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1.
Plant Dis ; 2023 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-37221243

RESUMEN

Bacterial panicle blight (BPB) has become one of the most destructive diseases of rice worldwide and Burkholderia gladioli and B. glumae are two major pathogens causing BPB (1). This disease causes several types of damage, most importantly grain spotting, rot, and panicle blight, which can result in yield losses of 75% or more (1,3). In recent years, symptoms including sheath rot, grain spotting, grain rot, and panicle blight have been observed in both inbred and hybrid rice varieties. These symptoms resemble those of BPB and cause cultivar-dependent yield losses. (3) also reported the same symptoms for BPB. To confirm the cause of the disease, 21 rice panicles (Haridhan, a local variety) with typical BPB symptoms were collected from a farmer's field in the region of Mymensingh, Bangladesh during the rainy season in mid-October, 2021. Due to the severity of the outbreak, the panicles became dark brown and produced chaffy grains; nearly 100% of the rice panicles in that field were severely infected. To identify the causal pathogen(s), 1g of rice grains from 20 plants with typical BPB symptoms were surface-sterilized by immersing them in 70% ethanol for a few seconds followed by sodium hypochlorite solution (3%) for 1min. The grains were then rinsed with sterilized distilled water three times. Surface-sterilized grains were then ground with a mortar and pestle; 5mL of sterile distilled water was added during grinding. The extracted suspension (20µL) was then either streaked or spread onto the selective medium (S-PG) (2). Bacterial colonies showing purple color on the S-PG medium were selected and purified as candidate pathogens. For molecular characterization, species specific primers targeting gyrB gene were used to perform PCR and resulted in 479bp as reported by (4). To verify further, the PCR products of 16SF & 16SR were amplified and sequenced partially producing around 1400bp (1) and five 16SF partial sequences were deposited into NCBI GenBank (OP108276 to OP108280). 16S rDNA and gyrB revealed almost 99% homology with Burkholderia gladioli (KU851248.1, MZ425424.1) and B. gladioli (AB220893, CP033430) respectively using BLAST analysis. These purified bacterial isolates produced a diffusible light-yellow pigment on King's B medium indicating toxoflavin production (3). The candidate five bacterial isolates were then confirmed by inoculating 10ml suspension 108CFU/mL into the panicles and sheaths of BRRIdhan28 in net house condition as described previously (1). All of the bacterial isolates obtained from the spotted rice grains produced light brown lesions on the inoculated leaf sheath as well as spotting on the grain. To fulfill Koch's postulates, the bacteria were re-isolated from the symptomatic panicles and were confirmed as B. gladioli by analyzing the sequences of gyrB and 16s rDNA genes. Taken together, these results confirmed that B. gladioli is responsible for causing BPB in the rice grain samples that we collected. To our knowledge, this is the first report of BPB caused by B. gladioli in Bangladesh and further research is necessary to develop an effective disease management technique, or else the production of rice will be severely hampered.

2.
Anal Chem ; 94(28): 10045-10053, 2022 07 19.
Artículo en Inglés | MEDLINE | ID: mdl-35792073

RESUMEN

The phosphonate group is a key pharmacophore in many antiviral, antimicrobial, and antineoplastic drugs. Due to its high polarity and short retention time, detecting and quantifying such phosphonate-containing drugs with LC/MS-based methods are challenging and require derivatization with hazardous reagents. Given the emerging importance of phosphonate-containing drugs, developing a practical, accessible, and safe method for their quantitation in pharmacokinetics (PK) studies is desirable. NMR-based methods are often employed in drug discovery but are seldom used for compound quantitation in PK studies. Here, we show that proton-phosphorous (1H-31P) heteronuclear single quantum correlation (HSQC) NMR allows for the quantitation of the phosphonate-containing enolase inhibitor HEX in plasma and tissues at micromolar concentrations. Although mice were shown to rapidly clear HEX from circulation (over 95% in <1 h), the plasma half-life of HEX was more than 1 h in rats and nonhuman primates. This slower clearance rate affords a significantly higher exposure of HEX in rat models compared to that in mouse models while maintaining a favorable safety profile. Similar results were observed for the phosphonate-containing antibiotic, fosfomycin. Our study demonstrates the applicability of the 1H-31P HSQC method to quantify phosphonate-containing drugs in complex biological samples and illustrates an important limitation of mice as preclinical model species for phosphonate-containing drugs.


Asunto(s)
Antineoplásicos , Organofosfonatos , Animales , Antineoplásicos/farmacocinética , Antivirales , Ratones , Organofosfonatos/química , Primates , Protones , Ratas
3.
NMR Biomed ; 35(2): e4628, 2022 02.
Artículo en Inglés | MEDLINE | ID: mdl-34642974

RESUMEN

Neurite orientation dispersion and density imaging (NODDI) enables the assessment of intracellular, extracellular, and free water signals from multi-shell diffusion MRI data. It is an insightful approach to characterize brain tissue microstructure. Single-shell reconstruction for NODDI parameters has been discouraged in previous studies caused by failure when fitting, especially for the neurite density index (NDI). Here, we investigated the possibility of creating robust NODDI parameter maps with single-shell data, using the isotropic volume fraction (fISO ) as a prior. Prior estimation was made independent of the NODDI model constraint using a dictionary learning approach. First, we used a stochastic sparse dictionary-based network (DictNet), which is trained with data obtained from in vivo and simulated diffusion MRI data, to predict fISO . In single-shell cases, the mean diffusivity and raw T2 signal with no diffusion weighting (S0 ) was incorporated in the dictionary for the fISO estimation. Then, the NODDI framework was used with the known fISO to estimate the NDI and orientation dispersion index (ODI). The fISO estimated using our model was compared with other fISO estimators in the simulation. Further, using both synthetic data simulation and human data collected on a 3 T scanner (both high-quality HCP and clinical dataset), we compared the performance of our dictionary-based learning prior NODDI (DLpN) with the original NODDI for both single-shell and multi-shell data. Our results suggest that DLpN-derived NDI and ODI parameters for single-shell protocols are comparable with original multi-shell NODDI, and the protocol with b = 2000 s/mm2 performs the best (error ~ 5% in white and gray matter). This may allow NODDI evaluation of studies on single-shell data by multi-shell scanning of two subjects for DictNet fISO training.


Asunto(s)
Imagen de Difusión por Resonancia Magnética/métodos , Neuritas , Recuento de Células , Simulación por Computador , Humanos
4.
Mol Biol Rep ; 49(9): 8449-8460, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35819558

RESUMEN

BACKGROUND: The SHANK3 gene encodes a master synaptic scaffolding protein at the excitatory synapse's postsynaptic density, which is predominantly responsible for constructing a synapse, maintaining synaptic structure, and functions. Recently, evidence from rare mutations and copy number variation provided an important clue about SHANK3 which acts as a strong candidate gene in the pathogenesis of Autism Spectrum Disorder (ASD). MATERIALS AND METHODS: To investigate potential allelic variants for the SHANK3 (rs9616915) gene as a genetic risk factor, we performed PCR-RFLP analysis and Sanger sequencing for 90 ASD and 90 healthy subjects. Moreover, to understand the functional and structural impacts of our selected non-synonymous SHANK3 SNP rs9616915, we have performed an in silico analysis. Subsequently, a meta-analysis of rs9616915 with a total of 6 eligible studies (including the present study) containing a total of 795 cases and 12,947 controls was obtained from a comprehensive online database search to evaluate the overall association with ASD. RESULTS: Our retrieved data, such as Pearson's chi-square test (p = 0.081) as well as logistic regression analysis of co-dominant (p = 0.1131), dominant (p = 0.3656) and recessive models (p = 0.0569) speculated no significant association between rs9616915 and our studied sample. Interestingly, by in silico analysis, we have observed two hydrogen bonds between amino acids instead of one hydrogen bond in the protein structure of rs9616915, which indicates this mutant structure could affect the proteins' stability. The findings of the meta-analysis revealed that four genetic association models were associated with ASD susceptibility. CONCLUSIONS: Our study suggested that targeted SHANK3 SNP of interest rs9616915 might not be associated with ASD in the southern part of the Bangladeshi population.


Asunto(s)
Trastorno del Espectro Autista , Proteínas del Tejido Nervioso , Pueblo Asiatico , Trastorno del Espectro Autista/genética , Variaciones en el Número de Copia de ADN , Predisposición Genética a la Enfermedad , Humanos , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo
5.
BMC Infect Dis ; 21(1): 1139, 2021 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-34743683

RESUMEN

BACKGROUND: The alarming rise in multi-drug resistant (MDR) zoonotic pathogens, including Campylobacter spp., has been threatening the health sector globally. In Bangladesh, despite rapid growth in poultry sector little is known about the potential risks of zoonotic pathogens in homestead duck flocks. The aim of this study was to understand the occurrence, species diversity, and multi-drug resistance in Campylobacter spp., and identify the associated risk factors in duck farms in Bangladesh. METHODS: The study involved 20 duck farms at 6 sub-districts of Mymensingh, Bangladesh. Monthly occurrence of Campylobacter spp. in potential sources at the farms during February-September, 2018, was detected by culture and PCR-based methods. Campylobacter isolates were examined for resistance to different antimicrobials. Risk factors, concerning climatic and environmental disposition, farm management, and anthropogenic practices, of Campylobacter infection were estimated by participatory epidemiological tools. RESULTS: Occurrence of Campylobacter spp. was detected in overall 36.90% (155/420) samples, more frequently in drinking water (60%, 30/50), followed by cloacal swab (37.50%, 75/200), egg surface swab (35%, 35/100) and soil of the duck resting places (30%, 15/50) but was not detected in feed samples (n = 20). PCR assays distinguished the majority (61.30%, 95/155) of the isolates as C. coli, while the rest (38.70%, 60/155) were C. jejuni. Notably, 41.7% (25/60) and 31.6% (30/95) strains of C. jejuni and C. coli, respectively, were observed to be MDR. The dynamics of Campylobacter spp., distinctly showing higher abundance during summer and late-monsoon, correlated significantly with temperature, humidity, and rainfall, while sunshine hours had a negative influence. Anthropogenic management-related factors, including, inadequate hygiene practices, use of untreated river water, wet duck shed, flock age (1-6 months), and unscrupulous use of antimicrobials were identified to enhance the risk of MDR Campylobacter infection. CONCLUSION: The present study clearly demonstrates that duck farms contribute to the enhanced occurrence and spread of potentially pathogenic and MDR C. coli and C. jejuni strains and the bacterial dynamics are governed by a combined interaction of environmental and anthropogenic factors. A long-term holistic research at the environment-animal-human interface would be integral to divulge health risk reduction approaches tackling the spread of Campylobacter spp. from duck farms.


Asunto(s)
Infecciones por Campylobacter , Campylobacter coli , Campylobacter jejuni , Campylobacter , Enfermedades de las Aves de Corral , Animales , Bangladesh/epidemiología , Campylobacter/genética , Infecciones por Campylobacter/epidemiología , Infecciones por Campylobacter/veterinaria , Pollos , Resistencia a Múltiples Medicamentos , Patos , Granjas , Humanos , Lactante , Enfermedades de las Aves de Corral/epidemiología , Factores de Riesgo
6.
Chemistry ; 25(70): 16037-16047, 2019 Dec 13.
Artículo en Inglés | MEDLINE | ID: mdl-31650641

RESUMEN

he mechanistic details of the aldol addition of N-amino cyclic carbamate (ACC) hydrazones is provided herein from both an experimental and computational perspective. When the transformation is carried out at room temperature the anti-aldol product is formed exclusively. Under these conditions the anti- and syn-aldolate intermediates are in equilibrium and the transformation is under thermodynamic control. The anti-aldolate that leads to the anti-aldol product was calculated to be 3.7 kcal mol-1 lower in energy at room temperature than that leading to the syn-aldol product, which sufficiently accounts for the exclusive formation of the anti-aldol product. When the reaction is conducted at -78 °C it is under kinetic control and favors formation of the syn-aldol addition product. In this case, it was found that a solvent separated aza-enolate anion and aldehyde form a σ-intermediate in which the lithium cation is coordinated to the aldehyde. The σ-intermediate collapses with a very small activation barrier to form the ß-alkoxy hydrazone intermediate. The chiral nonracemic lithium aza-enolate discriminates between the two diastereotopic faces of the pro-chiral aldehyde, and there is no rapid direct pathway that interconverts the two diastereomeric intermediates. Consequently, the reaction does not follow the Curtin-Hammett principle and the stereochemical outcome at low temperature instead depends on the relative energies of the two σ-intermediates.

7.
NMR Biomed ; 31(3)2018 03.
Artículo en Inglés | MEDLINE | ID: mdl-29315894

RESUMEN

Given the growing popularity of T1 -weighted/T2 -weighted (T1 w/T2 w) ratio measurements, the objective of the current study was to evaluate the concordance between T1 w/T2 w ratios obtained using conventional fast spin echo (FSE) versus combined gradient and spin echo (GRASE) sequences for T2 w image acquisition, and to compare the resulting T1 w/T2 w ratios with histologically validated myelin water fraction (MWF) measurements in several subcortical brain structures. In order to compare these measurements across a relatively wide range of myelin concentrations, whole-brain T1 w magnetization prepared rapid acquisition gradient echo (MPRAGE), T2 w FSE and three-dimensional multi-echo GRASE data were acquired from 10 participants with multiple sclerosis at 3 T. Then, after high-dimensional, non-linear warping, region of interest (ROI) analyses were performed to compare T1 w/T2 w ratios and MWF estimates (across participants and brain regions) in 11 bilateral white matter (WM) and four bilateral subcortical grey matter (SGM) structures extracted from the JHU_MNI_SS 'Eve' atlas. Although the GRASE sequence systematically underestimated T1 w/T2 w values compared to the FSE sequence (revealed by Bland-Altman and mountain plots), linear regressions across participants and ROIs revealed consistently high correlations between the two methods (r2 = 0.62 for all ROIs, r2 = 0.62 for WM structures and r2 = 0.73 for SGM structures). However, correlations between either FSE-based or GRASE-based T1 w/T2 w ratios and MWFs were extremely low in WM structures (FSE-based, r2 = 0.000020; GRASE-based, r2 = 0.0014), low across all ROIs (FSE-based, r2 = 0.053; GRASE-based, r2 = 0.029) and moderate in SGM structures (FSE-based, r2 = 0.20; GRASE-based, r2 = 0.17). Overall, our findings indicated a high degree of correlation (but not equivalence) between FSE-based and GRASE-based T1 w/T2 w ratios, and low correlations between T1 w/T2 w ratios and MWFs. This suggests that the two T1 w/T2 w ratio approaches measure similar facets of subcortical tissue microstructure, whereas T1 w/T2 w ratios and MWFs appear to be sensitized to different microstructural properties. On this basis, we conclude that multi-echo GRASE sequences can be used in future studies to efficiently elucidate both general (T1 w/T2 w ratio) and myelin-specific (MWF) tissue characteristics.


Asunto(s)
Corteza Cerebral/anatomía & histología , Imagen por Resonancia Magnética , Vaina de Mielina/metabolismo , Marcadores de Spin , Agua/química , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Modelos Lineales , Masculino , Persona de Mediana Edad , Adulto Joven
8.
J Org Chem ; 83(21): 12951-12964, 2018 11 02.
Artículo en Inglés | MEDLINE | ID: mdl-30200759

RESUMEN

The α-alkylation of ketones is a fundamental synthetic transformation. The development of asymmetric variants of this reaction is important given that numerous natural products, drugs, and related compounds exist as α-functionalized ketones or derivatives thereof. We previously reported our preliminary studies on the development of a new enantioselective ketone α-alkylation procedure using N-amino cyclic carbamate (ACC) auxiliaries. In comparison to other auxiliary-based methods, ACC alkylation offers a number of advantages and is both highly enantioselective and high yielding. Herein, we provide a full account of our studies on the enantioselective ACC ketone α-alkylation method.

9.
Mult Scler ; 22(9): 1133-43, 2016 08.
Artículo en Inglés | MEDLINE | ID: mdl-26503237

RESUMEN

BACKGROUND: Deep gray matter (DGM) is affected in relapsing-remitting multiple sclerosis (RRMS) and may be studied using short-term longitudinal MRI. OBJECTIVE: To investigate two-year changes in spin-echo transverse relaxation rate (R2) and atrophy in DGM, and its relationship with disease severity in RRMS patients. METHODS: Twenty six RRMS patients and 26 matched controls were imaged at 4.7 T. Multiecho spin-echo R2 maps and atrophy measurements were obtained in DGM at baseline and two-year follow-up. Differences between MRI measures and correlations to disease severity were examined. RESULTS: After two years, mean R2 values in the globus pallidus and pulvinar increased by ~4% (p<0.001) in patients and <1.7% in controls. Two-year changes in R2 showed significant correlation to disease severity in the globus pallidus, pulvinar, substantia nigra, and thalamus. Multiple regression of the two-year R2 difference using these four DGM structures as variables, yielded high correlation with disease severity (r=0.83, p<0.001). Two-year changes in volume and R2 showed significant correlation only for the globus pallidus in multiple sclerosis (MS) (p<0.05). CONCLUSIONS: Two-year difference R2 measurements in DGM correlate to disease severity in MS. R2 mapping and atrophy measurements over two years can be used to identify changes in DGM in MS.


Asunto(s)
Sustancia Gris/patología , Interpretación de Imagen Asistida por Computador/métodos , Imagen por Resonancia Magnética/métodos , Esclerosis Múltiple Recurrente-Remitente/patología , Adulto , Atrofia , Estudios de Casos y Controles , Progresión de la Enfermedad , Femenino , Humanos , Estudios Longitudinales , Masculino , Persona de Mediana Edad , Tamaño de los Órganos , Valor Predictivo de las Pruebas , Índice de Severidad de la Enfermedad , Factores de Tiempo
10.
Phys Med Biol ; 69(11)2024 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-38670141

RESUMEN

The relatively new tools of brain elastography have established a general trendline for healthy, aging adult humans, whereby the brain's viscoelastic properties 'soften' over many decades. Earlier studies of the aging brain have demonstrated a wide spectrum of changes in morphology and composition towards the later decades of lifespan. This leads to a major question of causal mechanisms: of the many changes documented in structure and composition of the aging brain, which ones drive the long term trendline for viscoelastic properties of grey matter and white matter? The issue is important for illuminating which factors brain elastography is sensitive to, defining its unique role for study of the brain and clinical diagnoses of neurological disease and injury. We address these issues by examining trendlines in aging from our elastography data, also utilizing data from an earlier landmark study of brain composition, and from a biophysics model that captures the multiscale biphasic (fluid/solid) structure of the brain. Taken together, these imply that long term changes in extracellular water in the glymphatic system of the brain along with a decline in the extracellular matrix have a profound effect on the measured viscoelastic properties. Specifically, the trendlines indicate that water tends to replace solid fraction as a function of age, then grey matter stiffness decreases inversely as water fraction squared, whereas white matter stiffness declines inversely as water fraction to the 2/3 power, a behavior consistent with the cylindrical shape of the axons. These unique behaviors point to elastography of the brain as an important macroscopic measure of underlying microscopic structural change, with direct implications for clinical studies of aging, disease, and injury.


Asunto(s)
Envejecimiento , Encéfalo , Diagnóstico por Imagen de Elasticidad , Humanos , Envejecimiento/fisiología , Encéfalo/diagnóstico por imagen , Anciano , Persona de Mediana Edad , Adulto , Elasticidad , Masculino , Viscosidad , Femenino , Anciano de 80 o más Años , Sustancia Blanca/diagnóstico por imagen , Adulto Joven
11.
Res Sq ; 2024 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-38946952

RESUMEN

Despite advancements, the prevalence of HIV-associated neurocognitive impairment remains at approximately 40%, attributed to factors like pre-cART (combination antiretroviral therapy) irreversible brain injury. People with HIV (PWH) treated with cART do not show significant neurocognitive changes over relatively short follow-up periods. However, quantitative neuroimaging may be able to detect ongoing subtle microstructural changes. This study aimed to investigate the sensitivity of tensor-valued diffusion encoding in detecting such changes in brain microstructural integrity in cART-treated PWH. Additionally, it explored relationships between these metrics, neurocognitive scores, and plasma levels of neurofilament light (NFL) chain and glial fibrillary acidic protein (GFAP). Using MRI at 3T, 24 PWH and 31 healthy controls underwent cross-sectional examination. The results revealed significant variations in b-tensor encoding metrics across white matter regions, with associations observed between these metrics, cognitive performance, and blood markers of neuronal and glial injury (NFL and GFAP). Moreover, a significant interaction between HIV status and imaging metrics was observed, particularly impacting total cognitive scores in both gray and white matter. These findings suggest that b-tensor encoding metrics offer heightened sensitivity in detecting subtle changes associated with axonal injury in HIV infection, underscoring their potential clinical relevance in understanding neurocognitive impairment in PWH.

12.
bioRxiv ; 2024 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-38352359

RESUMEN

Chronic back pain (CBP) is a global health concern with significant societal and economic burden. While various predictors of back pain chronicity have been proposed, including demographic and psychosocial factors, neuroimaging studies have shown that brain characteristics can serve as robust predictors of CBP. However, large-scale, multisite validation of these predictors is currently lacking. In two independent longitudinal studies, we examined white matter diffusion imaging data and pain characteristics in patients with subacute back pain (SBP) over six- and 12-month periods. Diffusion data from individuals with CBP and healthy controls (HC) were analyzed for comparison. Whole-brain tract-based spatial statistics analyses revealed that a cluster in the right superior longitudinal fasciculus (SLF) tract had larger fractional anisotropy (FA) values in patients who recovered (SBPr) compared to those with persistent pain (SBPp), and predicted changes in pain severity. The SLF FA values accurately classified patients at baseline and follow-up in a third publicly available dataset (Area under the Receiver Operating Curve ~ 0.70). Notably, patients who recovered had FA values larger than those of HC suggesting a potential role of SLF integrity in resilience to CBP. Structural connectivity-based models also classified SBPp and SBPr patients from the three data sets (validation accuracy 67%). Our results validate the right SLF as a robust predictor of CBP development, with potential for clinical translation. Cognitive and behavioral processes dependent on the right SLF, such as proprioception and visuospatial attention, should be analyzed in subacute stages as they could prove important for back pain chronicity.

13.
Magn Reson Med ; 70(5): 1340-6, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23325543

RESUMEN

Transverse relaxation (T2 ) mapping has many applications, including imaging of iron accumulation in grey matter. Using the typical multiecho spin-echo sequence with long echo trains, stimulated echo compensation can enable T2 fitting under conditions of variable radio frequency homogeneity arising from slice profile and in-plane radio frequency variation. Substantial reduction in the number of refocusing pulses could enable use at high magnetic fields where specific absorption rate is a major limitation, and enable multislice use with reduced incidental magnetization transfer at all field strengths. We examine the effect of reduced echo train lengths and multislice imaging on T2 fitting using stimulated echo compensation applied to iron-rich subcortical grey matter in human brain at 4.7 T. Our findings indicate that reducing from 20 echoes to as few as four echoes can maintain consistent T2 values when using stimulated echo compensation in grey and white matter, but not for cerebrospinal fluid. All territories produce marginal results when using standard exponential fitting. Savings from reduced echoes can be used to substantially increase slice coverage. In multislice mode, the resulting incidental magnetization transfer decreased brain signal but had minimal effect on measured T2 values.


Asunto(s)
Algoritmos , Encéfalo/anatomía & histología , Imagen Eco-Planar/métodos , Aumento de la Imagen/métodos , Interpretación de Imagen Asistida por Computador/métodos , Imagenología Tridimensional/métodos , Adulto , Femenino , Humanos , Masculino , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
14.
Front Neurol ; 14: 1168833, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37153663

RESUMEN

Artificial intelligence (AI) has made significant advances in the field of diffusion magnetic resonance imaging (dMRI) and other neuroimaging modalities. These techniques have been applied to various areas such as image reconstruction, denoising, detecting and removing artifacts, segmentation, tissue microstructure modeling, brain connectivity analysis, and diagnosis support. State-of-the-art AI algorithms have the potential to leverage optimization techniques in dMRI to advance sensitivity and inference through biophysical models. While the use of AI in brain microstructures has the potential to revolutionize the way we study the brain and understand brain disorders, we need to be aware of the pitfalls and emerging best practices that can further advance this field. Additionally, since dMRI scans rely on sampling of the q-space geometry, it leaves room for creativity in data engineering in such a way that it maximizes the prior inference. Utilization of the inherent geometry has been shown to improve general inference quality and might be more reliable in identifying pathological differences. We acknowledge and classify AI-based approaches for dMRI using these unifying characteristics. This article also highlighted and reviewed general practices and pitfalls involving tissue microstructure estimation through data-driven techniques and provided directions for building on them.

15.
Magn Reson Imaging ; 98: 115-123, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36682396

RESUMEN

PURPOSE: To investigate the relationship between pathological brain iron deposition and white matter hyperintensities (WMHs) in cerebral small vessel disease (CSVD), via Monte Carlo simulations of magnetic susceptibility imaging and the development of a novel imaging marker called the Expected Iron Coefficient (EIC). METHODS: A synthetic pathological model of a different number of impenetrable spheres at random locations was employed to represent pathological iron deposition. The diffusion process was simulated with a Monte Carlo method with adjustable parameters to manipulate sphere size, distribution, and extracellular properties. Quantitative susceptibility mapping (QSM) was performed in a clinical dataset to study CSVD to derive and evaluate QSM, R2*, the iron microenvironment coefficient (IMC), and the EIC in the presence of WMHs. RESULTS: The simulations show that QSM signals increase in the presence of increased tissue iron, confirming that the EIC increases with pathology. Clinical results demonstrate that while QSM, R2*, and the IMC do not show significant differences in brain iron, the EIC does in the context of CSVD. CONCLUSION: The EIC is more sensitive to subtle changes in brain iron deposition caused by pathology, even when QSM, R2*, and the IMC fail.


Asunto(s)
Enfermedades de los Pequeños Vasos Cerebrales , Leucoaraiosis , Sustancia Blanca , Humanos , Hierro , Imagen por Resonancia Magnética/métodos , Sustancia Blanca/diagnóstico por imagen , Encéfalo/diagnóstico por imagen , Interpretación de Imagen Asistida por Computador/métodos , Mapeo Encefálico , Sustancia Gris
16.
Front Hum Neurosci ; 17: 1196624, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37484918

RESUMEN

Background: The open-access UManitoba-JHU functionally defined human white matter (WM) atlas contains specific WM pathways and general WM regions underlying 12 functional brain networks in ICBM152 template space. However, it is not known whether any of these WM networks are disproportionately co-localized with periventricular and/or juxtacortical WM (PVWM and JCWM), which could potentially impact their ability to infer network-specific effects in future studies-particularly in patient populations expected to have disproportionate PVWM and/or JCWM damage. Methods: The current study therefore identified intersecting regions of PVWM and JCWM (defined as WM within 5 mm of the ventricular and cortical boundaries) and: (1) the ICBM152 global WM mask, and (2) all 12 UManitoba-JHU WM networks. Dice Similarity Coefficient (DSC), Jaccard Similarity Coefficient (JSC), and proportion of volume (POV) values between PVWM (and JCWM) and each functionally defined WM network were then compared to corresponding values between PVWM (and JCWM) and global WM. Results: Between the 12 WM networks and PVWM, 8 had lower DSC, JSC, and POV; 1 had lower DSC and JSC, but higher POV; and 3 had higher DSC, JSC, and POV compared to global WM. For JCWM, all 12 WM networks had lower DSC, JSC, and POV compared to global WM. Conclusion: The majority of UManitoba-JHU functionally defined WM networks exhibited lower than average spatial similarity with PVWM, and all exhibited lower than average spatial similarity with JCWM. This suggests that they can be used to explore network-specific WM changes, even in patient populations with known predispositions toward PVWM and/or JCWM damage.

17.
Heliyon ; 9(4): e14942, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37025871

RESUMEN

A key and ecologically sound strategy for integrated weed management is the use of varieties of weed-competitive crops. Utilizing wheat cultivars that are weed-competitive can lessen weed pressure and inordinate herbicide usage in wheat fields by a substantial amount. To assess the weed suppressibility of Bangladeshi wheat varieties, a field test was carried out in 2018 throughout the winter season at the Agronomy Field Laboratory, Bangladesh Agricultural University, Bangladesh. Tests on a total of 18 selected Bangladeshi wheat cultivars were conducted in both "weedy" and "weed-free" environments. Additionally, weed monoculture plots (without wheat) were kept. The experiment was replicated three times using a randomized complete block design (RCBD). The results demonstrated that wheat varieties' weed interference and production capabilities differed greatly. BARI Gom 22 permitted the most weed growth (35 m-2), whereas BARI Gom 23 allowed the least (15 m-2) at 60 DAS among the wheat types under study. Grain yield ranged between 4.42 t ha-1 (BARI Gom 20) and 5.45 t ha-1 (BARI Gom 26) in weed-free settings, whereas it fluctuated from 2.48 t ha-1 (BARI Gom 21) to 3.93 t ha-1(BARI Gom 33) in weedy condition. The extent of the relative yield loss brought on by weeds ranged from 24 to 53%, with BARI Gom 33 suffering the least and Binagom-1 suffering the most. The weed competitive index varied from 0.48 to 1.47 for the examined wheat types. Among the cultivars, Binagom-1 had the lowest WCI and BARI Gom 29 had the highest. Although BARI Gom 33 was the best yielder in weedy condition and had the lowest relative yield loss, its interference against weed was moderate. Relative to the other varieties under consideration, comparatively BARI Gom 33 was the best in terms of yield and weed interference, but it is also advocated that breeders should continually focus on developing a variety that has both excellent producing potential and robust weed suppression.

18.
Sci Rep ; 13(1): 4317, 2023 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-36922532

RESUMEN

Reports of cognitive impairment in inflammatory bowel disease (IBD) have been mixed. IBD and cardiovascular disease are often co-morbid, yet it remains unknown whether vascular comorbidity confers a risk for decreased cognitive functioning, as observed in other populations. Participants with IBD were recruited from a longitudinal study of immune-mediated disease. Participants were administered a standardized neuropsychological test protocol, evaluating information processing speed, verbal learning and memory, visual learning and memory, and verbal fluency/executive function. Cognitive test scores were standardized using local regression-based norms, adjusting for age, sex, and education. Vascular risk was calculated using a modified Framingham Risk Score (FRS). We tested the association between FRS and cognitive test scores using a quantile regression model, adjusting for IBD type. Of 84 IBD participants, 54 had ulcerative colitis and 30 had Crohn's disease; mean (SD) age was 53.36 (13.95) years, and a high proportion were females (n = 58). As the risk score (FRS) increased, participants demonstrated lower performance in information processing speed (ß = - 0.12; 95% CI - 0.24, - 0.006) and verbal learning (ß = - 0.14; 95% CI - 0.28, - 0.01) at the 50th percentile. After adjusting for IBD type and disease activity, higher FRS remained associated with lower information processing speed (ß = - 0.14; 95% CI - 0.27, - 0.065). Vascular comorbidity is associated with lower cognitive functioning in persons with IBD, particularly in the area of information processing speed. These findings suggest that prevention, identification, and treatment of vascular comorbidity in IBD may play a critical role for improving functional outcomes in IBD.


Asunto(s)
Colitis Ulcerosa , Enfermedades Inflamatorias del Intestino , Femenino , Humanos , Persona de Mediana Edad , Masculino , Estudios Longitudinales , Enfermedades Inflamatorias del Intestino/complicaciones , Enfermedades Inflamatorias del Intestino/epidemiología , Cognición , Comorbilidad , Colitis Ulcerosa/epidemiología
19.
Front Neurol ; 14: 1250894, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37928146

RESUMEN

Background: Fifty-one percent of individuals with multiple sclerosis (MS) develop cognitive impairment (CI) in information processing speed (IPS). Although IPS scores are associated with health and well-being, neural changes that underlie IPS impairments in MS are not understood. Resting state fMRI can provide insight into brain function changes underlying impairment in persons with MS. Objectives: We aimed to assess functional connectivity (FC) differences in (i) persons with MS compared to healthy controls (HC), (ii) persons with both MS and CI (MS-CI) compared to HC, (iii) persons with MS that are cognitively preserved (MS-CP) compared to HC, (iv) MS-CI compared to MS-CP, and (v) in relation to cognition within the MS group. Methods: We included 107 participants with MS (age 49.5 ± 12.9, 82% women), and 94 controls (age 37.9 ± 15.4, 66% women). Each participant was administered the Symbol Digit Modalities Test (SDMT) and underwent a resting state fMRI scan. The MS-CI group was created by applying a z-score cut-off of ≤-1.5 to locally normalized SDMT scores. The MS-CP group was created by applying a z-score of ≥0. Control groups (HCMS-CI and HCMS-CP) were based on the nearest age-matched HC participants. A whole-brain ROI-to-ROI analysis was performed followed by specific contrasts and a regression analysis. Results: Individuals with MS showed FC differences compared to HC that involved the cerebellum, visual and language-associated brain regions, and the thalamus, hippocampus, and basal ganglia. The MS-CI showed FC differences compared to HCMS-CI that involved the cerebellum, visual and language-associated areas, thalamus, and caudate. SDMT scores were correlated with FC between the cerebellum and lateral occipital cortex in MS. No differences were observed between the MS-CP and HCMS-CP or MS-CI and MS-CP groups. Conclusion: Our findings emphasize FC changes of cerebellar, visual, and language-associated areas in persons with MS. These differences were apparent for (i) all MS participants compared to HC, (ii) MS-CI subgroup and their matched controls, and (iii) the association between FC and SDMT scores within the MS group. Our findings strongly suggest that future work that examines the associations between FC and IPS impairments in MS should focus on the involvement of these regions.

20.
Inflamm Bowel Dis ; 2023 Sep 22.
Artículo en Inglés | MEDLINE | ID: mdl-37740523

RESUMEN

BACKGROUND: Vascular disease and cognitive impairment have been increasingly documented in inflammatory bowel disease (IBD), and both have been individually correlated with changes in brain structure. This study aimed to determine if both macro- and microstructural brain changes are prevalent in IBD and whether alterations in brain structure mediate the relationship between vascular disease and cognitive functioning. METHODS: Eighty-four IBD participants underwent multimodal magnetic resonance imaging. Volumetric and mean diffusivity measures of the thalamus, hippocampus, normal-appearing white matter, and white matter lesions were converted to age- and sex-adjusted z scores. Vascular comorbidity was assessed using a modified Framingham Risk Score and cognition was assessed using a battery of neuropsychological tests. Test scores were standardized using local regression-based norms. We generated summary statistics for the magnetic resonance imaging metrics and cognitive tests, and these were examined using canonical correlation analysis and linear regression modeling. RESULTS: Greater vascular comorbidity was negatively correlated with thalamic, normal-appearing white matter, and white matter lesion volumes. Higher Framingham Risk Score were also correlated with lower processing speed, learning and memory, and verbal fluency. Increased vascular comorbidity was predictive of poorer cognitive functioning, and this effect was almost entirely mediated (94.76%) by differences in brain structure. CONCLUSIONS: Vascular comorbidity is associated with deleterious effects on brain structure and lower cognitive functioning in IBD. These findings suggest that proper identification and treatment of vascular disease is essential to the overall management of IBD, and that certain brain areas may serve as critical targets for predicting the response to therapeutic interventions.


Vascular disease is associated with decreased cognitive performance in persons with inflammatory bowel disease, and this is mainly driven by changes in the brain, including both gray matter and white matter regions.

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