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1.
Invest Ophthalmol Vis Sci ; 60(6): 2140-2145, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31099830

RESUMO

Purpose: To determine the riboflavin concentration in the posterior corneal stroma, Descemet's membrane, and endothelium prior to UV irradiation in corneal cross-linking (CXL) in humans. Methods: Five human deepithelialized cadaver corneas were mounted into artificial anterior chambers. After the establishment of stable physiological hydration, two-photon imaging with a certified multiphoton tomograph was used to determine fluorescence intensity and second harmonic generation signals from collagen throughout each cornea by optical sectioning, with a step size of 2.5 µm. Afterward, 0.1% riboflavin solution was applied to the anterior corneal surface, similar to the standard CXL protocol. To determine the absolute riboflavin concentration immediately before UV irradiation, corneas were measured by two-photon imaging just at the end of the riboflavin imbibition and after riboflavin saturation. Results: The topical application of 0.1% riboflavin results in a riboflavin concentration that decreases to 0.035% in the posterior stroma. Inside Descemet's membrane and endothelium, the concentration drops further to only approximately 0.015% at the endothelial level. Local riboflavin distribution indicates a predominantly paracellular passive diffusion of riboflavin into the anterior chamber. Conclusion: The experimentally determined riboflavin concentration of 0.015% at the endothelium shows a substantial discrepancy of a factor of 1.7 to the previously theoretically calculated 0.025%. A lower riboflavin concentration at the endothelium may enable higher radiant exposures and further improve the efficacy of CXL.


Assuntos
Reagentes para Ligações Cruzadas , Epitélio Posterior/metabolismo , Fármacos Fotossensibilizantes/farmacocinética , Riboflavina/farmacocinética , Cadáver , Colágeno/metabolismo , Substância Própria/metabolismo , Lâmina Limitante Posterior/metabolismo , Humanos , Raios Ultravioleta
2.
J Cataract Refract Surg ; 45(1): 80-86, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30360937

RESUMO

PURPOSE: To estimate the noninvasive riboflavin concentration in the corneal stroma using a new ultraviolet-A (UVA) theranostic device for corneal crosslinking (CXL). SETTING: Vision Engineering Italy srl, Rome, Italy. DESIGN: Experimental study. METHODS: Fourteen human donor corneas were treated according to conventional (UVA irradiance of 3 mW/cm2 for 30 minutes) and rapid (10 mW/cm2 for 9 minutes) riboflavin-UVA CXL protocols using a theranostic UVA device. Five additional samples were treated by 0.5 mW/cm2 for 9 minutes and used as positive controls to determine riboflavin photodegradation under near ambient lighting conditions. A 20% dextran-enriched 0.1% riboflavin solution was used in all cases. The device consisted of a UVA light source; a red-green-blue camera, which acquires the fluorescence images of the cornea during treatment; and a single-board computer for managing the overall operations and the raw data processing. RESULTS: Preirradiation stromal soaking for 30 minutes achieved highly consistent intrastromal riboflavin concentration in all tissues (mean 0.015% ± 0.003% [SD]). There were no differences in the kinetics curves of riboflavin consumption between the 2 UVA irradiation protocols; the intrastromal riboflavin concentration decreased exponentially, with a mean constant energy rate of 2.8 ± 0.2 J/cm2. In the control group, the intrastromal riboflavin concentration decreased quasilinearly. CONCLUSIONS: The theranostic device provided estimates of the intrastromal concentration of riboflavin noninvasively during treatment. In the 3 to 10 mW/cm2 range of power densities, the consumption of riboflavin in the stroma by UVA irradiation was only energy dependent in accordance with the Bunsen-Roscoe law.


Assuntos
Substância Própria/metabolismo , Reagentes para Ligações Cruzadas , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/farmacocinética , Riboflavina/farmacocinética , Idoso , Colágeno/metabolismo , Sistemas Computacionais , Humanos , Pessoa de Meia-Idade , Doadores de Tecidos , Raios Ultravioleta
4.
São Paulo; s.n; s.n; 2019. 135 p. tab, graf.
Tese em Português | LILACS | ID: biblio-1049441

RESUMO

Introdução: A suplementação com ácido fólico (AF) é recomendada em algumas condições para evitar a deficiência de folato, como para mulheres no período periconcepcional e durante a gestação. Atualmente, existe uma preocupação quanto ao consumo excessivo de AF pela população pelo uso de suplementos com altas doses dessa vitamina. As vitaminas B6 e B2 agem como cofatores no metabolismo de um carbono, e o uso de altas doses de AF pode influenciar o metabolismo de ambas vitaminas e, consequentemente, interferir em metabolismos importantes das quais elas participam, como a via das quinureninas, e no sistema imune. Objetivo: Avaliar os efeitos da intervenção diária com uma alta dose de AF (5 mg) por 90 dias sobre marcadores do estado das vitaminas do complexo B, e as consequências sobre os metabólitos da via das quinureninas e o sistema imune em adultos saudáveis. Material e Métodos: 64 indivíduos saudáveis foram submetidos à intervenção diária com 5 mg de AF por 90 dias. Coletas de sangue foram realizadas antes (baseline) e após 45 e 90 dias de intervenção. As concentrações séricas de folato e vitamina B12 foram avaliadas por métodos microbiológicos. As concentrações séricas das vitaminas B6 (piridoxal 5'-fosfato (PLP), piridoxal (PL) e ácido 4-piridóxico (PA)), B2 (riboflavina e flavina mononucleotídeo (FMN)), B1 (tiamina e tiamina monofosfato (TMP)) e B3 (ácido nicotínico, nicotinamida e N1-metilnicotinamida), bem como de triptofano, quinurenina e metabólitos, foram avaliadas por LC-MS/MS. A proteína C-reativa ultrassensível (PCRus) foi determinada por imunoturbidimetria, e as concentrações séricas de interleucina (IL)-6, IL-8, IL-10, interferon gama (IFN-γ) e fator de necrose tumoral alfa (TNF-α) foram avaliadas por ensaio multiplex. A expressão de RNAm de DHFR (dihidrofolato redutase), MTHFR (metilenotetrahidrofolato redutase), IL8, TNFA e IFNG em leucócitos mononucleares (PBMC) foram avaliadas por PCR em tempo real. O número de células T regulatórias (Treg) (CD3+, CD4+, CD25high, FoxP3+, CD127-) foi avaliado após incubação dos PBMC com PMA e ionomicina ou veículo por 18h, por imunofenotipagem. Resultados: Houve um grande aumento das concentrações de folato sérico após 45 e 90 dias de intervenção com AF. Não houve diferença nas concentrações de vitamina B12 antes e após a intervenção. As concentrações séricas de PLP foram semelhantes antes e após a intervenção, entretanto, um aumento de PL sérico foi observado após 45 e 90 dias, e de PA após 45 dias, quando comparado ao baseline. Riboflavina e FMN foram maiores após 45 e 90 dias em relação ao baseline. A tiamina sérica foi menor após 45 dias, e as concentrações de TMP foram maiores após 90 dias quando comparados aos períodos anteriores. Não houve diferença nas concentrações de vitamina B3 antes e após a intervenção. Dentre os metabólitos da via das quinureninas, apenas o ácido antranílico apresentou aumento após 45 e 90 dias, enquanto o ácido picolínico diminuiu após 90 dias. PCRus, IL-6, IL-8, IL-10, IFN-γ e TNF-α séricos foram semelhantes no baseline e após a intervenção. Um aumento da expressão de RNAm de DHFR e TNFA foi observado após, respectivamente, 90 dias e 45 e 90 dias de intervenção. Após 90 dias de intervenção com AF, foi observada diminuição do número de células Treg após estímulo com PMA e ionomicina. Conclusão: O uso diário de 5 mg de AF foi associado a alterações nas concentrações séricas de marcadores do estado de vitaminas do complexo B e da via das quinureninas, bem como a diminuição do número de células Treg


Introduction: Folic acid (FA) supplementation is recommended in some conditions to avoid folate deficiency, as women during periconceptional period and pregnancy. Currently, there is a concern about the excessive consumption of FA by population by using supplements with high doses of this vitamin. Vitamins B6 and B2 are cofactors of enzymes of one carbon metabolism and, consequently, may disturb key metabolism in which they participate, as kynurenine pathway, and the immune system. Aim: To assess the effects of a daily intervention with high dose of FA (5 mg) for 90 days on biomarkers of complex B vitamins status and its outcomes in kynurenine pathway metabolites and immune system in healthy adults. Material and Methods: 64 healthy individuals were submitted to a daily intervention with 5 mg of FA for 90 days. Blood samples were collected before (baseline) and after 45 and 90 days of intervention. Serum folate and vitamin B12 were assessed by microbiological assays. Serum vitamin B6 (pyridoxal 5'-phosphate (PLP), pyridoxal (PL) and 4-pyridoxic acid (PA)), vitamin B2 (riboflavin and flavin mononucleotide (FMN)), vitamin B1 (thiamin and thiamin monophosphate)) and vitamin B3 (nicotinic acid, nicotinamide and N1-methylnicotinamide), as well as tryptophan, kynurenine and metabolites, were assessed by LC-MS/MS. C-reactive protein (hs-CPR) was assessed by immunoturbidimetry, and serum interleukin (IL)-6, IL-8, IL-10, interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) were assessed by multiplex assay. Mononuclear leukocytes mRNA expression of DHFR (dihydrofolate reductase), MTHFR (methylenetetrahydrofolate reductase), IL8, TNFA and IFNG were assessed by real time PCR. Regulatory T Cell (Treg) number (CD3+, CD4+, CD25high, FoxP3+, CD127-) was determined after mononuclear leukocytes incubation with PMA and ionomycin or vehicle for 18h, by immunophenotyping. Results: A great increase on serum folate was observed after 45 and 90 days of FA intervention. No differences in serum vitamin B12 were observed before and after intervention. Serum PLP was similar before and after intervention, however, an increase in serum PL was observed after 45 and 90 days, and in PA after 45 days, when compared to baseline. Riboflavin and FMN were increased after 45 and 90 days than in baseline. Serum thiamine was decreased after 45 days than in baseline. Serum TMP was increased after 90 days when compared with previous timepoints. No differences in vitamin B3 were observed after and before FA intervention. Among kynurenine pathway metabolites, anthranilic acid was increased after 45 and 90 days, while picolinic acid was decreased after 90 days. hs-CPR, serum IL-6, IL-8, IL-10, IFN-γ and TNF-α were similar at baseline and after intervention. An increase on mRNA expression of DHFR and TNFA was observed after, respectively, 90 days and 45 and 90 days of intervention. After 90 days of FA intervention, it was observed a decrease on Treg cell number after PMA and ionomycin stimulation. Conclusion: Daily use of 5 mg of FA was associated with changes in serum markers of B-complex vitamins status and kynurenine pathway, as well as decreased number of Treg cells


Assuntos
Humanos , Masculino , Feminino , Adulto , Riboflavina/farmacocinética , Vitamina B 6/farmacocinética , Ácido Fólico/administração & dosagem , Ácido Fólico/análise , Tiamina/farmacocinética , Linfócitos T Reguladores/classificação , Niacinamida/farmacocinética , Cinurenina/farmacocinética
5.
Int J Pharm ; 549(1-2): 370-379, 2018 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-30107218

RESUMO

Gastric floating tablets are a multifunctional dosage form with the merits of long-term gastric retention, sustained release and improved bioavailability though floating time and sustained release are usually not satisfied. Here we designed a novel gastric floating system by combining compressed tablets with 3D printed devices, wherein a riboflavin tablet was filled into a device. The table-filled device can be called a tablet-in-device (TiD) system. Commercial poly(lactic acid) filaments were used for fused deposition modeling (FDM) 3D printing of the body and cap of the device. Four types of TiD systems were prepared. The basic structures of them involved non-net, centrally symmetric double-net (including a peripheral sealed air-filled chamber and a centric net-on-both-sides chamber), single-net (including a sealed air-filled chamber on the top side and a net-on-one-side chamber on the bottom side), and eccentric double-net (including an eccentric net-on-both-sides chamber and an air-filled chamber). They were exquisitely designed after precise calculations of every chamber parameters according to the buoyant principle. All of them showed good floating ability, although only the latter two TiD systems were selected due to appropriate drug release. Compressed riboflavin tablets, consisting of riboflavin, lactose, hydroxypropyl methylcellulose (HPMC) and magnesium stearate, were prepared with the direct compaction method. All the tablets showed rapid drug release though the release was highly hindered by the devices in the TiD systems due to the barrier effect of devices and the tablet slurry formation. The single-net and double-net TiD systems achieved the cumulative release of 41% and 62% at 72 h, respectively, along with simultaneously well floating. In vivo long-term (>72 h) gastric floating function of TiD systems was further demonstrated on the rabbit models by the CT investigation. TiD systems are appropriate for oral administration of drugs with super long-term floating and controlled release in the gastric route.


Assuntos
Portadores de Fármacos , Poliésteres/química , Impressão Tridimensional , Riboflavina/administração & dosagem , Tecnologia Farmacêutica/métodos , Complexo Vitamínico B/administração & dosagem , Administração Oral , Animais , Preparações de Ação Retardada , Composição de Medicamentos , Liberação Controlada de Fármacos , Excipientes/química , Suco Gástrico/química , Suco Gástrico/metabolismo , Modelos Químicos , Coelhos , Riboflavina/química , Riboflavina/farmacocinética , Comprimidos , Complexo Vitamínico B/química , Complexo Vitamínico B/farmacocinética
6.
J Cataract Refract Surg ; 44(2): 237-242, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29526339

RESUMO

PURPOSE: To compare the corneal stromal riboflavin concentration and distribution using 2 transepithelial corneal crosslinking (CXL) systems. SETTING: Absorption Systems, San Diego, California, USA. DESIGN: Experimental study. METHODS: The stromal riboflavin concentration of 2 transepithelial CXL systems was compared in rabbit eyes in vivo. The systems were the Paracel/Vibex Xtra, comprising riboflavin 0.25% solution containing TRIS and ethylenediaminetetraacetic acid and an isotonic solution of riboflavin 0.25%, (Group 1) and the CXLO system (Group 2). Manufacturers' Instructions For Use were followed. The intensity of riboflavin fluorescence by slitlamp observation 10, 15, and 20 minutes after instillation was graded on a scale of 0 to 5. The animals were humanely killed and the corneal stromal samples analyzed with liquid chromatography and mass spectrometry. RESULTS: The mean riboflavin fluorescence intensity grades in Group 1 (4 eyes) were 3.8, 4.8, and 4.8 at 10, 15, and 20 minutes, respectively. The mean grades in Group 2 (3 eyes) were 2.0, 2.3, and 2.0, respectively. The riboflavin distribution was uniform in Group 1 but not in Group 2. The mean riboflavin concentration by liquid chromatography and mass spectrometry was 27.0 µg/g stromal tissue in Group 1 and 6.7 µg/g in Group 2. A stromal riboflavin concentration theoretically adequate for CXL, 15 µg/g, was achieved in all eyes in Group 1 and no eyes in Group 2. Slitlamp grading correlated well with liquid chromatography and mass spectrometry concentration (R2 = 0.940). CONCLUSIONS: The system used in Group 1 produced corneal riboflavin concentrations that were theoretically adequate for effective transepithelial CXL (≥15 µg/g), while the system in Group 2 did not. Slitlamp grading successfully estimated the corneal riboflavin concentration and can be used to ensure an adequate concentration of riboflavin in the cornea for transepithelial CXL.


Assuntos
Substância Própria/metabolismo , Epitélio Anterior/cirurgia , Fármacos Fotossensibilizantes/farmacocinética , Riboflavina/farmacocinética , Animais , Cromatografia Líquida , Reagentes para Ligações Cruzadas/farmacocinética , Desbridamento , Espectrometria de Massas , Coelhos
7.
Drug Metab Pharmacokinet ; 32(6): 311-314, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29162466

RESUMO

Myricetin is a flavonoid that inhibits human proton-coupled folate transporter (hPCFT) in a transient manner, in which inhibition is manifested in its presence, and also in a sustained manner, in which inhibition induced in its presence persists after its removal. In an effort to elucidate the mechanisms involved in those, we examined if myricetin might or might not act similarly on some other transporters. Transporters examined for that, in comparison with hPCFT, were its rat ortholog (rPCFT) and human riboflavin transporter 3 (hRFVT3). Experiments were conducted, using human embryonic kidney 293 cells transiently expressing the transporter to be examined, to assess the effects of myricetin (100 µM) on the uptake of folate by the PCFTs and riboflavin by hRFVT3. For hPCFT, myricetin was confirmed to induce a transient inhibition and also a sustained inhibition. However, myricetin induced neither transient nor sustained type of rPCFT inhibition. hRFVT3 was inhibited by myricetin in a transient manner, but not in a sustained manner. These results suggest the involvement of a hPCFT-specific mechanism in the sustained inhibition. The transient inhibition may be induced by a mechanism specific to hPCFT and also hRFVT3.


Assuntos
Flavonoides/farmacologia , Proteínas do Tecido Nervoso/antagonistas & inibidores , Transportador de Folato Acoplado a Próton/antagonistas & inibidores , Animais , Relação Dose-Resposta a Droga , Flavonoides/metabolismo , Ácido Fólico/farmacocinética , Células HEK293 , Humanos , Proteínas de Membrana Transportadoras/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Transportador de Folato Acoplado a Próton/metabolismo , Ratos , Riboflavina/farmacocinética , Relação Estrutura-Atividade
8.
J Cataract Refract Surg ; 43(5): 680-686, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28602332

RESUMO

PURPOSE: To determine the intrastromal concentration of riboflavin in nanotechnology-based transepithelial corneal crosslinking. SETTING: Consiglio Nazionale delle Ricerche, Messina, Italy. DESIGN: Experimental study. METHODS: Six human donor sclerocorneal tissues were used to evaluate penetration of nanotechnology-based riboflavin 0.1% solution in the stroma through the intact epithelium. Three additional tissues were deepithelialized and soaked with dextran 20.0%-enriched riboflavin 0.1% solution for 30 minutes. After corneal soaking with riboflavin, all tissues were irradiated using a 10 mW/cm2 device for 9 minutes. Two-photon emission fluorescence (TPEF) axial scanning measurements were collected in all specimens before treatment and immediately after corneal soaking with riboflavin and ultraviolet-A (UVA) irradiation of the cornea. The absorbance spectra of each tissue were collected at the same time intervals. The TPEF signals and absorbance spectra were used to calculate the concentration-depth profile of riboflavin in the corneal stroma during treatments. RESULTS: The mean stromal riboflavin concentration was 0.008% ± 0.003% (SD) and 0.017% ± 0.001% after transepithelial soaking with the nanotechnology-based solution and standard soaking, respectively (P = .001). After UVA irradiation of the cornea, the mean consumption of riboflavin was 52% ± 13% and 67% ± 2% in the study group and control group, respectively (P < .01). CONCLUSIONS: The nanotechnology-based platform was effective in enriching the anterior stroma with riboflavin through the intact epithelium, although the riboflavin concentration-depth profile rapidly decreased across the mid and posterior stroma. The treatment-induced stiffening effect on the corneal stroma was not assessed in this study.


Assuntos
Reagentes para Ligações Cruzadas , Nanotecnologia , Riboflavina , Córnea/efeitos dos fármacos , Substância Própria/efeitos dos fármacos , Reagentes para Ligações Cruzadas/farmacocinética , Humanos , Riboflavina/farmacocinética , Raios Ultravioleta
9.
Mater Sci Eng C Mater Biol Appl ; 75: 425-432, 2017 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-28415481

RESUMO

An interpenetrated polymer network (IPN) poly(NIPAAm-co-AAc) hydrogel was synthesized by two polymerization method: emulsion and solution polymerization. The pH- and temperature-sensitive hydrogel was loaded by swelling with riboflavin drug, a B2 vitamin. The release of riboflavin as a function of time has been achieved under different pH and temperature environments. The determination of experimental conditions and the analysis of drug delivery results were achieved using response surface methodology (RSM). In this work, artificial neural networks (ANNs) in MATLAB were also used to model the release data. The predictions from the ANN model, which associated input variables, produced results showing good agreement with experimental data compared to the RSM results.


Assuntos
Resinas Acrílicas , Hidrogéis , Modelos Químicos , Rede Nervosa , Riboflavina , Resinas Acrílicas/química , Resinas Acrílicas/farmacocinética , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacocinética , Temperatura Alta , Humanos , Hidrogéis/química , Hidrogéis/farmacocinética , Concentração de Íons de Hidrogênio , Riboflavina/química , Riboflavina/farmacocinética
11.
Mini Rev Med Chem ; 17(12): 1075-1111, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-27457213

RESUMO

BACKGROUND: Vitamins are chemical compounds whose derivatives are involved in vital metabolic pathways of all living organisms. The complete endogenous biosynthesis of vitamins can be performed by many bacteria, yeast and plants, but humans need to acquire most of these essential nutrients with food. In recent years, new types of action of the well-recognized vitamins or their more sophisticated relationships have been reported. CONCLUSION: In this review we present the current knowledge of factors that can influence the yield and regulation of vitamin B1, B2, B3 and B9 biosynthesis in plants which can be important for human nutrition. A summary of modern methods applied for vitamin analysis in biological materials is also provided. Contributions of selected vitamins to the homeostasis of the human organism, as well as their relations to the progress or prevention of some important diseases such as cancer, cardiovascular diseases, diabetes and Alzheimer's disease are discussed in the light of recent investigations. Better understanding of the mechanisms of vitamin uptake by human tissues and possible metabolic or genetic backgrounds of vitamin deficiencies can open new perspectives on the medical strategies and biotechnological processes of food fortification.


Assuntos
Ácido Fólico/biossíntese , Niacinamida/biossíntese , Riboflavina/biossíntese , Tiamina/biossíntese , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Disponibilidade Biológica , Suplementos Nutricionais , Ácido Fólico/administração & dosagem , Ácido Fólico/farmacocinética , Humanos , Doenças Metabólicas/tratamento farmacológico , Doenças Metabólicas/patologia , Niacinamida/administração & dosagem , Niacinamida/farmacocinética , Plantas/química , Plantas/metabolismo , Riboflavina/administração & dosagem , Riboflavina/farmacocinética , Tiamina/administração & dosagem , Tiamina/farmacocinética
12.
J Refract Surg ; 32(12): 798-802, 2016 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-27930789

RESUMO

PURPOSE: To determine the riboflavin concentration gradient in the anterior corneal stroma when using hydroxypropyl methylcellulose (HPMC) or dextran as the carrier agent. METHODS: Four different groups of porcine corneas (5 each) were compared regarding the riboflavin concentration in the anterior stroma. Prior to all experiments, stable hydration conditions were established for the corresponding solution. The dextran groups were treated with 0.1% riboflavin in 20% dextran for 10 and 30 minutes and the HPMC groups with 0.1% riboflavin in 1.1% HPMC for 10 and 30 minutes. After imbibition, nonlinear microscopy and consecutive image analysis were used to determine two-photon fluorescence intensities. To determine the riboflavin concentration, corneas were saturated and measured a second time by two-photon microscopy. With this measurement, a proper correction for absorption and scattering could be performed. Ultraviolet-A (UVA) transmission was measured after the application time for each group. RESULTS: Riboflavin concentration decreased with increasing depth and increased with longer application times in all groups. Comparing the dextran for 30 minutes and HPMC for 10 minutes groups, a significantly higher stromal riboflavin concentration was found within the most anterior 70 µm in the dextran group for 30 minutes, whereas deeper than 260 µm HPMC-assisted imbibition for 10 minutes yielded higher concentrations. In dextran-treated corneas, values obtained from pachymetry were substantially reduced, whereas HPMC-assisted imbibition led to a decent swelling. UVA transmission values were higher in dextran-assisted imbibition than in HPMC-assisted imbibition. CONCLUSIONS: Stromal riboflavin gradients are similar when applied in dextran for 30 minutes and HPMC for 10 minutes. When using HPMC solutions, a shallower cross-linked volume is expected due to a higher corneal hydration. [J Refract Surg. 2016;32(12):798-802.].


Assuntos
Substância Própria/metabolismo , Dextranos/farmacocinética , Portadores de Fármacos , Derivados da Hipromelose/farmacocinética , Fármacos Fotossensibilizantes/farmacocinética , Riboflavina/farmacocinética , Animais , Córnea/fisiologia , Paquimetria Corneana , Reagentes para Ligações Cruzadas , Microscopia de Fluorescência por Excitação Multifotônica , Fotoquimioterapia , Suínos , Raios Ultravioleta
13.
Bioconjug Chem ; 27(9): 2048-61, 2016 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-27412680

RESUMO

Riboflavin (RF) is an essential vitamin for cellular metabolism. Recent studies have shown that RF is internalized through RF transporters, which are highly overexpressed by prostate and breast cancer cells, as well as by angiogenic endothelium. Here, we present an optimized synthesis protocol for preparing tailor-made amphiphilic phospholipid-based RF derivatives using phosphoramidite chemistry. The prepared RF amphiphile-RfdiC14-can be inserted into liposome formulations for targeted drug delivery. The obtained liposomes had a hydrodynamic size of 115 ± 5 nm with narrow size distribution (PDI 0.06) and a zeta potential of -52 ± 3 mV. In vitro uptake studies showed that RfdiC14-containing liposomes were strongly internalized in HUVEC, PC3, and A431 cells, in a specific and transporter-mediated manner. To assess the RF targeting potential in vivo, an amphiphile containing PEG spacer between RF and a lipid was prepared-DSPE-PEG-RF. The latter was successfully incorporated into long-circulating near-infrared-labeled liposomes (141 ± 1 nm in diameter, PDI 0.07, zeta potential of -33 ± 1 mV). The longitudinal µCT/FMT biodistribution studies in PC3 xenograft bearing mice demonstrated similar pharmacokinetics profile of DSPE-PEG-RF-functionalized liposomes compared to control. The subsequent histological evaluation of resected tumors revealed higher degree of tumor retention as well as colocalization of targeted liposomes with endothelial cells emphasizing the targeting potential of RF amphiphiles and their utility for the lipid-containing drug delivery systems.


Assuntos
Portadores de Fármacos/química , Interações Hidrofóbicas e Hidrofílicas , Nanomedicina , Fosfolipídeos/química , Neoplasias da Próstata/metabolismo , Riboflavina/química , Animais , Transporte Biológico , Linhagem Celular Tumoral , Portadores de Fármacos/metabolismo , Portadores de Fármacos/farmacocinética , Humanos , Lipossomos , Masculino , Camundongos , Camundongos Nus , Riboflavina/metabolismo , Riboflavina/farmacocinética , Distribuição Tecidual
14.
J Cataract Refract Surg ; 42(3): 462-8, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27063528

RESUMO

PURPOSE: To determine the diffusion of riboflavin from intrastromal channels through the effective diffusion coefficients compared with traditional axial diffusion with epithelium on or off. SETTING: Advanced Optical Imaging Laboratory, University College Dublin, and Wellington Eye Clinic, Sandyford, Dublin, Ireland. DESIGN: Experimental study. METHODS: The rate of diffusion in whole-mounted porcine eyes was monitored for a 30 minutes using an optical setup with a charge-coupled device camera and a bandpass filter (central wavelength 550 nm and 40 nm bandpass) to image the fluorescence under ultraviolet illumination (365 nm wavelength). For comparison, an isotropic corneal stroma with an annular channel was modeled numerically for different diffusion constants and boundary conditions. RESULTS: Numerical and experimental results were compared, allowing determination of the effective diffusion coefficient for each case. Experimental results for 6 different riboflavin solutions were in all cases found to be higher than for the common crosslinking (CXL) riboflavin protocol, where the diffusion constant is D0 = 6.5 × 10(-5) mm(2)/sec. For the intrastromal channel, 2 isotonic solutions containing riboflavin 0.1% correlated with a diffusion constant of 5D0 = 32.5 × 10(-5) mm(2)/sec. Hypotonic solutions and transepithelium had a higher diffusion coefficient approaching 10D0 = 65.0 × 10(-5) mm(2)/sec, which is an order-of-magnitude increase compared with the typical diffusion coefficient found in standard CXL. CONCLUSIONS: In this study, riboflavin had a faster stromal diffusion when injected into a corneal channel than when applied as drops to the anterior corneal surface. Further numerical modeling might allow optimization of the channel structure for any specific choice of riboflavin.


Assuntos
Substância Própria/metabolismo , Reagentes para Ligações Cruzadas/farmacocinética , Fármacos Fotossensibilizantes/farmacocinética , Riboflavina/farmacocinética , Administração Tópica , Animais , Desbridamento , Difusão , Epitélio Anterior/cirurgia , Injeções Intraoculares , Microscopia de Fluorescência , Soluções Oftálmicas , Suínos , Tomografia de Coerência Óptica
15.
Invest Ophthalmol Vis Sci ; 57(2): 476-83, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26868750

RESUMO

PURPOSE: We investigated the concentration of riboflavin in human donor corneas during corneal cross-linking using two-photon optical microscopy and spectrophotometry. METHODS: Eight corneal tissues were de-epithelialized and soaked with 20% dextran-enriched 0.1% riboflavin solution for 30 minutes. After stromal soaking, three tissues were irradiated using a 3 mW/cm2 UV-A device for 30 minutes and three tissues irradiated using a 10 mW/cm2 device for 9 minutes. Two additional tissues were used as positive controls. A Ti:sapphire laser at 810 nm was used to perform two-photon emission fluorescence (TPEF) and second harmonic generation axial scanning measurements in all specimens before and after stromal soaking and after UV-A irradiation. In addition, spectrophotometry was used to collect the absorbance spectra of each tissue at the same time intervals. Analysis of the absorbance spectra and TPEF signals provided measures of the concentration depth profile of riboflavin in corneal stroma. RESULTS: After stromal soaking, the average peak concentration of riboflavin (0.020% ± 0.001%) was found between a stromal depth of 100 and 250 µm; the concentration of riboflavin was almost constant up to 320 ± 53 µm depth, then decreased toward the endothelium, though riboflavin was still enriched in the posterior stroma (0.016%% ± 0.001%). After conventional and accelerated UV-A irradiation, the concentration of riboflavin decreased uniformly 87% ± 2% and 67% ± 3% (P < 0.001), respectively. CONCLUSIONS: The combined use of two-photon optical microscopy and spectrophotometry provides relevant information for investigating the concentration of riboflavin in corneal stroma. The method can assist with the assessment of novel riboflavin formulations and different UV-A irradiation protocols.


Assuntos
Substância Própria/metabolismo , Reagentes para Ligações Cruzadas , Fármacos Fotossensibilizantes/farmacocinética , Riboflavina/farmacocinética , Raios Ultravioleta , Idoso , Colágeno/metabolismo , Córnea/efeitos da radiação , Humanos , Microscopia de Fluorescência por Excitação Multifotônica , Pessoa de Meia-Idade , Imagem Óptica , Espectrofotometria , Doadores de Tecidos
16.
Biol Trace Elem Res ; 173(1): 168-76, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26781955

RESUMO

An 84-day feeding trial was conducted in growing turkeys to measure the bioavailability of Cu, Zn and Mn from a commercial mineral chelate and corresponding inorganic salts in composite feeds containing supplemental riboflavin (B2) and/or pyridoxine (B6). A total of 320, 28-day-old British United Turkeys (BUT) were assigned to eight dietary treatments in a 2 × 4 factorial arrangement comprising two trace mineral sources: chelated trace mineral blend (CTMB) and its corresponding inorganic trace minerals blend (ITMB) fed solely or with supplements of vitamin B2 (8 ppm) or B6 (7 ppm) or 8 ppm B2 + 7 ppm B6. Each treatment was replicated four times with 10 turkeys each. It was observed that turkeys fed with diets supplemented solely with ITMB elicited higher (P < 0.05) Zn excretion than their counterparts fed with diets containing ITMB with supplements of vitamins B2 and/or B6. Manganese retention was lower (P < 0.05) in turkeys fed with diets supplemented solely with ITMB than those fed with diets containing vitamins B2 and/or B6 additives. Combination of CTMB or ITMB with B6 improved (P < 0.05) the concentration of Mn in the liver and Cu in the bone. It was concluded that the minerals in CTMB were more available to the animals than ITMB. Furthermore, vitamins B2 and/or B6 supplementation improved the bioavailability of the inorganic Cu, Zn and Mn in growing turkeys and tended to reduce the concentration of these trace elements in birds' excreta.


Assuntos
Ração Animal , Quelantes/farmacologia , Cobre , Suplementos Nutricionais , Manganês , Piridoxina , Riboflavina , Perus/crescimento & desenvolvimento , Zinco , Animais , Cobre/farmacocinética , Cobre/farmacologia , Manganês/farmacocinética , Manganês/farmacologia , Piridoxina/farmacocinética , Piridoxina/farmacologia , Riboflavina/farmacocinética , Riboflavina/farmacologia , Zinco/farmacocinética , Zinco/farmacologia
17.
Curr Eye Res ; 41(9): 1166-72, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-26766395

RESUMO

PURPOSE: To investigate the composition and concentration of individual riboflavin compounds in the corneal stroma in vivo after soaking with various commercially available riboflavin formulations. METHODS: Experiments were performed in 26 rabbit corneas in vivo: 24 corneas were soaked with riboflavin formulations for 30 minutes or with 0.9% NaCl for control (n = 2). After treatment, corneas were excised and prepared for ultra-high-pressure liquid chromatography (UHPLC) analysis. Additionally, computational chemical analysis of riboflavin compounds and keratan sulfate were performed. RESULTS: The amount of riboflavin and riboflavin phosphate isomers in cornea decreased by a factor of 10 to 100, when compared to the amount in riboflavin formulations. In particular, we found an inverse relationship in the ratio of riboflavin to riboflavin phosphate isomer concentration between formulations and cornea. The electronegativity and ionization potential of riboflavin and phosphate isomers are different. CONCLUSIONS: The inverse relationship observed might be explained by a stronger electronegativity of the phosphate isomers, leading to a stronger repulsion by corneal proteoglycans. Indicating the individual concentration of riboflavin compounds in formulations is more representative than the total riboflavin concentration. Riboflavin formulations and CXL protocols might be improved considering the differences in diffusion and ionization potentials of the different riboflavin compounds.


Assuntos
Substância Própria/metabolismo , Reagentes para Ligações Cruzadas/farmacocinética , Ceratocone/tratamento farmacológico , Riboflavina/farmacocinética , Animais , Cromatografia Líquida de Alta Pressão , Colágeno/farmacologia , Substância Própria/efeitos dos fármacos , Substância Própria/patologia , Modelos Animais de Doenças , Ceratocone/diagnóstico , Ceratocone/metabolismo , Masculino , Fármacos Fotossensibilizantes/farmacocinética , Coelhos , Raios Ultravioleta
18.
Invest Ophthalmol Vis Sci ; 57(2): 594-603, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24644053

RESUMO

PURPOSE: We compared an iontophoresis riboflavin delivery technique for transepithelial corneal collagen crosslinking (I-CXL) with a conventional CXL (C-CXL). METHODS: We designed three experimental sets using 152 New Zealand rabbits to study riboflavin application by iontophoresis using charged riboflavin solution (Ricrolin+) with a 1-mA current for 5 minutes. The first set was to compare riboflavin concentration measured by HPLC in corneas after iontophoresis or conventional riboflavin application. The second set was to analyze autofluorescence and stromal collagen modification immediately and 14 days after I-CXL or C-CXL, by using nonlinear two-photon microscopy (TP) and second harmonic generation (SHG). In the third set, physical modifications after I-CXL and C-CXL were evaluated by stress-strain measurements and by studying corneal resistance against collagenase digestion. RESULTS: Based on HPLC analysis, we found that iontophoresis allowed riboflavin diffusion with 2-fold less riboflavin concentration than conventional application (936.2 ± 312.5 and 1708 ± 908.3 ng/mL, respectively, P < 0.05). Corneal TP and SHG imaging revealed that I-CXL and C-CXL resulted in a comparable increased anterior and median stromal autofluorescence and collagen packing. The stress at 10% strain showed a similar stiffness of corneas treated by I-CXL or C-CXL (631.9 ± 241.5 and 680.3 ± 216.4 kPa, respectively, P = 0.908). Moreover, we observed an increased resistance against corneal collagenase digestion after I-CXL and C-CXL (61.90% ± 5.28% and 72.21% ± 4.32% of remaining surface, respectively, P = 0.154). CONCLUSIONS: This experimental study suggests that I-CXL is a promising alternative methodology for riboflavin delivery in crosslinking treatments, preserving the epithelium.


Assuntos
Colágeno/administração & dosagem , Iontoforese/métodos , Ceratocone/tratamento farmacológico , Riboflavina/administração & dosagem , Animais , Reagentes para Ligações Cruzadas , Modelos Animais de Doenças , Epitélio Anterior , Feminino , Ceratocone/metabolismo , Ceratocone/patologia , Coelhos , Riboflavina/farmacocinética , Complexo Vitamínico B/administração & dosagem , Complexo Vitamínico B/farmacocinética
19.
Vopr Pitan ; 85(6): 72-9, 2016.
Artigo em Russo | MEDLINE | ID: mdl-29376311

RESUMO

Amorphous silica (SiO2) in the form of nanoparticles (NPs) is widely used as a food additive E551 in many enriched foods and food supplements. The aim of this study was to evaluate the effect of oral administration of SiO2 NPs on assimilation and metabolism of vitamins B1, B2 and B6 in laboratory rats. Amorphous SiO2 «Orisil-300 ®¼ was used with the size of the primary NPs 20-60 nm according to the electronic, atomic force microscopy and dynamic light scattering. The experiment was conducted on 8 groups of growing male Wistar rats (with initial body weight 70-80g) number, respectively, 7, 7, 10, 10, 12, 12, 14 and 16 animals. Animals of the 1st, 3rd, 4th and 5th groups received through­out the experiment balanced semi-synthetic diet. Animals of the 2nd group received a diet depleted of vitamins B1, B2 and B6 until day 21; animals of the 6th, 7th and 8th groups -the same diet from the 1st to the 21th day, and then, before the closure of the experiment, the diet provided with the indicated B vitamins at 100% of normal level. From day 22 of experiment and until the end at day 29 the animals of the 3rd and 6th groups received deionized water (placebo) through intragastric gavage; rat of the 4th and 7th groups -aqueous suspension of SiO2 dose of 1 mg/kg body weight /day, and the 5th and 8th group -100 mg/kg/day. Urinary excretion of thiamine, riboflavin, 4-pyridoxilic acid and liver and brain content of vitamins B1 and B2 (after acid and enzyme hydrolysis) were deter­mined by fluorimetric methods. It was found that rats in group 2 lagged in weight gain at day 21 significantly compared to group 1, and developed a marked deficiency of vitamins B1, B2 and B6 according to studied safety parameters. In groups from 6 to 8 at day 29 par­tial recovery was achieved in vitamin status. Administration of SiO2 to animal of groups 4 and 5, with normal consumption of B vitamins, had no significant effect on any param­eters of vitamin status in comparison to group 3. However, intragastric administration of SiO2 led in animals of groups 7 and 8 to an increase in the urinary excretion of vitamins B1 and B2 and lowering of their content in liver as compared to group 6. Administration of SiO2 had no effect on indices of vitamin B6 sufficiency. Possible reasons are discussed for the adverse lowering impact of SiO2 NPs on the availability of vitamins B1 and B2 and their increased clearance from the body.


Assuntos
Portadores de Fármacos , Nanopartículas , Riboflavina , Dióxido de Silício , Tiamina , Vitamina B 6 , Animais , Portadores de Fármacos/química , Portadores de Fármacos/farmacocinética , Portadores de Fármacos/farmacologia , Masculino , Nanopartículas/química , Nanopartículas/uso terapêutico , Ratos , Ratos Wistar , Riboflavina/química , Riboflavina/farmacocinética , Riboflavina/farmacologia , Dióxido de Silício/química , Dióxido de Silício/farmacocinética , Dióxido de Silício/farmacologia , Tiamina/química , Tiamina/farmacocinética , Tiamina/farmacologia , Vitamina B 6/química , Vitamina B 6/farmacocinética , Vitamina B 6/farmacologia
20.
Vestn Oftalmol ; 132(6): 29-35, 2016.
Artigo em Russo | MEDLINE | ID: mdl-28121296

RESUMO

AIM: To evaluate the dynamics of riboflavin changes in the aqueous humour of the anterior chamber (AHAC) of rabbits' eyes during standard ultraviolet (UV) cross-linking with account to the area of corneal debridement. MATERIAL AND METHODS: Forty two rabbits were studied sequentially. The following solutions of riboflavin were used for cornea saturation: IR - 0.1% isosmotic riboflavin, D - Dextralink (0.1% riboflavin with 20% dextran), R - 0.1% riboflavin with 1.0% hydroxypropylmethylcellulose (HPMC). Each solution was evaluated in 3 groups that differed in the diameter of corneal debridement: group 1 - Epi-Off 3 mm (IR-3, D-3, P-3), group 2 - Epi-Off 6 mm (IR-6, D-6, R-6), and group 3 - Epi-Off 9 mm (IR-9, D-9, R-9). Aqueous humour sampling (252 samples in total) was performed in 10-minute intervals within a 60 minute period. Riboflavin levels were measured by enzyme-linked immunoassay (ID-Vit microbiological test system; Immundiagnostik, Germany). RESULTS: Stable growth rates of riboflavin level in the AHAC (with maximum values reached at 30-40 min) were observed for solutions D and R, regardless of the variant of corneal debridement. Moreover, throughout the whole follow-up period and regardless of the area of corneal debridement, the solution D provided a relatively lower concentration of riboflavin in the AHAC as compared to the two other solutions. At 30 minutes, when the cornea was considered ready for UV irradiation, the riboflavin level in the AHAC ranged from 385±26.1 µg/l (D-9) to 665±28 µg/l (R-9). In groups IR-9, IR-6, P-6, IR-3, and P-3 riboflavin levels were found to be in the same range starting at 20 minutes. However, even a sufficient concentration of riboflavin in the cornea or AHAC cannot guarantee safe and effective UV cross-linking, since the removed epithelium limits the area of the stroma that can be saturated with riboflavin, while the area of UV exposure is 8-10 mm. CONCLUSION: Safe and efficient standard UV cross-linking may be performed only under sufficient saturation of the stroma with riboflavin, which in turn depends greatly on the area of corneal debridement (should be at least 8-9 mm). A solution of 0.1% riboflavin and 1.0% HPMC enables quick and pronounced saturation of the stroma and, thus, can be used in the UV cross-linking procedure, including cases of insufficient corneal thickness.


Assuntos
Câmara Anterior/metabolismo , Humor Aquoso/metabolismo , Doenças da Córnea/terapia , Fotoquimioterapia/métodos , Riboflavina , Animais , Disponibilidade Biológica , Doenças da Córnea/fisiopatologia , Modelos Animais de Doenças , Fármacos Fotossensibilizantes/administração & dosagem , Fármacos Fotossensibilizantes/farmacocinética , Coelhos , Riboflavina/administração & dosagem , Riboflavina/farmacocinética
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