Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 24
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sci Rep ; 11(1): 18240, 2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34521869

RESUMO

Beam self-cleaning (BSC) in graded-index (GRIN) multimode fibers (MMFs) has been recently reported by different research groups. Driven by the interplay between Kerr effect and beam self-imaging, BSC counteracts random mode coupling, and forces laser beams to recover a quasi-single mode profile at the output of GRIN fibers. Here we show that the associated self-induced spatiotemporal reshaping allows for improving the performances of nonlinear fluorescence (NF) microscopy and endoscopy using multimode optical fibers. We experimentally demonstrate that the beam brightness increase, induced by self-cleaning, enables two and three-photon imaging of biological samples with high spatial resolution. Temporal pulse shortening accompanying spatial beam clean-up enhances the output peak power, hence the efficiency of nonlinear imaging. We also show that spatiotemporal supercontinuum (SC) generation is well-suited for large-band NF imaging in visible and infrared domains. We substantiated our findings by multiphoton fluorescence imaging in both microscopy and endoscopy configurations.

2.
Sci Rep ; 10(1): 20481, 2020 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-33235274

RESUMO

A low intensity light beam emerges from a graded-index, highly multimode optical fibre with a speckled shape, while at higher intensity the Kerr nonlinearity may induce a spontaneous spatial self-cleaning of the beam. Here, we reveal that we can generate two self-cleaned beams with a mutual coherence large enough to produce a clear stable fringe pattern at the output of a nonlinear interferometer. The two beams are pumped by the same input laser, yet are self-cleaned into independent multimode fibres. We thus prove that the self-cleaning mechanism preserves the beams' mutual coherence via a noise-free parametric process. While directly related to the initial pump coherence, the emergence of nonlinear spatial coherence is achieved without additional noise, even for self-cleaning obtained on different modes, and in spite of the fibre structural disorder originating from intrinsic imperfections or external perturbations. Our discovery may impact theoretical approaches on wave condensation, and open new opportunities for coherent beam combining.

3.
Future Microbiol ; 15: 259-271, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32271108

RESUMO

Aim: Characterization of the ability of Fusobacterium nucleatum DSM 15643 and DSM 20482 strains in the presence of Cu2+ and H2O2 to reactive oxygen species generation. Method: Spectrophotometric ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) method was used. Results: Determination of: MIC for Cu2+, H2O2 and ABTS; survivability of F. nucleatum under atmospheric oxygen exposure; the level and rate constants of free radicals production by the bacteria. Conclusion: F. nucleatum in the presence of Cu2+ and H2O2 is able to generate free radicals. Reactive oxygen species are produced mainly outside the bacterial cell, which suggests that outer membrane proteins may be involved in oxidative process.


Assuntos
Fusobacterium nucleatum/química , Fusobacterium nucleatum/metabolismo , Espécies Reativas de Oxigênio/análise , Espécies Reativas de Oxigênio/metabolismo , Espectrofotometria/métodos , Benzotiazóis/química , Cobre/farmacologia , Fusobacterium nucleatum/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Ácidos Sulfônicos/química
4.
Opt Lett ; 44(21): 5318-5321, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31674997

RESUMO

We demonstrate experimentally, the generation of an intense broadband comb-like spectrum spontaneously built up through stimulated Raman scattering in a low-pressure CO2-filled hollow-core photonic crystal fiber pumped by a single infrared pump.

5.
Metallomics ; 11(10): 1700-1715, 2019 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-31490528

RESUMO

Copper(ii) complex formation processes between alloferon 1 (Allo1) (H1 GVSGH6 GQH9 GVH12G) analogues where the phenylalanine residue is introduced in the place of His residue H6F and H12F have been studied by potentiometric, UV-visible, CD and EPR spectroscopic, and MS methods. For the phenylalanine analogues of alloferon 1, complex speciation has been obtained for a 1 : 1, 2 : 1 and 3 : 1 metal-to-ligand molar ratio. At physiological pH and in 1 : 1 metal-to-ligand molar ratio the phenylalanine analogues of alloferon 1 form a CuL complex similar to that of alanine analogues with the 4N{NH2,N1Im,2NIm} coordination mode. The stability of the complexes of the phenylalanine analogues is higher in comparison to those of alanine analogues, but lower in comparison to those containing tryptophan. Injection of Allo12F into insects induced prominent apoptotic changes in all hemocytes. The presence of apoptotic bodies only in the insect hemolymph testifies to the fact that Allo12F is an extremely pro-apoptotic peptide.


Assuntos
Cobre/química , Cobre/farmacologia , Peptídeos/química , Peptídeos/farmacologia , Animais , Apoptose/efeitos dos fármacos , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Estabilidade de Medicamentos , Hemócitos/citologia , Hemócitos/efeitos dos fármacos , Fenilalanina/análogos & derivados , Fenilalanina/farmacologia , Tenebrio/citologia , Tenebrio/efeitos dos fármacos , Triptofano/análogos & derivados , Triptofano/farmacologia
6.
J Inorg Biochem ; 201: 110819, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31518869

RESUMO

The coordination capacity of the copper(II) ions with peptides (fragments of the P1 protein - one of the outer membrane protein from Fusobacterium nucleatum) based on the His-Xaa-His motif was carried out using potentiometric measurements, mass spectrometry and spectroscopic techniques: UV-Vis, CD and EPR. The selected tetrapeptides (Ac-HGHE-NH2, Ac-GHEH-NH2, Ac-HEHQ-NH2 and Ac-EHEH-NH2) form both mononuclear and bis-complexes with copper(II) ions. In the case of mononuclear complexes the CuL and CuLH-2 species dominate in the solution, where the coordination sphere is create by {2 × NIm} and {2 × NIm,2 × N-amide}, respectively. The Ac-HGHE-NH2 peptide form more stable the CuLH-2 complex with the 4 N{2 × NIm,2 × N-amide} binding site compared to the other ligands. The presence of glutamic acid residue in sequence Ac-HEHQ-NH2 produced the destabilization of the CuLH-2 complex in comparison to that of the Ac-HGHE-NH2 sequence. For the CuLH-3 complex the coordination process for complexes containing a histidyl residue in the first positions (H1) proceed towards C-terminal sequence of the peptide. The bis-complexes are formed in the solution, where the metal ion is bounded by four imidazole nitrogen atoms {4 × NIm}.


Assuntos
Proteínas da Membrana Bacteriana Externa/química , Complexos de Coordenação/química , Cobre/química , Oligopeptídeos/química , Fusobacterium nucleatum
7.
Adv Clin Exp Med ; 28(7): 945-954, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31111693

RESUMO

BACKGROUND: The use of a specialized MR-compatible incubator (INC) is very poorly described in the literature and only with regard to brain imaging. OBJECTIVES: To present our own experience with brain and body magnetic resonance imaging (MRI) in the INC in a large cohort of neonates. MATERIAL AND METHODS: A total of 555 examinations were performed in 530 newborns with the use of a 1.5T system and Nomag IC 1.5 incubator, equipped with head and body coils. RESULTS: More than half of neonates (54%) were prematurely born at 22 + 6-36 + 6 gestational weeks. They were examined from the first to 153 days of life (median: 18.5, mean: 37.7) with body weights 600-5000 g (mean: 3051 g), 23% of less than 2500 g. The proportion of brain MRIs to other body regions was 533:85 = 86%:14%. In 36.6% of cases, MRI showed more abnormalities than ultrasound (USG), in a further 21.8%, MRI diagnosis was completely different, in 4.7%, a pathology described on a USG was ruled out on MRI. The superiority of MRI over USG was 63.1%. CONCLUSIONS: MR-compatible incubator significantly increased the availability of MRI to newborns, especially to premature and unstable newborns. The integration of body coils into the INC increased the spectrum of examinations and made possible the scanning not only of the brain but also the body. Dedicated neonatal coils improved image quality and allowed more accurate diagnosis than the previously used adult coils. Immobilization of the babies in the INC by means of Velcro belts and head fixation inserts is better than in adult coils. The closed space of the INC isolates newborns to a greater extent from the negative influence of noise in the MR environment.


Assuntos
Incubadoras para Lactentes , Imageamento por Ressonância Magnética/instrumentação , Imageamento por Ressonância Magnética/métodos , Neuroimagem , Imagem Corporal Total , Encéfalo , Humanos , Recém-Nascido , Neuroimagem/métodos
8.
Pol J Radiol ; 84: e68-e72, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31019597

RESUMO

Purpose: Hypertrophic olivary degeneration (HOD) is a unique neurological condition caused by interruption of the dentato-rubro-olivary pathway, also known as the triangle of Guillain and Mollaret. Magnetic resonance (MR) imaging is the best modality to diagnose both the degeneration of the inferior olivary nucleus and the underlying cause. Case report: We describe a case of a unilateral HOD in a 16-year-old girl several months after a subtotal excision of a brainstem pilocytic astrocytoma. Taking into account the patient's history, tumour recurrence must have been considered, but the typical location and MR morphology, as well as the time of occurrence after brainstem surgery, contributed to the diagnosis of HOD. The causative factor was the interruption of the central tegmental tract, which forms one arm of the Guillain and Mollaret triangle. Additionally, this is an interesting case of a child, who stayed in a coma for several months following brainstem surgery, but finally was discharged home with only minor neurological defects and returned to normal life. Conclusions: Hypertrophic olivary degeneration is an infrequent neurological condition, especially in the paediatric population. Nevertheless, it should be considered when interpreting late postoperative scans of children with a history of a brain tumour.

9.
Phys Rev Lett ; 122(12): 123902, 2019 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-30978031

RESUMO

Classical nonlinear waves exhibit a phenomenon of condensation that results from the natural irreversible process of thermalization, in analogy with the quantum Bose-Einstein condensation. Wave condensation originates in the divergence of the thermodynamic equilibrium Rayleigh-Jeans distribution, which is responsible for the macroscopic population of the fundamental mode of the system. However, achieving complete thermalization and condensation of incoherent waves through nonlinear optical propagation is known to require prohibitive large interaction lengths. Here, we derive a discrete kinetic equation describing the nonequilibrium evolution of the random wave in the presence of a structural disorder of the medium. Our theory reveals that a weak disorder accelerates the rate of thermalization and condensation by several order of magnitudes. Such a counterintuitive dramatic acceleration of condensation can provide a natural explanation for the recently discovered phenomenon of optical beam self-cleaning. Our experiments in multimode optical fibers report the observation of the transition from an incoherent thermal distribution to wave condensation, with a condensate fraction of up to 60% in the fundamental mode of the waveguide trapping potential.

10.
Opt Lett ; 44(1): 171-174, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30645577

RESUMO

We experimentally study polarization dynamics of Kerr beam self-cleaning in a graded-index multimode optical fiber. We show that spatial beam cleaning is accompanied by nonlinear polarization rotation and a significant increase of the degree of linear polarization.

11.
J Inorg Biochem ; 189: 69-80, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30243120

RESUMO

Fusobacterium nucleatum is an anaerobic, Gram-negative bacteria linked to colon cancer. It is interesting to determine how metal ions interact with bacterial adhesin proteins. To this end, the coordination of ATDAAS-NH2 and MKKFL-NH2 fragments of Fusobacterium adhesin A (FadA) to copper(II) ions was studied by potentiometry, spectroscopic techniques (UV-Vis, CD, EPR and NMR) and the density functional theory (DFT) methods. At pH 6.8 (colon physiological pH), the metal ion in the first peptide (ATDAAS-NH2) is coordinated by one oxygen and three nitrogen donors while in the second one (MKKFL-NH2) - by sulfur and three nitrogen atoms. Both complexes form two five- and one six-membered stable chelate rings. Moreover, reactivity studies confirmed the production of reactive oxygen species such as hydroxyl radical, superoxide anion radical and singlet oxygen. Generation of reactive oxygen species (ROS) was observed during gel electrophoresis and spectroscopic assays with reporting molecules like NDMA (N,N-dimethyl-p-nitrosoaniline) and NBT (Nitrotetrazolium Blue Chloride). All reactions were conducted in the presence of hydrogen peroxide as endogenous oxidant.


Assuntos
Adesinas Bacterianas/química , Cobre/química , Fusobacterium nucleatum/química , Espectroscopia de Ressonância de Spin Eletrônica , Concentração de Íons de Hidrogênio , Potenciometria , Espécies Reativas de Oxigênio/química , Superóxidos/química
12.
Pol J Radiol ; 83: e94-e102, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30038684

RESUMO

Purpose: The purpose of this paper is to summarise and to present the experience of the main Polish centre for prenatal magnetic resonance imaging (MRI) and to discuss the place and role of MRI in antenatal diagnosis, management, and counselling. Material and methods: Retrospective analysis of the examinations performed in the years 2001-2017. Results: In total, 1221 medical records and/or image files were collected. The full documentation of ultrasonography and MRI referrals, reports, and images was not available in every case. During the first three years 98 pregnant women were examined (approximately 33 per year, one study per fortnight). After purchase of own MR scanner, the number of examinations grew constantly, reaching 208 in 2017, which means almost one per day, and the highest number was eight in one day. We examined 45 pairs of twins, including three pairs of conjoined twins. Conclusions: MRI at our Institute is a practically used second-line foetal imaging tool, necessary to confirm, complete, or correct sonographic diagnoses, with important impact on clinical decisions concerning management of pregnancy and of the neonate, termination of pregnancy, choice of the time, place, and mode of delivery, and neonatal care, as well as on counselling. In experienced hands, MRI is to date the last and the best non-invasive method of diagnosis in utero. It is frequently requested by the interdisciplinary team for foetal diagnosis and therapy and routinely performed in everyday practice.

13.
Eur J Hosp Pharm ; 25(1): 10-15, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29445453

RESUMO

By February 2019, the Polish pharmaceutical industry, community and hospital pharmacies, wholesalers and parallel traders must all comply with the EU-wide Falsified Medicines Directive (FMD) legislation (2011/62/EU), to ensure that no medicinal product is dispensed to a patient without proper tracking and authentication. Here we describe how Poland is complying with the new EU regulations, the actions that have been taken to incorporate the FMD into Polish Pharmaceutical Law and whether or not these actions are sufficient. We found that Poland is only partially compliant with the FMD and further actions need to be undertaken to fully meet the Delegated Act (DA) requirements. Moreover, there is lack of awareness in Poland about the prevalence of falsified medication and the time scale required for implementation of the DA. Based on our findings, we suggest that a public awareness campaign should be started to raise awareness of the increased number of falsified medicines in the legal supply chain and that drug authorisation systems are implemented by Polish pharmacies to support the FMD.

14.
Phys Rev Lett ; 118(24): 243901, 2017 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-28665655

RESUMO

Real-time access to the internal ultrafast dynamics of complex dissipative optical systems opens new explorations of pulse-pulse interactions and dynamic patterns. We present the first direct experimental evidence of the internal motion of a dissipative optical soliton molecule generated in a passively mode-locked erbium-doped fiber laser. We map the internal motion of a soliton pair molecule by using a dispersive Fourier-transform imaging technique, revealing different categories of internal pulsations, including vibrationlike and phase drifting dynamics. Our experiments agree well with numerical predictions and bring insights to the analogy between self-organized states of lights and states of the matter.

15.
Planta Med ; 83(14-15): 1159-1168, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28454190

RESUMO

Epilobium sp. are commonly used in traditional medicine in the treatment of early stages of benign prostatic hyperplasia and inflammation. It is suggested that a dominating constituent, oenothein B, is responsible for the extracts therapeutic effects. Several bioactivities were established for extracts and oenothein B in various in vitro models, but due to the questionable bioavailability of this dimeric macrocyclic ellagitannin, their significance in the in vivo effects remains unresolved. We have thus focused our attention on a complex comparative investigation of the in vitro and in vivo activities of phytochemically characterized Epilobium angustifolium aqueous extract and oenothein B on prostate cancer cells proliferation.Incubation of different cell lines with E. angustifolium aqueous extract resulted in a significant reduction of proliferation of PZ-HPV-7 and LNCaP cells, which was partly associated with antiandrogenic activity. These effects were fully congruent with oenothein B, examined in parallel. Oral supplementation of rats implanted with LNCaP cells with E. angustifolium aqueous extract 50-200 mg/kg b. w. resulted in a reduction of the occurrence of prostatic adenoma up to 13 %. Oenothein B was not detected in the urine and feces of the E. angustifolium aqueous extract-treated group, however, conjugates of nasutins gut microbiota metabolites of ellagitannins were detected in the urine, while in human volunteers supplemented with Epilobium tea, only urolithin conjugates were present.Despite observing significant and consistent effects in vitro and in vivo, we were unable to point out unequivocally the factors contributing to the observed E. angustifolium aqueous extract activity, facing the problems of an unknown metabolic fate of oenothein B and interspecies differences in E. angustifolium aqueous extract gut microbiota metabolism.


Assuntos
Epilobium/química , Taninos Hidrolisáveis/farmacologia , Extratos Vegetais/farmacologia , Hiperplasia Prostática/tratamento farmacológico , Neoplasias da Próstata/tratamento farmacológico , Animais , Linhagem Celular Tumoral , Humanos , Inflamação/tratamento farmacológico , Masculino , Medicina Tradicional , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Polifenóis/farmacologia , Ratos , Água
16.
Brain Dev ; 39(3): 203-210, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27832912

RESUMO

BACKGROUND: In neonatal brains diffusion restriction, which is not limited to the region of insult, but is also found in distant locations from it seems to be a frequent finding, called pre-Wallerian degeneration. OBJECTIVES: The purpose of this study was to describe these findings and to estimate the frequency of their occurrence with an attempt to determine their clinical significance. METHODS: 125 brain MRI examinations of neonates with confirmed brain damage performed or consulted in our Institute were retrospectively reviewed, focusing on the presence of restricted diffusion in corticospinal tracts (CST) and corpus callosum (CC). Apparent diffusion coefficients (ADC) were measured in callosal splenium and compared to normal neonatal brains. RESULTS: Restricted diffusion was found in 21 newborns (16.8%): in 4 in CST (3.2%), in 5 in CC (4.0%), in 12 in both (9.6%). Mean ADC value in CC was 0.638, standard deviation (SD): 0.211µm2/s and in the control group 0.995, SD: 0.162µm2/s (p=0,001). CONCLUSIONS: Neonatal brain MRI should be searched for DWI abnormalities which are not rare and require careful studying of ADC maps. Diffusion restriction in the corpus callosum and/or corticospinal tracts below the region of insult should not be mistaken for acute ischemia as it most likely reflects early phase of secondary neuronal degeneration called pre-Wallerian degeneration. This finding helps in prognostication and guides the management of the affected neonates.


Assuntos
Corpo Caloso/fisiopatologia , Imagem de Difusão por Ressonância Magnética , Processamento de Imagem Assistida por Computador , Tratos Piramidais/fisiopatologia , Corpo Caloso/crescimento & desenvolvimento , Imagem de Difusão por Ressonância Magnética/métodos , Feminino , Humanos , Recém-Nascido , Masculino , Tratos Piramidais/crescimento & desenvolvimento , Estudos Retrospectivos , Acidente Vascular Cerebral/fisiopatologia , Degeneração Walleriana/fisiopatologia
17.
Opt Lett ; 41(21): 5007-5010, 2016 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-27805671

RESUMO

A supercontinuum laser source was designed for multiplex-coherent anti-Stokes Raman scattering spectroscopy. This source was based on the use of a germanium-doped standard optical fiber with a zero dispersion wavelength at 1600 nm and pumped at 1064 nm. We analyzed the nonlinear spectro-temporal interrelations of a subnanosecond pulse propagating in a normal dispersion regime in the presence of a multiple Raman cascading process and strong conversion. The multiple Raman orders permitted the generation of a high-power flat spectrum with a specific nonlinear dynamics that can open the way to subnanosecond time-coded multiplex CARS systems.

18.
Phys Rev Lett ; 116(18): 183901, 2016 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-27203323

RESUMO

Spatiotemporal mode coupling in highly multimode physical systems permits new routes for exploring complex instabilities and forming coherent wave structures. We present here the first experimental demonstration of multiple geometric parametric instability sidebands, generated in the frequency domain through resonant space-time coupling, owing to the natural periodic spatial self-imaging of a multimode quasi-continuous-wave beam in a standard graded-index multimode fiber. The input beam was launched in the fiber by means of an amplified microchip laser emitting sub-ns pulses at 1064 nm. The experimentally observed frequency spacing among sidebands agrees well with analytical predictions and numerical simulations. The first-order peaks are located at the considerably large detuning of 123.5 THz from the pump. These results open the remarkable possibility to convert a near-infrared laser directly into a broad spectral range spanning visible and infrared wavelengths, by means of a single resonant parametric nonlinear effect occurring in the normal dispersion regime. As further evidence of our strong space-time coupling regime, we observed the striking effect that all of the different sideband peaks were carried by a well-defined and stable bell-shaped spatial profile.

20.
Pol J Radiol ; 80: 93-106, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25745524

RESUMO

Artifacts in magnetic resonance imaging and foreign bodies within the patient's body may be confused with a pathology or may reduce the quality of examinations. Radiologists are frequently not informed about the medical history of patients and face postoperative/other images they are not familiar with. A gallery of such images was presented in this manuscript. A truncation artifact in the spinal cord could be misinterpreted as a syrinx. Motion artifacts caused by breathing, cardiac movement, CSF pulsation/blood flow create a ghost artifact which can be reduced by patient immobilization, or cardiac/respiratory gating. Aliasing artifacts can be eliminated by increasing the field of view. An artificially hyperintense signal on FLAIR images can result from magnetic susceptibility artifacts, CSF/vascular pulsation, motion, but can also be found in patients undergoing MRI examinations while receiving supplemental oxygen. Metallic and other foreign bodies which may be found on and in patients' bodies are the main group of artifacts and these are the focus of this study: e.g. make-up, tattoos, hairbands, clothes, endovascular embolization, prostheses, surgical clips, intraorbital and other medical implants, etc. Knowledge of different types of artifacts and their origin, and of possible foreign bodies is necessary to eliminate them or to reduce their negative influence on MR images by adjusting acquisition parameters. It is also necessary to take them into consideration when interpreting the images. Some proposals of reducing artifacts have been mentioned. Describing in detail the procedures to avoid or limit the artifacts would go beyond the scope of this paper but technical ways to reduce them can be found in the cited literature.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...