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1.
Ophthalmologe ; 116(2): 152-163, 2019 Feb.
Artículo en Alemán | MEDLINE | ID: mdl-29404677

RESUMEN

BACKGROUND: Ischemic processes usually lead to the destruction of retinal cells and therefore play a key role in a multitude of eye diseases. OBJECTIVE: The aim of this study was to investigate whether bisperoxovanadium has a potential neuroprotective effect in an ischemia/reperfusion animal model. MATERIAL AND METHODS: Initially, ischemia was induced in one eye of an ischemia/reperfusion model and 3 days later, a 14-day medication-based treatment was initiated. Bisperoxovanadium was administered intraperitoneally every 3 days. Subsequently, the number of ganglion cells, the rate of apoptosis, amacrine cells, macroglia, microglia, and their activation state, as well as photoreceptors were determined by histological and immunohistochemical analyses. RESULTS: In comparison to the control group, a significant retinal ganglion cell loss, a significant reduction of the inner layers as well as a decrease in photoreceptor and amacrine cell numbers could be determined in the ischemic eyes. In addition, there was an increase in the number of microglia in these animals. The rats treated with bisperoxovanadium did not exhibit a significant neuroprotective effect regarding the number of ganglion cells, the rate of apoptosis, macroglia, amacrine cells, or photoreceptors; however, a low structural degeneration of photoreceptors could be observed as an effect of the treatment. Additionally, fewer microglia and activated microglia were observed after bisperoxovanadium treatment. CONCLUSION: Bisperoxovanadium seems to have only a marginal neuroprotective effect on ischemic retinae. It needs to be examined whether earlier therapy onset, higher dose or different route of administration would significantly improve the results or whether this therapeutic approach is unsuitable.


Asunto(s)
Enfermedades de la Retina , Animales , Modelos Animales de Enfermedad , Isquemia , Ratas , Retina , Enfermedades de la Retina/tratamiento farmacológico , Células Ganglionares de la Retina , Compuestos de Vanadio
2.
Pathol Oncol Res ; 25(1): 391-399, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29143233

RESUMEN

Improved knowledge of retinoblastoma chemotherapy resistance is needed to raise treatment efficiency. The objective of this study was to test whether etoposide alters glucosyl-ceramide, ceramide, sphingosine, and sphingosine-1-phosphate (sphingosine-1-P) levels in parental retinoblastoma cells (WERI Rb1) or their etoposide-resistant subclones (WERI EtoR). WERI Rb1 and WERI EtoR were incubated with 400 ng/ml etoposide for 24 h. Levels of glucosyl-ceramides, ceramides, sphingosine, sphingosine-1-P were detected by Q-TOF mass spectrometry. Statistical analysis was done by ANOVA followed by Tukey post-hoc test (p < 0.05). The mRNA expression of sphingolipid pathways enzymes in WERI Rb1, WERI EtoR and four human retinoblastoma tissue samples was analyzed by quantitative real-time PCR. Pathways enzymes mRNA expression confirmed similarities of human sphingolipid metabolism in both cell lines and tissue samples, but different relative expression. Significant up-regulation of sphingosine was seen in both cell lines (p < 0.001). Only sphingosine-1-P up-regulation was significantly increased in WERI EtoR (p < 0.01), but not in WERI Rb1 (p > 0.2). Both cell lines upregulate pro-apoptotic sphingosine after etoposide incubation, but only WERI EtoR produces additional survival favorable sphingosine-1-P. These data may suggest a role of sphingosine-1-P in retinoblastoma chemotherapy resistance, although this seems not to be the only resistance mechanism.


Asunto(s)
Antineoplásicos Fitogénicos/farmacología , Supervivencia Celular , Resistencia a Antineoplásicos , Etopósido/farmacología , Lisofosfolípidos/metabolismo , Retinoblastoma/patología , Esfingosina/análogos & derivados , Proliferación Celular , Humanos , Retinoblastoma/tratamiento farmacológico , Retinoblastoma/metabolismo , Esfingosina/metabolismo , Células Tumorales Cultivadas
3.
Small ; 14(16): e1703338, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29356378

RESUMEN

Development of efficient, affordable, and sustainable energy storage technologies has become an area of interest due to the worsening environmental issues and rising technological dependence on Li-ion batteries. Na-ion batteries (NIBs) have been receiving intensive research efforts during the last few years. Owing to their potentially low cost and relatively high energy density, NIBs are promising energy storage devices, especially for stationary applications. A fundamental understanding of electrode properties during electrochemical reactions is important for the development of low cost, high-energy density, and long shelf life NIBs. This Review aims to summarize and discuss reaction mechanisms of the major types of NIB electrode materials reported. By appreciating how the material works and the fundamental flaws it possesses, it is hoped that this Review will assist readers in coming up with innovative solutions for designing better materials for NIBs.

4.
Klin Monbl Augenheilkd ; 235(5): 597-602, 2018 May.
Artículo en Alemán | MEDLINE | ID: mdl-28147407

RESUMEN

Dry eye disease is one of the most common diagnoses in ophthalmology. A variety of subjective and objective test methods with imprecise limits and highly different sensitivities and specificities complicate the diagnosis. Especially mild to moderate pathological findings can be misdiagnosed. In recent years, new options have opened, through the development of new, clinical practicable diagnostic equipment, for example, for the analysis of tear film osmolarity or matrix metalloproteinases (MMP-9). The value of tear film osmolarity and determination of MMP-9 levels in the diagnosis of dry eye and its subtypes will be discussed and evaluated objectively, on the basis of published study results.


Asunto(s)
Síndromes de Ojo Seco , Metaloproteinasa 9 de la Matriz/análisis , Metaloproteinasas de la Matriz , Síndromes de Ojo Seco/diagnóstico , Humanos , Concentración Osmolar , Sensibilidad y Especificidad , Lágrimas/química
5.
Ophthalmologe ; 114(10): 901-905, 2017 Oct.
Artículo en Alemán | MEDLINE | ID: mdl-28956127

RESUMEN

Physicians in German university hospitals feel themselves confronted with a multiple workload due to patient care, teaching and research. Furthermore, this load is increased by administrative duties and conference trips; however, the framework conditions surrounding this multiple workload of patient care, research and teaching as well as administrative activities are becoming increasingly more difficult. In particular, there is very little free time for scientific activities. Research is therefore often carried out during leisure time. The path of the clinician scientist, a duo of scientiific and clinical activities, opens up many possibilities; however, the question arises whether the career path of a clinician scientist is even possible under the current conditions or whether this is an endangered "species". This article presents the problems but solutions and ideas are also developed for optimum organization of this multiple workload and to appreciate the additional value of clinician scientists.


Asunto(s)
Investigación Biomédica/estadística & datos numéricos , Internado y Residencia/estadística & datos numéricos , Selección de Profesión , Curriculum , Alemania , Hospitales Universitarios , Humanos , Carga de Trabajo
6.
Exp Eye Res ; 155: 107-120, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-28089775

RESUMEN

In order to understand the pathological processes of retinal diseases, experimental models are necessary. Cobalt, as part of the vitamin B12 complex, is important for neuronal integrity. However, it is known that high quantities of cobalt induce cytotoxic mechanisms via hypoxia mimicry. Therefore, we tested the degenerative effect of cobalt chloride (CoCl2) on neurons and microglia in a porcine retina organ culture model. Organotypic cultures of porcine retinas were cultured and treated with different concentrations of CoCl2 (0, 100, 300 and 500 µM) for 48 h. After four and eight days, CoCl2 induced a strong degeneration of the porcine retina, starting at 300 µM. A loss of retinal ganglion cells (RGCs, Brn-3a), amacrine cells (calretinin) and bipolar cells (PKCα) was observed. Additionally, a high expression of hypoxia induced factor-1a (HIF-1a) and heat shock protein 70 (HSP70) was noted at both points in time. Also, the Caspase 3 protein was activated and P21 expression was induced. However, only at day four, the Bax/Bcl-2 ratio was increased. The effect of CoCl2 was not restricted to neurons. CoCl2 concentrations reduced the microglia amount (Iba1) and activity (Iba1 + Fcγ-Receptor) at both points in time. These damaging effects on microglia were surprising, since CoCl2 causes hypoxia and a pro-inflammatory environment. However, high concentrations of CoCl2 also seem to be toxic to these cells. Similar degenerative mechanisms as in comparison to retinal ischemia animal models were observed. In summary, an effective and reproducible hypoxia-mimicking organotypic model for retinal degeneration was established, which is easy to handle and ready for drug studies.


Asunto(s)
Cobalto/efectos adversos , Regulación de la Expresión Génica , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Microglía/patología , Degeneración Retiniana/inducido químicamente , Células Ganglionares de la Retina/metabolismo , Neuronas Retinianas/patología , Animales , Antimutagênicos/efectos adversos , Apoptosis , Western Blotting , Supervivencia Celular , Modelos Animales de Enfermedad , Subunidad alfa del Factor 1 Inducible por Hipoxia/biosíntesis , Inmunohistoquímica , Microglía/efectos de los fármacos , Microglía/metabolismo , Técnicas de Cultivo de Órganos , ARN/genética , Especies Reactivas de Oxígeno/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Degeneración Retiniana/metabolismo , Degeneración Retiniana/patología , Células Ganglionares de la Retina/efectos de los fármacos , Células Ganglionares de la Retina/patología , Neuronas Retinianas/efectos de los fármacos , Neuronas Retinianas/metabolismo , Porcinos
7.
Microb Biotechnol ; 9(6): 746-757, 2016 11.
Artículo en Inglés | MEDLINE | ID: mdl-27364994

RESUMEN

Microbial water quality monitoring for the presence of faecal indicator bacteria (FIB) is a mandatory activity in many countries and is key in public health protection. Despite technological advances and a need for methodological improvements, chromogenic and fluorogenic enzymatic techniques remain the mainstays of water quality monitoring for both public health agencies and regulated utilities. We demonstrated that bioelectroanalytical approaches to FIB enumeration are possible and can be achieved using commercially available enzyme-specific resorufin glycosides, although these are expensive, not widely available or designed for purpose. Following this, we designed two naphthoquinone glycosides which performed better, achieving Escherichia coli detection in the range 5.0 × 102 to 5.0 × 105 CFU ml-1 22-54% quicker than commercially available resorufin glycosides. The molecular design of the naphthoquinone glycosides requires fewer synthetic steps allowing them to be produced for as little as US$50 per kg. Tests with environmental samples demonstrated the low tendency for abiotic interference and that, despite specificity being maintained between ß-glucuronidase and ß-galactosidase, accurate enumeration of E. coli in environmental samples necessitates development of a selective medium. In comparison to a commercially available detection method, which has U.S. Environmental Protection Agency (EPA) approval, our approach performed better at high organism concentrations, detecting 500 organisms in 9 h compared with 13.5 h for the commercial method. Bioelectroanalytical detection is comparable to current approved methods and with further development could result in improved detection times. A recent trend for low-cost open-source hardware means that automated, potentiostatically controlled E. coli detection systems could be constructed for less than US$100 per channel.


Asunto(s)
Carga Bacteriana/métodos , Técnicas Electroquímicas/métodos , Escherichia coli/metabolismo , Glicósidos/metabolismo , Naftoquinonas/metabolismo , Microbiología del Agua , Glicósidos/síntesis química , Naftoquinonas/síntesis química , Sensibilidad y Especificidad , Factores de Tiempo , Estados Unidos
8.
Materials (Basel) ; 8(4): 1714-1728, 2015 Apr 13.
Artículo en Inglés | MEDLINE | ID: mdl-28788027

RESUMEN

Ganciclovir and valganciclor are antiviral agents used for the treatment of cytomegalovirus retinitis. The conventional method for administering ganciclovir in cytomegalovirus retinitis patients is repeated intravitreal injections. In order to obviate the possible detrimental effects of repeated intraocular injections, to improve compliance and to eliminate systemic side-effects, we investigated the tuning of the ganciclovir pro-drug valganciclovir and the release from thin films of poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL), or mixtures of both, as a step towards prototyping periocular valganciclovir implants. To investigate the drug release, we established and evaluated a high throughput fluorescence-based quantification screening assay for the detection of valganciclovir. Our protocol allows quantifying as little as 20 ng of valganciclovir in 96-well polypropylene plates and a 50× faster analysis compared to traditional HPLC measurements. This improvement can hence be extrapolated to other polyester matrix thin film formulations using a high-throughput approach. The acidic microenvironment within the polyester matrix was found to protect valganciclovir from degradation with resultant increases in the half-life of the drug in the periocular implant to 100 days. Linear release profiles were obtained using the pure polyester polymers for 10 days and 60 days formulations; however, gross phase separations of PCL and acid-terminated PLGA prevented tuning within these timeframes due to the phase separation of the polymer, valganciclovir, or both.

9.
Ophthalmologe ; 112(1): 41-8, 2015 Jan.
Artículo en Alemán | MEDLINE | ID: mdl-24942221

RESUMEN

BACKGROUND: Although an elevated intraocular pressure (IOP) is known as the main risk factor for glaucoma, many studies also showed an involvement of the immune system in this disease. In this study we investigated if a moderate increase in IOP leads to activation of the complement system. METHODS: The IOP was elevated experimentally in the left eye of rats, whereas the fellow eye served as the control. The IOP was measured at regular intervals. The number of retinal ganglion cells (RGC) was quantified via NeuN staining. To evaluate the activation of the complement system staining for C3, membrane attack complex (MAC), and mannose-binding lectin (MBL) was performed. Furthermore, we investigated possible glia activation (GFAP and vimentin) and apoptosis (Bax). RESULTS: A moderate elevation of the IOP was noted from day 11 after induction of ocular hypertension (OHT) until the end of the study (28 days, p = 0.0005). In the OHT-group significantly fewer RGCs (p = 0.02) were detected. Additionally, we noted significant C3 and MAC activation in the ganglion cell layer (C3, p = 0.001 and MAC, p = 0.02) as well as in the total retina (C3, p = 0.002 and MAC, p = 0.012). An activation via the lectin pathway by MBL staining could not be detected (p = 0.40). At this point in time no alterations with regard to glia cells were noted (GFAP, p = 0.97 and vimentin, p = 0.99). No apoptosis via Bax pathway could be observed (p = 0.90). CONCLUSION: The results suggest that the complement system is involved in the loss of RGCs even by a moderate IOP elevation which was indicated by significantly more C3 and MAC depositions in the OHT group.


Asunto(s)
Activación de Complemento/inmunología , Complejo de Ataque a Membrana del Sistema Complemento/inmunología , Hipertensión Ocular/inmunología , Hipertensión Ocular/patología , Células Ganglionares de la Retina/inmunología , Células Ganglionares de la Retina/patología , Animales , Masculino , Ratas , Ratas Endogámicas Lew
10.
Mol Pharm ; 11(7): 2182-9, 2014 Jul 07.
Artículo en Inglés | MEDLINE | ID: mdl-24842574

RESUMEN

Three-dimensional (3D) cell culture has become increasingly adopted as a more accurate model of the complex in vivo microenvironment compared to conventional two-dimensional (2D) cell culture. Multicellular spheroids are important 3D cell culture models widely used in biological studies and drug screening. To facilitate simple spheroid manipulation, magnetic spheroids were generated from magnetically labeled cells using a scaffold-free approach. This method is applicable to a variety of cell types. The spheroids generated can be targeted and immobilized using magnetic field gradients, allowing media change or dilution to be performed with minimal disruption to the spheroids. Cells in magnetic spheroids showed good viability and displayed typical 3D morphology. Using this platform, a 28 day study was carried out using doxorubicin on magnetic MCF-7 spheroids. The results provided a proof-of-principle for using magnetic tumor spheroids in therapeutic studies. They can offer beneficial insights that help to bridge the gap between in vitro and in vivo models. Furthermore, this platform can be adapted for high-throughput screening in drug discovery.


Asunto(s)
Técnicas de Cultivo de Célula/métodos , Evaluación Preclínica de Medicamentos/métodos , Magnetismo/métodos , Esferoides Celulares/fisiología , Antineoplásicos/farmacología , Línea Celular , Línea Celular Tumoral , Doxorrubicina/farmacología , Descubrimiento de Drogas/métodos , Células HCT116 , Células HEK293 , Células HeLa , Humanos , Células MCF-7 , Fenómenos Magnéticos , Esferoides Celulares/efectos de los fármacos
11.
Drug Discov Today ; 19(6): 714-24, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24239726

RESUMEN

The advances in strategies for bone and cartilage regeneration have been centered on a concept that describes the close relationship between osteogenic cells, osteoconductive scaffolds, delivery growth factors and the mechanical environment. The dynamic nature of the tissue repair process involves intricate mimicry of signals expressed in the biological system in response to an injury. Recently, synergistic strategies involving hybrid delivery systems that provide sequential dual delivery of biomolecules and relevant topological cues received great attention. Future advances in tissue regeneration will therefore depend on multidisciplinary strategies that encompass the crux of tissue repair aimed at constructing the ideal functional regenerative scaffold. Here, functional scaffolds delivering therapeutics are reviewed in terms of their controlled release and healing capabilities.


Asunto(s)
Regeneración Ósea/fisiología , Cartílago/fisiología , Portadores de Fármacos/administración & dosificación , Sistemas de Liberación de Medicamentos/métodos , Andamios del Tejido , Animales , Regeneración Ósea/efectos de los fármacos , Cartílago/efectos de los fármacos , Humanos , Polímeros/administración & dosificación , Regeneración/efectos de los fármacos , Regeneración/fisiología , Andamios del Tejido/tendencias
12.
J Mater Sci Mater Med ; 24(8): 2013-27, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23670603

RESUMEN

Mechanical properties of collagen films are less than ideal for biomaterial development towards musculoskeletal repair or cardiovascular applications. Herein, we present a collagen-cellulose composite film (CCCF) compared against swine small intestine submucosa in regards to mechanical properties, cell growth, and histological analysis. CCCF was additionally characterized by FE-SEM, NMR, mass spectrometry, and Raman Microscopy to elucidate its physical structure, collagen-cellulose composition, and structure activity relationships. Mechanical properties of the CCCF were tested in both wet and dry environments, with anisotropic stress-strain curves that mimicked soft-tissue. Mesenchymal stem cells, human umbilical vein endothelial cells, and human coronary artery smooth muscle cells were able to proliferate on the collagen films with specific cell orientation. Mesenchymal stem cells had a higher proliferation index and were able to infiltrate CCCF to a higher degree than small intestine submucosa. With the underlying biological properties, we present a collagen-cellulose composite film towards forthcoming biomaterial-related applications.


Asunto(s)
Celulosa/química , Colágeno/química , Tejido Conectivo , Membranas Artificiales , Células Madre Mesenquimatosas/fisiología , Animales , Materiales Biomiméticos/síntesis química , Materiales Biomiméticos/química , Materiales Biomiméticos/farmacología , Polaridad Celular/efectos de los fármacos , Polaridad Celular/fisiología , Células Cultivadas , Celulosa/farmacología , Colágeno/farmacología , Células Endoteliales de la Vena Umbilical Humana/citología , Células Endoteliales de la Vena Umbilical Humana/efectos de los fármacos , Células Endoteliales de la Vena Umbilical Humana/fisiología , Humanos , Ensayo de Materiales , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/efectos de los fármacos , Ratones , Nanofibras/química , Ingeniería de Tejidos/instrumentación , Ingeniería de Tejidos/métodos , Andamios del Tejido/química
13.
Adv Healthc Mater ; 2(11): 1430-4, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23606526

RESUMEN

Magnetic spheroid manipulation can be carried out in hanging drops to generate distinctly structured heterotypic microtissues through sequential addition of cells or spheroid to homotypic spheroids. These spheroids can also be incorporated in a droplet-based assay to screen for therapeutic efficacy in prolonged studies. This simple and versatile technique can offer potential benefits in tissue engineering and drug screening applications.


Asunto(s)
Evaluación Preclínica de Medicamentos/métodos , Fenómenos Magnéticos , Esferoides Celulares/citología , Ingeniería de Tejidos/métodos , Células HEK293 , Humanos , Células Tumorales Cultivadas
14.
Acta Biomater ; 8(6): 2263-70, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22293582

RESUMEN

Pure polymer films cannot meet the diverse range of controlled release and material properties demanded for the fabrication of medical implants or other devices. Additives are added to modulate and optimize thin films for the desired qualities. To characterize the property trends that depend on additive concentration, an assay was designed which involved casting a single polyester poly(lactic-co-glycolic acid) (PLGA) film that blends a linear gradient of any PLGA-soluble additive desired. Four gradient PLGA films were produced by blending polyethylene glycol or the more hydrophobic polypropylene glycol. The films were made using a custom glass gradient maker in conjunction with a 180 cm film applicator. These films were characterized in terms of thickness, percent additive, total polymer (PLGA+additive), and controlled drug release using drug-like fluorescent molecules such as coumarin 6 (COU) or fluorescein diacetate (FDAc). Material properties of elongation and modulus were also accessed. Linear gradients of additives were readily generated, with phase separation being the limiting factor. Additive concentration had a Pearson's correlation factor (R) of >0.93 with respect to the per cent total release after 30 days for all gradients characterized. Release of COU had a near zero-order release over the same time period, suggesting that coumarin analogs may be suitable for use in PLGA/polyethylene glycol or PLGA/polypropylene glycol matrices, with each having unique material properties while allowing tuneable drug release. The gradient casting method described has considerable potential in offering higher throughput for optimizing film or coating material properties for medical implants or other devices.


Asunto(s)
Ácido Láctico , Ácido Poliglicólico , Colorantes Fluorescentes/química , Espectroscopía de Resonancia Magnética , Copolímero de Ácido Poliláctico-Ácido Poliglicólico
15.
Biomaterials ; 32(32): 8218-25, 2011 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-21807406

RESUMEN

In this paper, we explored how ZnO nanoparticles cross-interact with a critical tumor suppressive pathway centered around p53, which is one of the most important known tumor suppressors that protects cells from developing cancer phenotypes through its control over major pathways like apoptosis, senescence and cell cycle progression. We showed that the p53 pathway was activated in BJ cells (skin fibroblasts) upon ZnO nanoparticles treatment with a concomitant decrease in cell numbers. This suggests that cellular responses like apoptosis in the presence of ZnO nanoparticles require p53 as the molecular master switch towards programmed cell death. This also suggests that in cells without robust p53, protective response can be tipped towards carcinogenesis when stimulated by DNA damage inducing agents like ZnO nanoparticles. We observed this precarious tendency in the same BJ cells with p53 knocked down using endogeneous expressing shRNA. These p53 knocked down BJ cells became more resistant to ZnO nanoparticles induced cell death and increased cell progression. Collectively, our results suggest that cellular response towards specific nanoparticle induced cell toxicity and carcinogenesis is not only dependent on specific nanoparticle properties but also (perhaps more importantly) the endogenous genetic, transcriptomic and proteomic landscape of the target cells.


Asunto(s)
Daño del ADN , Nanopartículas/toxicidad , Transducción de Señal/efectos de los fármacos , Proteína p53 Supresora de Tumor/metabolismo , Óxido de Zinc/toxicidad , Animales , Muerte Celular/efectos de los fármacos , Línea Celular , Humanos , Ratones , Modelos Biológicos , Mutágenos/toxicidad , Nanopartículas/ultraestructura
16.
ACS Nano ; 5(8): 6410-6, 2011 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-21761867

RESUMEN

Inhaled nanoparticles (NPs) must first interact with the pulmonary surfactant (PS) lining layer that covers the entire internal surface of the respiratory tract and plays an important role in surface tension reduction and host defense. Interactions with the PS film determine the subsequent clearance, retention, and translocation of the inhaled NPs and hence their potential toxicity. To date, little is known how NPs interact with PS, and whether or not NPs have adverse effects on the biophysical function of PS. We found a time-dependent toxicological effect of hydroxyapatite NPs (HA-NPs) on a natural PS, Infasurf, and the time scale of surfactant inhibition after particle exposure was comparable to the turnover period of surfactant metabolism. Using a variety of in vitro biophysicochemical characterization techniques, we have determined the inhibition mechanism to be due to protein adsorption onto the HA-NPs. Consequently, depletion of surfactant proteins from phospholipid vesicles caused conversion of original large vesicles into much smaller vesicles with poor surface activity. These small vesicles, in turn, inhibited biophysical function of surfactant films after adsorption at the air-water interface. Cytotoxicity study found that the HA-NPs at the studied concentration were benign to human bronchial epithelial cells, thereby highlighting the importance of evaluating biophysical effect of NPs on PS. The NP-PS interaction mechanism revealed by this study may not only provide new insight into the toxicological study of nanoparticles but also shed light on the feasibility of NP-based pulmonary drug delivery.


Asunto(s)
Productos Biológicos , Fenómenos Biofísicos/efectos de los fármacos , Durapatita/efectos adversos , Durapatita/química , Nanopartículas/efectos adversos , Surfactantes Pulmonares , Pruebas de Toxicidad , Adsorción/efectos de los fármacos , Productos Biológicos/química , Productos Biológicos/metabolismo , Bronquios/citología , Supervivencia Celular/efectos de los fármacos , Citotoxinas/efectos adversos , Citotoxinas/química , Células Epiteliales/citología , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Células Epiteliales/ultraestructura , Humanos , Fosfolípidos/química , Fosfolípidos/metabolismo , Proteína B Asociada a Surfactante Pulmonar/química , Proteína B Asociada a Surfactante Pulmonar/metabolismo , Proteína C Asociada a Surfactante Pulmonar/química , Proteína C Asociada a Surfactante Pulmonar/metabolismo , Surfactantes Pulmonares/química , Surfactantes Pulmonares/metabolismo , Propiedades de Superficie
17.
J Pharm Sci ; 100(10): 4317-29, 2011 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-21607953

RESUMEN

Hydrophobic, antirestenotic drugs such as paclitaxel (PCTX) and rapamycin are often incorporated into thin film coatings for local delivery using implantable medical devices and polymers such as drug-eluting stents and balloons. Selecting the optimum coating formulation through screening the release profile of these drugs in thin films is time consuming and labor intensive. We describe here a high-throughput assay utilizing three model hydrophobic fluorescent compounds: fluorescein diacetate (FDAc), coumarin-6, and rhodamine 6G that were incorporated into poly(d,l-lactide-co-glycolide) (PLGA) and PLGA-polyethylene glycol films. Raman microscopy determined the hydrophobic fluorescent dye distribution within the PLGA thin films in comparison with that of PCTX. Their subsequent release was screened in a high-throughput assay and directly compared with HPLC quantification of PCTX release. It was observed that PCTX controlled-release kinetics could be mimicked by a hydrophobic dye that had similar octanol-water partition coefficient values and homogeneous dissolution in a PLGA matrix as the drug. In particular, FDAc was found to be the optimal hydrophobic dye at modeling the burst release as well as the total amount of PCTX released over a period of 30 days.


Asunto(s)
Fármacos Cardiovasculares/química , Materiales Biocompatibles Revestidos , Portadores de Fármacos , Colorantes Fluorescentes/química , Ensayos Analíticos de Alto Rendimiento , Ácido Láctico/química , Paclitaxel/química , Ácido Poliglicólico/química , Tecnología Farmacéutica/métodos , Fármacos Cardiovasculares/administración & dosificación , Química Farmacéutica , Cromatografía Líquida de Alta Presión , Cumarinas/química , Preparaciones de Acción Retardada , Fluoresceínas/química , Interacciones Hidrofóbicas e Hidrofílicas , Cinética , Espectroscopía de Resonancia Magnética , Microscopía , Microscopía Electrónica de Rastreo , Estructura Molecular , Paclitaxel/administración & dosificación , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Rodaminas/química , Solubilidad , Espectrometría de Fluorescencia , Espectrometría Raman , Propiedades de Superficie , Tiazoles/química
18.
Acta Biomater ; 7(5): 1973-83, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21300188

RESUMEN

Thin films of poly(lactic acid-co-glycolic acid) (PLGA) incorporating paclitaxel typically have slow release rates of paclitaxel of the order of 1 µg day(-1) cm(-2). For implementation as medical devices a range of zero order release rates (i.e. 1-15 µg day(-1) cm(-2)) is desirable for different tissues and pathologies. Eight and 35 kDa molecular weight polyethylene glycol (PEG) was incorporated at 15%, 25% and 50% weight ratios into PLGA containing 10 wt.% paclitaxel. The mechanical properties were assessed for potential use as medical implants and the rates of release of paclitaxel were quantified as per cent release and the more clinically useful rate of release in µg day(-1) cm(-2). Paclitaxel quantitation was correlated with the release of PEG from PLGA, to further understand its role in paclitaxel/PLGA release modulation. PEG release was found to correlate with paclitaxel release and the level of crystallinity of the PEG in the PLGA film, as measured by Raman spectrometry. This supports the concept of using a phase separating, partitioning compound to increase the release rates of hydrophobic drugs such as paclitaxel from PLGA films, where paclitaxel is normally homogeneously distributed/dissolved. Two formulations are promising for medical device thin films, when optimized for tensile strength, elongation, and drug release. For slow rates of paclitaxel release an average of 3.8 µg day(-1) cm(-2) using 15% 35k PEG for >30 days was achieved, while a high rate of drug release of 12 µg day(-1) cm(-2) was maintained using 25% 8 kDa PEG for up to 12 days.


Asunto(s)
Sistemas de Liberación de Medicamentos , Ácido Láctico/química , Fenómenos Mecánicos/efectos de los fármacos , Paclitaxel/farmacología , Polietilenglicoles/química , Ácido Poliglicólico/química , Interacciones Hidrofóbicas e Hidrofílicas/efectos de los fármacos , Microscopía Electrónica de Rastreo , Peso Molecular , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Espectrometría Raman , Propiedades de Superficie/efectos de los fármacos , Agua
19.
Curr Eye Res ; 35(11): 1034-9, 2010 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-20958192

RESUMEN

PURPOSE: The TonoPen applanation tonometry is an established method for intraocular pressure (IOP) measurement. The IOP is one of the main variables affecting retinal ganglion cell (RGC) loss in experimental animal models in ophthalmology and the main risk factor for human glaucoma. In this study, we examined if IOP measurements with the TonoPen itself lead to retinal ganglion cell loss or any other possible retina damages, such as intraocular bleedings or ablation, in Lewis rats. METHODS: Three groups of rats (n = 5 each) were formed. IOP monitoring, using a TonoPen XL, was performed on groups 1 and 3. Animals in groups 1 and 2 received funduscopies before and after one and two weeks of the study, in order to detect possible abnormalities. After two weeks, retinal flatmounts were stained to detect ganglion cells. RGCs were manually counted in eight predefined areas to compare mean RGC densities between groups 1 and 2 (IOP readings vs. no readings), using student t-test. RESULTS: No significant difference in RGC density between animals that underwent IOP readings and controls could be observed (p = 0.8). As expected, no IOP alterations were monitored in groups 1 and 3 throughout the study. No retinal abnormalities, such as bleeding or retina ablation, were detectable. CONCLUSION: We could detect no effects on retinal ganglion cell survival in Lewis rats or any other damages to the retina caused by IOP measurements using a TonoPen XL. This study proposes that repeated applanation tonometry does not affect RGC numbers, one of the main monitored variables in most glaucoma model studies. Therefore, the use of a TonoPen XL for repeated IOP monitoring in Lewis rats can be considered harmless.


Asunto(s)
Presión Intraocular/fisiología , Células Ganglionares de la Retina/citología , Tonometría Ocular , Animales , Recuento de Células , Supervivencia Celular , Masculino , Ratas , Ratas Endogámicas Lew
20.
Curr Eye Res ; 35(10): 900-8, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20858111

RESUMEN

PURPOSE: Antibodies against heat shock proteins have been identified in sera of human glaucoma patients in several studies and immunization with heat shock protein 60 (HSP 60) causes retinal ganglion cell (RGC) loss in an animal model of experimental autoimmune glaucoma. The aim of this study was to observe the time course of increased anti-retina antibody appearance in the serum and characterize the identification of prominent autoantibodies that accompany HSP 60 immunization in a rat model of experimental autoimmune glaucoma. METHODS: Eight weeks after immunization with HSP 60 retinal flatmounts were prepared and RGCs were counted in eight predefined areas and compared to controls. Serum collected before, as well as four and eight weeks after, immunization was used to detect antibody patterns against bovine retinal antigens using Western blotting techniques. These patterns were analyzed by multivariate statistical methods. Autoantibodies that were prominently increased were further identified through mass spectrometry. Intraocular pressure was measured throughout the study. RESULTS: After eight weeks, animals immunized with HSP 60 showed significant RGC loss of retinal flatmounts (P = 0.02), which was intraocular pressure independent. Early changes in antibody profiles, many of them significant upregulations, were detected. Antigens with significantly upregulated antibody reactivity after four weeks were identified as histone H2B type 1, S-arrestin, glial fibrillary acidic protein, vimentin, and heat shock protein 60. These upregulated autoantibodies returned to normal levels four weeks following their initial upregulation. Antibodies against retinaldehyde binding protein 1 on the other hand became upregulated after eight weeks. CONCLUSION: This is the first study to identify the appearance and disappearance of retinal autoantibodies in the serum of rats at several time-points following their initial upregulation in response to HSP 60 immunization in a model of experimental autoimmune glaucoma.


Asunto(s)
Autoanticuerpos/sangre , Enfermedades Autoinmunes/inmunología , Chaperonina 60/inmunología , Glaucoma/inmunología , Inmunización , Animales , Enfermedades Autoinmunes/sangre , Enfermedades Autoinmunes/patología , Regulación hacia Abajo , Glaucoma/sangre , Glaucoma/patología , Masculino , Ratas , Ratas Endogámicas Lew , Retina/inmunología , Células Ganglionares de la Retina/patología , Factores de Tiempo , Regulación hacia Arriba
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