trypanosomatid of insects, was purified 11-fold by ammonium sulfate precipitation, gel filtration on a Shinpack Diol-150 column, and anion-exchange chromatography in a MONO Q column, both using the HPLC system. The proteinase appeared as a single band with an apparent molecular mass of 62 kDa in SDS-PAGE, under reducing conditions, and was optimally active at 37 degrees C and pH 6.0. The enzyme showed 62% residual activity at 50 degrees C for 30 min. The proteinase was completely inhibited by 1, 10-phenanthroline, indicating that the enzyme belongs to the metalloproteinase class. This is the first report of the purification of an extracellular metalloproteinase from the Crithidia species. The possible role of this enzyme in the digestive tract of the insect host is discussed.


Assuntos
Crithidia/enzimologia , Metaloendopeptidases/química , Metaloendopeptidases/isolamento & purificação , Animais , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão , Cromatografia por Troca Iônica , Eletroforese em Gel de Poliacrilamida , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Insetos , Metaloendopeptidases/antagonistas & inibidores , Peso Molecular , Fenantrolinas/farmacologia , Inibidores de Proteases/farmacologia , Temperatura , Zinco/farmacologia
6.
Fitoterapia ; 72(1): 40-5, 2001 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11163939

RESUMO

Xylopia frutescens is a tree native to the Brazilian Amazon whose seeds are rich in kaurenoic acid, a diterpene that showed in vitro activity against Trypanosoma cruzi. Aiming to find out alternative sources for kaurenoic acid, the content of some kaurane diterpenes was evaluated in X. aromatica and X. brasiliensis, species occurring in the Cerrado area of Minas Gerais, and also in X. frutescens. A reversed phase HPLC isocratic method was developed and validated to perform the assays. Kaurenoic acid was found to be the most abundant diterpene within the analyzed species, with a 3.16+/-0.97% content in the seeds of X. frutescens, which also presented the highest amount of xylopic acid (1.09+/-0.33%). The highest concentration of 16-alpha-hydroxykauranoic acid (1.96+/-1.58%) was found in the stems of X. aromatica.


Assuntos
Diterpenos/análise , Extratos Vegetais/química , Plantas Medicinais/química , Cromatografia Líquida de Alta Pressão , Diterpenos/química , Humanos
8.
Acta Physiol Lat Am ; 28(4-5): 19-26, 1978.
Artigo em Inglês | MEDLINE | ID: mdl-122174

RESUMO

The presence of acetylcholine in aqueous extracts of the fruit of Solanum nigrum Linn. (black nightshade) has been established based upon the following pharmacological tests: a) isotonic contraction of the isolated toad rectus abdominis; b) negative chronotropic and inotropic action on the isolated toad heart; c) isotonic contraction of the isolated guinea pig's ileum; d) isotonic contraction of the rat's isolated jejunum; 3) decrease on the cat's arterial blood pressure; f) secretory effects on the rat's submaxillary gland. These actions were selectively blocked by curate or atropine and disappeared after incubation of the extract at 37 C with plasma. Further evidence showing that the fruit of the black nightshade contains acetylcholine was obtained by chromatographic separation of the aqueous extract. The average content of acetylcholine was found to be 250 micrograms/g of fruit.


Assuntos
Acetilcolina/análise , Extratos Vegetais/análise , Alcaloides de Solanáceas/análise , Animais , Pressão Sanguínea/efeitos dos fármacos , Bufo marinus , Gatos , Cromatografia em Camada Fina , Cobaias , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Ratos , Glândula Submandibular/efeitos dos fármacos , Glândula Submandibular/metabolismo
9.
Acta Physiol Lat Am ; 28(4-5): 19-26, 1978.
Artigo em Inglês | BINACIS | ID: bin-47363

RESUMO

The presence of acetylcholine in aqueous extracts of the fruit of Solanum nigrum Linn. (black nightshade) has been established based upon the following pharmacological tests: a) isotonic contraction of the isolated toad rectus abdominis; b) negative chronotropic and inotropic action on the isolated toad heart; c) isotonic contraction of the isolated guinea pigs ileum; d) isotonic contraction of the rats isolated jejunum; 3) decrease on the cats arterial blood pressure; f) secretory effects on the rats submaxillary gland. These actions were selectively blocked by curate or atropine and disappeared after incubation of the extract at 37 C with plasma. Further evidence showing that the fruit of the black nightshade contains acetylcholine was obtained by chromatographic separation of the aqueous extract. The average content of acetylcholine was found to be 250 micrograms/g of fruit.

10.
Acta physiol. latinoam ; 28(4-5): 19-26, 1978.
Artigo em Espanhol | LILACS-Express | BINACIS | ID: biblio-1158595

RESUMO

The presence of acetylcholine in aqueous extracts of the fruit of Solanum nigrum Linn. (black nightshade) has been established based upon the following pharmacological tests: a) isotonic contraction of the isolated toad rectus abdominis; b) negative chronotropic and inotropic action on the isolated toad heart; c) isotonic contraction of the isolated guinea pig’s ileum; d) isotonic contraction of the rat’s isolated jejunum; 3) decrease on the cat’s arterial blood pressure; f) secretory effects on the rat’s submaxillary gland. These actions were selectively blocked by curate or atropine and disappeared after incubation of the extract at 37 C with plasma. Further evidence showing that the fruit of the black nightshade contains acetylcholine was obtained by chromatographic separation of the aqueous extract. The average content of acetylcholine was found to be 250 micrograms/g of fruit.

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