Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 104
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Trauma Case Rep ; 37: 100564, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34917734

RESUMO

Candida pericarditis is a rare condition which has previously been described after cardiothoracic surgery and immunosuppressive states (Geisler et al., 1981; Eng et al., 1981; Kraus et al., 1988; Kaufman et al., 1988; Tang et al., 2009; Glower et al., 1990; Carrel et al., 1991; Rabinovici et al., 1997; Canver et al., 1998; Farjah et al., 2005; Gronemeyer et al., 1982 [1-11]). We describe the case of a 19-year-old male blunt trauma patient, who survived a damage control thoracotomy and laparotomy with splenectomy, who later developed a loculated Candida pericardial effusion, complicated with cardiac tamponade and multiple organ failure, and required antifungals and surgical reintervention with thoracotomy for drainage. A literature search of the reported cases demonstrates that Candida pericarditis is indeed a rare but fatal condition if not identified and treated appropriately. This article discusses the difficulties we encountered while recognizing the disorder in our patient and proposes a guideline to adequately treat the condition in an effective and timely manner. Candida pericarditis poses a special challenge for the physician since its correct diagnosis and management requires a multidisciplinary approach.

2.
Opt Express ; 21(11): 13134-44, 2013 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-23736567

RESUMO

An overdense plasma layer irradiated by intense light can exhibit dramatic nonlinear-optical effects due to a relativistic mass-effect of free electrons: highly-multiple hysteresises of reflection and transition, and emergence of immobile waves of large amplitude. Those are trapped quasi-soliton spikes sustained by a weak pumping having a tiny fraction of their peak intensity once they have been excited first by higher power pumping. The phenomenon persists even in the layers with "soft", wash-out boundaries, as well as in a semi-infinite plasma with low absorption.

3.
Phys Rev Lett ; 109(15): 153901, 2012 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-23102308

RESUMO

Wave transport in a media with a slow spatial gradient of its characteristics is found to exhibit a universal wave pattern ("gradient marker") in a vicinity of the maxima or minima of the gradient. The pattern is common for optics, quantum mechanics, and any other propagation governed by the same wave equation. Derived analytically, it has an elegantly simple yet nontrivial profile found in perfect agreement with numerical simulations for specific examples. We also find resonant states in continuum in the case of quantum wells, and formulated criteria for their existence.

4.
Opt Express ; 17(12): 10035-43, 2009 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-19506654

RESUMO

An ion, atom, molecule or macro-particle in a trap can exhibit large motional oscillations due to the Doppler-affected radiation pressure by a laser, blue-detuned from an absorption line of a particle. This oscillator can be nearly thresholdless, but under certain conditions it may exhibit huge hysteretic excitation. Feasible applications include a "Foucault pendulum" in a trap, a rotation sensor, single atom spectroscopy, isotope separation, etc.


Assuntos
Micromanipulação/métodos , Modelos Teóricos , Nanopartículas/química , Nanopartículas/efeitos da radiação , Pinças Ópticas , Oscilometria/métodos , Simulação por Computador , Movimento (Física)
5.
Opt Express ; 17(8): 6194-202, 2009 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-19365442

RESUMO

Relativistically-intense laser beam with large field gradient ("laser gate") enables strong inelastic scattering of electrons crossing the beam. This process allows for multi-MeV electron net acceleration per pass within the wavelength space. Inelastic scattering even in low-gradient laser field may also induce extremely tight temporal focusing and electron bunch formation down to quantum, zeptosecond limit.


Assuntos
Desenho Assistido por Computador , Lasers , Modelos Teóricos , Aceleradores de Partículas/instrumentação , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
6.
Phys Rev Lett ; 101(13): 133902, 2008 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-18851449

RESUMO

We predict nanoscale field and dipole patterns due to the broken uniformity of a laser-driven local field in 1D and 2D lattices. They may result in size-related resonances and large field enhancement, which in turn can give rise to low-intensity nonlinear optical effects, e.g., optical bistability, even in the ultimate case of a pair of coupled atoms. At certain, "magic" numbers and configurations of atoms in a lattice, the system may exhibit the self-induced cancellation of the suppression of a local field.

7.
Opt Lett ; 31(3): 335-7, 2006 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-16480200

RESUMO

We propose a free-space terminator and broadband interferometry based on a coherent blackbody effect in an ultrathin nonreflecting metallic layer in the microwave to infrared domains. A frequency-insensitive device consisting of a metallic layer in a ring (Sagnac) interferometer can be used for autocorrelation measurements of extremely broad EM spectra.

8.
Phys Rev Lett ; 95(5): 053601, 2005 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-16090874

RESUMO

A relativistic field-gradient (ponderomotive) force in a laser standing wave ceases to exist in a familiar form; e.g., the adiabatic Hamiltonian is not separable into kinetic and potential energies for electrons moving in the antinode planes. We show that the force in the direction across the initial motion of an electron reverses its sign and makes the high-field areas attractive for electrons, opposite to a regular ponderomotive force. The reversal occurs at a relativistic-scale incident momentum, and represents the only effect known so far that pins down a distinct borderline between relativistic and nonrelativistic motion.

9.
J Oral Rehabil ; 31(4): 373-8, 2004 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15089945

RESUMO

Conventional glass-ionomer cements (GICs) have a slow maturation time. Reduction in time of maturation may be achieved by acceleration of the setting reaction. One factor that assists this is the reduction in glass particle size producing a larger surface area for reaction. The resulting rapid set and more rapid maturation should potentially lead to less long-term degradation. Biaxial strength measurements were made with respect to time for two GICs of similar compositions but with differing particle size distributions at different time intervals after immersion in both water and artificial saliva. There was little difference between the strength of the two materials over periods up to 12 weeks. A theoretical estimation of the relative surface areas of glasses showed that, despite there being twice the surface area available for reaction for one glass, there was little difference in strengths values between the two materials at any of the times tested here. The similarity in strength values despite this substantial difference suggests that the larger particles may have a greater influence in the cement forming process.


Assuntos
Cimentos de Ionômeros de Vidro , Análise do Estresse Dentário/métodos , Humanos , Teste de Materiais , Tamanho da Partícula , Saliva , Resistência à Tração , Fatores de Tempo , Água
10.
Phys Rev Lett ; 91(14): 143401, 2003 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-14611522

RESUMO

We predict that Coulomb explosion of a nanoscale cluster, which is ionized by high-intensity laser radiation and has a naturally occurring spatial density profile, will invariably produce shock waves. In most typical situations, two shocks, a leading and a trailing one, form a shock shell that eventually encompasses the entire cluster. Being the first example of shock waves on the nanometer scale, this phenomenon promises interesting effects and applications, including high-rate nuclear reactions inside each individual cluster.

11.
Int Endod J ; 36(8): 527-32, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12887381

RESUMO

AIM: To determine the flow characteristics and subcutaneous tissue reactions to five endodontic sealers. METHODOLOGY: The materials used were Procosol, AH26, Endomethasone, Sealapex and Endion. The sealers were prepared following the manufacturers' instructions, and 0.075 mL of each material was placed on a glass surface, which was then rotated 90 degrees. The samples were stored at 37 degrees C and 95% humidity. The displacement of the sealer was recorded by measuring the difference between its original position and the position recorded at 15 and 60 min. Three samples of each material were used. Two pockets were created in the back of Wistar rats, and one silicone tube, 1 mm in diameter and 1 cm in length, was implanted in each. One was filled with one of the materials under study, and the other empty tube was implanted as a control. Fourteen days after implantation, the animals were sacrificed, and samples of the skin containing the tubes were histologically processed. Histological and histomorphometric evaluations of the tissues adjacent to the open end of the tube were carried out the volume of tissue reaction was measured histomorphometrically according to standard stereological principles. Results were statistically analysed using analysis of variance and Duncan's test. RESULTS: The highest flow values were obtained with Sealapex and AH26. Time significantly affected the flow and the material (P < (1001). Procosol and Endion produced the most severe histological reactions: these were outlined by fibrous tissue; AH26. Endomethasone and Sealapex produced reactions of smaller size and with more moderately defined limits. CONCLUSIONS: The flow did not correlate with the degree of inflammatory response. Procosol and Endion produced the most severe tissue reactions, whereas Endomethasone, Sealapex and AH26 produced only minimum reactions.


Assuntos
Materiais Restauradores do Canal Radicular/química , Materiais Restauradores do Canal Radicular/toxicidade , Timol/análogos & derivados , Análise de Variância , Animais , Bismuto/química , Bismuto/toxicidade , Hidróxido de Cálcio/química , Hidróxido de Cálcio/toxicidade , Dexametasona/química , Dexametasona/toxicidade , Combinação de Medicamentos , Resinas Epóxi/química , Resinas Epóxi/toxicidade , Fibroblastos/efeitos dos fármacos , Reação a Corpo Estranho/induzido quimicamente , Formaldeído/química , Formaldeído/toxicidade , Cimentos de Ionômeros de Vidro/química , Cimentos de Ionômeros de Vidro/toxicidade , Hidrocortisona/química , Hidrocortisona/toxicidade , Teste de Materiais , Ratos , Ratos Wistar , Resinas Sintéticas/química , Resinas Sintéticas/toxicidade , Reologia , Salicilatos/química , Salicilatos/toxicidade , Prata/química , Prata/toxicidade , Pele/efeitos dos fármacos , Estatísticas não Paramétricas , Timol/química , Timol/toxicidade , Titânio/química , Titânio/toxicidade , Viscosidade , Óxido de Zinco/química , Óxido de Zinco/toxicidade , Cimento de Óxido de Zinco e Eugenol/química , Cimento de Óxido de Zinco e Eugenol/toxicidade
12.
Phys Rev Lett ; 88(7): 074801, 2002 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-11863902

RESUMO

Electromagnetic bursts of substantial energy on a nuclear time scale of 10(-21)-10(-22) s [zeptosecond (zs) to sub-zs] can theoretically be generated by a perawatt or multiterawatt laser beam focused on a subwavelength-size solid particle or thin wire. Terawatt laser in a similar setup could be instrumental in reaching the subattosecond domain. The system may also generate a half-cycle pulse magnetic field on astrophysical scale up to approximately 10(6) T.

13.
Acta Odontol Latinoam ; 15(1-2): 15-9, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-15208938

RESUMO

When evaluating the antimicrobial effect of endodontic sealers it is important to study the variation of pH, since this is one of the properties that may inhibit the microbial growth and influence biocompatibility. The aim of this study was to evaluate the capacity of several endodontic sealers without calcium hydroxide to modify the pH of the solution in which they were immersed. The sealers used were: Endomethasone C-Septodont (EC), Bio Seal-Ogna (BS), Diaket-Espe (D), Procosol-StarDental (P), AH26-Dentsply (AH), Ketac Endo-Espe (KE), AHPlus-Dentsply (AHP), Endion-Voco (E), Endomethasone-Septodont (EM), EZ Fill-Essential Dental Systems (EZ). Samples of each material were placed in tubes with phosphate saline solution (PBS). The pH was determined at 2, 5, 12, 20, 30, 60, and 90 days. A tube with solution alone was taken as control. Statistical analysis of the results was performed by ANOVA. Material, sample, time and material-time interaction elicited statistically significant differences (p < 0.05). The variation of pH produced by immersion of endodontic sealers depends on the composition of the material.


Assuntos
Materiais Restauradores do Canal Radicular/química , Timol/análogos & derivados , Análise de Variância , Bismuto/química , Dexametasona/química , Combinação de Medicamentos , Resinas Epóxi/química , Formaldeído/química , Cimentos de Ionômeros de Vidro/química , Hidrocortisona/química , Concentração de Íons de Hidrogênio , Imersão , Polivinil/química , Resinas Sintéticas/química , Prata/química , Timol/química , Fatores de Tempo , Titânio/química , Óxido de Zinco/química
14.
Acta odontol. latinoam ; 15(1-2): 15-9, 2002.
Artigo em Espanhol | LILACS-Express | LILACS, BINACIS | ID: biblio-1157647

RESUMO

When evaluating the antimicrobial effect of endodontic sealers it is important to study the variation of pH, since this is one of the properties that may inhibit the microbial growth and influence biocompatibility. The aim of this study was to evaluate the capacity of several endodontic sealers without calcium hydroxide to modify the pH of the solution in which they were immersed. The sealers used were: Endomethasone C-Septodont (EC), Bio Seal-Ogna (BS), Diaket-Espe (D), Procosol-StarDental (P), AH26-Dentsply (AH), Ketac Endo-Espe (KE), AHPlus-Dentsply (AHP), Endion-Voco (E), Endomethasone-Septodont (EM), EZ Fill-Essential Dental Systems (EZ). Samples of each material were placed in tubes with phosphate saline solution (PBS). The pH was determined at 2, 5, 12, 20, 30, 60, and 90 days. A tube with solution alone was taken as control. Statistical analysis of the results was performed by ANOVA. Material, sample, time and material-time interaction elicited statistically significant differences (p < 0.05). The variation of pH produced by immersion of endodontic sealers depends on the composition of the material.

15.
Acta odontol. latinoam ; 15(1-2): 15-9, 2002.
Artigo em Inglês | BINACIS | ID: bin-39024

RESUMO

When evaluating the antimicrobial effect of endodontic sealers it is important to study the variation of pH, since this is one of the properties that may inhibit the microbial growth and influence biocompatibility. The aim of this study was to evaluate the capacity of several endodontic sealers without calcium hydroxide to modify the pH of the solution in which they were immersed. The sealers used were: Endomethasone C-Septodont (EC), Bio Seal-Ogna (BS), Diaket-Espe (D), Procosol-StarDental (P), AH26-Dentsply (AH), Ketac Endo-Espe (KE), AHPlus-Dentsply (AHP), Endion-Voco (E), Endomethasone-Septodont (EM), EZ Fill-Essential Dental Systems (EZ). Samples of each material were placed in tubes with phosphate saline solution (PBS). The pH was determined at 2, 5, 12, 20, 30, 60, and 90 days. A tube with solution alone was taken as control. Statistical analysis of the results was performed by ANOVA. Material, sample, time and material-time interaction elicited statistically significant differences (p < 0.05). The variation of pH produced by immersion of endodontic sealers depends on the composition of the material.

17.
J Biol Chem ; 274(32): 22243-50, 1999 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-10428791

RESUMO

The superoxide-generating neutrophil NADPH oxidase can be activated in cell-free reconstitution systems by several agonists, most notably arachidonic acid and the detergent sodium dodecyl sulfate. In this study, we show that both phosphatidic acids and diacylglycerols can serve separately as potent, physiologic activators of NADPH oxidase in a cell-free system. Stimulation of superoxide generation by these lipids was dependent upon both Mg(2+) and agonist concentration. Activation of NADPH oxidase by phosphatidic acids did not appear to require their conversion to corresponding diacylglycerols by phosphatidate phosphohydrolase, since diacylglycerols were much slower than phosphatidic acids to activate the system and required the presence of ATP. Stimulation of the oxidase by dioctanoylglycerol proved to be by a means other than the activation of protein kinase C. Instead, dioctanoylglycerol was converted to dioctanoylphosphatidic acid by an endogenous diacylglycerol kinase present in the cell-free reaction system. This conversion was sensitive to the diacylglycerol kinase inhibitor R59949 and explains the markedly slower kinetics of activation and the novel ATP requirement seen with dioctanoylglycerol. The level of dioctanoylphosphatidic acid formed was suboptimal for NADPH oxidase activation but could synergize with the unmetabolized dioctanoylglycerol to activate superoxide generation.


Assuntos
Diglicerídeos/metabolismo , NADPH Oxidases/metabolismo , Neutrófilos/enzimologia , Ácidos Fosfatídicos/metabolismo , Sistema Livre de Células , Diacilglicerol Quinase/antagonistas & inibidores , Diglicerídeos/farmacologia , Sinergismo Farmacológico , Ativação Enzimática , Humanos , Cinética , Ácidos Fosfatídicos/farmacologia , Piperidinas/farmacologia , Quinazolinas/farmacologia , Quinazolinonas , Sistemas do Segundo Mensageiro , Superóxidos/metabolismo
18.
Endod Dent Traumatol ; 15(1): 42-5, 1999 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10219154

RESUMO

The aim of this study was to determine the in vitro antimicrobial effect of six endodontic sealers after 2, 20 and 40 days. The sealers studied were Apexit, Endion, AH26, AH-Plus. Procosol and Ketac Endo. The microorganisms used were Candida albicans, Staphylococcus aureus, Streptococcus mutans and Actinomyces israelii. Petri dishes were filled with sterile agar and 0.1-ml wells were prepared and filled with the sealers. The agar plates were stored for 24 h at 37 degrees C. The samples were then removed, immersed in 4.5 ml of culture medium and divided into three groups. The samples in group 1 were stored for 2 days at 37 degrees C whereas the samples of groups 2 and 3 were stored at 4 degrees C for 20 and 40 days respectively. The samples were then removed and discarded, and 0.1 ml of the culture medium was seeded on the agar plates in order to perform colony forming unit counts. Apexit, Endion and AH-Plus produced slight inhibition on Streptococcus mutans at 20 days and on Actinomyces israelii at every time interval. No effect was found on Candida albicans and Staphylococcus aureus. Ketac Endo only produced an antimicrobial effect on Actinomyces israelii at 2 and 40 days. AH26 and Procosol showed antimicrobial effect at 40 days on Candida albicans, at 20 and 40 days on Streptococcus mutans and Staphylococcus aureus, and an effective inhibition on Actinomyces israelii at every time interval. Statistical analysis revealed both sealers and microorganisms to be significant factors affecting results in groups 2 and 3. In conclusion, the sealers evaluated in this study showed different inhibitory effects depending on time span. Overall, sealers containing cugenol and formaldehyde proved to be most effective against the microorganisms at the time intervals studied.


Assuntos
Materiais Restauradores do Canal Radicular/farmacologia , Actinomyces/efeitos dos fármacos , Análise de Variância , Bismuto/química , Bismuto/farmacologia , Hidróxido de Cálcio/química , Hidróxido de Cálcio/farmacologia , Candida albicans/efeitos dos fármacos , Contagem de Colônia Microbiana , Combinação de Medicamentos , Resinas Epóxi/química , Resinas Epóxi/farmacologia , Cimentos de Ionômeros de Vidro/química , Cimentos de Ionômeros de Vidro/farmacologia , Concentração de Íons de Hidrogênio , Metenamina/química , Metenamina/farmacologia , Testes de Sensibilidade Microbiana , Resinas Sintéticas/farmacologia , Materiais Restauradores do Canal Radicular/química , Prata/química , Prata/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Streptococcus mutans/efeitos dos fármacos , Titânio/química , Titânio/farmacologia , Óxido de Zinco/farmacologia
19.
J Med Chem ; 41(19): 3635-44, 1998 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-9733488

RESUMO

We have synthesized the first deoxy analogues of myo-inositol 3,4,5, 6-tetrakisphosphate (1) [Ins(3,4,5,6)P4], rac-2-deoxy-myo-inositol 3, 4,5,6-tetrakisphosphate (rac-2), 2-deoxy-myo-inositol 1,4,5, 6-tetrakisphosphate (ent-2), and rac-1-deoxy-myo-inositol 3,4,5, 6-tetrakisphosphate (rac-3). In order to evaluate the binding properties of the three derivatives to the yet unidentified intracellular binding sites for Ins(3,4,5,6)P4, the analogues were converted to membrane-permeant derivatives. Starting with common inositol precursors, various forms of Barton-McCombie deoxygenation and classical protection/deprotection procedures yielded the desired precursors rac-1-O-butyryl-2-deoxy-myo-inositol (rac-12), ent-3-O-butyryl-2-deoxy-myo-inositol (ent-12), and rac-2-O-butyryl-1-deoxy-myo-inositol (rac-19), respectively. Phosphorylation and subsequent deprotection yielded rac-2, ent-2, and rac-3. Alternatively, phosphorylation followed by alkylation with acetoxymethyl bromide gave the membrane-permeant derivatives 1-O-butyryl-2-deoxy-myo-inositol 3,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester (rac-5), 3-O-butyryl-2-deoxy-myo-inositol 1,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester (ent-5), and 2-O-butyryl-1-deoxy-myo-inositol 3,4,5,6-tetrakisphosphate octakis(acetoxymethyl) ester (rac-6), respectively. We examined the potency of the membrane-permeant deoxy derivatives in inhibition of calcium-mediated chloride secretion (CaMCS) in intact T84 cells. Compared to the 1,2-di-O-butyryl-myo-inositol 3,4,5, 6-tetrakisphosphate octakis(acetoxymethyl) ester (4), the membrane-permeant derivative of Ins(3,4,5,6)P4 (1), the 2-deoxy derivative (rac-5) exhibited a slightly weaker inhibitory effect, while the enantiomerically pure 2-deoxy-Ins(1,4,5,6)P4 (ent-5) and the 1-deoxy derivative (rac-6) were inactive. As expected, the effect was stereoselective. Thus, the 1-hydroxyl group is apparently essential for binding and the inhibitory effect of Ins(3,4,5,6)P4 on chloride secretion, whereas the 2-hydroxyl group plays a less important role.


Assuntos
Células Epiteliais/efeitos dos fármacos , Fosfatos de Inositol/agonistas , Fosfatos de Inositol/síntese química , Transdução de Sinais/fisiologia , Cálcio/metabolismo , Linhagem Celular , Permeabilidade da Membrana Celular , Cloretos/metabolismo , Células Epiteliais/metabolismo , Humanos , Fosfatos de Inositol/química , Fosfatos de Inositol/farmacologia , Estereoisomerismo
20.
J Cell Sci ; 111 ( Pt 2): 283-94, 1998 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9405319

RESUMO

To understand how phosphatidylinositol 3-kinase (PI3K) modulates cell structure and function, we examined the molecular and cellular defects of a Dictyostelium mutant strain (pik1(Delta)2(Delta)) missing two (DdPIK1 and 2) of three PI3K genes, which are homologues of the mammalian p110 subunit. Levels of [32P]phosphatidylinositol 3, 4 bisphosphate (PI(3,4)P2) and [32P]phosphatidylinositol trisphosphate (PIP3) were reduced in pik1(Delta)2(Delta), which had major defects in morphological and functional correlates of macropinocytosis. This was accompanied by dramatic deficits in a subset of F-actin-enriched structures such as circular ruffles, actin crowns and pseudopodia. Although pik1(Delta)2(Delta) were mobile, they failed to aggregate into streams. Therefore we conclude that PIK1 and 2, possibly through modulation of the levels of PIP3 and PI(3,4)P2, regulate the organization of actin filaments necessary for circular ruffling during macropinocytosis, the extension of pseudopodia and the aggregation of cells into streams, but not the regulation of cell motility.


Assuntos
Actinas/metabolismo , Dictyostelium/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosfatos de Fosfatidilinositol/metabolismo , Pinocitose/fisiologia , Animais , Movimento Celular , Dictyostelium/genética , Teste de Complementação Genética , Mutagênese , Fagocitose , Fosfatidilinositol 3-Quinases/genética , Radioisótopos de Fósforo , Vacúolos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...