Water driven adsorption of amino acids on the (101) anatase TiO2 surface: an ab initio study

Arg, Lys and Asp amino acids are known to play a critical role in the adhesion of the RKLPDA engineered peptide on the (101) surface of the titania anatase phase. To understand their contribution to peptide adhesion, we have considered the relevant charge states due to protonation (Arg and Lys) or deprotonation (Asp) occurring in neutral water solution, and studied their adsorption on the (101) anatase TiO2 surface by ab initio total energy calculations based on density functional theory. The adsorption configurations on the hydrated surface are compared to those on the dry surface considering also the presence of the hydration shell around amino acid side-chains. This study explains how water molecules mediate the adsorption of charged amino acids showing that protonated amino acids are chemically adsorbed much more strongly than de-protonated Asp. Moreover it is shown that the polar screening of the hydration shell reduces the adsorption energy of the protonated amino acids to a small extent, thus evidencing that both Arg and Lys strongly adhere on the (101) anatase TiO2 surface in neutral water solution and that they play a major role in the adhesion of the RKLPDA peptide

Assessment of White Matter Tract Damage in Patients with Amyotrophic Lateral Sclerosis: A Diffusion Tensor MR Imaging Tractography Study

BACKGROUND AND PURPOSE: Most DTI studies in ALS have been limited to the assessment of the CST damage. In this study, we used DTI tractography to investigate whether microstructural abnormalities occur in the major motor and extramotor WM tracts in mildly disabled patients with ALS. MATERIALS AND METHODS: Brain conventional MR imaging and DTI were performed in 24 patients with probable or definite ALS and mild disability (ALSFRS score, ≥20) and 20 healthy controls. The mean disease progression rate was 0.62 (range = 0.08–2.50). DTI tractography was used to segment the CST, the corpus callosum, and the major WM association tracts (ie, cingulum, uncinate fasciculus, inferior fronto-occipital, inferior longitudinal, and superior longitudinal fasciculi). RESULTS: Compared with healthy controls, patients with ALS showed significantly decreased FA and significantly increased MD and radial D of the CST bilaterally (P values from .005 to .01). Patients with ALS also had a significantly increased axial D of the right uncinate fasciculus relative to controls (P = .04). CST FA significantly correlated with the rate of disease progression (right CST: r = −0.50, P = .02; left CST: r = −0.41, P = .05). CONCLUSIONS: Patients with ALS and mild disability have preferential damage to the CST. The association of CST damage with the rate of disease progression suggests that DTI has the potential to provide in vivo markers of ALS evolution. The subtle involvement of the uncinate fasciculus may precede the appearance of behavioral symptoms in patients with ALS

Cognitive Functions and White Matter Tract Damage in Amyotrophic Lateral Sclerosis: A Diffusion Tensor Tractography Study

BACKGROUND AND PURPOSE: ALS is predominantly a disease of the motor system, but cognitive and behavioral symptoms also are observed. DT MR imaging is sensitive to microstructural changes occurring in WM tracts of patients with ALS. In this study, we investigated the association between cognitive functions and extramotor WM tract abnormalities in ALS patients. MATERIALS AND METHODS: DT MR imaging was obtained from 16 nondemented patients with ALS and 15 healthy controls. Patients with ALS underwent a neuropsychologic and behavioral evaluation. DT tractography was used to asses the integrity of the CST, corpus callosum, and the major long-range association tracts. The relationship between DT MR imaging metrics and cognitive functions was tested by using linear model analyses, adjusting for age and clinical disability. RESULTS: Eleven patients (69%) scored below the fifth percentile in at least 1 cognitive test, and 2 of them had a mild executive impairment. Performances at tests assessing attention and executive functions correlated with DT MR imaging metrics of the corpus callosum, CST, and long association WM tracts bilaterally, including the cingulum, inferior longitudinal, inferior fronto-occipital, and uncinate fasciculi. Verbal learning and memory test scores were associated with fornix DT MR imaging values, whereas visual-spatial abilities correlated with left uncinate fractional anisotropy. CONCLUSIONS: WM tract degeneration is associated with neuropsychologic deficits in patients with ALS. DT tractography holds promise to gain insight into the role of the brain WM network abnormalities in the development of cognitive impairment in patients with ALS

Patterns of Brain Structural Changes in First-Contact, Antipsychotic Drug-Naïve Patients with Schizophrenia

BACKGROUND AND PURPOSE: Previous studies have suggested that structural changes do occur in the brain of patients with schizophrenia compared with healthy control participants. However, findings from such studies are inconclusive, probably because of the different methodologic approaches, the clinical heterogeneity of patient samples, and also the fact that patients enrolled were treated with antipsychotic drugs. The aim of this study was to investigate brain GM volumes and intrinsic structural WM changes in first-contact, antipsychotic drug-naive patients with schizophrenia. MATERIALS AND METHODS: A total of 43 first-contact, drug-naive, patients with schizophrenia and 17 age-matched control participants were studied. All participants underwent T1-weighted MR imaging and DTI scans. Voxel-based morphometry and tract-based spatial statistics were used to compare GM volumes and WM DTI metrics between groups. MR imaging measures were correlated with the duration of the untreated psychosis and the clinical positive and negative symptoms. RESULTS: Compared with control participants, patients with schizophrenia showed smaller volumes of the temporal, parietal, and occipital GM, and a pattern of decreased mean diffusivity and increased fractional anisotropy in the brain stem and cerebellum bilaterally, interhemispheric and cortico-cortical connections bilaterally, and right anterior and posterior limb of the internal capsule. In patients, decreased mean diffusivity and increased fractional anisotropy in several brain regions were related to a longer duration of the untreated psychosis and the severity of positive symptoms. CONCLUSIONS: First-contact, drug-naive, patients with schizophrenia present with volumetric and DTI changes, which correlated with their clinical features. This study increases our knowledge on the neural networks involved in the pathophysiologic mechanisms of schizophrenia

the topography of brain microstructural damage in amyotrophic lateral sclerosis assessed using diffusion tensor mr imaging

BACKGROUND AND PURPOSE: ALS leads to macrostructural (ie, cortical atrophy and hyperintensities along the corticospinal tract) and microstructural (ie, gray matter intrinsic damage) central nervous system abnormalities. We used a multimodal voxelwise imaging approach to assess microstructural changes independent of macrostructural volume loss in patients with ALS compared with HCs. MATERIALS AND METHODS: Twenty-three patients with ALS and 14 HCs were studied. Conventional imaging and DTI were performed. Images were processed by using SPM5 to assess measures of gray and white matter atrophy as well as microstructural damage (ie, MD and FA). DTI alterations independent of volume loss were investigated. RESULTS: When we accounted for both gray and white matter atrophy, patients with ALS showed increased MD values in several gray and white matter areas mainly located in the orbitofrontal and frontotemporal regions bilaterally, in the right genu of the corpus callosum, and in the right posterior limb of the internal capsule. When we accounted for white matter volume loss, patients with ALS showed decreased FA along the corticospinal tract bilaterally and in the left inferior frontal lobe relative to HCs. The MD of the orbitofrontal regions bilaterally was associated significantly with disease duration. CONCLUSIONS: In patients with ALS, DTI detects microstructural changes independent of brain tissue loss. The affected regions included both motor and extramotor areas. The extent of ALS-related DTI abnormalities was greater than that disclosed by the volumetric analysis

The geometrical nature of optical resonances : from a sphere to fused dimer nanoparticles

We study the electromagnetic response of smooth gold nanoparticles with shapes varying from a single sphere to two ellipsoids joined smoothly at their vertices. We show that the plasmonic resonance visible in the extinction and absorption cross sections shifts to longer wavelengths and eventually disappears as the mid-plane waist of the composite particle becomes narrower. This process corresponds to an increase of the numbers of internal and scattering modes that are mainly confined to the surface and coupled to the incident field. These modes strongly affect the near field, and therefore are of great importance in surface spectroscopy, but are almost undetectable in the far field

Effectiveness and safety of virtual reality rehabilitation after stroke: an overview of systematic reviews

Background: Virtual reality (VR) is an innovative neurorehabilitation modality that has been variously examined in systematic reviews. We assessed VR effectiveness and safety after cerebral stroke. Methods: In this overview of systematic reviews, we searched eleven databases (Cochrane Database of Systematic Reviews, EMBASE, MEDLINE, SCOPUS, ISI Web of Science, CINAHL, PsycINFO, Pedro, Otseeker, Healthevidence.org, Epistemonikos) and grey literature from inception to January 17, 2023. Studies eligible for inclusion were systematic reviews published in English that included adult patients with a clinical diagnosis of stroke (acute to chronic phase) undergoing any kind of immersive, semi-immersive or non-immersive VR intervention with or without conventional therapy versus conventional therapy alone. The primary outcome was motor upper limb function and activity. The secondary outcomes were gait and balance, cognitive and mental function, limitation of activities, participation, and adverse events. We calculated the degree of overlap between reviews based on the corrected covered area (CCA). Methodological quality was assessed using the A MeaSurement Tool to Assess systematic Reviews (AMSTAR 2) and the Certainty of Evidence (CoE) using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) approach. Discordances between results were examined using a conceptual framework based on the Jadad algorithm. This overview is registered with PROSPERO, CRD42022329263. Findings: Of the 58 reviews included (n = 345 unique primary studies), 42 (72.4%) had conducted meta-analysis. More than half of the reviews (58.6%) were published between 2020 and 2022 and many (77.6%) were judged critically low in quality by AMSTAR 2. Most reported the Fugl Meyer Assessment scale (FMA-UE) to measure upper limb function and activity. For the primary outcome, there was a moderate overlap of primary studies (CCA 9.0%) with discordant findings. Focusing on upper limb function (FMA-UE), VR with or without conventional therapy seems to be more effective than conventional therapy alone, with low to moderate CoE and probable to definite clinical relevance. For secondary outcomes there was uncertainty about the superiority or no difference between groups due to substantial heterogeneity of measurement scales (eg, methodological choices). A few reviews (n = 6) reported the occurrence of mild adverse events. Interpretation: Current evidence suggests that multiple meta-analyses agreed on the superiority of VR with or without conventional therapy over conventional therapy on FME-UE for upper limb. Clinicians may consider embedding VR technologies into their practice as appropriate with patient's goals, abilities, and preferences. However, caution is needed given the poor methodological quality of reviews. Funding: Italian Ministry of Health

Variabilidad interanual a interdecádica de la precipitación en Patagonia norte

Se estudia la variabilidad interanual e interdecádica de la precipitación de verano y de invierno en la región norte de la Patagonia argentina, denominada Pampa Amarilla (RPA), para el período 1969-2006. El régimen anual muestra un marcado cambio del ciclo anual sobre una transecta noreste-sudoeste que atraviesa RPA. Hacia el noreste el ciclo anual de precipitación presenta los mayores registros, y muestra marcado mínimo invernal junto con máximo estival equinoccial (marzo). Hacia el sudoeste, los registros son menores, con uniforme distribución a lo largo del ciclo anual, presentando mínimos invernales ligeros. La distribución de frecuencia observada de las anomalías de precipitación, para verano e invierno, tienden a mostrar una mayor ocurrencia de frecuencias negativas en el intervalo (-100; 0)mm, con una ligera mayor probabilidad de ocurrencia de extremos positivos. Las tendencias de las series del semestre cálido son positivas y significativas hacia el norte, con excepción en la zona centro. Para el semestre frío, las tendencias son positivas y significativas en el norte y sudeste de la RPA. Es posible caracterizar toda la RPA mediante dos índices de precipitación para verano e invierno, respectivamente. Estos índices de precipitación regional no presentan tendencia significativa. El verano puede subdividirse en dos subregiones, norte y sur, con diverso comportamiento interanual. En el norte los ciclos dominantes son de 5 años a 8 años; y en el sur, en las bandas 2-4 años, ca. 11 años y ca. 15 años. El invierno presenta una variabilidad interanual espacialmente homogénea con cuasi-ciclos significativos en tomo a 4-5 años y 11 años. En ambas estaciones, los procesos de baja frecuencia de entre 2 y 6 años podrían estar relacionados al Modo Anular del Sur (MAS). El cuasi-ciclo solar podría estar involucrado también. Para veranos, la circulación troposférica de capas bajas, asociada a precipitación, también es discriminante entre norte y sur. Los centros de acción asociados a la precipitación en la subregión norte se localizan hacia latitudes medias sobre el Mar Argentino. Los asociados a la precipitación en la subregión sur se localizan hacia más altas latitudes. En general, actividad anticiclónica sobre la sobre el Mar Argentino y Patagonia de latitudes medias está asociada al ingreso de humedad desde el este y mayor precipitación sobre RPA en verano. En cambio, la actividad ciclónica en dicha región inhibe la precipitación. Para el invierno, la precipitación está más asociada a oestes más intensificados sobre el sur del Pacifico. El Niño-Oscilación del Sur (ENOS) parece también afectar la precipitación de verano.The objective is to analyze the interannual to interdecadal variability in summer and winter precipitation on the northem argentine Patagonia región, called Pampa Amarilla (RPA), during 1969-2006. The annual regime shows a strong change on annual cycle along the northeast-southwest transect in the RPA. Towards the northeast the annual cycle of precipitation has the máximum records with winter mínima and summer equinoccial maxima (March). Towards the southwest the records are smaller, with uniform distribution throughout the anual cycle, presenting slight winter minimum. The observed frequency distribution of the precipitation anomalies tends to show greater occurrence of negative frequencies in the interval (- 100; 0)mm with a slight major probability of occurrence of positive anomalies interval (right tail). The interannual variations for the warm period show, over the north sub-region, a positive and significative trend. An exception is the central region which trend is negative and significative. In the cold season, positive and significative trends are observed, especially in the north and in the southeast areas of the RPA. The RPA can be chracterized by devicing two precipitation indices, one for summer and the other for winter. The indices do not show significant trends. For the summer it is possible to split the región into two: one the northern RPA and the other the southern RPA, with diverse inter-annual behavior. In the northern the dominant cycles are 5 years and to 8 years, and in the southern, around 2-4 years, 11 years and 15 years. During the winter the whole RPA behaves as a uniform region with significant cuasi-cycles around 4-5 years and 11 years. For both summer and winter the regional precipitation indices do not show significant trends. The low-frequency processes between 2 and 6 years could be related to the Southern Annular Mode (SAM). The solar cuasi-cycle could be also involved. For the summer, the tropospheric circulation of lower levels is different in northern and southern RPA. The centers of precipitation at northern RPA are located towards mid-latitudes over the the Argentine Sea. Those associated with the precipitation in southern RPA, are located towards higher latitudes. Generally, anticyclonic activity on the Argentine Sea and Patagonia in high latitudes, can be associated with moisture advection from the east and more precipitation. However, the cyclonic activity at mid-latitudes around the Patagonia inhibits the precipitation. Over the Pacific side, the induced circulation centers seems to act by blocking the westerlies. For winter the precipitation is more associated to westerlies intensified in southern Pacific. The Niño- Southern Oscillation (ENSO) also seems to have influence on the summer precipitation.Asociación Argentina de Geofísicos y Geodesta