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1.
Folia Neuropathol ; 59(3): 322-326, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34628798

RESUMO

Metastasis to a meningioma is an uncommon phenomenon however reported in the literature. Meningiomas are common primary intracranial tumours which most frequently occur to be a recepient of metastases. A 66-year-old female presented with rapid development of visual acuity and visual field loss in the right eye with ipsilateral oculomotor nerve palsy. Magnetic resonance imaging (MRI) showed well-defined tumour intensely enhanced with contrast like a typical skull base meningioma. The neuropathological examination revealed two different morphological fragments of the tumour. In the cell-rich part of the tumour, immunopositivity for CK, chromogranin, and SY were detected. The less cellular portion of the tumour, immunopositivity to epithelial membrane antigen (EMA) and vimentin were detected. To our knowledge, we present the first rare metastasis of neuroendocrine carcinoma to the medial sphenoid meningioma that preceded the clinical symptoms of systemic neuroendocrine carcinoma.

2.
Int J Mol Sci ; 22(14)2021 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-34299377

RESUMO

The results of time-resolved fluorescence measurements of flavin mononucleotide (FMN) in rigid polyvinyl alcohol films (PVA) demonstrate that fluorescence intensity decays are strongly accelerated in the presence of fluorescent dimers and nonradiative energy transfer processes. The fluorescence decay originating both from H and J dimer states of FMN was experimentally observed for the first time. The mean fluorescence lifetimes for FMN dimers were obtained: τfl = 2.66 ns (at λexc = 445 nm) and τfl = 2.02 (at λexc = 487 nm) at λobs = 600 nm and T = 253 K from H and J state of dimers, respectively. We show that inhomogeneous orientational broadening of energy levels (IOBEL) affects the shape of the fluorescence decay and leads to the dependence of the average monomer fluorescence lifetime on excitation wavelength. IOBEL affected the nonradiative energy transfer and indicated that different flavin positioning in the protein pocket could (1) change the spectroscopic properties of flavins due to the existence of "blue" and "red" fluorescence centers, and (2) diminish the effectiveness of energy transfer between FMN molecules.


Assuntos
Mononucleotídeo de Flavina/química , Álcool de Polivinil/química , Dimerização , Transferência de Energia , Polarização de Fluorescência/métodos , Polímeros/química , Espectrometria de Fluorescência/métodos
3.
Pol Merkur Lekarski ; 49(291): 231-234, 2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34218246

RESUMO

Vascular injury during lumbar disc surgery was first reported as a complication in 1945 by Linton and White [32]. Injuries of the major blood vessels located anteriorly to the spine in the retroperitoneal space are rare but occur suddenly and are life-threatening. The authors present anatomo-topographical background of this complication, standards of diagnostic process and treatment on the base of literature as well the surgical and endovascular management of this complication. The authors performed a literature search for reported iatrogenic vascular injuries due to lumbar disc surgery. We were able to find 10 case series and 17 single case reports describing this rare but serious lumbar disc surgeryrelated complication. Overall, there were 159 patients who developed vascular injury due to lumbar disc surgery. The surgical exploration and repair has been done in 116 patients. In last decades due to rapid development of endovascular techniques this complication was repaired endovascular techniques in 21 patients. The most common lumbar level which resulted in iatrogenic vascular injury was L4-L5. There were reported 66 deaths and in 83 patients the postoperative period was uneventful. CONCLUSIONS: We would like to highlight the occurrence of this complication and introduction of rapid management to prevent the fatal outcome. Lumbar disc surgery is one of the most often performed procedures in neurosurgical wards. The awareness of this life-threatening complication should be known to all members of an operative team. The knowledge of proper management of this serious adverse event may save a patient's life.


Assuntos
Deslocamento do Disco Intervertebral , Lesões do Sistema Vascular , Humanos , Doença Iatrogênica , Artéria Ilíaca , Vértebras Lombares
4.
Pol Merkur Lekarski ; 49(290): 150-152, 2021 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-33895764

RESUMO

Damage to large abdominal vessels during lumbar discectomy surgery is a rare but life-threatening complication. A CASE REPORT: The authors present the case of a 57-year-old patient who received surgery for critical degenerative lumbal spinal stenosis on the L4-L5 level. The diagnosis was based on strong right sciatica and neurogenic claudication. A bilateral laminotomy from the right and a microdiscectomy were performed. During surgery, no bleeding from the intervertebral space was observed and blood pressure was low but stable from the beginning. After surgery, the patient was in good general and neurological condition, without preoperative right-sided sciatica. Within a few hours after the operation, the circulatory and respiratory systems were stable with normal saturation and the patient did not report shortness of breath. Paleness of the skin and mucous membranes was observed. Follow-up morphology tests performed at 6 and 10.5 hours after surgery showed a decrease in the level of erythrocytes. The patient had palpable tenderness in the left hypochondriac region. Suspicion of bleeding into the abdominal cavity from arteries or iliac veins was stated. Immediately, an angio-computed tomography (CT) of the abdominal cavity was performed, which confirmed the presence of a hematoma in the peritoneal space and a pseudoaneurysm of the left iliac artery. The patient was urgently transported to the Vascular Surgery Clinic, where a Y-type covered stent was implanted percutaneously into both iliac arteries. After the procedure, there were symptoms of ischaemia in the left lower extremity and intermittent claudication. A Doppler study showed signs of narrowing at the stent level on the left side. The patient was reoperated after a CT check-up and a second stent was implanted into the left iliac artery, which allowed vasodilation and true flow in the artery. CONCLUSIONS: The authors suggest that both the neurosurgeon and anaesthesiologist should have been aware of the possibility of such a rare but life-threatening complication as iliac vessel damage during lumbar discectomy surgery. A quick diagnosis and implementation of a proper procedure reduces the high mortality rate caused by this complication. In cases of a sudden unjustified drop in blood pressure during lumbar discectomy, an immediate laparotomy should be performed to find and repair the site of laceration of a vessel. In patients who are stable hemodynamically, performing an angio-CT function of the abdominal cavity is suggested and the damaged artery should be treated with a covered stent.


Assuntos
Artéria Ilíaca , Vértebras Lombares , Discotomia/efeitos adversos , Humanos , Doença Iatrogênica , Artéria Ilíaca/diagnóstico por imagem , Artéria Ilíaca/cirurgia , Laminectomia , Vértebras Lombares/diagnóstico por imagem , Vértebras Lombares/cirurgia , Pessoa de Meia-Idade
5.
J Phys Chem B ; 2021 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-33661000

RESUMO

Thermally activated delayed fluorescence (TADF) has recently become an extensively investigated phenomenon due to its high potential for application in organic optoelectronics. Currently, there is still lack of a model describing correctly basic photophysical parameters of organic TADF emitters. This article presents such a photophysical model describing the rates of intersystem crossing (ISC), reverse ISC (rISC), and radiative deactivation in various media and emphasizing key importance of molecular vibrations on the example of a popular TADF dye 9,10-dihydro-9,9-dimethyl-10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-acridine (DMAC-TRZ). The presented experimental and theoretical investigations prove that ISC and rISC can occur efficiently between the singlet and triplet states of the same charge-transfer nature (1CT and 3CT, respectively). In emitters with the orthogonal donor and acceptor fragments, such spin-forbidden 1CT ↔ 3CT transitions are activated by molecular vibrations. Namely, the change of dihedral angle between the donor and the acceptor affords reasonable spin-orbit coupling, which together with a small energy gap and reorganization energy enable 1CT ↔ 3CT transition rates reaching 1 × 107 s-1. Evidence of direct 1CT ↔ 3CT spin-flip and negligible role of a second triplet state, widely believed as a key parameter in the design of (r)ISC materials, change significantly the current understanding of TADF mechanism. In authors' opinion, photophysics, and molecular design principles of TADF emitters should be revised considering the importance of vibrationally enhanced 1CT ↔ 3CT transitions.

6.
Materials (Basel) ; 13(22)2020 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-33207805

RESUMO

The present work describes synthesis, characterization, and use of a new dansyl-labelled Ag@SiO2 nanocomposite as an element of a new plasmonic platform to enhance the fluorescence intensity. Keeping in mind that typical surface plasmon resonance (SPR) characteristics of silver nanoparticles coincide well enough with the absorption of dansyl molecules, we used them to build the core of the nanocomposite. Moreover, we utilized 10 nm amino-functionalized silica shell as a separator between silver nanoparticles and the dansyl dye to prevent the dye-to-metal energy transfer. The dansyl group was incorporated into Ag@SiO2 core-shell nanostructures by the reaction of aminopropyltrimethoxysilane with dansyl chloride and we characterized the new dansyl-labelled Ag@SiO2 nanocomposite using transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). Additionally, water wettability measurements (WWM) were carried out to assess the hydrophobicity and hydrophilicity of the studied surface. We found that the nanocomposite deposited on a semitransparent silver mirror strongly increased the fluorescence intensity of dansyl dye (about 87-fold) compared with the control sample on the glass, proving that the system is a perfect candidate for a sensitive plasmonic platform.

7.
Org Biomol Chem ; 18(38): 7635-7648, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-32960207

RESUMO

This article presents novel fluorescent probes, based on the excited-state intramolecular proton transfer (ESIPT) phenomenon and flavonols, sensitive to the action of specific glycosidases. 4'-Substituted flavonols were synthesized, using various approaches, and glycosylated with d-glucose, N-acetyl-d-glucosamine and d-glucuronic acid. Evaluation of the ß-glycosidase activities was performed in neutral and acidic pH. In all the cases examined, an acidic environment accelerated enzymatic hydrolysis. It was demonstrated that the 4'-chloroflavonyl glycosides of all sugars tested, both in neutral and acidic pH, are the ones most sensitive to the presence of hydrolase. In turn, 4'-dimethylaminoflavonyl glucoside is not sensitive to glucosidase action at all. Generally, the rate of enzymatic hydrolysis increases as the electron-withdrawing nature of the 4'-substituent increases. An exception is the trifluoromethyl group which, in spite of having the most favourable Hammett constant, does not contribute enough to increase the rate of hydrolysis of its glucoside. The presented experimental results are supported by the electrostatic potential (ESP) analysis and related to the mechanisms of glycoside bond enzymatic hydrolysis.

8.
Materials (Basel) ; 13(13)2020 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-32640655

RESUMO

The investigation of innovative label-free α-amino acids detection methods represents a crucial step for the early diagnosis of several diseases. While 1,8-diazafluoren-9-one (DFO) is known in forensic application because of the fluorescent products by reacting with the amino acids present in the papillary exudate, its application for diagnostic purposes has not been fully investigated. The stabilization of DFO over a transparent substrate allows its complexation with biomolecules for the detection of α-amino acids. In this study, DFO was immobilized into a titanium dioxide (TiO2) matrix for the fluorescence detection of glycine, as a target α-amino acid (a potential marker of the urogenital tract cancers). The DFO/TiO2 composite was characterized by atomic force microscopy, spectroscopic ellipsometry, fluorescence spectroscopy and fluorescence microscopy. The performed fluorescent studies indicate spectacular formation of aggregates at higher concentration. The measurements performed using various fluorescence and microscopic techniques together with the suitable analysis show that the aggregates are able to emit short-lived fluorescence.

9.
Artigo em Inglês | MEDLINE | ID: mdl-23832219

RESUMO

Time-resolved emission spectra of 4-dimethylamino-4'-cyano-stilbene (DMACS) and 3,5,4'-trihydroxy-stilbene (resveratrol, RSV) in propylene glycol and in rigid silica xerogel matrix at 23°C were studied. For the polar molecule DMACS in propylene glycol, a 66nm shift of maximum wavelength of emission spectra was observed within 1ns after excitation, and most of the shift occurred during the first 200ps. For resveratrol in propylene glycol no such a shift was observed. The rigid silica environment eliminates some deactivation pathways and stabilizes spectroscopic properties of both molecules. Spectral properties of nonpolar and high dipole moment molecules in viscous liquids and rigid environments are compared. Results are explained on the basis of intramolecular processes and solute-solvent relaxation, as well.


Assuntos
Nitrilas/química , Propilenoglicol/química , Sílica Gel/química , Solventes/química , Estilbenos/química , Resveratrol , Espectrometria de Fluorescência , Fatores de Tempo , Viscosidade
10.
J Mol Model ; 19(10): 4195-201, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23512181

RESUMO

The problem of extending the utilizable range of Förster resonance energy transfer (FRET) is of great current interest, due to the demand of conformation studies of larger biological structures at distances exceeding typical limiting distance of 100 Å. One of the ways to address this issue is the use of so-called antenna effect. In the present work, the influence of the antenna effect on the FRET efficiency is investigated by the Monte Carlo analysis. The previously published results Bojarski et al. (J Phys Chem B 115:10120-10125, 2011) indicate that using a simple model of donor linked with a protein labeled with multiple acceptors, significantly increases the transfer efficiency in comparison with donor-single acceptor system. The effect is stronger if the transition moments of acceptors are mutually parallel. In this work, to extend the scope of possible biological systems to be analyzed, different distributions of donor-acceptors distance are analyzed, as well as the size and shape of the attached molecule.


Assuntos
Corantes Fluorescentes/química , Algoritmos , Simulação por Computador , Fluorescência , Transferência Ressonante de Energia de Fluorescência , Modelos Químicos , Método de Monte Carlo , Proteínas/química
11.
Przegl Lek ; 70(8): 638-42, 2013.
Artigo em Polonês | MEDLINE | ID: mdl-24466709

RESUMO

The paper reviews less known radiation accidents in the history, from deadly ones to those with short-term effects. Many of them were diagnosed with notable delay, particularly ones linked to lack of knowledge or criminal actions. In physician's life, the probability to examine the victim of radiation accident is extremely low, but still exists. Therefore an adequate amount of knowledge of radiation consequences should be provided in a training curricula of medical studies and medical specialization programmes, particularly those of internal medicine and clinical toxicology, also in ones of environmental protection, environmental health and medical physics.


Assuntos
Saúde Ambiental/história , Física Médica/história , Lesões por Radiação/história , Liberação Nociva de Radioativos/história , História do Século XX , História do Século XXI , Humanos
12.
J Phys Chem Lett ; 3(23): 3626-31, 2012 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-26290997

RESUMO

First analysis of strong directional surface plasmon-coupled emission (SPCE) of ground-state formed intermolecular aggregates of Rhodamine 110 (R110) in silica nanofilms deposited on silver nanolayers is reported. Until now, the processes of energy transport and its trapping due to aggregate formation have not been studied in the presence of SPCE. A new approach to multicomponent systems with weakly and strongly fluorescent centers making use of fluorophore-surface plasmon interaction is presented. The analysis is based on comparison of experimental free-space emission spectra (F-SE), experimental SPCE with theoretical surface plasmon resonance spectra (SPR). It is shown that, due to the dispersion of SPCE, the detection of weak aggregate emission is straightforward if only the monomers and aggregates fluorescence spectra are somewhat spectrally shifted. SPCE studies confirmed the formation of weakly fluorescent higher order aggregates of R110 in silica films. The results indicate that the increase of energy transfer from monomers to aggregates is due to fluorophore-plasmon interaction.

13.
J Phys Chem B ; 115(33): 10120-5, 2011 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-21780798

RESUMO

A new method for extending the utilizable range of Förster resonance energy transfer (FRET) is proposed and tested by the Monte Carlo technique. The obtained results indicate that the efficiency of FRET can be significantly enhanced at a given distance if the energy transfer takes place toward multiple acceptors that are closely located on a macromolecule instead of a single acceptor molecule as it is currently used in FRET analysis. On the other hand, reasonable FRET efficiency can be obtained at significantly longer distances than in the case of a single acceptor. Randomly distributed and parallel orientated acceptor transition moments with respect to the transition moment of the donor molecule have been analyzed as two extreme cases. As expected, a parallel orientation of donor and acceptor transition moments results in a more efficient excitation energy transfer. This finding could be used to directly reveal the assembly/deassembly of large protein complexes in a cell by fluorescence microscopy.


Assuntos
Transferência Ressonante de Energia de Fluorescência , Corantes Fluorescentes/química , Método de Monte Carlo
14.
Chemphyschem ; 12(13): 2449-52, 2011 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-21751334

RESUMO

The first observation of strong directional surface-plasmon-coupled emission (SPCE) of Rhodamine 110 in silica nanofilms deposited on silver nanolayers is reported. The preparation of the material is described in detail. The intensity of SPCE exceeds 10 times that of free space fluorescence and total linear light polarization in the SPCE ring is observed. A new experimental setup and an original data collection method is presented. Our material completely preserves its fluorescence properties for at least eight months.


Assuntos
Nanoestruturas/química , Rodaminas/química , Dióxido de Silício/química , Espectrometria de Fluorescência , Ressonância de Plasmônio de Superfície
15.
J Lumin ; 130(12): 2446-2451, 2010 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-21331290

RESUMO

Concentration is a key determining factor in the fluorescence properties of organic fluorophores. We studied self-quenching of disodium fluorescein (uranin) fluorescence in polyvinyl alcohol (PVA) thin films. The concentration dependent changes in brightness and anisotropy were followed by a lifetime decrease. We found that at a concentration of 0.54 M, the lifetime decreases to 7 ps. At a concentration of 0.18 M the lifetime was 10 ps with the relatively high quantum yield of 0.002. In these conditions the fluorescence intensity decay was homogeneous (well approximated by a single lifetime). We realized that such a sample was an ideal fluorescence lifetime standard for spectroscopy and microscopy, and therefore characterized instrument response functions for a time-domain technique. We show that self-quenched uranin enables measurements free of the color effect, making it a superior choice for a lifetime reference over scattered light.

16.
Folia Neuropathol ; 45(3): 120-5, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17849362

RESUMO

Hemangioblastomas of the central nervous system are often accompanied by a cyst exhibiting an extensive astroglial reaction. The cyst's wall might be composed of various astroglial elements including reactive pilocytic or gemistocytic and hypertrophic astrocytes. The small tissue samples composed of compact gliotic tissue are sometimes nonrepresentative for primary hemangioblastoma tumour and might be confused with both pilocytic and diffuse infiltrative astrocytoma. Moreover, vascular anomalies of hemangioblastoma-like pattern could be combined with true neoplastic glial proliferation. Such association of glioma with certain types of vascular anomalies has been designated as angioglioma. In the current study we evaluated a series of hemangioblastomas accompanied by advanced astrogliosis of adjacent brain tissue. In some cases the histopathological features of pilocytic gliosis with numerous Rosenthal fibres and eosinophilic granular bodies strongly suggest the diagnosis of pilocytic astrocytoma. One tumour was identified as an angioglioma exhibiting a combination of hemangioblastoma-like tissue and pilocytic astrocytoma. The recognition of such an entity is important in differential tumour diagnosis and prognosis.


Assuntos
Neoplasias Cerebelares/patologia , Glioma/patologia , Hemangioblastoma/patologia , Neoplasias da Medula Espinal/patologia , Astrocitoma/irrigação sanguínea , Astrocitoma/patologia , Biópsia , Vasos Sanguíneos/patologia , Neoplasias Cerebelares/irrigação sanguínea , Neoplasias Cerebelares/cirurgia , Glioma/cirurgia , Hemangioblastoma/irrigação sanguínea , Hemangioblastoma/cirurgia , Humanos , Neoplasias da Medula Espinal/irrigação sanguínea , Neoplasias da Medula Espinal/cirurgia
17.
Exp Brain Res ; 181(1): 109-15, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17333006

RESUMO

Inhibition underlies cognitive processes such as overcoming habitual responses, suppressing of goal-irrelevant information, and switching of attention between stimuli or task rules. These processes are thought to depend on the frontal lobes. However, the precise role of the ventral frontal regions (orbitofrontal cortex) in these processes remains elusive. In the present study, our goal was to clarify the role of the orbitofrontal cortex in cognitive inhibition by examining the effects of focal lesions to the medial orbitofrontal cortex (posterior part of the gyrus rectus) on performance in tasks that required inhibitory control. Patients who had undergone surgery for an anterior communicating artery aneurysm and normal control subjects (C) participated in the study. The patients were subdivided into three groups: those with resection of the left (LGR+) or right (RGR+) gyrus rectus, and without such a resection (GR-). The Stroop Color-Word test, Trail Making B test, and the Category test were used as instruments for assessing response inhibition, switching between concrete stimuli, and switching between abstract task rules, respectively. In addition, the Digit Symbol test was used to examine sustained attention and processing speed. In the Stroop Color-Word test, the RGR+ group performed worse than all other groups. In the Trail Making B test, the RGR+ and LGR+ groups performed worse than both the GR- and C groups. In the Category test and Digit Symbol test, the groups did not differ significantly from each other. Our study indicates a specific contribution of the medial orbitofrontal cortex to response inhibition and stimulus-based switching of attention.


Assuntos
Atenção/fisiologia , Cognição/fisiologia , Inibição Psicológica , Córtex Pré-Frontal/fisiopatologia , Adulto , Feminino , Lateralidade Funcional/fisiologia , Humanos , Aneurisma Intracraniano/patologia , Aneurisma Intracraniano/cirurgia , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Córtex Pré-Frontal/lesões
18.
J Fluoresc ; 16(3): 309-16, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16470351

RESUMO

Multistep intermolecular energy migration between elongated fluorophores (carbocyanines) in uniaxially oriented polymer films is studied based on fluorescence depolarization and Monte-Carlo simulations. Contrary to disordered systems it is found experimentally that the concentration depolarization of fluorescence in uniaxially oriented films is extremely weak despite effective energy migration. Based on the concentration depolarization experiment in the ordered matrix it is possible to estimate the angle between absorption and fluorescence transition moments of carbocyanines. The values of that angle are very close to those obtained from other methods.

19.
Neurol Neurochir Pol ; 39(4): 328-34, 2005.
Artigo em Polonês | MEDLINE | ID: mdl-16096939

RESUMO

The aim of the study was to present the authors' own experience and discuss the treatment method of arachnoid cysts of the middle cranial fossa disclosed as subdural hematoma. Three cases of male patients operated on because of chronic subdural hematoma are presented. Control CT studies after evacuation of hematomas revealed arachnoid cysts of the middle cranial fossa and all patients were qualified for delayed cystocisternostomy by open craniotomy. Indirect signs of presence of arachnoid cysts in the form of bony abnormalities and expanded the middle cranial fossa in the first CT were seen in all patients. Cysts were asymptomatic until the injury in all cases. The volumes of cysts in MRI scans were: 17.8 ml, 52.9 ml and 92.4 ml, respectively. All cysts were type II according to Galassi classification. After control MRI described above made to evaluate cyst appearance, delayed cystocisternostomy to basal cisterns was undertaken in two cases with full success. No complications were observed. The third patient refused surgery. During surgery the thick and non-transparent medial cyst wall and arachnoidea of tentorial notch cisterns were observed impeding the exact identification of neurovascular structures. In our opinion arachnoid cysts of the middle cranial fossa revealed as subdural hematoma should be operated on in two stages: in the first step subdural hematoma should be evacuated and in the second step cystocisternostomy should be performed. With regard to observed morphological changes of arachnoidea and cyst walls we think that open cystocisternostomy is treatment of choice in these cases.


Assuntos
Cistos Aracnóideos/diagnóstico por imagem , Fossa Craniana Média/diagnóstico por imagem , Hematoma Subdural/diagnóstico por imagem , Adulto , Cistos Aracnóideos/complicações , Cistos Aracnóideos/cirurgia , Doença Crônica , Fossa Craniana Média/cirurgia , Diagnóstico Diferencial , Escala de Coma de Glasgow , Cefaleia/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Tomografia Computadorizada por Raios X
20.
Biophys Chem ; 99(1): 1-15, 2002 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-12223235

RESUMO

We apply and quantify two techniques to incorporate carotenoids into liposomes: (i). preparation of unilamellar liposomes from mixtures of phospholipids and a carotenoid or cholesterol; (ii). insertion of carotenoids into prepared liposomes. Homogeneous liposomal fractions with a vesicle size diameter of approximately 50 nm were obtained by an extrusion method. The resulting vesicles were subjected to a three-dimensional light scattering cross-correlation measurement in order to evaluate their size distribution. The fluorescent dyes Laurdan, DiI-C(18), C(6)-NBD-PC were used to label the liposomes and to evaluate modulations of ordering, hydrophobicity and permeability to water molecules adjacent to the bilayer in the presence of carotenoids and/or cholesterol. Zeaxanthin incorporation (up to 0.1-1 mol%) attributes to the symmetric and ordered structure of the bilayer, causing both a strong hydrophobicity and a lower water permeability at the polar region of the membrane. The incorporation of lutein has similar effects, but its ordering effect is inferior in the polar region and superior in the non-polar region of the membrane. beta-Carotene, which can be incorporated at lower effective concentrations only, distributes in a more disordered way in the membrane, but locates preferentially in the non-polar region and, compared to lutein and zeaxanthin, it induces a less ordered structure, a higher hydrophobicity and a lower water permeability on the bilayer.


Assuntos
Carotenoides/metabolismo , Lipossomos/síntese química , Colesterol/metabolismo , Corantes Fluorescentes , Interações Hidrofóbicas e Hidrofílicas , Bicamadas Lipídicas/síntese química , Bicamadas Lipídicas/química , Lipossomos/química , Luteína/metabolismo , Métodos , Permeabilidade , Fosfolipídeos/metabolismo , Xantofilas , Zeaxantinas , beta Caroteno/análogos & derivados , beta Caroteno/metabolismo
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