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1.
Psychol Med ; 54(5): 1034-1044, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37753626

RESUMEN

BACKGROUND: Social cognition impairments are a common feature of alcohol use disorders (AUD). However, it remains unclear whether these impairments are solely the consequence of chronic alcohol consumption or whether they could be a marker of vulnerability. METHODS: The present study implemented a family history approach to address this question for a key process of social cognition: theory of mind (ToM). Thirty healthy adults with a family history of AUD (FH+) and 30 healthy adults with a negative family history of AUD (FH-), matched for age, sex, and education level, underwent an fMRI cartoon-vignette paradigm assessing cognitive and affective ToM. Participants also completed questionnaires evaluating anxiety, depressive symptoms, childhood trauma, and alexithymia. RESULTS: Results indicated that FH+ individuals differed from FH- individuals on affective but not cognitive ToM processing, at both the behavioral and neural levels. At the behavioral level, the FH+ group had lower response accuracy for affective ToM compared with the FH- group. At the neural level, the FH+ group had higher brain activations in the left insula and inferior frontal cortex during affective ToM processing. These activations remained significant when controlling for depressive symptoms, anxiety, and childhood trauma. CONCLUSIONS: These findings highlight difficulties during affective ToM processing among first-degree relatives of AUD patients, supporting the idea that some of the impairments exhibited by these patients may already be present before the onset of AUD and may be considered a marker of vulnerability.


Asunto(s)
Alcoholismo , Teoría de la Mente , Adulto , Humanos , Teoría de la Mente/fisiología , Alcoholismo/diagnóstico por imagen , Afecto/fisiología , Consumo de Bebidas Alcohólicas , Cognición/fisiología
2.
Neuroimage ; 281: 120373, 2023 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-37696425

RESUMEN

The left temporo-parietal cortex (TPC) is crucial for phonological decoding, i.e., for learning and retaining sound-letter mappings, and appears hypoactive in dyslexia. Here, we tested the causal contribution of this area for reading in typical readers with transcranial magnetic stimulation (TMS) and explored the reading network's response with fMRI. By investigating the underlying neural correlates of stimulation-induced modulations of the reading network, we can help improve targeted interventions for individuals with dyslexia. 28 typical adult readers overtly read simple and complex words and pseudowords during fMRI after effective and sham TMS over the left TPC. To explore differences in functional activation and effective connectivity within the reading network, we performed univariate and multivariate analyses, as well as dynamic causal modeling. While TMS-induced effects on reading performance and brain activation showed large individual variability, multivariate analyses revealed a shift in activation in the left inferior frontal cortex for pseudoword reading after effective TMS. Furthermore, TMS increased effective connectivity from the left ventral occipito-temporal cortex to the left TPC. In the absence of effects on reading performance, the observed changes in task-related activity and the increase in functional coupling between the two core reading nodes suggest successful short-term compensatory reorganization in the reading network following TMS-induced disruption. This study is the first to explore neurophysiological changes induced by TMS to a core reading node in typical readers while performing an overt reading task. We provide evidence for remote stimulation effects and emphasize the relevance of functional interactions in the reading network.


Asunto(s)
Mapeo Encefálico , Dislexia , Adulto , Humanos , Encéfalo/fisiología , Estimulación Magnética Transcraneal , Lóbulo Frontal , Imagen por Resonancia Magnética
3.
Opt Express ; 26(12): 15769-15784, 2018 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-30114833

RESUMEN

We propose a method for improving the quantification of neutron imaging measurements with scintillator-camera based detectors by correcting for systematic biases introduced by scattered neutrons and other sources such as light reflections in the detector system. This method is fully experimental, using reference measurements with a grid of small black bodies (BB) to measure the bias contributions directly. Using two test samples, one made of lead alloy and having a moderate (20%) neutron transmission and one made of stainless-steel and having a very low (1%) transmission, we evaluated the improvement brought by this method in reducing both the average quantification bias and the uncertainty around this average bias after tomographic reconstruction. The results show that a reduction of the quantification bias of up to one order of magnitude can be obtained. For moderately transparent samples, little sensitivity is observed to the parameters used for the correction. For the more challenging sample with very low transmission, a correct placement of the BB grid is of utmost importance for a successful correction.

4.
Soft Matter ; 13(8): 1594-1623, 2017 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-28128838

RESUMEN

We have extended an existing hybrid MD-SCF simulation technique that employs a coarsening step to enhance the computational efficiency of evaluating non-bonded particle interactions. This technique is conceptually equivalent to the single chain in mean-field (SCMF) method in polymer physics, in the sense that non-bonded interactions are derived from the non-ideal chemical potential in self-consistent field (SCF) theory, after a particle-to-field projection. In contrast to SCMF, however, MD-SCF evolves particle coordinates by the usual Newton's equation of motion. Since collisions are seriously affected by the softening of non-bonded interactions that originates from their evaluation at the coarser continuum level, we have devised a way to reinsert the effect of collisions on the structural evolution. Merging MD-SCF with multi-particle collision dynamics (MPCD), we mimic particle collisions at the level of computational cells and at the same time properly account for the momentum transfer that is important for a realistic system evolution. The resulting hybrid MD-SCF/MPCD method was validated for a particular coarse-grained model of phospholipids in aqueous solution, against reference full-particle simulations and the original MD-SCF model. We additionally implemented and tested an alternative and more isotropic finite difference gradient. Our results show that efficiency is improved by merging MD-SCF with MPCD, as properly accounting for hydrodynamic interactions considerably speeds up the phase separation dynamics, with negligible additional computational costs compared to efficient MD-SCF. This new method enables realistic simulations of large-scale systems that are needed to investigate the applications of self-assembled structures of lipids in nanotechnologies.


Asunto(s)
Hidrodinámica , Simulación de Dinámica Molecular , Solventes/química
6.
Ann Hematol ; 93(2): 267-77, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24292560

RESUMEN

This retrospective study evaluated the benefit of alemtuzumab monotherapy in unselected patients with advanced B-cell chronic lymphocytic leukemia (CLL) and prolymphocytic leukemia (B-PLL) to definitely describe the impact of this antibody in clinical routine use. Data were collected from 208 consecutive, mainly pretreated, patients with CLL (n = 202), and B-PLL (n = 6) who had received alemtuzumab. Response, progression-free survival (PFS), and overall survival (OS) in various settings were assessed, and toxicities were documented. In these routine patients, a comparably low cumulative dose of alemtuzumab (median, 403 mg) was applied. In CLL, overall response rate was 32 %, and various pre-therapeutic parameters were predictive for inferior response, among them, the prior administration of ≥3 therapy lines (P < 0.001), refractoriness to fludarabine (P = 0.002), and bulky lymphadenopathy (P = 0.003). PFS and OS after start of alemtuzumab were 6.2 and 21.0 months, respectively. Bulky lymphadenopathy was the prominent risk factor for both inferior PFS (P < 0.001) and OS (P = 0.002). In B-PLL, four patients experienced a fatal outcome, whereas two patients had some benefit with alemtuzumab. The main adverse effects were CMV reactivation (20 %) and a broad spectrum of infections, which together were the main reasons for treatment interruption and/or premature termination. In conclusion, alemtuzumab administered even at low dose levels was effective but overall considerably toxic in routine CLL patients. We emphasize that alemtuzumab remains an important therapeutic option in subsets of CLL patients.


Asunto(s)
Anticuerpos Monoclonales Humanizados/administración & dosificación , Antineoplásicos/administración & dosificación , Leucemia Linfocítica Crónica de Células B/tratamiento farmacológico , Leucemia Prolinfocítica Tipo Células B/tratamiento farmacológico , Adulto , Anciano , Anciano de 80 o más Años , Alemtuzumab , Anticuerpos Monoclonales Humanizados/efectos adversos , Antineoplásicos/efectos adversos , Supervivencia sin Enfermedad , Relación Dosis-Respuesta a Droga , Estudios de Seguimiento , Humanos , Leucemia Linfocítica Crónica de Células B/mortalidad , Leucemia Prolinfocítica Tipo Células B/mortalidad , Persona de Mediana Edad , Estudios Retrospectivos , Tasa de Supervivencia
7.
Alcohol Clin Exp Res (Hoboken) ; 48(2): 362-374, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38243915

RESUMEN

BACKGROUND: Impairments in executive function and social cognition are highly prevalent in individuals with an alcohol use disorder (AUD). Some studies show that similar difficulties are displayed by individuals with a positive family history of AUD (FH+) compared with individuals with a negative family history (FH-). Yet, no studies have jointly investigated cognitive and affective theory of mind at the behavioral level. Moreover, some studies show preserved executive and socioemotional functioning in FH+ participants. One possible explanation for these divergent results is that FH+ individuals are cognitively heterogeneous. In this study, we examined the frequency and co-occurrence of difficulties in executive function and social cognition among FH+ individuals at the individual level. METHODS: Sixty FH+ and 60 FH- participants matched on age, sex, and education level were included. They completed tasks assessing executive functions (Stroop, Trail Making Test) and affective and cognitive theory of mind (Movie for the Assessment of Social Cognition). They also completed self-report questionnaires measuring impulsivity, alexithymia, and empathy. Single-case analyses assessed the proportion of FH+ participants with difficulties in executive function and/or theory of mind. RESULTS: FH+ individuals exhibited difficulties in response inhibition and made more errors during theory of mind processing, indicating an absence of mental state representation, compared with FH- individuals. In the FH+ sample, 53.33% had executive function and/or theory of mind difficulties. Those with lower theory of mind scores reported higher alexithymia and lower empathy on self-report measures. CONCLUSIONS: FH+ individuals display heterogeneous executive function and theory of mind abilities. Given that they mostly occur independently of one another, executive function and theory of mind difficulties may be distinct vulnerability markers in AUD.

8.
Opt Express ; 21(14): 16431-43, 2013 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-23938494

RESUMEN

In this study we present a new measurement technique to investigate the timescales of back side ablation of conductive films, using Molybdenum as an application example from photovoltaics. With ultrashort laser pulses at fluences below 0.6 J/cm(2), we ablate the Mo film in the shape of a fully intact Mo 'disc' from a transparent substrate. By monitoring the time-dependent current flow across a specifically developed test structure, we determine the time required for the lift-off of the disc. This value decreases with increasing laser fluence down to a minimum of 21 ± 2 ns. Furthermore, we record trajectories of the discs using a shadowgraphic setup. Ablated discs escape with a maximum velocity of 150 ± 5 m/s whereas droplets of Mo forming at the center of the disc can reach velocities up to 710 ± 11 m/s.


Asunto(s)
Conductometría/métodos , Rayos Láser , Ensayo de Materiales/métodos , Membranas Artificiales , Molibdeno/química , Molibdeno/efectos de la radiación , Refractometría/métodos , Molibdeno/análisis
9.
Br J Anaesth ; 111(5): 736-42, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23811425

RESUMEN

BACKGROUND: Predicting the response of cardiac output to volume administration remains an ongoing clinical challenge. The objective of our study was to compare the ability to predict volume responsiveness of various functional measures of cardiac preload. These included pulse pressure variation (PPV), stroke volume variation (SVV), and the recently launched automated respiratory systolic variation test (RSVT) in patients after major surgery. METHODS: In this prospective study, 24 mechanically ventilated patients after major surgery were enrolled. Three consecutive volume loading steps consisting of 300 ml 6% hydroxyethylstarch 130/0.4 were performed and cardiac index (CI) was assessed by transpulmonary thermodilution. Volume responsiveness was considered as positive if CI increased by >10%. RESULTS: In total 72 volume loading steps were analysed, of which 41 showed a positive volume response. Receiver operating characteristic (ROC) curve analysis revealed an area under the curve (AUC) of 0.70 for PPV, 0.72 for SVV and 0.77 for RSVT. Areas under the curves of all variables did not differ significantly from each other (P>0.05). Suggested cut-off values were 9.9% for SVV, 10.1% for PPV, and 19.7° for RSVT as calculated by the Youden Index. CONCLUSION: In predicting fluid responsiveness the new automated RSVT appears to be as accurate as established dynamic indicators of preload PPV and SVV in patients after major surgery. The automated RSVT is clinically easy to use and may be useful in guiding fluid therapy in ventilated patients.


Asunto(s)
Presión Sanguínea/fisiología , Fluidoterapia/métodos , Cuidados Posoperatorios/métodos , Mecánica Respiratoria/fisiología , Adulto , Anciano , Anciano de 80 o más Años , Resistencia de las Vías Respiratorias , Algoritmos , Anestesia General , Presión Arterial/fisiología , Automatización , Gasto Cardíaco/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Monitoreo Fisiológico , Periodo Posoperatorio , Valor Predictivo de las Pruebas , Estudios Prospectivos , Curva ROC , Volumen Sistólico/fisiología , Termodilución , Adulto Joven
10.
J Phys Condens Matter ; 33(21)2021 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-33592585

RESUMEN

The generalized Langevin equation is a model for the motion of coarse-grained particles where dissipative forces are represented by a memory term. The numerical realization of such a model requires the implementation of a stochastic delay-differential equation and the estimation of a corresponding memory kernel. Here we develop a new approach for computing a data-driven Markov model for the motion of the particles, given equidistant samples of their velocity autocorrelation function. Our method bypasses the determination of the underlying memory kernel by representing it via up to about twenty auxiliary variables. The algorithm is based on a sophisticated variant of the Prony method for exponential interpolation and employs the positive real lemma from model reduction theory to extract the associated Markov model. We demonstrate the potential of this approach for the test case of anomalous diffusion, where data are given analytically, and then apply our method to velocity autocorrelation data of molecular dynamics simulations of a colloid in a Lennard-Jones fluid. In both cases, the velocity autocorrelation function and the memory kernel can be reproduced very accurately. Moreover, we show that the algorithm can also handle input data with large statistical noise. We anticipate that it will be a very useful tool in future studies that involve dynamic coarse-graining of complex soft matter systems.

11.
Urology ; 156: 147-153, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34186136

RESUMEN

OBJECTIVE: To report feasibility and outcome of salvage robotic-assisted laparoscopic radical prostatectomy (S-RALP) after focal therapy using high-intensity focused ultrasound (HIFU) treatment compared to primary robotic-assisted laparoscopic radical prostatectomy (pRALP). METHODS: In this bicentric trial patients undergoing S-RALP for detection of WHO2016/ISUP Grade Group 2 or 3 prostate cancer were previously treated in prospective focal HIFU trials. Perioperative data, complications, oncological and functional outcome were analysed. Patients who underwent pRALP were matched in a ratio 2(pRALP):1(S-RALP) according to preoperatively functional, oncological and clinical parameters. RESULTS: A total of 39 patients were included in the study (13S-RALP, 26pRALP). Median operative time in the S-RALP group was 260minutes (pRALP: 257minutes), blood loss was 230ml (pRALP: 300ml). Complications occurred in 46.2% (6/13) of S-RALP patients (pRALP: 26.9%), including four Clavien-Dindo III complications (pRALP: 2/26). In S-RALP adverse histological outcome (≥pT3a, pN+ or R1) was detected in 23.1% (3/13) (pRALP: 26.9%). There was one patient with PSA-persistence (pRALP: 2/26). Regarding functional outcomes there was no difference between the two groups observed (incontinence P=.71, erectile function P=.21). CONCLUSION: S-RALP should be offered to patients with an early relapse after focal HIFU. The early oncological outcome is satisfactory and functional outcome one year postoperatively is similar to pRALP. However, S-RALP is associated with a higher rate of Clavien-Dindo III complications (mainly, placement of a drainage), of which patients should be informed beforehand.


Asunto(s)
Disfunción Eréctil , Tratamiento con Ondas de Choque Extracorpóreas/métodos , Complicaciones Posoperatorias , Prostatectomía , Neoplasias de la Próstata , Procedimientos Quirúrgicos Robotizados , Terapia Recuperativa , Incontinencia Urinaria , Pérdida de Sangre Quirúrgica/estadística & datos numéricos , Terapia Combinada/métodos , Investigación sobre la Eficacia Comparativa , Disfunción Eréctil/diagnóstico , Disfunción Eréctil/etiología , Humanos , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Evaluación de Procesos y Resultados en Atención de Salud , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/terapia , Antígeno Prostático Específico/análisis , Prostatectomía/efectos adversos , Prostatectomía/métodos , Neoplasias de la Próstata/sangre , Neoplasias de la Próstata/patología , Neoplasias de la Próstata/fisiopatología , Neoplasias de la Próstata/terapia , Procedimientos Quirúrgicos Robotizados/efectos adversos , Procedimientos Quirúrgicos Robotizados/métodos , Terapia Recuperativa/efectos adversos , Terapia Recuperativa/métodos , Incontinencia Urinaria/diagnóstico , Incontinencia Urinaria/etiología
12.
J Exp Med ; 132(4): 673-93, 1970 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-5508376

RESUMEN

Complement-mediated lysis of sheep erythrocytes coated with optimal concentrations of rabbit IgG hemolysin was inhibited by euglobulin fractions from the sera of patients with seropositive rheumatoid arthritis. That this was due to direct interaction with the IgG coat on the red cell rather than a nonspecific reaction with complement in the fluid phase was confirmed by controls using cells coated with IgM hemolysin. The inhibitory activity was recovered in purified IgM rheumatoid factor preparations and could be absorbed out with insoluble aggregated human IgG. The inhibitory potency of the rheumatoid factors correlated well with their sheep cell agglutination titers. Inhibition was not the result of physical aggregation of the erythrocytes by rheumatoid factor. Kinetic studies were consistent with the view that rheumatoid factor displaces C1q from its binding to IgG. Paradoxically, at suboptimal sensitizing concentrations of IgG hemolysin, rheumatoid factor enhances the fixation of complement. These results can be interpreted on the basis of the blockage of complement fixation by IgG and its replacement by a relatively weak direct fixation by the IgM rheumatoid factor. Thus, the interaction of RF with IgG generates only a limited ability to fix complement which, when contrasted with the fixation at suboptimal concentrations of IgG hemolysin alone, appears as net enhancement; when this is contrasted with fixation occurring with optimal concentrations of IgG, it appears as net inhibition.


Asunto(s)
Proteínas del Sistema Complemento , Hemólisis , Inmunoglobulina G , Inmunoglobulina M , Factor Reumatoide , Complejo Antígeno-Anticuerpo , Artritis Reumatoide/inmunología , Membrana Celular , Pruebas de Fijación del Complemento , Eritrocitos/inmunología , Pruebas de Hemaglutinación , Proteínas Hemolisinas , Humanos , Inmunoglobulinas , Cinética , Unión Proteica
13.
Urol Oncol ; 38(4): 225-230, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-31628038

RESUMEN

PURPOSE: To investigate focal therapy using High Intensity Focused Ultrasound (HIFU) for the treatment of localized prostate cancer (CaP), we analyzed the safety and complications of this procedure. METHODS: Patients (pts) eligible for this multicenter prospective cohort study suffered from low to intermediate risk localized CaP with no prior treatment. After tumor identification on multiparametric MRI and in prostate biopsy, the lesions were treated with HIFU observing a safety margin of 8 to 10 mm. Adverse events (AE) after 30 and 90 days, as well as the required interventions were assessed and stratified for treatment localizations. RESULTS: Of the 98 men included in the study in two European centers, 35 (35.7%) experienced AEs in the first 30 days after HIFU intervention with Clavien-Dindo grade ≤ II: 15 pts (15.3%) had a postoperative urinary tract infection and 26 pts (26.5%) a urinary retention. Four pts (4.1%) underwent subsequent intervention (Clavien-Dindo grade IIIa/b). The number of late postoperative complications occurring between 30 and 90 days after intervention was low (2.0%). The highest complication rate was associated with tumors located at the anterior base (50.0%). The inclusion of the urethra in the ablation zone led to AEs in 20 out of 41 cases (48.8%) and represented a significant risk factor for complications within 30 days (odds ratio = 2.53; 95% confidence interval: 1.08-5.96; P = 0.033). CONCLUSIONS: Focal therapy of CaP lesions with a robotic HIFU-probe is safe and renders an acceptable rate of minor early AEs. The inclusion of the urethra in the ablation zone leads to an increase in early complications and should be avoided whenever possible.


Asunto(s)
Neoplasias de la Próstata/diagnóstico por imagen , Ultrasonido Enfocado Transrectal de Alta Intensidad/métodos , Anciano , Estudios de Cohortes , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Neoplasias de la Próstata/patología , Resultado del Tratamiento
14.
Science ; 188(4192): 1020-2, 1975 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-1145185

RESUMEN

From a family of 14 individuals, evidence was obtained suggesting linkage between the HL-A haplotypes and the transmission of a 50 percent deficit in the functional activity of the C2 component of complement.


Asunto(s)
Complemento C2/deficiencia , Proteínas del Sistema Complemento/deficiencia , Ligamiento Genético , Antígenos HLA , Antígenos de Histocompatibilidad , Adolescente , Adulto , Anciano , Alelos , Femenino , Heterocigoto , Homocigoto , Humanos , Masculino , Persona de Mediana Edad , Linaje
15.
Science ; 179(4073): 569-71, 1973 Feb 09.
Artículo en Inglés | MEDLINE | ID: mdl-4346825

RESUMEN

Glucose-induced release of insulin from perifused rat islets is associated with elevated islet adenosine 3',5'-monophosphate. If values for adenosine 3',5'-monophosphate are compared to insulin release during theophylline or glucose stimulation and theophylline plus glucose stimulation, it suggests a minor role for adenosine 3',5'-monophosphate in directly stimulating insulin release but a prominent role in modulating glucose-induced release of insulin.


Asunto(s)
AMP Cíclico/metabolismo , Glucosa/farmacología , Insulina/metabolismo , Islotes Pancreáticos/metabolismo , Animales , AMP Cíclico/fisiología , Secreción de Insulina , Islotes Pancreáticos/efectos de los fármacos , Masculino , Ratas , Teofilina/farmacología
16.
J Chem Phys ; 131(23): 231102, 2009 Dec 21.
Artículo en Inglés | MEDLINE | ID: mdl-20025306

RESUMEN

We present a Monte Carlo simulation technique by which the free energy of disordered systems can be computed directly. It is based on thermodynamic integration. The central idea is to construct an analytically solvable reference system from a configuration which is representative for the state of interest. The method can be applied to lattice models (e.g., the Ising model) as well as off-lattice molecular models. We focus mainly on the more challenging off-lattice case. We propose a Monte Carlo algorithm, by which the thermodynamic integration path can be sampled efficiently. At the examples of the hard sphere liquid and a hard disk solid with a defect, we discuss several properties of the approach.

18.
Sci Rep ; 8(1): 15049, 2018 10 09.
Artículo en Inglés | MEDLINE | ID: mdl-30301970

RESUMEN

Highly invasive animal based test procedures for risk assessment such as the Draize eye test are under increasing criticism due to poor transferability for the human organism and animal-welfare concerns. However, besides all efforts, the Draize eye test is still not completely replaced by alternative animal-free methods. To develop an in vitro test to identify all categories of eye irritation, we combined organotypic cornea models based on primary human cells with an electrical readout system that measures the impedance of the test models. First, we showed that employing a primary human cornea epithelial cell based model is advantageous in native marker expression to the primary human epidermal keratinocytes derived models. Secondly, by employing a non-destructive measuring system based on impedance spectroscopy, we could increase the sensitivity of the test system. Thereby, all globally harmonized systems categories of eye irritation could be identified by repeated measurements over a period of 7 days. Based on a novel prediction model we achieved an accuracy of 78% with a reproducibility of 88.9% to determine all three categories of eye irritation in one single test. This could pave the way according to the 3R principle to replace the Draize eye test.


Asunto(s)
Córnea/efectos de los fármacos , Ojo/efectos de los fármacos , Animales , Biomarcadores , Córnea/metabolismo , Espectroscopía Dieléctrica , Epitelio Corneal/efectos de los fármacos , Epitelio Corneal/metabolismo , Ojo/metabolismo , Humanos , Queratinocitos/metabolismo , Piel/efectos de los fármacos , Piel/metabolismo , Pruebas de Visión
19.
J Appl Crystallogr ; 51(Pt 2): 386-394, 2018 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-29657567

RESUMEN

The development of neutron imaging from a qualitative inspection tool towards a quantitative technique in materials science has increased the requirements for accuracy significantly. Quantifying the thickness or the density of polycrystalline samples with high accuracy using neutron imaging has two main problems: (i) the scattering from the sample creates artefacts on the image and (ii) there is a lack of specific reference attenuation coefficients. This work presents experimental and simulation results to explain and approach these problems. Firstly, a series of neutron radiography and tomography experiments of iron, copper and vanadium are performed and serve as a reference. These materials were selected because they attenuate neutrons mainly through coherent (Fe and Cu) and incoherent (V) scattering. Secondly, an ad hoc Monte Carlo model was developed, based on beamline, sample and detector parameters, in order to simulate experiments, understand the physics involved and interpret the experimental data. The model, developed in the McStas framework, uses a priori information about the sample geometry and crystalline structure, as well as beamline settings, such as spectrum, geometry and detector type. The validity of the simulations is then verified with experimental results for the two problems that motivated this work: (i) the scattering distribution in transmission imaging and (ii) the calculated attenuation coefficients.

20.
Curr Biol ; 5(9): 993-4, 1995 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-8542292

RESUMEN

Cyclophilins have prolyl isomerase activity, but evidence for their suggested role in protein folding in cells has been scarce; now they have been found to accelerate the folding of mitochondrial precursor proteins.


Asunto(s)
Isomerasas de Aminoácido/metabolismo , Proteínas Portadoras/metabolismo , Pliegue de Proteína , Animales , Mitocondrias/metabolismo , Isomerasa de Peptidilprolil , Precursores de Proteínas/metabolismo , Tetrahidrofolato Deshidrogenasa/metabolismo
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