Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 43
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
J Fish Biol ; 100(5): 1171-1186, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35184288

RESUMEN

Several hundred catfish species (order: Siluriformes) belonging to 11 families inhabit Africa, of which at least six families are endemic to the continent. Although four of those families are well-known to belong to the 'Big-Africa clade', no previous study has addressed the phylogenetic placement of the endemic African catfish family Austroglanididae in a comprehensive framework with molecular data. Furthermore, interrelationships within the 'Big-Africa clade', including the most diverse family Mochokidae, remain unclear. This study was therefore designed to help reconstruct inter- and intrarelationships of all currently valid mochokid genera, to infer their position within the 'Big Africa clade' and to establish a first molecular phylogenetic hypothesis of the relationships of the enigmatic Austroglanididae within the Siluriformes. We assembled a comprehensive mitogenomic dataset comprising all protein coding genes and representing almost all recognized catfish families (N = 33 of 39) with carefully selected species (N = 239). We recovered the monophyly of the previously identified multifamily clades 'Big Asia' and 'Big Africa' and determined Austroglanididae to be closely related to Pangasiidae, Ictaluroidea and Ariidae. Mochokidae was recovered as the sister group to a clade encompassing Auchenoglanididae, Claroteidae, Malapteruridae and the African Schilbeidae, albeit with low statistical support. The two mochokid subfamilies Mochokinae and Chiloglanidinae as well as the chiloglanid tribe Atopochilini were recovered as reciprocally monophyletic. The genus Acanthocleithron forms the sister group of all remaining Mochokinae, although with low support. The genus Atopodontus is the sister group of all remaining Atopochilini. In contrast to morphological reconstructions, the monophyly of the genus Chiloglanis was strongly supported in our analysis, with Chiloglanis macropterus nested within a Chiloglanis sublineage encompassing only other taxa from the Congo drainage. This is an important result because the phylogenetic relationships of C. macropterus have been controversial in the past, and because we and other researchers assumed that this species would be resolved as sister to most or all other members of Chiloglanis. The apparent paraphyly of Synodontis with respect to Microsynodontis provided an additional surprise, with Synodontis punu turning out to be the sister group of the latter genus.


Asunto(s)
Bagres , África , Animales , Asia , Congo , Filogenia , Análisis de Secuencia de ADN
2.
Eur J Oper Res ; 291(1): 379-393, 2021 May 16.
Artículo en Inglés | MEDLINE | ID: mdl-33041471

RESUMEN

In this work, we investigate the challenges public-sector organizations face when seeking to leverage prescriptive analytics and provide insights into the public value such data-driven tools and methods can provide. Using the strategic triangle of value, legitimacy, and operational capacity as a starting point, we derive a framework to assess public-sector prescriptive analytics initiatives, along with six guiding questions that structure the assessment process. We present a case study applying prescriptive analytics to the placement of charge points in urban areas, a critical challenge many municipalities are currently facing in the transition towards electric mobility. Reflecting on the analytics application as well as its development and implementation process through the guiding questions, we derive key lessons for public-sector organizations seeking to apply prescriptive analytics.

3.
Dev Psychobiol ; 58(1): 17-26, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26248474

RESUMEN

Both Williams syndrome (WS) and autism spectrum disorders (ASD) are associated with unusual auditory phenotypes with respect to processing vocal and musical stimuli, which may be shaped by the atypical social profiles that characterize the syndromes. Autonomic nervous system (ANS) reactivity to vocal and musical emotional stimuli was examined in 12 children with WS, 17 children with ASD, and 20 typically developing (TD) children, and related to their level of social functioning. The results of this small-scale study showed that after controlling for between-group differences in cognitive ability, all groups showed similar emotion identification performance across conditions. Additionally, in ASD, lower autonomic reactivity to human voice, and in TD, to musical emotion, was related to more normal social functioning. Compared to TD, both clinical groups showed increased arousal to vocalizations. A further result highlighted uniquely increased arousal to music in WS, contrasted with a decrease in arousal in ASD and TD. The ASD and WS groups exhibited arousal patterns suggestive of diminished habituation to the auditory stimuli. The results are discussed in the context of the clinical presentation of WS and ASD.


Asunto(s)
Trastorno del Espectro Autista/psicología , Sistema Nervioso Autónomo/fisiopatología , Emociones/fisiología , Música , Ajuste Social , Síndrome de Williams/psicología , Estimulación Acústica , Adolescente , Nivel de Alerta/fisiología , Trastorno del Espectro Autista/fisiopatología , Niño , Expresión Facial , Femenino , Humanos , Masculino , Percepción Social , Habla/fisiología , Síndrome de Williams/fisiopatología
4.
J Microencapsul ; 30(7): 667-73, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23448182

RESUMEN

For the treatment of glioblastoma multiforme, an "anticancer drug cocktail" delivered by biodegradable poly-lactide-co-glycolide (PLGA)-microspheres is proposed. Celecoxib, etoposide, and elacridar were encapsulated by an oil/water emulsification solvent evaporation method. Drug-loaded microspheres were analyzed for their physicochemical properties and evaluated in a rat glioblastoma model. Microspheres had a mean diameter 10-20 µm, and encapsulation rates varied upon lipophilicity of the drug (celecoxib: 97.4 ± 0.4%; elacridar: 98.1 ± 0.3%; and etoposide: 38.7 ± 8.3%). Drug release of celecoxib and elacridar resulted in a burst (t50: 3.1 h and 1.0 h, respectively) while etoposide release was slower (t50: 45.3 h). The comparison of celecoxib (p = 0.021) and etoposide microspheres (p = 0.002) as well as their combination (p = 0.011) led to a significant increase in the probability of survival compared to blank microspheres. Local delivery of celecoxib and etoposide microspheres was found to be suitable for the treatment of glioblastoma in rats although simultaneous drug administration did not improve the therapeutic outcome.


Asunto(s)
Acridinas/administración & dosificación , Antineoplásicos Fitogénicos/administración & dosificación , Inhibidores de la Ciclooxigenasa 2/administración & dosificación , Etopósido/administración & dosificación , Glioblastoma/tratamiento farmacológico , Pirazoles/administración & dosificación , Sulfonamidas/administración & dosificación , Tetrahidroisoquinolinas/administración & dosificación , Acridinas/uso terapéutico , Animales , Antineoplásicos Fitogénicos/uso terapéutico , Celecoxib , Inhibidores de la Ciclooxigenasa 2/uso terapéutico , Portadores de Fármacos/química , Etopósido/uso terapéutico , Ácido Láctico/química , Masculino , Microesferas , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico-Ácido Poliglicólico , Pirazoles/uso terapéutico , Ratas , Ratas Endogámicas F344 , Sulfonamidas/uso terapéutico , Tetrahidroisoquinolinas/uso terapéutico
5.
Science ; 381(6665): eade2833, 2023 09 29.
Artículo en Inglés | MEDLINE | ID: mdl-37769075

RESUMEN

Although some lineages of animals and plants have made impressive adaptive radiations when provided with ecological opportunity, the propensities to radiate vary profoundly among lineages for unknown reasons. In Africa's Lake Victoria region, one cichlid lineage radiated in every lake, with the largest radiation taking place in a lake less than 16,000 years old. We show that all of its ecological guilds evolved in situ. Cycles of lineage fusion through admixture and lineage fission through speciation characterize the history of the radiation. It was jump-started when several swamp-dwelling refugial populations, each of which were of older hybrid descent, met in the newly forming lake, where they fused into a single population, resuspending old admixture variation. Each population contributed a different set of ancient alleles from which a new adaptive radiation assembled in record time, involving additional fusion-fission cycles. We argue that repeated fusion-fission cycles in the history of a lineage make adaptive radiation fast and predictable.


Asunto(s)
Adaptación Biológica , Cíclidos , Especiación Genética , Lagos , Animales , Cíclidos/clasificación , Cíclidos/genética , Filogenia , África Oriental
6.
Exp Dermatol ; 21(3): 233-5, 2012 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-22379974

RESUMEN

For finite dose skin absorption experiments, a homogeneous donor distribution over the skin surface is usually assumed. However, the influence of the surface distribution on skin absorption is still unknown. The aim of this study was to evaluate the influence of the application area on the permeation of drugs during finite dose skin absorption experiments in static Franz diffusion cells. Permeation experiments with stained aqueous drug formulations were conducted, and the application area was determined by a suitable, objective, automated computational approach. The permeation of caffeine is strongly dependent on the application area. The variability between single experiments decreased when including the application area. For the lipophilic flufenamic acid, this was not the case. The variability highly increased after inclusion of the application area. Thus, a correction of the area is misleading. In summary, depending on the drug's physicochemical characteristics, the application area may influence skin absorption.


Asunto(s)
Cafeína/farmacocinética , Ácido Flufenámico/farmacocinética , Absorción Cutánea/fisiología , Piel/metabolismo , Administración Cutánea , Humanos , Permeabilidad
7.
J Comput Chem ; 31(9): 1911-8, 2010 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-20082382

RESUMEN

We present a Lamarckian genetic algorithm (LGA) variant for flexible ligand-receptor docking which allows to handle a large number of degrees of freedom. Our hybrid method combines a multi-deme LGA with a recently published gradient-based method for local optimization of molecular complexes. We compared the performance of our new hybrid method to two non gradient-based search heuristics on the Astex diverse set for flexible ligand-receptor docking. Our results show that the novel approach is clearly superior to other LGAs employing a stochastic optimization method. The new algorithm features a shorter run time and gives substantially better results, especially with increasing complexity of the ligands. Thus, it may be used to dock ligands with many rotatable bonds with high efficiency.


Asunto(s)
Algoritmos , Modelos Genéticos , Proteínas/química , Simulación por Computador , Ligandos , Conformación Proteica , Proteínas/metabolismo
8.
Radiat Oncol ; 15(1): 183, 2020 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-32727533

RESUMEN

BACKGROUND: To evaluate 106Ruthenium Brachytherapy in management of medium sized uveal melanoma, with emphasis on 5-year outcome and toxicity. METHODS: From April 2007 to October 2015, 39 patients with medium sized uveal melanoma were treated with 106 Ru eye plaques brachytherapy. At the time of diagnosis, the mean tumor depth was 3.7 mm (±SD:1.6 mm). The mean dose at the tumor apex was 141.4 Gy (± SD: 12.1 Gy) and 557.7 Gy (± SD: 257.3 Gy) to the sclera. RESULTS: Mean follow-up was 69.5 months (± SD: 53.8 months). Thirty-four patients (87.1%) remained free of recurrence. Twenty-six patients (66.7%) demonstrated a complete tumor regression after a median period of 12 months (3-60 mon.). By the final examination, the visual acuity of 26 patients (66.7%) was better than 20/200, and 12 patients (30.7%) had a visual acuity better than 20/40. Retinopathy was detected in 11 patients (28.2%). After treatments only one patient (5.1%) had active vascular changes by the last examination. Moderate optic neuropathy was observed in 4 patients (10.3%). Cataract development was diagnosed in 21 patients (53.8%), and 16 patients (41%) had bilateral cataract development. Special emphasis was made on patients with larger tumors. Twelve out of the 39 patients had a tumor with a depth of 5 mm or more. There was no significant difference in local control or in side effects between both groups observed. CONCLUSIONS: Our study proved 106Ru -brachytherapy to be an excellent treatment option with regard to tumor control and preservation of the visual acuity in well-selected patients. Our data suggested that this treatment is also suitable for tumors with a depth of more than 5 mm.


Asunto(s)
Braquiterapia/métodos , Melanoma/radioterapia , Rutenio/uso terapéutico , Neoplasias de la Úvea/radioterapia , Adulto , Anciano , Anciano de 80 o más Años , Braquiterapia/efectos adversos , Femenino , Humanos , Masculino , Melanoma/patología , Persona de Mediana Edad , Dosificación Radioterapéutica , Neoplasias de la Úvea/patología , Agudeza Visual
9.
J Comput Chem ; 30(9): 1371-8, 2009 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-19031415

RESUMEN

We present a novel method for the local optimization of molecular complexes. This new approach is especially suited for usage in molecular docking. In molecular modeling, molecules are often described employing a compact representation to reduce the number of degrees of freedom. This compact representation is realized by fixing bond lengths and angles while permitting changes in translation, orientation, and selected dihedral angles. Gradient-based energy minimization of molecular complexes using this representation suffers from well-known singularities arising during the optimization process. We suggest an approach new in the field of structure optimization that allows to employ gradient-based optimization algorithms for such a compact representation. We propose to use exponential mapping to define the molecular orientation which facilitates calculating the orientational gradient. To avoid singularities of this parametrization, the local minimization algorithm is modified to change efficiently the orientational parameters while preserving the molecular orientation, i.e. we perform well-defined jumps on the objective function. Our approach is applicable to continuous, but not necessarily differentiable objective functions. We evaluated our new method by optimizing several ligands with an increasing number of internal degrees of freedom in the presence of large receptors. In comparison to the method of Solis and Wets in the challenging case of a non-differentiable scoring function, our proposed method leads to substantially improved results in all test cases, i.e. we obtain better scores in fewer steps for all complexes.


Asunto(s)
Simulación por Computador , Modelos Químicos , Algoritmos , Ligandos , Teoría Cuántica
10.
Pharm Res ; 26(6): 1379-97, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19240984

RESUMEN

PURPOSE: To investigate mechanisms of compound-corneocyte interactions in a combined experimental and theoretical approach. MATERIALS AND METHODS: Experimental methods are presented to investigate compound-corneocyte interactions in terms of dissolution within water of hydration and protein binding and to quantify the extent of the concurrent mechanisms. Results are presented for three compounds: caffeine, flufenamic acid, and testosterone. Two compartmental stratum corneum models M1 and M2 are formulated based on experimentally determined input parameters describing the affinity to lipid, proteins and water. M1 features a homogeneous protein compartment and considers protein interactions only via intra-corneocyte water. In M2 the protein compartment is sub-divided into a cornified envelope compartment interacting with inter-cellular lipids and a keratin compartment interacting with water. RESULTS: For the non-protein binding caffeine the impact of the aqueous compartment on stratum corneum partitioning is overestimated but is successfully modeled after introducing a bound water fraction that is non-accessible for compound dissolution. For lipophilic, keratin binding compounds (flufenamic acid, testosterone) only M2 correctly predicts a concentration dependence of stratum corneum partition coefficients. CONCLUSIONS: Lipophilic and hydrophilic compounds interact with corneocytes. Interactions of lipophilic compounds are probably confined to the corneocyte surface. Interactions with intracellular keratin may be limited by their low aqueous solubility.


Asunto(s)
Cafeína/farmacocinética , Células Epidérmicas , Epidermis/metabolismo , Ácido Flufenámico/farmacocinética , Testosterona/farmacocinética , Transporte Biológico , Cafeína/metabolismo , Epidermis/química , Femenino , Ácido Flufenámico/metabolismo , Humanos , Queratinas/análisis , Queratinas/metabolismo , Lípidos/análisis , Modelos Biológicos , Unión Proteica , Absorción Cutánea , Solubilidad , Testosterona/metabolismo , Agua/análisis , Agua/metabolismo
11.
Mol Immunol ; 45(5): 1308-17, 2008 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-17964653

RESUMEN

House dust mite allergy occurs in 10-20% of the population. Improvement of the present immunotherapy requires detailed knowledge about the structure of the allergens. Mimotopes selected from phage peptide libraries imitate the conformational epitopes of a natural allergen. The aim of our study was to generate epitope mimics for the two major allergens of house dust mite. When the monoclonal anti-Der p 1 and anti-Der p 2 antibodies were used for biopannings, mimotopes were selected which bound also specific IgE from human allergic patients' sera. The conformational matching of these mimotopes on the 3D structure of the natural allergens determined discontinuous epitopes in both cases, representing conformational B-cell epitopes relevant for binding of human IgE. Therefore, these mimotopes are potential candidates for the directed induction of blocking antibodies and epitope-specific immunotherapy of mite allergy.


Asunto(s)
Antígenos Dermatofagoides/inmunología , Epítopos de Linfocito B/inmunología , Imitación Molecular , Animales , Proteínas de Artrópodos , Cisteína Endopeptidasas , Humanos , Hipersensibilidad/terapia , Inmunoglobulina E/metabolismo , Inmunoterapia , Biblioteca de Péptidos , Conformación Proteica
12.
Eur J Pharm Biopharm ; 141: 111-120, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31100430

RESUMEN

The number of models for assessing the solubility of active pharmaceutical ingredients (APIs) in polymeric matrices on the one hand and the extent of available associated data on the other hand has been rising steadily in the past few years. However, according to our knowledge an overview on the methods used for prediction and the respective experimental data is missing. Therefore, we compiled experimental data, the techniques used for their determination and the models used for estimating the solubility. Our focus was on polymers commonly used in spray drying and hot-melt extrusion to form amorphous solid dispersions (ASDs), namely polyvinylpyrrolidone grades (PVP), polyvinyl acetate (PVAc), vinylpyrrolidone-vinyl acetate copolymer (copovidone, COP), polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft polymer (Soluplus®, SOL), different types of methacrylate copolymers (PMMA), polyethylene glycol grades (PEG) and hydroxypropyl-methylcellulose grades (HPMC). The literature data were further supplemented by our own results. The final data set included 37 APIs and two sugar derivatives. The majority of the prediction models was constituted by the melting point depression method, dissolution endpoint measurements, indirect solubility determination by Tg and the use of low molecular weight analogues. We observed that the API solubility depended more on the working group which conducted the experiments than on the measuring technique used. Furthermore, this compilation should assist researchers in choosing a prediction method suited for their investigations. Furthermore, a statistical assessment using recursive feature elimination was performed to identify descriptors of molecules, which are connected to the API solubility in polymeric matrices. It is capable of predicting the criterium 20% API soluble at 100 °C (Yes/No) for an unknown compound with a balanced accuracy of 71%. The identified 8 descriptors to be connected to API solubility in polymeric matrices were the number of hydrogen bonding donors, three descriptors related to the hydrophobicity of the molecule, glass transition temperature, fractional negative polar van der Waals surface area, out-of-plane potential energy and the fraction of rotatable bonds. Finally, in addition to our own model, the data set should help researchers in training their own solubility prediction models.


Asunto(s)
Preparaciones Farmacéuticas/química , Polímeros/química , Solubilidad/efectos de los fármacos , Química Farmacéutica/métodos , Composición de Medicamentos/métodos , Derivados de la Hipromelosa/química , Polietilenglicoles/química , Polivinilos/química , Povidona/análogos & derivados , Povidona/química , Pirrolidinas/química , Temperatura de Transición , Compuestos de Vinilo/química
13.
Eur J Pharm Biopharm ; 68(2): 368-79, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-17766097

RESUMEN

This work describes a framework for in-silico modelling of in-vitro diffusion experiments illustrated in an accompanying paper [S. Hansen, A. Henning, A. Naegel, M. Heisig, G. Wittum, D. Neumann, K.-H. Kostka, J. Zbytovska, C.M. Lehr, U.F. Schaefer, In-silico model of skin penetration based on experimentally determined input parameters. Part I: experimental determination of partition and diffusion coefficients, Eur. J. Pharm. Biopharm. 68 (2008) 352-367 [corrected] A mathematical model of drug permeation through stratum corneum (SC) and viable epidermis/dermis is presented. The underlying geometry for the SC is of brick-and-mortar character, meaning that the corneocytes are completely embedded in the lipid phase. The geometry is extended by an additional compartment for the deeper skin layers (DSL). All phases are modelled with homogeneous diffusivity. Lipid-donor and SC-DSL partition coefficients are determined experimentally, while corneocyte-lipid and DSL-lipid partition coefficients are derived consistently with the model. Together with experimentally determined apparent lipid- and DSL-diffusion coefficients, these data serve as direct input for computational modelling of drug transport through the skin. The apparent corneocyte diffusivity is estimated based on an approximation, which uses the apparent SC- and lipid-diffusion coefficients as well as corneocyte-lipid partition coefficients. The quality of the model is evaluated by a comparison of concentration-SC-depth-profiles of the experiment with those of the simulation. Good agreements are obtained, and by an analysis of the underlying model, critical parameters of the models can be identified more easily.


Asunto(s)
Modelos Biológicos , Absorción Cutánea , Difusión
14.
Eur J Pharm Biopharm ; 68(2): 352-67, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-17587558

RESUMEN

Mathematical modeling of skin transport is considered a valuable alternative of in-vitro and in-vivo investigations especially considering ethical and economical questions. Mechanistic diffusion models describe skin transport by solving Fick's 2nd law of diffusion in time and space; however models relying entirely on a consistent experimental data set are missing. For a two-dimensional model membrane consisting of a biphasic stratum corneum (SC) and a homogeneous epidermal/dermal compartment (DSL) methods are presented to determine all relevant input parameters. The data were generated for flufenamic acid (M(W) 281.24g/mol; logK(Oct/H2O) 4.8; pK(a) 3.9) and caffeine (M(W) 194.2g/mol; logK(Oct/H2O) -0.083; pK(a) 1.39) using female abdominal skin. K(lip/don) (lipid-donor partition coefficient) was determined in equilibration experiments with human SC lipids. K(cor/lip) (corneocyte-lipid) and K(DSL/lip) (DSL-lipid) were derived from easily available experimental data, i.e. K(SC/don) (SC-donor), K(lip/don) and K(SC/DSL) (SC-DSL) considering realistic volume fractions of the lipid and corneocyte phases. Lipid and DSL diffusion coefficients D(lip) and D(DSL) were calculated based on steady state flux. The corneocyte diffusion coefficient D(cor) is not accessible experimentally and needs to be estimated by simulation. Based on these results time-dependent stratum corneum concentration-depth profiles were simulated and compared to experimental profiles in an accompanying study.


Asunto(s)
Ácido Flufenámico/farmacocinética , Modelos Biológicos , Absorción Cutánea , Difusión , Femenino , Humanos
15.
PLoS One ; 13(12): e0209323, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-30576343

RESUMEN

Information forms the basis for all human behavior, including the ubiquitous decision-making that people constantly perform in their every day lives. It is thus the mission of researchers to understand how humans process information to reach decisions. In order to facilitate this task, this work proposes LASSO regularization as a statistical tool to extract decisive words from textual content in order to study the reception of granular expressions in natural language. This differs from the usual use of the LASSO as a predictive model and, instead, yields highly interpretable statistical inferences between the occurrences of words and an outcome variable. Accordingly, the method suggests direct implications for the social sciences: it serves as a statistical procedure for generating domain-specific dictionaries as opposed to frequently employed heuristics. In addition, researchers can now identify text segments and word choices that are statistically decisive to authors or readers and, based on this knowledge, test hypotheses from behavioral research.


Asunto(s)
Lenguaje , Modelos Estadísticos , Biometría/métodos , Toma de Decisiones , Humanos , Modelos Lineales , Lingüística , Modelos Psicológicos
16.
Int J Psychophysiol ; 61(1): 47-56, 2006 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16759726

RESUMEN

While the processing of verbal and psychophysiological indices of emotional arousal have been investigated extensively in relation to the left and right cerebral hemispheres, it remains poorly understood how both hemispheres normally function together to generate emotional responses to stimuli. Drawing on a unique sample of nine high-functioning subjects with complete agenesis of the corpus callosum (AgCC), we investigated this issue using standardized emotional visual stimuli. Compared to healthy controls, subjects with AgCC showed a larger variance in their cognitive ratings of valence and arousal, and an insensitivity to the emotion category of the stimuli, especially for negatively-valenced stimuli, and especially for their arousal. Despite their impaired cognitive ratings of arousal, some subjects with AgCC showed large skin-conductance responses, and in general skin-conductance responses discriminated emotion categories and correlated with stimulus arousal ratings. We suggest that largely intact right hemisphere mechanisms can support psychophysiological emotional responses, but that the lack of interhemispheric communication between the hemispheres, perhaps together with dysfunction of the anterior cingulate cortex, interferes with normal verbal ratings of arousal, a mechanism in line with some models of alexithymia.


Asunto(s)
Agenesia del Cuerpo Calloso , Nivel de Alerta/fisiología , Emociones/fisiología , Reconocimiento Visual de Modelos/fisiología , Adulto , Síntomas Afectivos/fisiopatología , Atención/fisiología , Concienciación/fisiología , Corteza Cerebral/fisiopatología , Cognición/fisiología , Cuerpo Calloso/patología , Cuerpo Calloso/fisiopatología , Dominancia Cerebral/fisiología , Femenino , Respuesta Galvánica de la Piel/fisiología , Giro del Cíngulo/fisiopatología , Humanos , Imagen por Resonancia Magnética , Masculino , Valores de Referencia
17.
J Nanosci Nanotechnol ; 6(9-10): 3303-9, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-17048551

RESUMEN

Nanoparticles (NP) are employed in various therapeutic approaches for innovative drug delivery strategies. Among them, there is drug delivery to the brain and sustained release forms for intravenous drug delivery. In order to optimize drug carriers and to elucidate involved mechanisms such as bioadhesion and cellular uptake, NP were surface modified and analyzed for their interaction with human endothelial cells in cell culture. Fluorescently labeled NP of different diameters (50 to 1000 nm) were surface modified either by simple adsorption of chitosan or by covalent binding to the lectin ulex europaeus agglutinin and thereafter applied to human endothelial cells for different incubation periods. After incubation with NP the binding of NP was quantified directly by the fluorescence emission signals from the cell layers. In order to visualize the binding behaviour, NP were localized three-dimensionally in the cell layer by confocal laser scanning microscopy. Cell binding experiments in phosphate buffer were observed to be particle size dependent with the 50 nm NP showing the highest binding percentage over all experiments. Binding decreased with increasing particle diameter and shorter incubation interval. The adhesion was further enhanced by NP surface modifications in the order blank < chitosan < lectin. The presence of plasma proteins enhanced the adhesiveness of chitosan coated NP, while the binding of lectin coated NP was inhibited. Experiments at 4 degrees C indicated the involvement of an active process in the binding of NP to endothelial cells.


Asunto(s)
Células Endoteliales/fisiología , Nanopartículas/química , Nanopartículas/ultraestructura , Adhesivos Tisulares/química , Adhesividad , Adhesión Celular/fisiología , Células Cultivadas , Células Endoteliales/citología , Humanos , Ensayo de Materiales , Tamaño de la Partícula
18.
Mol Immunol ; 42(3): 319-25, 2005 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15589320

RESUMEN

The disialoganglioside GalAcbeta1-4(NeuAcalpha2-8NeuAcalpha2-3)Galbeta1-4Glcbeta1-1Cer (GD2) is expressed on various tumors, including neuroblastoma, and was defined as a relevant tumor antigen. The monoclonal anti-GD2 antibody 14.18 is widely used for diagnostic purposes in neuroblastoma, and in its mouse/human chimeric form (ch14.18) now enters passive immunotherapeutic regimens in phase II clinical trials. This study aimed to generate structural mimics of the 14.18 epitope of GD2. Therefore, we used the ch14.18 antibody for selecting immunoreactive GD2 peptide mimotopes from a decamer phage display library. In all, 13 GD2 peptide mimics could be determined by biopanning and their specificity was demonstrated by exclusive recognition by the ch14.18 antibody. Furthermore, their nature of being GD2 mimics and their degree of mimicry was confirmed by competition with the natural antigen. When performing a comparative visualization of the GD2 epitope and selected mimotopes using a three-dimensional computer modeling system (BALLView), we demonstrated fitting of the GD2 molecule and the mimotopes in the antigen-binding pouch of a GD2 specific antibody. Moreover, the computer modeling argued for optimal affinity of the GD2 mimotopes. We thus provide evidence that the generation of GD2 peptide mimotopes is successful when using the neuroblastoma antibody ch14.18 for selection, and that this approach might offer a tool to develop a vaccination strategy against this malignant pediatric tumor.


Asunto(s)
Antígenos de Carbohidratos Asociados a Tumores/química , Gangliósidos/química , Gangliósidos/inmunología , Imitación Molecular/inmunología , Neuroblastoma/inmunología , Péptidos/química , Péptidos/inmunología , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/inmunología , Antígenos de Carbohidratos Asociados a Tumores/inmunología , Antígenos de Carbohidratos Asociados a Tumores/aislamiento & purificación , Unión Competitiva , Ensayo de Inmunoadsorción Enzimática/métodos , Epítopos/química , Epítopos/inmunología , Epítopos/aislamiento & purificación , Humanos , Fragmentos Fab de Inmunoglobulinas/inmunología , Ratones , Datos de Secuencia Molecular , Biblioteca de Péptidos , Péptidos/aislamiento & purificación , Conformación Proteica
19.
Eur J Pharm Biopharm ; 107: 40-8, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27349807

RESUMEN

A new predictive micro-scale solubility and process model for amorphous solid dispersions (ASDs) by hot-melt extrusion (HME) is presented. It is based on DSC measurements consisting of an annealing step and a subsequent analysis of the glass transition temperature (Tg). The application of a complex mathematical model (BCKV-equation) to describe the dependency of Tg on the active pharmaceutical ingredient (API)/polymer ratio, enables the prediction of API solubility at ambient conditions (25°C). Furthermore, estimation of the minimal processing temperature for forming ASDs during HME trials could be defined and was additionally confirmed by X-ray powder diffraction data. The suitability of the DSC method was confirmed with melt rheological trials (small amplitude oscillatory system). As an example, ball milled physical mixtures of dipyridamole, indomethacin, itraconazole and nifedipine in poly(vinylpyrrolidone-co-vinylacetate) (copovidone) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus®) were used.


Asunto(s)
Química Farmacéutica , Calor , Polímeros/química , Difracción de Polvo , Solubilidad
20.
J Neural Eng ; 2(1): S91-S104, 2005 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-15876659

RESUMEN

Current research towards retina implants for partial restoration of vision in blind humans with retinal degenerative dysfunctions focuses on implant and stimulation experiments and technologies. In contrast, our approach takes the availability of an epiretinal multi-electrode neural interface for granted and studies the conditions for successful joint information processing of both retinal prosthesis and brain. Our proposed learning retina encoder (RE) includes information processing modules to simulate the complex mapping operation of parts of the 5-layered neural retina and to provide an iterative, perception-based dialog between RE and human subject. Alternative information processing technologies in the learning RE are being described, which allow an individual optimization of the RE mapping operation by means of iterative tuning with learning algorithms in a dialog between implant wearing subject and RE. The primate visual system is modeled by a retina module (RM) composed of spatio-temporal (ST) filters and a central visual system module (VM). RM performs a mapping 1 of an optical pattern P1 in the physical domain onto a retinal output vector R1(t) in a neural domain, whereas VM performs a mapping 2 of R1(t) in a neural domain onto a visual percept P2 in the perceptual domain. Retinal ganglion cell properties represent non-invertible ST filters in RE, which generate ambiguous output signals. VM generates visual percepts only if the corresponding R1(t) is properly encoded, contains sufficient information, and can be disambiguated. Based on the learning RE and the proposed visual system model, a novel retina encoder (RE*) is proposed, which considers both ambiguity removal and miniature eye movements during fixation. Our simulation results suggest that VM requires miniature eye movements under control of the visual system to retrieve unambiguous patterns P2 corresponding to P1. For retina implant applications, RE* can be tuned to generate optimal ganglion cell codes for epiretinal stimulation.


Asunto(s)
Terapia por Estimulación Eléctrica/métodos , Estimulación Eléctrica/métodos , Modelos Neurológicos , Red Nerviosa/fisiología , Patrones de Reconocimiento Fisiológico/fisiología , Células Fotorreceptoras/fisiología , Corteza Visual/fisiología , Potenciales de Acción/fisiología , Animales , Simulación por Computador , Humanos , Estimulación Luminosa/métodos , Prótesis e Implantes , Degeneración Retiniana/fisiopatología , Degeneración Retiniana/rehabilitación , Percepción Visual/fisiología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA