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1.
Mol Cell ; 66(1): 129-140.e7, 2017 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-28388438

RESUMEN

ATAXIN-2 (ATX2) has been implicated in human neurodegenerative diseases, yet it remains elusive how ATX2 assembles specific protein complexes to execute its physiological roles. Here we employ the posttranscriptional co-activator function of Drosophila ATX2 to demonstrate that LSM12 and ME31B/DDX6 are two ATX2-associating factors crucial for sustaining circadian rhythms. LSM12 acts as a molecular adaptor for the recruitment of TWENTY-FOUR (TYF) to ATX2. The ATX2-LSM12-TYF complex thereby stimulates TYF-dependent translation of the rate-limiting clock gene period (per) to maintain 24 hr periodicity in circadian behaviors. In contrast, ATX2 contributes to NOT1-mediated gene silencing and associates with NOT1 in a ME31B/DDX6-dependent manner. The ME31B/DDX6-NOT1 complex does not affect PER translation but supports high-amplitude behavioral rhythms along with ATX2, indicating a PER-independent clock function of ATX2. Taken together, these data suggest that the ATX2 complex may switch distinct modes of posttranscriptional regulation through its associating factors to control circadian clocks and ATX2-related physiology.


Asunto(s)
Ataxina-2/metabolismo , Conducta Animal , Relojes Circadianos , Péptidos y Proteínas de Señalización del Ritmo Circadiano/metabolismo , Ritmo Circadiano , ARN Helicasas DEAD-box/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/enzimología , Locomoción , Neuronas/enzimología , Interferencia de ARN , Animales , Animales Modificados Genéticamente , Ataxina-2/genética , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Línea Celular , Péptidos y Proteínas de Señalización del Ritmo Circadiano/genética , ARN Helicasas DEAD-box/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/citología , Drosophila melanogaster/genética , Genotipo , Complejos Multiproteicos , Mutación , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , Fenotipo , Proteínas de Unión al ARN , Transducción de Señal , Factores de Tiempo , Transfección
2.
J Neurogenet ; 37(1-2): 36-46, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36457164

RESUMEN

Circadian rhythms and sleep homeostasis constitute the two-process model for daily sleep regulation. However, evidence for circadian control of sleep-wake cycles has been relatively short since clock-less animals often show sleep behaviors quantitatively comparable to wild-type. Here we examine Drosophila sleep behaviors under different light-dark regimes and demonstrate that circadian clocks gate light-induced arousal. Genetic excitation of tyrosine decarboxylase 2 (TDC2)-expressing neurons suppressed sleep more evidently at night, causing nocturnal activity. The arousal effects were likely mediated in part by glutamate transmission from the octopaminergic neurons and substantially masked by light. Application of T12 cycles (6-h light: 6-h dark) further showed that the light-sensitive effects of TDC2 neurons depended on the time of the day. In particular, light-sensing via visual input pathway led to strong sleep suppression at subjective night, and such an effect disappeared in clock-less mutants. Transgenic mapping revealed that light-induced arousal and free-running behavioral rhythms require distinct groups of circadian pacemaker neurons. These results provide convincing evidence that circadian control of sleep is mediated by the dedicated clock neurons for light-induced arousal.


Asunto(s)
Proteínas de Drosophila , Drosophila , Animales , Drosophila/fisiología , Sueño/fisiología , Ritmo Circadiano/fisiología , Animales Modificados Genéticamente , Nivel de Alerta/fisiología , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/fisiología
3.
Sensors (Basel) ; 23(23)2023 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-38067924

RESUMEN

We present a 320 × 240 CMOS image sensor (CIS) using the proposed hybrid-correlated multiple sampling (HMS) technique with an adaptive dual-gain analog-to-digital converter (ADC). The proposed HMS improves the noise characteristics under low illumination by adjusting the ADC gain according to the incident light on the pixels. Depending on whether it is less than or greater than 1/4 of the full output voltage range from pixels, either correlated multiple sampling or conventional-correlated double sampling (CDS) is used with different slopes of the ramping signals. The proposed CIS achieves 11-bit resolution of the ADC using an up-down counter that controls the LSB depending on the ramping signals used. The sensor was fabricated using a 0.11 µm CIS process, and the total chip area was 2.55 mm × 4.3 mm. Compared to the conventional CDS, the measurement results showed that the maximum dark random noise was reduced by 26.7% with the proposed HMS, and the maximum figure of merit was improved by 49.1%. The total power consumption was 5.1 mW at 19 frames per second with analog, pixel, and digital supply voltages of 3.3 V, 3.3 V, and 1.5 V, respectively.

4.
Analyst ; 147(2): 274-281, 2022 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-34889326

RESUMEN

In this study, we demonstrate an acoustofluidic device that enables single-file focusing of submicron particles and bacteria using a two-dimensional (2D) acoustic standing wave. The device consists of a 100 µm × 100 µm square channel that supports 2D particle focusing in the channel center at an actuation frequency of 7.39 MHz. This higher actuation frequency compared with conventional bulk acoustic systems enables radiation-force-dominant motion of submicron particles and overcomes the classical size limitation (≈2 µm) of acoustic focusing. We present acoustic radiation force-based focusing of particles with diameters less than 0.5 µm at a flow rate of 12 µL min-1, and 1.33 µm particles at flow rates up to 80 µL min-1. The device focused 0.25 µm particles by the 2D acoustic radiation force while undergoing a channel cross-section centered, single-vortex acoustic streaming. A suspension of bacteria was also investigated to evaluate the biological relevance of the device, which demonstrated the alignment of bacteria in the channel at a flow rate of up to 20 µL min-1. The developed acoustofluidic device can align submicron particles within a narrow flow stream in a highly robust manner, validating its use as a flow-through focusing chamber to perform high-throughput and accurate flow cytometry of submicron objects.


Asunto(s)
Acústica , Sonido , Bacterias , Citometría de Flujo , Tamaño de la Partícula
5.
Anal Chem ; 92(17): 11530-11534, 2020 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-32799523

RESUMEN

Diabetes mellitus is one of the most common chronic diseases worldwide. Generally, the levels of fasting or postprandial blood glucose and other biomarkers, such as glycated albumin, glycated hemoglobin, and 1,5-anhydroglucitol, are used to diagnose or monitor diabetes progression. In the present study, we developed a sensor to simultaneously detect the glucose levels and glycation ratios of human serum albumin using a lateral flow assay. Based on the specific enzymatic reactions and immunoassays, a spiked glucose solution, total human serum albumin, and glycated albumin were measured simultaneously. To test the performance of the developed sensor, clinical serum samples from healthy subjects and patients with diabetes were analyzed. The glucose level and glycation ratios of the clinical samples were determined with reasonable correlation. The R-squared values of glucose level and glycation ratio measurements were 0.932 and 0.930, respectively. The average detection recoveries of the sensor were 85.80% for glucose and 98.32% for the glycation ratio. The glucose level and glycation ratio in our results were crosschecked with reference diagnostic values of diabetes. Based on the outcomes of the present study, we propose that this novel platform can be utilized for the simultaneous detection of glucose and glycation ratios to diagnose and monitor diabetes mellitus.


Asunto(s)
Biomarcadores/análisis , Glucemia/análisis , Colodión/química , Diabetes Mellitus/diagnóstico , Hiperglucemia/diagnóstico , Albúmina Sérica/análisis , Ampirona/química , Técnicas Biosensibles , Quitosano/química , Colorimetría , Colorantes/química , Enzimas Inmovilizadas/química , Enzimas Inmovilizadas/metabolismo , Glucosa Oxidasa/química , Glucosa Oxidasa/metabolismo , Productos Finales de Glicación Avanzada , Glicosilación , Peroxidasa de Rábano Silvestre/química , Peroxidasa de Rábano Silvestre/metabolismo , Humanos , Límite de Detección , Papel , Albúmina Sérica Glicada
6.
Langmuir ; 35(16): 5549-5556, 2019 Apr 23.
Artículo en Inglés | MEDLINE | ID: mdl-30929428

RESUMEN

We investigated the effect of the morphological structure of a graphene oxide (GO) monolayer on the dewetting dynamics of the upper polymer thin films. The Langmuir-Schaefer (LS) technique was used to prepare a wrinkled GO ( wrGO) structure with a root mean square (rms) roughness of 22.7 Å. The dewetting behavior of poly(methyl methacrylate) (PMMA) thin films on the wrGO monolayers was perfectly prevented, whereas the PMMA thin films on a flat GO monolayer were dewetted at 203 °C. This wrinkle effect of the GO can be also obtained when the GOs monolayers are intercalated to the PMMA/polystyrene (PS) interface. In this multilayer, the flat GO monolayer at the interface between the PS and PMMA layers was spontaneously roughened with rms roughness of 46.9 Å after annealing and also prohibited the dewetting behavior. From the results, we found that to improve the compatibility of polymer blends by adding the two-dimensional nanosheets, it is important to control the morphological structure of the sheets at the interface, along with manipulation of the GO-polymer interactions.

7.
Bioconjug Chem ; 29(4): 1446-1453, 2018 04 18.
Artículo en Inglés | MEDLINE | ID: mdl-29570268

RESUMEN

Realizing the significant roles of vicinal-dithiol proteins (VDPs) in maintaining the cellular redox homeostasis and their implication in many diseases, we synthesized a smart arsenate based fluorescent probe 1 which can preferentially target the mitochondrial membrane-bound vicinal dithiol proteins (VDPs), especially voltage-dependent anion channel (VDAC2). The probe targetability was demonstrated by in vitro studies such as colocalization, stimulated emission depletion (STED) super-resolution imaging, proteomic MS/MS analysis, and Western blot analysis. The probe represents a rare example of fluorescence labeling of mitochondrial membrane-bound VDPs and can provide a new way to construct VDPs-specific fluorescent probes to gain deeper understanding of their roles in mitochondrial-related disorders.


Asunto(s)
Arseniatos/química , Colorantes Fluorescentes/química , Proteínas de Transporte de Membrana Mitocondrial/análisis , Membranas Mitocondriales/química , Compuestos de Sulfhidrilo/análisis , Células HeLa , Humanos , Microscopía Fluorescente/métodos , Membranas Mitocondriales/ultraestructura , Imagen Óptica/métodos , Oxidación-Reducción , Canal Aniónico 2 Dependiente del Voltaje/análisis
8.
Langmuir ; 34(4): 1681-1690, 2018 01 30.
Artículo en Inglés | MEDLINE | ID: mdl-29293348

RESUMEN

We have studied an orientation structure of self-assembled block copolymers (dPS-b-PMMA) of deuterated polystyrene (dPS) and poly(methyl methacrylate) (PMMA) confined between graphene oxide (GO) surfaces. The results of combination techniques, such as neutron reflectivity, time-of-flight secondary-ion mass spectrometry, grazing-incidence small-angle X-ray scattering, and scanning electron microscopy, show that self-assembled domains of the block copolymers in thin films near the GO sheets are oriented perpendicular to the surface of the GO monolayers, in contrast to the horizontal lamellar structure of the copolymer thin film in the absence of the GO monolayers. This is due to the amphiphilic nature of the GO, which leads to a nonpreferential interaction of both dPS and PMMA blocks. Double-sided confinement with the GO monolayers further extends the ordering behavior of the dPS-b-PMMA thin films. Continuous vertical orientation of the block copolymer thin films is also obtained in the presence of alternating GO layers within thick copolymer films.

9.
Bioconjug Chem ; 26(12): 2474-80, 2015 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-26588433

RESUMEN

An endoplasmic reticulum (ER) membrane-selective chemosensor composed of BODIPY and coumarin moieties and a long alkyl chain (n-C18) was synthesized. The emission ratio of BODIPY to coumarin depends on the solution viscosity. The probe is localized to the ER membrane and was applied to reveal the reduced ER membrane fluidity under ER stress conditions.


Asunto(s)
Compuestos de Boro/química , Cumarinas/química , Estrés del Retículo Endoplásmico , Retículo Endoplásmico/química , Colorantes Fluorescentes/química , Fluidez de la Membrana , Retículo Endoplásmico/metabolismo , Células HeLa , Humanos , Microscopía Fluorescente , Espectrometría de Fluorescencia
10.
Front Bioeng Biotechnol ; 12: 1367141, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38532875

RESUMEN

Induced pluripotent stem cell (iPSC)-derived cardiac organoids offer a versatile platform for personalized cardiac toxicity assessment, drug screening, disease modeling, and regenerative therapies. While previous image-based contractility analysis techniques allowed the assessment of contractility of two-dimensional cardiac models, they face limitations, including encountering high noise levels when applied to three-dimensional organoid models and requiring expensive equipment. Additionally, they offer fewer functional parameters compared to commercial software. To address these challenges, we developed an open-source, particle image velocimetry-based software (PIV-MyoMonitor) and demonstrated its capacity for accurate contractility analysis in both two- and three-dimensional cardiac models using standard lab equipment. Comparisons with four other open-source software programs highlighted the capability of PIV-MyoMonitor for more comprehensive quantitative analysis, providing 22 functional parameters and enhanced video outputs. We showcased its applicability in drug screening by characterizing the response of cardiac organoids to a known isotropic drug, isoprenaline. In sum, PIV-MyoMonitor enables reliable contractility assessment across various cardiac models without costly equipment or software. We believe this software will benefit a broader scientific community.

11.
Soa Chongsonyon Chongsin Uihak ; 35(3): 197-209, 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38966201

RESUMEN

Objectives: In this functional magnetic resonance imaging study, we aimed to investigate the differences in brain activation between individuals with autism spectrum disorder (ASD) and typically developing (TD) individuals during perspective taking. We also examined the association between brain activation and empathic and interoceptive abilities. Methods: During scanning, participants from the ASD (n=17) and TD (n=22) groups were shown pain stimuli and asked to rate the level of the observed pain from both self- and other-perspectives. Empathic abilities, including perspective taking, were measured using an empathic questionnaire, and three dimensions of interoception were assessed: interoceptive accuracy, interoceptive sensibility, and interoceptive trait prediction errors. Results: During self-perspective taking, the ASD group exhibited greater activation in the left precuneus than the TD group. During other-perspective taking, relative hyperactivation extended to areas including the right precuneus, right superior frontal gyrus, left caudate nucleus, and left amygdala. Brain activation levels in the right superior frontal gyrus while taking other-perspective were negatively correlated with interoceptive accuracy, and those in the left caudate were negatively correlated with perspective taking ability in the ASD group. Conclusion: Individuals with ASD show atypical brain activation during perspective taking. Notably, their brain regions associated with stress reactions and escape responses are overactivated when taking other-perspective. This overactivity is related to poor interoceptive accuracy, suggesting that individuals with ASD may experience difficulties with the self-other distinction or atypical embodiment when considering another person's perspective.

12.
Cognition ; 230: 105285, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36152391

RESUMEN

Recent studies have shown that the ability to process number in the face of conflicting dimensions of magnitude is a crucial aspect of numerosity judgments, relying in part on the inhibition of the non-numerical dimensions. Here we report, for the first time, that these inhibitory control processes are specific to the conflicting dimension of magnitude. Using a non-symbolic numerical comparison task adapted to a conflict adaptation paradigm on a group of 82 adults, we show that congruency effects between numerical and non-numerical information were reduced only when the conflicting dimension was the same in the preceding incongruent trial. Attention to number thus involves inhibitory control processes acting at a specific level of information. These results contribute to better characterize the domain general abilities involved in numerical cognition, and provide evidence for a specific interaction between numerosity perception and inhibitory control.


Asunto(s)
Cognición , Inhibición Psicológica , Adulto , Humanos , Juicio/fisiología
13.
J Biomol Struct Dyn ; 41(11): 5138-5151, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-35612882

RESUMEN

Euphausia superba (Antarctic krill) serine protease (ESP) was investigated to gain insights into the activity-structural relationship, folding behavior, and regulation of the catalytic function. We purified ESP from the krill muscle and characterized biochemical distinctions via enzyme kinetics. Studies of inhibition kinetics and unfolding in the presence of a serine residue modifier, such as phenylmethanesulfonyl fluoride, were conducted. Structural characterizations were measured by spectrofluorimetry, including 1-anilinonaphthalene-8-sulfonate dye labeling for hydrophobic residues. The computational simulations such as docking and molecular dynamics were finally conducted to detect key residues and folding behaviors in a nano-second range. The kinetic parameters of ESP were measured as KmBANH = 0.97 ± 0.15 mM and kcat/KmBANH = 4.59 s-1/mM. The time-interval kinetics measurements indicated that ESP inactivation was transformed from a monophase to a biphase process to form a thermodynamically stable state. Spectrofluorimetry measurements showed that serine is directly connected to the regional folding of ESP. Several osmolytes such as proline and glycine only partially protected the inactive form of ESP by serine modification. Computational molecular dynamics and docking simulations showed that three serine residues (Ser183, Ser188, and Ser207) and Cys184, Val206, and Gly209 are key residues of catalytic functions. Our study revealed the functional roles of serine residues as key residues of catalytic function at the active site and of the structural conformation as key folding factors, where ESP displays a flexible property of active site pocket compared to the overall structure.Communicated by Ramaswamy H. Sarma.


Asunto(s)
Euphausiacea , Animales , Euphausiacea/química , Serina Proteasas , Serina Endopeptidasas , Regiones Antárticas , Serina
14.
Cells ; 12(20)2023 10 23.
Artículo en Inglés | MEDLINE | ID: mdl-37887348

RESUMEN

The mTOR signaling pathway integrates signaling inputs from nutrients, including glucose and amino acids, which are precisely regulated by transporters depending on nutrient levels. The L-type amino acid transporter 1 (LAT1) affects the activity of mTORC1 through upstream regulators that sense intracellular amino acid levels. While mTORC1 activation by LAT1 has been thoroughly investigated in cultured cells, the effects of LAT1 expression on the activity of mTORC2 has scarcely been studied. Here, we provide evidence that LAT1 recruits and activates mTORC2 on the lysosome for PMA-induced cell migration. LAT1 is translocated to the lysosomes in cells treated with PMA in a dose- and time-dependent manner. Lysosomal LAT1 interacted with mTORC2 through a direct interaction with Rictor, leading to the lysosomal localization of mTORC2. Furthermore, the depletion of LAT1 reduced PMA-induced cell migration in a wound-healing assay. Consistent with these results, the LAT1 N3KR mutant, which is defective in PMA-induced endocytosis and lysosomal localization, did not induce mTORC2 recruitment to the lysosome, with the activation of mTORC2 determined via Akt phosphorylation or the LAT1-mediated promotion of cell migration. Taken together, lysosomal LAT1 recruits and activates the mTORC2 complex and downstream Akt for PMA-mediated cell migration. These results provide insights into the development of therapeutic drugs targeting the LAT1 amino acid transporter to block metastasis, as well as disease progression in various types of cancer.


Asunto(s)
Transportador de Aminoácidos Neutros Grandes 1 , Lisosomas , Proteínas Proto-Oncogénicas c-akt , Movimiento Celular/fisiología , Lisosomas/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina , Diana Mecanicista del Complejo 2 de la Rapamicina/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transportador de Aminoácidos Neutros Grandes 1/metabolismo
15.
Med Phys ; 50(2): 791-807, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36273397

RESUMEN

BACKGROUND: Diagnostic performance based on x-ray breast imaging is subject to breast density. Although digital breast tomosynthesis (DBT) is reported to outperform conventional mammography in denser breasts, mass detection and malignancy characterization are often considered challenging yet. PURPOSE: As an improved diagnostic solution to the dense breast cases, we propose a dual-energy DBT imaging technique that enables breast compositional imaging at comparable scanning time and patient dose compared to the conventional single-energy DBT. METHODS: The proposed dual-energy DBT acquires projection data by alternating two different energy spectra. Then, we synthesize unmeasured projection data using a deep neural network that exploits the measured projection data and adjacent projection data obtained under the other x-ray energy spectrum. For material decomposition, we estimate partial path lengths of an x-ray through water, lipid, and protein from the measured and the synthesized projection data with the object thickness information. After material decomposition in the projection domain, we reconstruct material-selective DBT images. The deep neural network is trained with the numerical breast phantoms. A pork meat phantom is scanned with a prototype dual-energy DBT system to demonstrate the feasibility of the proposed imaging method. RESULTS: The developed deep neural network successfully synthesized missing projections. Material-selective images reconstructed from the synthesized data present comparable compositional contrast of the cancerous masses compared with those from the fully measured data. CONCLUSIONS: The proposed dual-energy DBT scheme is expected to substantially contribute to enhancing mass malignancy detection accuracy particularly in dense breasts.


Asunto(s)
Neoplasias de la Mama , Mamografía , Humanos , Femenino , Mamografía/métodos , Estudios de Factibilidad , Densidad de la Mama , Neoplasias de la Mama/diagnóstico por imagen , Redes Neurales de la Computación , Fantasmas de Imagen , Intensificación de Imagen Radiográfica
16.
Clin Transl Radiat Oncol ; 40: 100625, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37090849

RESUMEN

Purpose: This work evaluates an online adaptive (OA) workflow for head-and-neck (H&N) intensity-modulated proton therapy (IMPT) and compares it with full offline replanning (FOR) in patients with large anatomical changes. Methods: IMPT treatment plans are created retrospectively for a cohort of eight H&N cancer patients that previously required replanning during the course of treatment due to large anatomical changes. Daily cone-beam CTs (CBCT) are acquired and corrected for scatter, resulting in 253 analyzed fractions. To simulate the FOR workflow, nominal plans are created on the planning-CT and delivered until a repeated-CT is acquired; at this point, a new plan is created on the repeated-CT. To simulate the OA workflow, nominal plans are created on the planning-CT and adapted at each fraction using a simple beamlet weight-tuning technique. Dose distributions are calculated on the CBCTs with Monte Carlo for both delivery methods. The total treatment dose is accumulated on the planning-CT. Results: Daily OA improved target coverage compared to FOR despite using smaller target margins. In the high-risk CTV, the median D98 degradation was 1.1 % and 2.1 % for OA and FOR, respectively. In the low-risk CTV, the same metrics yield 1.3 % and 5.2 % for OA and FOR, respectively. Smaller setup margins of OA reduced the dose to all OARs, which was most relevant for the parotid glands. Conclusion: Daily OA can maintain prescription doses and constraints over the course of fractionated treatment, even in cases of large anatomical changes, reducing the necessity for manual replanning in H&N IMPT.

17.
Phys Med Biol ; 68(8)2023 04 03.
Artículo en Inglés | MEDLINE | ID: mdl-36930985

RESUMEN

Objective. The TOol for PArticle Simulation (TOPAS) is a Geant4-based Monte Carlo software application that has been used for both research and clinical studies in medical physics. So far, most users of TOPAS have focused on radiotherapy-related studies, such as modeling radiation therapy delivery systems or patient dose calculation. Here, we present the first set of TOPAS extensions to make it easier for TOPAS users to model medical imaging systems.Approach. We used the extension system of TOPAS to implement pre-built, user-configurable geometry components such as detectors (e.g. flat-panel and multi-planar detectors) for various imaging modalities and pre-built, user-configurable scorers for medical imaging systems (e.g. digitizer chain).Main results. We developed a flexible set of extensions that can be adapted to solve research questions for a variety of imaging modalities. We then utilized these extensions to model specific examples of cone-beam CT (CBCT), positron emission tomography (PET), and prompt gamma (PG) systems. The first of these new geometry components, the FlatImager, was used to model example CBCT and PG systems. Detected signals were accumulated in each detector pixel to obtain the intensity of x-rays penetrating objects or prompt gammas from proton-nuclear interaction. The second of these new geometry components, the RingImager, was used to model an example PET system. Positron-electron annihilation signals were recorded in crystals of the RingImager and coincidences were detected. The simulated data were processed using corresponding post-processing algorithms for each modality and obtained results in good agreement with the expected true signals or experimental measurement.Significance. The newly developed extension is a first step to making it easier for TOPAS users to build and simulate medical imaging systems. Together with existing TOPAS tools, this extension can help integrate medical imaging systems with radiotherapy simulations for image-guided radiotherapy.


Asunto(s)
Programas Informáticos , Tomografía Computarizada por Rayos X , Humanos , Simulación por Computador , Protones , Algoritmos , Método de Montecarlo
18.
Front Oncol ; 13: 1333039, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38510267

RESUMEN

Purpose: To demonstrate the suitability of optically stimulated luminescence detectors (OSLDs) for accurate simultaneous measurement of the absolute point dose and dose-weighted linear energy transfer (LETD) in an anthropomorphic phantom for experimental validation of daily adaptive proton therapy. Methods: A clinically realistic intensity-modulated proton therapy (IMPT) treatment plan was created based on a CT of an anthropomorphic head-and-neck phantom made of tissue-equivalent material. The IMPT plan was optimized with three fields to deliver a uniform dose to the target volume covering the OSLDs. Different scenarios representing inter-fractional anatomical changes were created by modifying the phantom. An online adaptive proton therapy workflow was used to recover the daily dose distribution and account for the applied geometry changes. To validate the adaptive workflow, measurements were performed by irradiating Al2O3:C OSLDs inside the phantom. In addition to the measurements, retrospective Monte Carlo simulations were performed to compare the absolute dose and dose-averaged LET (LETD) delivered to the OSLDs. Results: The online adaptive proton therapy workflow was shown to recover significant degradation in dose conformity resulting from large anatomical and positioning deviations from the reference plan. The Monte Carlo simulations were in close agreement with the OSLD measurements, with an average relative error of 1.4% for doses and 3.2% for LETD. The use of OSLDs for LET determination allowed for a correction for the ionization quenched response. Conclusion: The OSLDs appear to be an excellent detector for simultaneously assessing dose and LET distributions in proton irradiation of an anthropomorphic phantom. The OSLDs can be cut to almost any size and shape, making them ideal for in-phantom measurements to probe the radiation quality and dose in a predefined region of interest. Although we have presented the results obtained in the experimental validation of an adaptive proton therapy workflow, the same approach can be generalized and used for a variety of clinical innovations and workflow developments that require accurate assessment of point dose and/or average LET.

19.
Eur Spine J ; 21(12): 2620-5, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22825631

RESUMEN

INTRODUCTION: Symptomatic thoracic disc herniations (TDHs) are uncommon and can be surgically treated. Although transthoracic decompression is considered the gold standard, it is associated with significant comorbidities. In particular, approach via a posterior laminectomy has been associated with poor results. Several strategies have been developed for the resection of TDHs without manipulating the spinal cord. We describe a minimally invasive technique by using 3-D navigation and tubular retractors with the aid of a robotic holder via an oblique paraspinal approach. MATERIALS AND METHODS: The 20-mm working tube via an oblique trajectory through the fascia provides a good surgical field for thoracic discectomy through a microscope. We present our first five patients with TDHs operated using this minimally invasive approach. RESULTS: Neurological symptoms were improved postoperatively, and there were no surgical complications. There was no instability or recurrence during the follow-up period. CONCLUSION: The oblique paraspinal approach may offer an alternative surgical option for treating TDHs.


Asunto(s)
Discectomía Percutánea/instrumentación , Discectomía Percutánea/métodos , Desplazamiento del Disco Intervertebral/cirugía , Robótica/instrumentación , Vértebras Torácicas/cirugía , Adulto , Anciano , Descompresión Quirúrgica/instrumentación , Descompresión Quirúrgica/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neuronavegación , Robótica/métodos
20.
J Spinal Disord Tech ; 25(4): E93-102, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22425887

RESUMEN

STUDY DESIGN: Retrospective review OBJECTIVE: To determine the efficacy of management of cerebrospinal fluid (CSF) leakage after the anterior thoracic approach. SUMMARY OF BACKGROUND DATA: CSF leakage after incidental durotomy commonly occurs after anterior thoracic ossification of posterior longitudinal ligament (OPLL) surgery. Pseudomeningocele will invariably form under such circumstances. Among them, uncontrolled CSF leakage with a fistulous condition is problematic. As a solution, we have managed these durotomies with chest drains alone without any CSF drainage by the concept of a "volume-controlled pseudomeningocele." METHODS: Between 2001 and 2009, CSF leakage occurred in 26 patients (37.7%) of the total 69 patients who underwent anterior decompression for thoracic OPLL. In the initial 11 cases, subarachnoid drainage was utilized as an augmentive measure in combination with chest tube drainage in the postoperative period (group A). In the subsequent 15 cases, the durotomy was managed in a similar manner but in the absence of any subarachnoid drainage (group B). Various parameters such as the duration of postoperative hospital stay, clinical outcome score, drainage output, resolution of CSF leakage, complications, and additional surgery performed were analyzed and compared between the 2 groups. A resolution of the CSF leakage grading system was also proposed for the residual pseudomeningocele that formed in each group. RESULTS: There were statistically no significant differences in the outcome parameters between the 2 groups and also in patients with grade I or grade II residual pseudomeningocele of the new grading system. Two complications occurred in group A. No reexploration for persistent CSF leakage was required in both groups. CONCLUSIONS: CSF leakage managed with controlled chest tube drainage can produce a comparable result with those with additional subarachnoid drainage when watertight dural repair is impossible. The concept of controlled pseudomeningocele may be a useful and practical technique for the treatment of CSF leakage after anterior thoracic OPLL surgery.


Asunto(s)
Líquido Cefalorraquídeo , Descompresión Quirúrgica/efectos adversos , Drenaje/métodos , Duramadre/lesiones , Osificación del Ligamento Longitudinal Posterior/cirugía , Vértebras Torácicas/cirugía , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos
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