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1.
Sci Rep ; 10(1): 20339, 2020 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-33230155

RESUMO

We have derived an expression of the Dzyaloshinskii-Moriya interaction (DMI), where all the three components of the DMI vector can be calculated independently, for a general, non-collinear magnetic configuration. The formalism is implemented in a real space-linear muffin-tin orbital-atomic sphere approximation (RS-LMTO-ASA) method. We have chosen the Cr triangular trimer on Au(111) and Mn triangular trimers on Ag(111) and Au(111) surfaces as numerical examples. The results show that the DMI (module and direction) is drastically different between collinear and non-collinear states. Based on the relation between the spin and charge currents flowing in the system and their coupling to the non-collinear magnetic configuration of the triangular trimer, we demonstrate that the DMI interaction can be significant, even in the absence of spin-orbit coupling. This is shown to emanate from the non-collinear magnetic structure, that can induce significant spin and charge currents even with spin-orbit coupling is ignored.

2.
J Phys Condens Matter ; 26(20): 206003, 2014 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-24786650

RESUMO

The magnetic properties of FexCo1-x nanochains on Pt(1 1 1) were studied using the first-principles real-space linear muffin-tin orbital-atomic sphere approximation (RS-LMTO-ASA) method within the density functional theory. The relative amounts of Fe and Co atoms in a chosen nanochain were varied and several possible arrangements of the atomic species were taken into account. The results of the exchange interaction demonstrates ferromagnetic coupling for the nanowires. Our calculations of Fe and Co average magnetic moments reveal a large enhancement of both spin and orbital moments compared to Fe-Co films deposited on a Pt(1 1 1) surface. The trend for the orbital moments with respect to stoichiometry differs from all previous higher-dimensional Fe-Co alloys on Pt(1 1 1) studies.


Assuntos
Cobalto/química , Compostos de Ferro/química , Campos Magnéticos , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Modelos Químicos , Platina/química , Simulação por Computador , Impedância Elétrica , Imãs , Conformação Molecular , Propriedades de Superfície
3.
Talanta ; 81(1-2): 556-64, 2010 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-20188962

RESUMO

An adsorptive stripping voltammetric protocol coupled with a rotating-disc bismuth film electrode for the determination and speciation of chromium (III) and chromium (VI) in the presence of diethylenetriaminepentaacetic acid (DTPA) is presented. The developed methodology involves a mass-transport controlled preconcentration step, during which a Cr(III)-DTPA complex is adsorbed onto a pre-plated rotating-disc bismuth film electrode held at -0.4V, followed by a reductive square wave stripping scan. At -1.07 V vs. Ag/AgCl, a peak is recorded due to the catalytic reduction of Cr(III)-DTPA to Cr(II)-DTPA. As a result of different chemical behaviours of Cr(III) and Cr(VI) in the presence of DTPA, the corresponding voltammetric signals presented different stabilities in time. A univariate optimization study was performed with several experimental parameters as variables. For Cr(VI) and total chromium, Cr(III)+Cr(VI), an accumulation time of 60s at -0.4V vs. Ag/AgCl resulted in detection limits of 0.336 and 0.414 nM and quantification limits of 1.12 and 1.40 nM, respectively. The relative standard deviation for 10 measurements of 5.0 nM chromate was 2.4%. Interference of other electroactive trace metals and surfactants was considered. A simple speciation scheme was proposed and satisfactorily applied to Cr(III) and Cr(VI) determinations in river water samples.


Assuntos
Bismuto/química , Cromo/análise , Cromo/química , Adsorção , Eletroquímica , Eletrodos , Química Verde , Nitratos/química , Ácido Pentético/química , Rotação , Fatores de Tempo , Água/química
4.
J Oral Pathol Med ; 38(9): 701-7, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19659475

RESUMO

BACKGROUND: Galectin-3 has been implicated in tumor progression of some malignancies as thyroid, prostate, and salivary gland tumors. Recently, it has been suggested that this protein may be an important mediator of the beta-catenin/Wnt pathway. Moreover, nuclear galectin-3 expression has been implicated in cell proliferation, promoting cyclin D1 activation. Thus, the present study aimed to correlate galectin-3 expression with beta-catenin and cyclin D1 expressions in adenoid cystic carcinoma (ACC) and in polymorphous low-grade adenocarcinoma (PLGA). METHODS: Fifteen formalin-fixed paraffin-embedded cases of each tumor were retrieved from the files of the Surgical Oral Pathology Service at the University of São Paulo and the proteins were analyzed by immunohistochemistry. RESULTS: Adenoid cystic carcinoma showed galectin-3 immunostaining mainly in the nuclei, while PLGA revealed a positive mostly cytoplasmic reaction to galectin-3 in the largest part of tumor cells. Both tumors showed intense cytoplasmic/nuclear staining for beta-catenin in majority of cases. Cyclin D1 immunoreactivity was not detected in 14/15 PLGA and showed specific nuclear staining in 10/15 cases of ACC in more than 5% of the neoplastic cells. Cyclin D1 expression was correlated with cytoplasmic and nuclear galectin-3 expression in ACC (P < 0.05). CONCLUSIONS: These results suggest that in ACC galectin-3 may play a role in cellular proliferation through cyclin D1 activation. In addition, nuclear expression of galectin-3 in ACC may be related to a more aggressive behavior of this lesion. Although beta-catenin seems to play a role in carcinogenesis in both lesions, it seems that it does not bind to galectin-3 for cyclin D1 stimulation.


Assuntos
Adenocarcinoma/metabolismo , Carcinoma Adenoide Cístico/metabolismo , Ciclina D1/biossíntese , Galectina 3/biossíntese , Neoplasias das Glândulas Salivares/metabolismo , beta Catenina/biossíntese , Adenocarcinoma/química , Adenocarcinoma/patologia , Carcinoma Adenoide Cístico/química , Membrana Celular/metabolismo , Núcleo Celular/metabolismo , Transformação Celular Neoplásica , Citoplasma/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Imuno-Histoquímica , Estudos Retrospectivos , Neoplasias das Glândulas Salivares/química , Transdução de Sinais , Proteínas Wnt/fisiologia
5.
Talanta ; 72(4): 1392-9, 2007 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-19071774

RESUMO

A bismuth film electrode was tested and proposed as an environmentally friendly sensor for the determination of trace levels of Tl(I) in non-deoxygenated solutions. Determination of thallium was made by anodic stripping voltammetry at a rotating-disc bismuth film electrode plated in situ, using acetate buffer as the supporting electrolyte. The stripping step was carried out by a square wave potential-time excitation signal. A univariate optimisation study was performed with several experimental parameters as variables. Under the selected optimised conditions, a linear calibration plot was obtained in the submicromolar concentration range, allowing the electrochemical determination of thallium in trace amounts; the calculated detection limit was 10.8nM and the relative standard deviation for 15 measurements of 0.1muM Tl(I) was +/-0.2%, for a 120s accumulation time. Interference of other metals on the response of Tl(I) was investigated. Application to real environmental samples was tested. The bismuth film electrode appears to be a promising tool for electroanalytical purposes, ensuring the use of clean methodology.

6.
Anal Chim Acta ; 579(2): 227-34, 2006 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-17723747

RESUMO

Electroanalytical techniques have been used to determine methylmercury at low levels in environmental matrices. The electrochemical behaviour of methylmercury at carbon microelectrodes in a hydrochloric acid medium using cyclic, square wave and fast-scan linear-sweep voltammetric techniques has been investigated. The analytical utility of the methylmercury reoxidation peak has been explored, but the recorded peak currents were found to be poorly reproducible. This is ascribed to two factors: the adsorption of insoluble chloromercury compounds on the electrode surface, which appears to be an important contribution to hinder the voltammetric signal of methylmercury; and the competition between the reoxidation of the methylmercury radical and its dimerization reaction, which limits the reproducibility of the methylmercury peak. These problems were successfully overcome by adopting the appropriate experimental conditions. Fast-scan rates were employed and an efficient electrochemical regeneration procedure of the electrode surface was achieved, under potentiostatic conditions in a mercury-free solution containing potassium thiocyanate--a strong complexing agent. The influence of chloride ion concentration was analysed. Interference by metals, such as lead and cadmium, was considered. Calibration plots were obtained in the micromolar and submicromolar concentration ranges, allowing the electrochemical determination of methylmercury in trace amounts. An estuarine water sample was analysed using the new method with a glassy carbon microelectrode.

7.
Arq. bras. med. vet. zootec ; 55(3): 357-360, jun. 2003. tab
Artigo em Português | LILACS | ID: lil-350617

RESUMO

Determinou-se a composiçäo química do sorgo pela espectroscopia de reflectância no infravermelho próximo (NIRS), comparando-a com os dados obtidos pelas análises convencionais de laboratório. Foram utilizadas 132 amostras de quatro variedades de sorgo: AG212 (porte alto), AG 2002 (porte alto), AG 2005 (duplo propósito) e AG 213 (porte alto). Com o intuito de se obter uma curva ampla, todas as amostras foram agrupadas compondo uma curva denominada sorgo in natura. As variáveis avaliadas foram carboidratos solúveis (CHO sol), fibra detergente neutro (FDN), fibra detergente ácido (FDA), proteína bruta (PB), matéria seca (MS) e digestibilidade in vitro da matéria seca (DIVMS). Utilizou-se o tratamento de absorbância e foram encontrados os seguintes coeficientes de determinaçäo ( por cento): CHO sol = 98,7, FDN = 96,4, FDA = 98,1, PB = 99,5, MS = 95,8 e DIVMS = 93,1. A calibraçäo foi boa (baixo erro de calibraçäo e alto coeficiente de determinaçäo) para o tratamento de absorbância.


Assuntos
Grão Comestível , Espectroscopia de Luz Próxima ao Infravermelho
8.
Arq Bras Cardiol ; 76(6): 483-95, 2001 Jun.
Artigo em Inglês, Português | MEDLINE | ID: mdl-11449294

RESUMO

OBJECTIVE: We conducted a comparative analysis of the in-hospital outcomes of patients who underwent primary percutaneous transluminal angioplasty (PTCA) or stent implantation because of an acute myocardial infarction (AMI) related to an acute vein graft occlusion. METHODS: Since 1991 the Brazilian Society of Hemodynamic and Interventional Cardiology has maintained a large database (CENIC). From these, we selected all consecutive patients, who underwent primary PTCA or stenting in the first 24 hours of AMI, with the target vessel being an occluded vein graft. Immediate results and major coronary events occurring up until hospital discharge were analyzed. RESULTS: During this period, 5,932 patients underwent primary PTCA or stenting; 158 (3%) of the procedures were performed because of an acute vein graft occlusion. Stenting was performed in 74 (47%) patients. Patients treated with stents had a higher success rate and lower mean residual stenosis compared with those who underwent primary balloon PTCA. The incidence of reinfarction and death were similar for stenting and balloon PTCA. CONCLUSION: Primary percutaneous treatment of AMI related to acute vein graft occlusion is still an uncommon practice. Primary stenting improved luminal diameter and offered higher rates of success; however, this strategy did not reduce the in-hospital reinfarction and death rate, compared with that occurring with PTCA treatment.


Assuntos
Angioplastia Coronária com Balão , Oclusão de Enxerto Vascular/terapia , Infarto do Miocárdio/terapia , Veia Safena/transplante , Stents , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/mortalidade , Sistema de Registros , Resultado do Tratamento
9.
Sao Paulo Med J ; 119(1): 4-6, 2001 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-11175617

RESUMO

CONTEXT: Breast cancer is the most important neoplasm in adult women, and its worldwide incidence is growing. The tumoral stroma is very important for modulating the growth and invasion of the tumor itself. The relationship between these two components is not completely understood. Schirrous carcinoma is a variant of ductal invasive carcinoma in which the stroma is very desmoplastic, and the importance of this finding still a motive for debate in the literature. OBJECTIVE: To compare the desmoplastic reactions against biological markers, such as estrogen and progesterone receptors, oncoprotein c-erbB-2 and oncoprotein p53, with the objective of studying the relationship between the tumoral stroma and epithelial cancer cells. TYPE OF STUDY: Retrospective study. SETTING: Cancer Hospital A C Camargo and Faculty of Medicine of Ribeirão Preto, University of São Paulo, São Paulo, Brazil. SAMPLE: 107 adult women operated because of ductal invasive carcinoma. The cases were separated into 4 groups according to the desmoplastic reaction - less than 15 per cent, between 15-50 per cent, 51-85 per cent, and more than 85 per cent fibrosis. The grade of fibrosis was determined by picrus-sirius staining and quantified by using a microscope with a stereo-imaging grid. Immunohistochemical methods were used to determine the expression of the hormonal receptors and c-erbB-2/p53 oncoprotein. MAIN MEASUREMENTS: Extent of desmoplastic reaction versus expression of estrogen and progesterone receptors, oncoprotein c-erbB-2, and oncoprotein p53. RESULTS: The results showed that schirrous carcinoma expresses oncoprotein p53 more frequently than other carcinomas with less extensive desmoplastic reaction. There were no differences between the grade of fibrosis and the other biological markers. CONCLUSION: The intense stromal reaction in invasive ductal carcinoma may modulate the expression of p53. Further investigations should be made with the aim of understanding how this expression determines the proliferative activity in schirrous carcinoma, and whether this overexpression is secondary to mutation of the p53 gene or due to modulation of other molecules of the stroma.


Assuntos
Neoplasias da Mama/metabolismo , Carcinoma Ductal de Mama/metabolismo , Receptor ErbB-2/metabolismo , Receptores de Esteroides/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Adulto , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/genética , Carcinoma Ductal de Mama/genética , Feminino , Humanos , Mutação , Receptor ErbB-2/genética , Receptores de Estrogênio/genética , Receptores de Estrogênio/metabolismo , Receptores de Progesterona/genética , Receptores de Progesterona/metabolismo , Receptores de Esteroides/genética , Estudos Retrospectivos , Proteína Supressora de Tumor p53/genética
11.
Nephrol Dial Transplant ; 13(3): 570-2, 1998 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-9550629

RESUMO

We observed six cases of patients in a dialysis programme who were apparently intoxicated by ingestion of star fruit. After ingestion of 2-3 fruits or 150-200 ml of the fruit juice, the six patients, who had previously been stable in a regular dialysis programme, developed a variety of symptoms ranging from insomnia and hiccups to agitation, mental confusion and (in one case) death. In preliminary investigations to characterize the hypothetical neurotoxin in the fruit, an extract, when injected intraperitoneally or intracerebroventricularly in rats, provoked persistent convulsions of the tonic-clonic type. It appears that star fruit (Averrhoa carambola) contains an excitatory neurotoxin. Patients with renal failure on conservative or dialysis treatment should be dissuaded from ingestion of the fruit.


Assuntos
Frutas/envenenamento , Diálise Renal , Idoso , Animais , Brasil , Confusão/induzido quimicamente , Nefropatias Diabéticas/complicações , Nefropatias Diabéticas/terapia , Feminino , Soluço/induzido quimicamente , Humanos , Masculino , Pessoa de Meia-Idade , Neurotoxinas/envenenamento , Diálise Peritoneal Ambulatorial Contínua , Extratos Vegetais/envenenamento , Ratos , Convulsões/induzido quimicamente , Transtornos do Sono-Vigília/induzido quimicamente
12.
Talanta ; 41(9): 1597-601, 1994 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18966108

RESUMO

An adsorptive stripping voltammetry method for the determination of traces of molybdenum(VI) in flowing solution at a wall-jet electrode sensor has been developed. After adsorption of a molybdenum complex on a wall-jet mercury film electrode, the complex is reduced by a square wave scan. More satisfactory results were obtained using 8-hydroxyquinoline as a complexing agent in nitrate medium than using Toluidine Blue in oxalic acid. Enhanced sensitivity was achieved by optimizing adsorption time and square wave parameter values. The detection limit of Mo(VI) was found to be at the nanomolar level. Interference of some other metallic species in the determination of nanomolar Mo(VI) was also investigated: Cu(II), Zn(II), Mn(II) do not interfere at 10 muM, whereas 1 muM FeEDTA(-) causes an increase in peak current. This iron interference was removed effectively with citric acid.

13.
Cancer Epidemiol Biomarkers Prev ; 3(4): 331-3, 1994 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-8061582

RESUMO

Tumor suppressor genes APC and MCC were identified recently, and their chromosomal location was ascribed to chromosome 5q21. Mutations in the APC gene give rise to familial adenomatous polyposis and occur in many perhaps even the majority, of sporadic colon cancers. Loss of heterozygosity has been described in other human tumors such as lung and esophageal cancers. Here we show loss of heterozygosity (LOH) in 87 patients with breast cancer for the APC and/or MCC loci using a polymerase chain reaction-LOH assay. LOH affected loci in APC exons 11 and 15 in 9 of 35 (25%) and 4 of 34 (11%) heterozygous patients, respectively. LOH at the MCC exon 10 locus occurred in 7 of 40 (17%) informative samples. These data suggest that allelic deletion of APC and/or MCC is probably involved in the pathogenesis and/or progression of a subset of breast cancers.


Assuntos
Neoplasias da Mama/genética , Deleção Cromossômica , Genes APC/genética , Genes MCC/genética , Sequência de Bases , DNA de Neoplasias/análise , Éxons , Feminino , Heterozigoto , Humanos , Dados de Sequência Molecular , Mutação , Reação em Cadeia da Polimerase
14.
Arq Bras Cardiol ; 58(1): 1-4, 1992 Jan.
Artigo em Português | MEDLINE | ID: mdl-1444860

RESUMO

PURPOSE: To study anatomical limitation of coronary angioplasty, as alternative therapy in patients with multivessel disease and submitted to bypass surgery. METHODS: In 380 patients with multivessel disease and submitted to previous coronary bypass surgery, age ranged from 41 to 72 (average = 51) years, being 68% males. The following parameters were analyzed in the coronary arteriographies: anatomic aspects of the coronary arteries and distribution of the atherosclerotic stenosis. The patients were arranged in accordance to the criteria: complete revascularization, incomplete and no indication for coronary angioplasty. RESULTS: The patients were arranged in 3 different groups: I-80 (21%) patients included those in whom complete revascularization would be possible; II--55 (14.5%) patients in whom only incomplete revascularization but satisfactory would be possible and III--245 (65.5%) those patients in whom coronary angioplasty would no have indication. The data referind the patients of groups I and II were analyzed together--135 (35.5%) and arranged according to the number of arteries involved. It was observed: two vessel disease--71.8%, three vessel--18.6% and 4 or more vessel--9.6%. In group III it was observed 51.0% of the patients with 3 or more vessel disease. The major factors to contra indicate coronary angioplasty in group III included: chronic coronary obstruction 99 (40.4%); diffuse disease 11 (4.5%); technical difficulties 10 (4.1%); left main coronary artery obstruction 5 (2%) or when two or more causes were combined 120 (49%). CONCLUSIONS: Patients with multivessel disease and classic indication for coronary bypass surgery, have a basic limitation for angioplasty due to several anatomic factors. However, coronary angioplasty could be beneficial for a selected group of patients (35.5%) whenever a complete or incomplete revascularization could be obtained.


Assuntos
Angioplastia com Balão , Doença das Coronárias/terapia , Vasos Coronários/patologia , Revascularização Miocárdica , Adulto , Idoso , Contraindicações , Angiografia Coronária , Doença das Coronárias/diagnóstico por imagem , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
20.
Allergol Immunopathol (Madr) ; 10(2): 91-4, 1982.
Artigo em Espanhol | MEDLINE | ID: mdl-6213139

RESUMO

Lung function tests were done on 42 patients, 22 asthmatics and 20 normal volunteers. The peak flow and expiratory flows at different levels of the forced vital capacity curve were evaluated. The flow-volume curves were obtained with a conventional spirometer, and the peak flow was determined with a Wright flowmeter. The peak flow obtained by the two methods were within the normal range, although the values registered by the Wright flowmeter were consistently lower. A reduction of the expiratory flow in the distal part of the vital capacity curve was observed in asthmatics, suggesting small airways obstruction. In conclusion, peak flow is not of use in the detection of predominantly distal airways obstruction.


Assuntos
Asma/fisiopatologia , Fluxo Expiratório Forçado , Fluxo Expiratório Máximo , Adulto , Feminino , Humanos , Pneumopatias Obstrutivas/fisiopatologia , Masculino , Pessoa de Meia-Idade , Reologia , Espirometria , Capacidade Vital
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