Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 18 de 18
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sensors (Basel) ; 23(21)2023 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-37960698

RESUMO

This paper proposes a non-contact continuous respiration monitoring method based on Fringe Projection Profilometry (FPP). This method aims to overcome the limitations of traditional intrusive techniques by providing continuous monitoring without interfering with normal breathing. The FPP sensor captures three-dimensional (3D) respiratory motion from the chest wall and abdomen, and the analysis algorithms extract respiratory parameters. The system achieved a high Signal-to-Noise Ratio (SNR) of 37 dB with an ideal sinusoidal respiration signal. Experimental results demonstrated that a mean correlation of 0.95 and a mean Root-Mean-Square Error (RMSE) of 0.11 breaths per minute (bpm) were achieved when comparing to a reference signal obtained from a spirometer.


Assuntos
Taxa Respiratória , Parede Torácica , Humanos , Respiração , Monitorização Fisiológica/métodos , Razão Sinal-Ruído
2.
Int J Mol Sci ; 24(7)2023 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-37047829

RESUMO

Neuroendocrine tumours of the gastrointestinal tract are rare. The incidence has increased in recent years due to improvements in diagnostic methods for detecting these lesions. These tumours have a poor prognosis, especially when detected at an advanced stage. The basis of the treatment is resection, and non-surgical treatments are also standard in the treatment process. The situation is similar in even rarer neuroendocrine tumours of the reproductive tract, which are associated with an equally poor prognosis. In this article, we focus on learning about the risk factors (including genetic mutations) that increase the risk of the disease and comparing the effectiveness of non-surgical treatments-chemotherapy, radiotherapy, peptide receptor radionuclide therapy, somatostatin analogues, and immunotherapy. The efficacy of these treatments varies, and immunotherapy appears to be a promising form of treatment; however, this requires further research.


Assuntos
Neoplasias Gastrointestinais , Tumores Neuroendócrinos , Neoplasias Pancreáticas , Humanos , Tumores Neuroendócrinos/diagnóstico , Tumores Neuroendócrinos/epidemiologia , Tumores Neuroendócrinos/terapia , Somatostatina , Resultado do Tratamento , Fatores de Risco , Trato Gastrointestinal , Neoplasias Gastrointestinais/diagnóstico , Neoplasias Gastrointestinais/epidemiologia , Neoplasias Gastrointestinais/terapia , Neoplasias Pancreáticas/tratamento farmacológico
3.
Nutrients ; 15(6)2023 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-36986218

RESUMO

The etiopathogenesis of acne is complex, as several endo- and exogenous factors that affect the sebaceous-hair unit are involved in the development of acne lesions. The main aim of the study was to evaluate selected metabolic parameters before treatment. Another goal of the study was to determine the correlation between selected metabolic and dietary parameters and the severity of acne before treatment. The third objective was to assess the severity of acne before and after treatment, considering the type of treatment used. The final objective was to assess the relationship between the difference in acne severity before and after treatment, considering the type of treatment used and factors of dairy or sweets intake. 168 women participated in the study. The patients belonged to two groups: the study group (99 patients with acne vulgaris) and the control group (69 patients without skin lesions). The study group was divided into subgroups according to the treatment used: contraceptive preparation, contraceptive preparation and cyproterone acetate, and contraceptive preparation and isotretinoin preparation. We found that LDL levels and consumption of sweets correlated with acne severity. The mainstay of acne treatment is contraceptive treatment (ethinylestradiol and drospirenone). The effectiveness of the three contraceptive-based treatments was confirmed by observing the severity of acne. There were no significant correlations between the difference in acne severity before and after treatment with the three treatments and factors of dairy or sweet consumption.


Assuntos
Acne Vulgar , Anticoncepcionais Orais , Humanos , Feminino , Adulto Jovem , Acne Vulgar/tratamento farmacológico , Etinilestradiol , Acetato de Ciproterona
4.
Small ; 19(2): e2202343, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36394151

RESUMO

Ectopic pregnancy (EP) is the leading cause of maternity-related death in the first trimester of pregnancy. Approximately 98% of ectopic implantations occur in the fallopian tube, and expedient management is crucial for preventing hemorrhage and maternal death in the event of tubal rupture. Current ultrasound strategies misdiagnose EP in up to 40% of cases, and the failure rate of methotrexate treatment for confirmed EP exceeds 10%. Here the first theranostic strategy for potential management of EP is reported using a near-infrared naphthalocyanine dye encapsulated within polymeric nanoparticles. These nanoparticles preferentially accumulate in the developing murine placenta within 24 h following systemic administration, and enable visualization of implantation sites at various gestational stages via fluorescence and photoacoustic imaging. These nanoparticles do not traverse the placental barrier to the fetus or impact fetal development. However, excitation of nanoparticles localized in specific placentas with focused NIR light generates heat (>43 °C) sufficient for disruption of placental function, resulting in the demise of targeted fetuses with no effect on adjacent fetuses. This novel approach would enable diagnostic confirmation of EP when current imaging strategies are unsuccessful, and elimination of EP could subsequently be achieved using the same nano-agent to generate localized hyperthermia resulting in targeted placental impairment.


Assuntos
Hipertermia Induzida , Gravidez Ectópica , Gravidez , Feminino , Humanos , Animais , Camundongos , Placenta/diagnóstico por imagem , Gravidez Ectópica/terapia , Tubas Uterinas/diagnóstico por imagem , Ultrassonografia
5.
Adv Healthc Mater ; 12(9): e2202946, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36495088

RESUMO

Photoacoustic imaging (PAI) has tremendous potential for improving ovarian cancer detection. However, the lack of effective exogenous contrast agents that can improve PAI diagnosis accuracy significantly limits this application. This study presents a novel contrast nanoagent with a specific spectral signature that can be easily distinguished from endogenous chromophores in cancer tissue, allowing for high-contrast tumor visualization. Constructed as a 40 nm biocompatible polymeric nanoparticle loaded with two naphthalocyanine dyes, this agent is capable of efficient ovarian tumor accumulation after intravenous injection. The developed nanoagent displays a spectral signature with two well-separated photoacoustic peaks of comparable PA intensities in the near-infrared (NIR) region at 770 and 860 nm, which remain unaffected in cancer tissue following systemic delivery. In vivo experiments in mice with subcutaneous and intraperitoneal ovarian cancer xenografts validate that this specific spectral signature allows for accurate spectral unmixing of the nanoagent signal from endogenous contrast in cancer tissue, allowing for sensitive noninvasive cancer diagnosis. In addition, this nanoagent can selectively eradicate ovarian cancer tissue with a single dose of photothermal therapy by elevating the intratumoral temperature to ≈49 °C upon exposure to NIR light within the 700-900 nm range.


Assuntos
Nanopartículas , Neoplasias Ovarianas , Técnicas Fotoacústicas , Humanos , Feminino , Animais , Camundongos , Neoplasias Ovarianas/diagnóstico por imagem , Fototerapia/métodos , Nanopartículas/uso terapêutico , Polímeros , Diagnóstico por Imagem , Técnicas Fotoacústicas/métodos
6.
Cancers (Basel) ; 14(20)2022 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-36291906

RESUMO

Cutaneous melanoma is a relatively common neoplasm, with fairly well understood pathogenesis, risk factors, prognosis and therapeutic protocols. The incidence of this disease is increasing every year. The situation is different for rare malignancies such as vulvar melanomas and for the even rarer vaginal melanomas. The risk factors for vulvovaginal tumors are not fully understood. The basis of treatment in both cases is surgical resection; however, other types of treatments such as immunotherapy are available. This paper focuses on comparing the pathogenesis and risk factors associated with these neoplasms as well as the efficacy of two groups of drugs-anti-PD-L1 and anti-CTLA4 inhibitors-against both cutaneous melanoma and melanoma of the lower genital tract (vulva and vagina). In the case of cutaneous melanoma, the situation looks more optimistic than for vulvovaginal melanoma, which has a much worse prognosis and, as it turns out, shows a poorer response to immune therapy.

8.
J Med Chem ; 64(12): 8798-8805, 2021 06 24.
Artigo em Inglês | MEDLINE | ID: mdl-34081463

RESUMO

We have synthesized and characterized a library of near-infrared (NIR) heptamethine cyanine dyes for biomedical application as photoacoustic imaging and photothermal agents. These hydrophobic dyes were incorporated into a polymer-based nanoparticle system to provide aqueous solubility and protection of the photophysical properties of each dye scaffold. Among those heptamethine cyanine dyes analyzed, 13 compounds within the nontoxic polymeric nanoparticles have been selected to exemplify structural relationships in terms of photostability, photoacoustic imaging, and photothermal behavior within the NIR (∼650-850 nm) spectral region. The most contributing structural features observed in our dye design include hydrophobicity, rotatable bonds, heavy atom effects, and stability of the central cyclohexene ring within the dye core. The NIR agents developed within this project serve to elicit a structure-function relationship with emphasis on their photoacoustic and photothermal characteristics aiming at producing customizable NIR photoacoustic and photothermal tools for clinical use.


Assuntos
Corantes Fluorescentes/farmacologia , Indóis/farmacologia , Nanopartículas/química , Linhagem Celular Tumoral , Corantes Fluorescentes/síntese química , Humanos , Indóis/síntese química , Microscopia de Fluorescência , Técnicas Fotoacústicas/métodos , Terapia Fototérmica/métodos
9.
RSC Adv ; 11(47): 29486-29497, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35479549

RESUMO

Peri-necrotic tumor regions have been found to be a source of cancer stem cells (CSC), important in tumor recurrence. Necrotic and peri-necrotic tumor zones have poor vascular supply, limiting effective exposure to systemically administered therapeutics. Therefore, there is a critical need to develop agents that can effectively target these relatively protected tumor areas. We have developed a multi-property nanoplatform with necrosis avidity, fluorescence imaging and X-ray tracking capabilities to evaluate its feasibility for therapeutic drug delivery. The developed nanoparticle consists of three elements: poly(ethylene glycol)-block-poly(ε-caprolactone) as the biodegradable carrier; hypericin as a natural compound with fluorescence and necrosis avidity; and gold nanoparticles for X-ray tracking. This reproducible nanoparticle has a hydrodynamic size of 103.9 ± 1.7 nm with a uniform spherical morphology (polydispersity index = 0.12). The nanoparticle shows safety with systemic administration and a stable 30 day profile. Intravenous nanoparticle injection into a subcutaneous tumor-bearing mouse and intra-arterial nanoparticle injection into rabbits bearing VX2 orthotopic liver tumors resulted in fluorescence and X-ray attenuation within the tumors. In addition, ex vivo and histological analysis confirmed the accumulation of hypericin and gold in areas of necrosis and peri-necrosis. This nanoplatform, therefore, has the potential to enhance putative therapeutic drug delivery to necrotic and peri-necrotic areas, and may also have an application for monitoring early response to anti-tumor therapies.

10.
Molecules ; 25(12)2020 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-32630496

RESUMO

Here, we report the syntheses of two pentamethine cyanine dyes containing quinolinium rings and substituted with either hydrogen (3) or bromine (4) at the meso carbon. The electron withdrawing bromine atom stabilizes dye 4 in aqueous buffer, allowing complex formation to occur between the dye and double-helical DNA. UV-visible, CD, and fluorescence spectra recorded at low DNA concentrations suggest that dye 4 initially binds to the DNA as a high-order aggregate. As the ratio of DNA to dye is increased, the aggregate is converted to monomeric and other low-order dye forms that interact with DNA in a non-intercalative fashion. The brominated dye 4 is relatively unreactive in the dark, but, under 707-759 nm illumination, generates hydroxyl radicals that cleave DNA in high yield (pH 7.0, 22 °C). Dye 4 is also taken up by ES2 ovarian carcinoma cells, where it is non-toxic under dark conditions. Upon irradiation of the ES2 cells at 694 nm, the brominated cyanine reduces cell viability from 100 ± 10% to 14 ± 1%. Our results suggest that 2-quinolinium-based carbocyanine dyes equipped with stabilizing electron withdrawing groups may have the potential to serve as sensitizing agents in long-wavelength phototherapeutic applications.


Assuntos
Carbocianinas/química , Clivagem do DNA , DNA de Neoplasias/química , Corantes Fluorescentes/química , Neoplasias Ovarianas/metabolismo , Fotoquímica , Compostos de Quinolínio/química , Apoptose , Proliferação de Células , Feminino , Fluorescência , Humanos , Neoplasias Ovarianas/patologia , Espectroscopia de Luz Próxima ao Infravermelho , Células Tumorais Cultivadas
11.
Small ; 16(18): e1906936, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32250034

RESUMO

Endometriosis is a painful disorder where endometrium-like tissue forms lesions outside of the uterine cavity. Intraoperative identification and removal of these lesions are difficult. This study presents a nanoplatform that concurrently delineates and ablates endometriosis tissues using real-time near-infrared (NIR) fluorescence and photothermal therapy (PTT). The nanoplatform consists of a dye, silicon naphthalocyanine (SiNc), capable of both NIR fluorescence imaging and PTT, and a polymeric nanoparticle as a SiNc carrier to endometriosis tissue following systemic administration. To achieve high contrast during fluorescence imaging of endometriotic lesions, nanoparticles are constructed to be non-fluorescent prior to internalization by endometriosis cells. In vitro studies confirm that these nanoparticles activate the fluorescence signal following internalization in macaque endometrial stromal cells and ablate them by increasing cellular temperature to 53 ° C upon interaction with NIR light. To demonstrate in vivo efficiency of the nanoparticles, biopsies of endometrium and endometriosis from rhesus macaques are transplanted into immunodeficient mice. Imaging with the intraoperative Fluobeam 800 system reveals that 24 h following intravenous injection, nanoparticles efficiently accumulate in, and demarcate, endometriotic grafts with fluorescence. Finally, the nanoparticles increase the temperature of endometriotic grafts up to 47 °C upon exposure to NIR light, completely eradicating them after a single treatment.


Assuntos
Endometriose , Hipertermia Induzida , Nanopartículas , Fototerapia , Animais , Endometriose/diagnóstico por imagem , Endometriose/terapia , Feminino , Humanos , Macaca mulatta , Camundongos , Imagem Óptica
12.
Mol Pharm ; 17(5): 1538-1545, 2020 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-32212709

RESUMO

Necrosis targeting and imaging has significant implications for evaluating tumor growth, therapeutic response, and delivery of therapeutics to perinecrotic tumor zones. Hypericin is a hydrophobic molecule with high necrosis affinity and fluorescence imaging properties. To date, the safe and effective delivery of hypericin to areas of necrosis in vivo remains a challenge because of its incompatible biophysical properties. To address this issue, we have developed a biodegradable nanoparticle (Hyp-NP) for delivery of hypericin to tumors for necrosis targeting and fluorescence imaging. The nanoparticle was developed using methoxy poly(ethylene glycol)-b-poly(ε-caprolactone) and hypericin by a modified solvent evaporation technique. The size of Hyp-NP was 19.0 ± 1.8 nm from cryo-TEM and 37.3 ± 0.7 nm from dynamic light-scattering analysis with a polydispersity index of 0.15 ± 0.01. The encapsulation efficiency of hypericin was 95.05% w/w by UV-vis absorption. After storage for 30 days, 91.4% hypericin was retained in Hyp-NP with nearly no change in hydrodynamic size, representing nanoparticle stability. In an ovarian cancer cell line, Hyp-NP demonstrated cellular internalization with intracellular cytoplasmic localization and preserved fluorescence and necrosis affinity. In a mouse subcutaneous tumor model, tumor accumulation was noted at 8 h postinjection, with near-complete clearance at 96 h postinjection. Hyp-NP was shown to be tightly localized within necrotic tumor zones. Histological analysis of harvested organs demonstrated no gross abnormalities, and in vitro, no hemolysis was observed. This proof-of-concept study demonstrates the potential clinical applications of Hyp-NP for necrosis targeting.


Assuntos
Nanopartículas/química , Neoplasias/tratamento farmacológico , Imagem Óptica/métodos , Perileno/análogos & derivados , Animais , Antracenos , Linhagem Celular Tumoral , Feminino , Humanos , Camundongos , Necrose , Neoplasias/diagnóstico por imagem , Perileno/química , Perileno/farmacocinética , Perileno/farmacologia , Perileno/toxicidade
13.
Chem Commun (Camb) ; 55(84): 12667-12670, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31584046

RESUMO

We have synthesized symmetrical carbocyanine dyes in which two 4-quinolinium rings are joined by a pentamethine bridge that is meso-substituted with H or Cl. Irradiation of the halogenated dye at 830 nm produces hydroxyl radicals that generate DNA direct strand breaks. This represents the first reported example of DNA photocleavage upon single photon excitation of a chromophore at wavelengths above 800 nm.


Assuntos
Carbocianinas/química , Clivagem do DNA/efeitos da radiação , DNA/química , Corantes Fluorescentes/química , Quinolinas/química , Antineoplásicos/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Humanos , Radical Hidroxila/química , Raios Infravermelhos , Estrutura Molecular , Imagem Óptica , Processos Fotoquímicos , Fótons , Espectrometria de Fluorescência
14.
Theranostics ; 8(19): 5276-5288, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30555546

RESUMO

Muscle atrophy occurs during chronic diseases, resulting in diminished quality of life and compromised treatment outcomes. There is a high demand for therapeutics that increase muscle mass while abrogating the need for special dietary and exercise requirements. Therefore, we developed an efficient nanomedicine approach capable of increasing muscle mass. Methods: The therapy is based on nanoparticle-mediated delivery of follistatin messenger RNA (mRNA) to the liver after subcutaneous administration. The delivered mRNA directs hepatic cellular machinery to produce follistatin, a glycoprotein that increases lean mass through inhibition of negative regulators of muscle mass (myostatin and activin A). These factors are elevated in numerous disease states, thereby providing a target for therapeutic intervention. Results: Animal studies validated that mRNA-loaded nanoparticles enter systemic circulation following subcutaneous injection, accumulate and internalize in the liver, where the mRNA is translated into follistatin. Follistatin serum levels were elevated for 72 h post injection and efficiently reduced activin A and myostatin serum concentrations. After eight weeks of repeated injections, the lean mass of mice in the treatment group was ~10% higher when compared to that of the controls. Conclusion: Based on the obtained results demonstrating an increased muscle mass as well as restricted fat accumulation, this nanoplatform might be a milestone in the development of mRNA technologies and the treatment of muscle wasting disorders.


Assuntos
Portadores de Fármacos/administração & dosagem , Folistatina/genética , Fígado/metabolismo , Desenvolvimento Muscular/efeitos dos fármacos , Nanopartículas/administração & dosagem , RNA Mensageiro/administração & dosagem , Animais , Injeções Subcutâneas , Camundongos , Resultado do Tratamento
15.
Nanomedicine ; 14(4): 1395-1405, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29635082

RESUMO

Herein, we report an efficient combinatorial therapy for metastatic ovarian cancer based on siRNA-mediated suppression of DJ-1 protein combined with a low dose of cisplatin. DJ-1 protein modulates, either directly or indirectly, different oncogenic pathways that support and promote survival, growth, and invasion of ovarian cancer cells. To evaluate the potential of this novel therapy, we have engineered a cancer-targeted nanoplatform and validated that DJ-1 siRNA delivered by this nanoplatform after intraperitoneal injection efficiently downregulates the DJ-1 protein in metastatic ovarian cancer tumors and ascites. In vivo experiments revealed that DJ-1 siRNA monotherapy outperformed cisplatin alone by inhibiting tumor growth and increasing survival of mice with metastatic ovarian cancer. Finally, three cycles of siRNA-mediated DJ-1 therapy in combination with a low dose of cisplatin completely eradicated ovarian cancer tumors from the mice, and there was no cancer recurrence detected for the duration of the study, which lasted 35 weeks.


Assuntos
Antineoplásicos/uso terapêutico , Cisplatino/uso terapêutico , Neoplasias Ovarianas/tratamento farmacológico , Proteína Desglicase DJ-1/metabolismo , RNA Interferente Pequeno/genética , Animais , Antineoplásicos/administração & dosagem , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Cisplatino/administração & dosagem , Feminino , Humanos , Camundongos , Camundongos Nus , Neoplasias Ovarianas/genética , Proteína Desglicase DJ-1/genética
16.
Sci Rep ; 6: 31750, 2016 08 30.
Artigo em Inglês | MEDLINE | ID: mdl-27572704

RESUMO

2-Hydroxy-propyl-ß-cyclodextrin (HPßCD), a cholesterol scavenger, is currently undergoing Phase 2b/3 clinical trial for treatment of Niemann Pick Type C-1 (NPC1), a fatal neurodegenerative disorder that stems from abnormal cholesterol accumulation in the endo/lysosomes. Unfortunately, the extremely high doses of HPßCD required to prevent progressive neurodegeneration exacerbates ototoxicity, pulmonary toxicity and autophagy-based cellular defects. We present unexpected evidence that a poly (ethylene glycol) (PEG)-lipid conjugate enables cholesterol clearance from endo/lysosomes of Npc1 mutant (Npc1(-/-)) cells. Herein, we show that distearyl-phosphatidylethanolamine-PEG (DSPE-PEG), which forms 12-nm micelles above the critical micelle concentration, accumulates heavily inside cholesterol-rich late endosomes in Npc1(-/-) cells. This potentially results in cholesterol solubilization and leakage from lysosomes. High-throughput screening revealed that DSPE-PEG, in combination with HPßCD, acts synergistically to efflux cholesterol without significantly aggravating autophagy defects. These well-known excipients can be used as admixtures to treat NPC1 disorder. Increasing PEG chain lengths from 350 Da-30 kDa in DSPE-PEG micelles, or increasing DSPE-PEG content in an array of liposomes packaged with HPßCD, improved cholesterol egress, while Pluronic block copolymers capable of micelle formation showed slight effects at high concentrations. We postulate that PEG-lipid based nanocarriers can serve as bioactive drug delivery systems for effective treatment of lysosomal storage disorders.


Assuntos
Colesterol/metabolismo , Micelas , Doença de Niemann-Pick Tipo C/tratamento farmacológico , Fosfatidiletanolaminas/farmacologia , Polietilenoglicóis/farmacologia , Solventes/farmacologia , 2-Hidroxipropil-beta-Ciclodextrina/farmacologia , Animais , Células Cultivadas , Sinergismo Farmacológico , Fibroblastos/efeitos dos fármacos , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos Knockout , Modelos Biológicos , Proteína C1 de Niemann-Pick , Proteínas/genética
17.
Artigo em Inglês | MEDLINE | ID: mdl-26542891

RESUMO

The deployment of molecular to microscale carriers for intracellular delivery has tremendous potential for biology and medicine, especially for in vivo therapies. The field remains limited, however, by a poor understanding of how carriers gain access to the cell interior. In this review, we provide an overview of the different types of carriers, their speculated modes of entry, putative pathways of vesicular transport, and sites of endosomal escape. We compare this alongside pertinent examples from the cell biology of how viruses, bacteria, and their effectors enter cells and escape endosomal confinement. We anticipate insights into the mechanisms of cellular entry and endosomal escape will benefit future research efforts on effective carrier-mediated intracellular delivery. WIREs Nanomed Nanobiotechnol 2016, 8:465-478. doi: 10.1002/wnan.1377 For further resources related to this article, please visit the WIREs website.


Assuntos
Transporte Biológico , Portadores de Fármacos , Endossomos , Nanopartículas/química , Portadores de Fármacos/química , Portadores de Fármacos/metabolismo , Endossomos/química , Endossomos/metabolismo
18.
J Phys Chem C Nanomater Interfaces ; 116(10): 6320-6331, 2012 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-22822414

RESUMO

Age-related bone fragility fractures present a significant problem for public health. Measures of bone quality are increasingly recognized to complement the conventional bone mineral density (BMD) based assessment of fracture risk. The ability to probe and understand bone quality at the molecular level is desirable in order to unravel how the structure of organic matrix and its association with mineral contribute to the overall mechanical properties. The (13)C{(31)P} REDOR MAS NMR (Rotational Echo Double Resonance Magic Angle Spinning Nuclear Magnetic Resonance) technique is uniquely suited for the study of the structure of the organic-mineral interface in bone. For the first time, we have applied it successfully to analyze the structure of intact (non-powdered) human cortical bone samples, from young healthy and old osteoporotic donors. Loading problems associated with the rapid rotation of intact bone were solved using a Finite Element Analysis (FEA) approach, and a method allowing osteoporotic samples to be balanced and spun reproducibly is described. REDOR NMR parameters were set to allow insight into the arrangement of the amino acids at the mineral interface to be accessed, and SVD (Singular Value Decomposition) was applied to enhance the signal to noise ratio and enable a better analysis of the data. From the REDOR data, it was found that carbon atoms belonging to citrate/glucosaminoglycans (GAGs) are closest to the mineral surface regardless of age or site. In contrast, the arrangement of the collagen backbone at the interface varied with site and age. The relative proximity of two of the main amino acids in bone matrix proteins, hydroxyproline and alanine, with respect to the mineral phase was analyzed in more detail, and discussed in view of glycation measurements which were carried out on the tissues. Overall, this work shows that the (13)C{(31)P} REDOR NMR approach could be used as a complementary technique to assess a novel aspect of bone quality, the organic-mineral interface structure.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...