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1.
Hum Brain Mapp ; 45(5): e26634, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38553856

RESUMEN

Cerebral small vessel disease (SVD) can disrupt the global brain network and lead to cognitive impairment. Conversely, cognitive reserve (CR) can improve one's cognitive ability to handle damaging effects like SVD, partly by optimizing the brain network's organization. Understanding how SVD and CR collectively influence brain networks could be instrumental in preventing cognitive impairment. Recently, brain redundancy has emerged as a critical network protective metric, providing a nuanced perspective of changes in network organization. However, it remains unclear how SVD and CR affect global redundancy and subsequently cognitive function. Here, we included 121 community-dwelling participants who underwent neuropsychological assessments and a multimodal MRI examination. We visually examined common SVD imaging markers and assessed lifespan CR using the Cognitive Reserve Index Questionnaire. We quantified the global redundancy index (RI) based on the dynamic functional connectome. We then conducted multiple linear regressions to explore the specific cognitive domains related to RI and the associations of RI with SVD and CR. We also conducted mediation analyses to explore whether RI mediated the relationships between SVD, CR, and cognition. We found negative correlations of RI with the presence of microbleeds (MBs) and the SVD total score, and a positive correlation of RI with leisure activity-related CR (CRI-leisure). RI was positively correlated with memory and fully mediated the relationships between the MBs, CRI-leisure, and memory. Our study highlights the potential benefits of promoting leisure activities and keeping brain redundancy for memory preservation in older adults, especially those with SVD.


Asunto(s)
Enfermedades de los Pequeños Vasos Cerebrales , Disfunción Cognitiva , Reserva Cognitiva , Humanos , Anciano , Persona de Mediana Edad , Cognición , Encéfalo/diagnóstico por imagen , Disfunción Cognitiva/psicología , Imagen por Resonancia Magnética , Enfermedades de los Pequeños Vasos Cerebrales/complicaciones
2.
J Magn Reson Imaging ; 57(1): 238-245, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-35735742

RESUMEN

BACKGROUND: Widespread white matter (WM) injury is a hallmark feature of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). However, controversies about the mechanism of WM tract injury exist persistently. Excessive iron accumulation, frequently reported in CADASIL patients, might cause WM tract injury. PURPOSE: To test the association between iron accumulation and WM tract injury in CADASIL patients. STUDY TYPE: Retrospective. POPULATION: A total of 35 CADASIL patients (age = 50.4 ± 6.4, 62.9% female) and 48 healthy controls (age = 55.7 ± 8.0, 68.8% female). FIELD STRENGTH/SEQUENCE: Diffusion-weighted spin-echo echo-planar sequence; enhanced susceptibility-weighted angiography (ESWAN) gradient echo sequence on a 3 T scanner. ASSESSMENT: The phase images acquired by ESWAN were used to calculate quantitative susceptibility mapping (QSM). Iron accumulation was evaluated in deep gray matters using QSM. WM tract injury was quantified by diffusion metrics based on WM major tracts skeleton. We compared iron deposition between groups and analyzed the correlation between WM tract injury and iron deposition in regions showing significant differences from healthy controls. Exploratory analysis was carried out to investigate whether WM tract injury mediated the relationship between iron deposition and cognitive impairment evaluated by Mini-Mental State Examination (MMSE). STATISTICAL TESTS: General linear model (GLM), partial correlation, stepwise linear regression and mediation analysis were used. The threshold of statistical significance was set as p < 0.05. RESULTS: Compared with healthy controls, CADASIL patients had significantly increased iron deposition in the caudate and putamen. Aberrant iron deposition in these two regions was significantly associated with decreased WM fractional anisotropy (FA) (caudate, r = -0.373; putamen, r = - 0.421), and increased radial diffusivity (RD) (caudate, r = 0.372; putamen, r = 0.386). Furthermore, WM tract injury mediated the relationship between iron deposition and cognitive impairment. DATA CONCLUSION: Patients with CADASIL show increased iron deposition in the caudate and putamen that is correlated to WM tract injury, which may in turn mediate the association with cognitive impairment. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.


Asunto(s)
CADASIL , Sustancia Blanca , Humanos , Femenino , Masculino , CADASIL/complicaciones , CADASIL/diagnóstico por imagen , Sustancia Blanca/diagnóstico por imagen , Estudios Retrospectivos , Imagen por Resonancia Magnética , Hierro , Encéfalo/diagnóstico por imagen
3.
Eur Radiol ; 2023 Dec 13.
Artículo en Inglés | MEDLINE | ID: mdl-38092950

RESUMEN

OBJECTIVE: To investigate the effect of cholinergic pathways damage caused by white matter hyperintensities (WMHs) on cognitive function in moyamoya disease (MMD). METHODS: We included 62 patients with MMD from a prospectively enrolled cohort. We evaluated the burden of cholinergic pathways damage caused by WMHs using the Cholinergic Pathways Hyperintensities Scale (CHIPS). Cognitive function was evaluated with the Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Cognitive impairment was determined according to the cut-off of MMSE and education. Multivariate linear and logistic regression models were used to analyze whether CHIPS was independently associated with cognition. Receiver operating characteristic curve analysis was performed to identify the ability of CHIPS in discriminating cognitive impairment and normal cognition. RESULTS: CHIPS was associated with both MMSE and MoCA (ß = - 0.601 and ß = - 0.672, both p < 0.001). After correcting age, sex, education, volumes of limbic areas, and other factors, CHIPS remained to be independently associated with both MMSE and MoCA (ß = - 0.388 and ß = - 0.334, both p < 0.001). In the logistic regression, only CHIPS was associated with cognitive impairment (odds ratio = 1.431, 95% confidence interval = 1.103 to 1.856, p = 0.007). The optimal cut-off of CHIPS score was 10, yielding a sensitivity of 87.5% and a specificity of 78.3% in identifying MMD patients with cognitive impairment. CONCLUSIONS: The damage of cholinergic pathways caused by WMHs plays an independent effect on cognition and CHIPS could be a useful method in identifying MMD patients likely to be cognitive impairment. CLINICAL RELEVANCE STATEMENT: This study shows that Cholinergic Pathways Hyperintensities Scale (CHIPS) could be a simple and reliable method in identifying cognitive impairment for patients with moyamoya disease. CHIPS could be helpful in clinical practice, such as guiding treatment decisions and predicting outcome. KEY POINTS: • Cholinergic Pathways Hyperintensities Scale was significantly associated with cognitive screening tests in patients with moyamoya disease. • Cholinergic Pathways Hyperintensities Scale plays an independent effect on cognitive impairment in patients with moyamoya disease. • Cholinergic Pathways Hyperintensities Scale shows higher accuracy than education, volumes of limbic areas, and sex in identifying cognitive impairment in moyamoya disease.

4.
Eur Radiol ; 33(11): 8057-8066, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37284868

RESUMEN

OBJECTIVES: Venous pathology could contribute to the development of parenchymal lesions in cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). We aim to identify presumed periventricular venous infarction (PPVI) in CADASIL and analyze the associations between PPVI, white matter edema, and microstructural integrity within white matter hyperintensities (WMHs) regions. METHODS: We included forty-nine patients with CADASIL from a prospectively enrolled cohort. PPVI was identified according to previously established MRI criteria. White matter edema was evaluated using the free water (FW) index derived from diffusion tensor imaging (DTI), and microstructural integrity was evaluated using FW-corrected DTI parameters. We compared the mean FW values and regional volumes with different levels of FW (ranging from 0.3 to 0.8) in WMHs regions between the PPVI and non-PPVI groups. We used intracranial volume to normalize each volume. We also analyzed the association between FW and microstructural integrity in fiber tracts connected with PPVI. RESULTS: We found 16 PPVIs in 10 of 49 CADASIL patients (20.4%). The PPVI group had larger WMHs volume (0.068 versus 0.046, p = 0.036) and higher FW in WMHs (0.55 versus 0.52, p = 0.032) than the non-PPVI group. Larger areas with high FW content were also found in the PPVI group (threshold: 0.7, 0.47 versus 0.37, p = 0.015; threshold: 0.8, 0.33 versus 0.25, p = 0.003). Furthermore, higher FW correlated with decreased microstructural integrity (p = 0.009) in fiber tracts connected with PPVI. CONCLUSIONS: PPVI was associated with increased FW content and white matter degeneration in CADASIL patients. CLINICAL RELEVANCE STATEMENT: PPVI is an important factor related with WMHs, and therefore, preventing the occurrence of PPVI would be beneficial for patients with CADASIL. KEY POINTS: •Presumed periventricular venous infarction is important and occurs in about 20% of patients with CADASIL. •Presumed periventricular venous infarction was associated with increased free water content in the regions of white matter hyperintensities. •Free water correlated with microstructural degenerations in white matter tracts connected with the presumed periventricular venous infarction.


Asunto(s)
CADASIL , Sustancia Blanca , Humanos , CADASIL/complicaciones , CADASIL/diagnóstico por imagen , CADASIL/patología , Sustancia Blanca/diagnóstico por imagen , Sustancia Blanca/patología , Imagen de Difusión Tensora , Imagen por Resonancia Magnética/métodos , Edema/patología , Agua , Encéfalo/patología
5.
Appl Opt ; 62(19): 5057-5063, 2023 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-37707206

RESUMEN

The Ronchi test is widely used for wavefront measurements in advanced lithography tools, and a physical optics explanation of the Ronchi test based on scalar diffraction theory can be found in numerous publications. However, for high-numerical aperture (high-NA) lithography projection lenses, the vector nature of light should be considered when performing wavefront measurements, especially the effect of polarization aberrations on the wavefront test results. In this paper, a vector model for describing shearing interferometry for high-NA lithography projection lenses is established. In addition to considering the vector nature of light, the vector model also calculates the Ronchigram on the screen of a detector at any distance from a diffraction grating, as opposed to the distance restriction for the Fraunhofer diffraction approximation used by the existing methods. Using the developed mathematical model of the Ronchi test, the Ronchigrams of high-NA lithography projection lenses under non-polarized illumination are simulated, and the effect of the distance between the diffraction grating and the detection screen on the wavefront measurement accuracy are discussed.

6.
Hum Brain Mapp ; 43(17): 5310-5325, 2022 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-35822593

RESUMEN

White matter hyperintensities (WMH) are a typical feature of cerebral small vessel disease (CSVD), which contributes to about 50% of dementias worldwide. Microstructural alterations in deep white matter (DWM) have been widely examined in CSVD. However, little is known about abnormalities in superficial white matter (SWM) and their relevance for processing speed, the main cognitive deficit in CSVD. In 141 CSVD patients, processing speed was assessed using Trail Making Test Part A. White matter abnormalities were assessed by WMH burden (volume on T2-FLAIR) and diffusion MRI measures. SWM imaging measures had a large contribution to processing speed, despite a relatively low SWM WMH burden. Across all imaging measures, SWM free water (FW) had the strongest association with processing speed, followed by SWM mean diffusivity (MD). SWM FW was the only marker to significantly increase between two subgroups with the lowest WMH burdens. When comparing two subgroups with the highest WMH burdens, the involvement of WMH in the SWM was accompanied by significant differences in processing speed and white matter microstructure. Mediation analysis revealed that SWM FW fully mediated the association between WMH volume and processing speed, while no mediation effect of MD or DWM FW was observed. Overall, results suggest that the SWM has an important contribution to processing speed, while SWM FW is a sensitive imaging marker associated with cognition in CSVD. This study extends the current understanding of CSVD-related dysfunction and suggests that the SWM, as an understudied region, can be a potential target for monitoring pathophysiological processes.


Asunto(s)
Enfermedades de los Pequeños Vasos Cerebrales , Leucoaraiosis , Sustancia Blanca , Humanos , Sustancia Blanca/diagnóstico por imagen , Enfermedades de los Pequeños Vasos Cerebrales/complicaciones , Enfermedades de los Pequeños Vasos Cerebrales/diagnóstico por imagen , Imagen de Difusión por Resonancia Magnética , Cognición , Imagen por Resonancia Magnética
7.
Appl Opt ; 61(29): 8624-8632, 2022 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-36255994

RESUMEN

Thermal aberrations caused by absorption of laser beams degrade the image quality of exposure tools during the working process. Many compensators, such as lens movement or lens deformation, are used to compensate for low-order thermal aberrations of optical systems. In this paper, an apparatus with higher-order aberration correction capability is presented. The main principle of the apparatus is to actively heat and cool the lens near the pupil to generate a desired temperature profile to compensate for thermal aberrations. We first introduce the basic concept of the apparatus. Then we establish an analytical model to describe the lens temperature of the apparatus based on its working principle and demonstrate its compensation capability. Finally, an algorithm for dynamic thermal aberrations compensation is proposed to overcome the time lag effects of a thermally controlled lens.

8.
Opt Express ; 29(14): 21530-21538, 2021 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-34265938

RESUMEN

A distributed refractive index (RI) sensor based on high-performance optical frequency domain reflectometry was developed by bending a piece of standard single-mode fiber to excite sets of higher-order modes that penetrate the surrounding medium. External variations in RI modifies the profiles of the sets of excited higher-order modes, which are then partially coupled back into the fiber core and interfere with the fundamental mode. Accordingly, the fundamental mode carries the outer varied RI information, and RI sensing can be achieved by monitoring the wavelength shift of the local Rayleigh backscattered spectra. In the experiment, an RI sensitivity of 39.08 nm/RIU was achieved by bending a single-mode fiber to a radius of 4 mm. Additionally, the proposed sensor maintains its buffer coating intact, which boosts its practicability and application adaptability.

9.
J Magn Reson Imaging ; 54(4): 1326-1336, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-33998738

RESUMEN

BACKGROUND: Perivascular spaces (PVSs) are important component of the brain glymphatic system. While visual rating has been widely used to assess PVS, computational measures may have higher sensitivity for capturing PVS characteristics under disease conditions. PURPOSE: To compute quantitative and morphological PVS features and to assess their associations with vascular risk factors and cerebral small vessel disease (CSVD). STUDY TYPE: Prospective. POPULATION: One hundred sixty-one middle-aged/later middle-aged subjects (age = 60.4 ± 7.3). SEQUENCE: 3D T1-weighted, T2-weighted and T2-FLAIR sequences, and susceptibility-weighted multiecho gradient-echo sequence on a 3 T scanner. ASSESSMENT: Automated PVS segmentation was performed on sub-millimeter T2-weighted images. Quantitative and morphological PVS features were calculated in white matter (WM) and basal ganglia (BG) regions, including volume, count, size, length (Lmaj ), width (Lmin ), and linearity. Visual PVS scores were also acquired for comparison. STATISTICAL TESTS: Simple and multiple linear regression analyses were used to explore the associations among variables. RESULTS: WM-PVS visual score and count were associated with hypertension (ß = 0.161, P < 0.05; ß = 0.193, P < 0.05), as were BG-PVS rating score, volume, count and Lmin (ß = 0.197, P < 0.05; ß = 0.170, P < 0.05; ß = 0.200, P < 0.05; ß = 0.172, P < 0.05). WM-PVS size was associated with diabetes (ß = 0.165, P < 0.05). WM-PVS and BG-PVS were associated with CSVD markers, especially white matter hyperintensities (WMHs) (P < 0.05). Multiple regression analysis showed that WM/BG-PVS quantitative measures were widely associated with vascular risk factors and CSVD markers (P < 0.05). Morphological measures were associated with WMH severity in WM region and also associated with lacunes and microbleeds (P < 0.05) in BG region. DATA CONCLUSION: These novel PVS measures may capture mild PVS alterations driven by different pathologies. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.


Asunto(s)
Enfermedades de los Pequeños Vasos Cerebrales , Sustancia Blanca , Anciano , Enfermedades de los Pequeños Vasos Cerebrales/diagnóstico por imagen , Humanos , Imagen por Resonancia Magnética , Persona de Mediana Edad , Estudios Prospectivos , Factores de Riesgo , Sustancia Blanca/diagnóstico por imagen
10.
Hum Brain Mapp ; 41(3): 605-616, 2020 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-31675160

RESUMEN

Cognitive processing speed is crucial for human cognition and declines with aging. White matter hyperintensity (WMH), a common sign of WM vascular damage in the elderly, is closely related to slower psychomotor processing speed. In this study, we investigated the association between WMH and psychomotor speed changes through a comprehensive assessment of brain structural and functional features. Multi-modal MRIs were acquired from 60 elderly adults. Psychomotor processing speeds were assessed using the Trail Making Test Part A (TMT-A). Linear regression analyses were performed to assess the associations between TMT-A and brain features, including WMH volumes in five cerebral regions, diffusivity parameters in the major WM tracts, regional gray matter volume, and brain activities across the whole brain. Hierarchical regression analysis was used to demonstrate the contribution of each index to slower psychomotor processing speed. Linear regression analysis demonstrated that WMH volume in the occipital lobe and fractional anisotropy of the forceps major, an occipital association tract, were associated with TMT-A. Besides, resting-state brain activities in the visual cortex connected to the forceps major were associated with TMT-A. Hierarchical regression showed fractional anisotropy of the forceps major and regional brain activities were significant predictors of TMT-A. The occurrence of WMH, combined with the disruption of passing-through fiber integrity and altered functional activities in areas connected by this fiber, are associated with a decline of psychomotor processing speed. While the causal relationship of this WMH-Tract-Function-Behavior link requires further investigation, this study enhances our understanding of these complex mechanisms.


Asunto(s)
Envejecimiento/patología , Envejecimiento/fisiología , Corteza Cerebral/fisiología , Leucoaraiosis/patología , Desempeño Psicomotor/fisiología , Anciano , Mapeo Encefálico , Corteza Cerebral/diagnóstico por imagen , Femenino , Humanos , Leucoaraiosis/diagnóstico por imagen , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Prueba de Secuencia Alfanumérica
11.
J Magn Reson Imaging ; 52(2): 512-519, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-31981400

RESUMEN

BACKGROUND: The degeneration of the corticospinal tract (CST) in chronic stroke has been widely described using diffusion tensor imaging and correlates with the extent of motor deficits. However, only a few studies have reported the early degeneration in the distal CST during the acute stage of stroke and pathological changes in the distal CST have not been described. PURPOSE: To study the microstructural changes along the CST beyond the ischemic lesion in acute stroke using diffusion kurtosis imaging (DKI). STUDY TYPE: Prospective. POPULATION: In all, 48 patients (26 males, 22 females; mean age 58.27 ± 12.89 years) with acute ischemic stroke. SEQUENCE: A DKI sequence with three b-values (0, 1000, and 2000 s/mm2 ) at 3.0T MRI. ASSESSMENT: The kurtosis and tensor parameters were derived from DKI and were compared along the length of the CST beyond the ischemic lesion between the affected and unaffected hemispheres using both voxelwise and slicewise analysis. The degree of neurological deficits was evaluated using the National Institute of Health Stroke Score (NIHSS) and the Barthel index and the clinical outcome at 3 months was evaluated using a modified Rankin scale. STATISTICAL TESTS: Paired t-tests, a linear mixed model, and multivariate linear regression. RESULTS: Voxelwise analysis demonstrated increased mean kurtosis, increased axial kurtosis, and decreased axial diffusivity in the affected CST, which were seen only at the level of the cerebral peduncle (all corrected P < 0.05). Slicewise analysis also demonstrated increased axial kurtosis in the cerebral peduncle of the affected CST (corrected P < 0.05). The axial kurtosis from slicewise analysis independently correlated with the motor component of NIHSS (ß = 0.297, P = 0.040). DATA CONCLUSION: Our findings suggest that early anterograde degeneration occurs along the axon direction in the distal CST in acute stroke, and can be detected using DKI. Moreover, acute axonal degeneration along the CST correlated with motor deficits. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 1 J. Magn. Reson. Imaging 2020;52:512-519.


Asunto(s)
Isquemia Encefálica , Accidente Cerebrovascular , Anciano , Isquemia Encefálica/complicaciones , Isquemia Encefálica/diagnóstico por imagen , Imagen de Difusión por Resonancia Magnética , Imagen de Difusión Tensora , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Tractos Piramidales/diagnóstico por imagen , Accidente Cerebrovascular/diagnóstico por imagen
12.
Appl Opt ; 59(15): 4692-4696, 2020 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-32543578

RESUMEN

Computer-aided alignment is very important for the correction of aberrations due to construction imperfections of microlithographic optical systems. The compensation results mostly depend on the selection of compensators. In this paper, an effective method for compensation selection considering optomechanical constraints is presented. The techniques are based on the linearity of compensators and treat compensator selection as a combinatorial optimization problem with the objective of minimum residual aberrations and compensator adjustment ranges. The method is reliable and offers a better combination of compensators under constraints of optomechanical structure. As an example, the method was applied to a lithographic lens with a numerical aperture (NA) of 0.75. The results show that compensators with minimum objective function value would get minimum residual aberrations and adjustment ranges compared to those with larger objective function values. This method presented in this paper could be a good solution for compensation selection in lithographic lenses and other similar optical systems.

13.
Eur Radiol ; 29(1): 115-123, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-29926208

RESUMEN

OBJECTIVES: To test the hypothesis that abnormal corpus callosum (CC) induced by diabetes may impair inter-hemispheric sensorimotor functional connectivity (FC) that is associated with poor clinical outcome after stroke. METHODS: Forty-five patients with acute ischaemic stroke in the middle cerebral artery territory and 14 normal controls participated in the study. CC was divided into five subregions on three-dimensional T1-weighted image. The microstructural integrity of each subregion of CC was analysed by DTI and the inter-hemispheric FCs in primary motor cortex (M1-M1 FC) and primary sensory cortex (S1-S1 FC) were examined by resting-state functional magnetic resonance imaging. RESULTS: Diabetic patients (n = 26) had significantly lower fractional anisotropy (FA) in the isthmus of CC (CCisthmus) when compared with non-diabetic patients (n = 19) and normal controls (p < 0.0001). In addition, diabetic patients had the lowest M1-M1 FC (p = 0.015) and S1-S1 FC (p = 0.001). In diabetic patients, reduced FA of CCisthmus correlated with decreased M1-M1 FC (r = 0.549, p = 0.004) and S1-S1 FC (r = 0.507, p = 0.008). Decreased M1-M1 FC was independently associated with poor outcome after stroke in patients with diabetes (odds ratio = 0.448, p = 0.017). CONCLUSIONS: CC degeneration induced by diabetes impairs sensorimotor connectivity and dysfunction of motor connectivity can contribute to poor recovery after stroke in patients with diabetes. KEY POINTS: • Abnormal isthmus of corpus callosum in stroke patients with diabetes. • Abnormal isthmus of corpus callosum correlated with decreased inter-hemispheric sensorimotor connectivity. • Decreased motor connectivity correlated with poor stroke outcome in diabetic patients.


Asunto(s)
Isquemia Encefálica/complicaciones , Cuerpo Calloso/diagnóstico por imagen , Complicaciones de la Diabetes , Imagen por Resonancia Magnética/métodos , Enfermedades del Sistema Nervioso/etiología , Enfermedad Aguda , Anciano , Isquemia Encefálica/diagnóstico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedades del Sistema Nervioso/diagnóstico
14.
Appl Opt ; 57(29): 8654-8663, 2018 Oct 10.
Artículo en Inglés | MEDLINE | ID: mdl-30461940

RESUMEN

High laser absorption and strong resolution enhancement technology make thermal aberration control of lithography lenses more challenging. We present an active lens that uses four bellows actuators to generate astigmatism (Z5) on the lens surface. The apparatus utilizes optical path difference to compensate the system wavefront. In order to assess the specifications of the compensator, the finite element method and experimental analyses are carried out to obtain and validate the general properties of the apparatus. The results show that the Z5 deformation quantity of lens's upper surface exceeds 600 nm; further, Z5 coefficient accuracy is better than ±1 nm. The apparatus can be an efficient compensator for thermal aberration compensation, especially aberration caused by the dipole illumination.

15.
Eur J Neurosci ; 46(7): 2308-2314, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28833690

RESUMEN

Stroke recovery with changes in volume and perfusion of grey matter (GM) tissues remains largely unknown. We hypothesized that GM atrophy co-existed with GM plasticity presenting with increased volume and perfusion in specific regions in the period of post-stroke recovery. Twelve well-recovered stroke patients with pure subcortical lesions in the middle cerebral artery-perfused zone were included. All of them underwent structural and perfusion magnetic resonance imaging (MRI) examinations at admission and a mean of 6 months after stroke onset. Differences in GM volume (GMV) on structural images and cerebral blood flow (CBF) derived from perfusion images between two examinations were compared using voxel-based morphometry. The associations between changes in GMV and CBF with clinical scores were analysed. Decreased GMV was found in post-central gyrus, pre-central gyrus, precuneus, angular gyrus, insula, thalamus and cerebellum, and increased GMV was found in hippocampus, orbital gyrus and lingual gyrus (all corrected P < 0.05) at the follow-up examination. Increased CBF was found in subcallosal cingulate gyrus, hippocampus and lingual gyrus (all corrected P < 0.05) at the follow-up examination. Only decreased GMV in the anterior lobe of cerebellum was negatively associated with improvement of Barthel index (ß = -0.683, P = 0.014). Our study provides the imaging evidence of GM atrophy co-existing with GM plasticity involving in increased volume and perfusion in specific regions (including cognition, vision and emotion) in well-recovered stroke patients, which advances our understanding of neurobiology of stroke recovery.


Asunto(s)
Isquemia Encefálica/diagnóstico por imagen , Sustancia Gris/diagnóstico por imagen , Accidente Cerebrovascular/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Encéfalo/diagnóstico por imagen , Isquemia Encefálica/rehabilitación , Circulación Cerebrovascular , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Rehabilitación de Accidente Cerebrovascular
16.
Epilepsy Behav ; 70(Pt A): 259-264, 2017 05.
Artículo en Inglés | MEDLINE | ID: mdl-28427841

RESUMEN

Mesial temporal lobe epilepsy (mTLE) is a common type of drug-resistant epilepsy and secondarily generalized tonic-clonic seizures (sGTCS) have devastating consequences for patients' safety and quality of life. To probe the mechanism underlying the genesis of sGTCS, we investigated the structural differences between patients with and without sGTCS in a cohort of mTLE with radiologically defined unilateral hippocampal sclerosis. We performed voxel-based morphometric analysis of cortex and vertex-wise shape analysis of subcortical structures (the basal ganglia and thalamus) on MRI of 39 patients (21 with and 18 without sGTCS). Comparisons were initially made between sGTCS and non-sGTCS groups, and subsequently made between uncontrolled-sGTCS and controlled-sGTCS subgroups. Regional atrophy of the ipsilateral ventral pallidum (cluster size=450 voxels, corrected p=0.047, Max voxel coordinate=107, 120, 65), medial thalamus (cluster size=1128 voxels, corrected p=0.049, Max voxel coordinate=107, 93, 67), middle frontal gyrus (cluster size=60 voxels, corrected p<0.05, Max voxel coordinate=-30, 49.5, 6), and contralateral posterior cingulate cortex (cluster size=130 voxels, corrected p<0.05, Max voxel coordinate=16.5, -57, 27) was found in the sGTCS group relative to the non-sGTCS group. Furthermore, the uncontrolled-sGTCS subgroup showed more pronounced atrophy of the ipsilateral medial thalamus (cluster size=1240 voxels, corrected p=0.014, Max voxel coordinate=107, 93, 67) than the controlled-sGTCS subgroup. These findings indicate a central role of thalamus and pallidum in the pathophysiology of sGTCS in mTLE.


Asunto(s)
Epilepsia del Lóbulo Temporal/diagnóstico por imagen , Globo Pálido/diagnóstico por imagen , Imagen por Resonancia Magnética , Convulsiones/diagnóstico por imagen , Tálamo/diagnóstico por imagen , Adulto , Atrofia/patología , Estudios de Cohortes , Estudios Transversales , Epilepsia del Lóbulo Temporal/patología , Epilepsia del Lóbulo Temporal/fisiopatología , Femenino , Globo Pálido/patología , Globo Pálido/fisiopatología , Humanos , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Calidad de Vida , Convulsiones/patología , Convulsiones/fisiopatología , Tálamo/patología , Tálamo/fisiopatología , Adulto Joven
17.
Cancer Invest ; 34(9): 459-464, 2016 Oct 20.
Artículo en Inglés | MEDLINE | ID: mdl-27673353

RESUMEN

Des-γ-carboxyprothrombin (DCP), an abnormal prothrombin produced in human hepatocellular carcinoma (HCC), plays crucial roles in the progression of HCC. DCP binding to cellular mesenchymal-epithelial transition factor (c-Met) is an initial event and consequently stimulates HCC through the increase of c-Met-Janus kinase 1- signal transducers and activators of transcription pathways. DCP stimulates HCC invasion through activation of matrix metalloproteinase via upregulation of extracellular signal-regulated kinase-mitogen-activated protein kinase (MAPK) pathway. DCP stimulates HCC angiogenesis through activation of the DCP-kinase insert domain receptor-phospholipaseC-γ-MAPK pathway. Identification of these pathways is important for designing the therapeutic strategy for HCC.


Asunto(s)
Biomarcadores/metabolismo , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patología , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patología , Precursores de Proteínas/metabolismo , Protrombina/metabolismo , Transducción de Señal , Progresión de la Enfermedad , Humanos , Janus Quinasa 1/metabolismo , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Invasividad Neoplásica , Metástasis de la Neoplasia , Neovascularización Patológica , Fosfolipasa C gamma/metabolismo , Unión Proteica , Precursores de Proteínas/biosíntesis , Protrombina/biosíntesis , Proteínas Proto-Oncogénicas c-met/metabolismo , Factor de Transcripción STAT3/metabolismo , Receptor 2 de Factores de Crecimiento Endotelial Vascular/metabolismo
18.
Cerebrovasc Dis ; 42(1-2): 49-56, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26986824

RESUMEN

BACKGROUND: Diabetes mellitus (DM) is associated with a wide range of microvascular abnormalities in the brain. These include the dysfunction of the blood brain barrier (BBB). In this study, we test the hypotheses that disruption of the BBB in patients presenting with acute stroke is common in patients with DM and is related to outcome. METHODS: Sixty-two consecutive patients with ischemic stroke in the middle cerebral artery territory were enrolled within 3-7 days after onset. In ischemic lesion, BBB disruption was detected by parenchymal enhancement (PE) on 5 min delayed post-contrast T1 weighted imaging. National Institute of Health Stroke Score (NIHSS) assessed neurologic impairment on admission. Clinical outcome at 3 months was classified as unfavorable if the modified Rankin scale was >1. The independent factors associated with clinical outcome were analyzed using multivariate logistic regression analysis and OR with its 95% CIs were estimated. RESULTS: An unfavorable stroke outcome was found in 19 diabetic patients and 21 non-diabetic patients. Diabetic patients had a significantly higher frequency of PE than non-diabetic patients (58.6 vs. 27.3%, p = 0.013) and DM was independently associated with PE (OR 4.40; 95% CI 1.22-15.83; p = 0.023). PE was significantly more common in diabetic patients with unfavorable stroke outcome (73.7%) than in other 3 subgroups: diabetic patients with favorable stroke outcome (30.0%), non-diabetic patients with favorable stroke outcome (38.1%) and unfavorable stroke outcome (8.3%; p = 0.002). PE was independently associated with unfavorable outcome (UO) in diabetic stroke (DS; OR 7.04; 95% CI 1.20-41.52; p = 0.031). Admission NIHSS score was associated with UO in non-DS (NDS) (OR 1.71; 95% CI 1.10-2.66; p = 0.017). CONCLUSIONS: Compared with NDS, DS had increased BBB disruption defined by the presence of PE. A different form of the relationship between admission NIHSS and UO in NDS, BBB disruption was related with UO in diabetic patients after stroke.


Asunto(s)
Barrera Hematoencefálica/diagnóstico por imagen , Complicaciones de la Diabetes/diagnóstico por imagen , Imagen de Difusión por Resonancia Magnética , Infarto de la Arteria Cerebral Media/diagnóstico por imagen , Angiografía por Resonancia Magnética , Adulto , Anciano , Anciano de 80 o más Años , Barrera Hematoencefálica/fisiopatología , Distribución de Chi-Cuadrado , Complicaciones de la Diabetes/fisiopatología , Evaluación de la Discapacidad , Femenino , Humanos , Infarto de la Arteria Cerebral Media/fisiopatología , Modelos Logísticos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Oportunidad Relativa , Pronóstico , Estudios Prospectivos , Factores de Riesgo , Factores de Tiempo
19.
Appl Opt ; 55(15): 4186-91, 2016 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-27411148

RESUMEN

As a crucial step for thermal aberration prediction, thermal simulation is an effective way to acquire the temperature distribution of lenses. In the case of rigorous thermal simulation with the finite volume method, the amount of absorbed energy and its distribution within lens elements should be provided to guarantee simulation accuracy. In this paper, a computational method for simulation of thermal load distribution concerning lens material absorption was proposed based on light intensity of lens elements' surfaces. An algorithm for the verification of the method was also introduced, and the results showed that the method presented in this paper is an effective solution for thermal load distribution in a lithographic lens.

20.
Zhonghua Yu Fang Yi Xue Za Zhi ; 50(3): 255-60, 2016 Mar.
Artículo en Zh | MEDLINE | ID: mdl-26957245

RESUMEN

OBJECTIVE: To determine the level of genetic variation of human parainfluenza virus type 3 (HPIV-3), and to describe infection and co-infection characteristics of HPIV-3 in children. METHODS: Single respiratory samples from 856 pediatric patients with acute respiratory tract infection (ARI) in Hangzhou were collected from December 2009 to March 2013. All samples were screened for HPIV-3 by real-time RT-PCR and followed by HN sequencing and phylogenetic analysis. In all RSV positive specimens, we screened for the other pathogens, and co-infection characteristics were evaluated. RESULTS: A total of 9.6% of 856 samples were positive for HPIV-3, the nucleotide among the strains ranged from 96.9% to 100%. All Hangzhou strains were placed in C3 subgroup based on HN gene analysis. 49% (n=41) of all HPIV-3-positive children with ARI were found to be co-infected with at least one of the other pathogen. The highest co-infection rate of HPIV-3 was with HRV (n=17). Children in the younger groups (≤12 months old) were significantly more prone to be co-infected with other pathogen (χ(2)=4.78, P=0.029). Pneumonia infection rate was significantly higher in the mono-infection group than the co-infection group (χ(2)=3.92, P=0.048). CONCLUSION: HPIV-3 was an important pathogen in children with ARI in Hangzhou. HN gene variation rate was low, but showed a more local pattern. The co-infections with other respiratory viruses were popular. Except for pneumonia, no significant differences in other clinical presentation between the HPIV-3 mono-infection and co-infection groups were observed.


Asunto(s)
Virus de la Parainfluenza 3 Humana , Infecciones del Sistema Respiratorio/virología , Infecciones por Respirovirus/epidemiología , Niño , China/epidemiología , Variación Genética , Humanos , Filogenia , Reacción en Cadena en Tiempo Real de la Polimerasa , Infecciones del Sistema Respiratorio/epidemiología
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