Loading Determination of DMTr-substituted Resins for Large-scale Oligonucleotide Synthesis.

The loading (i.e., substitution) of solid supports for oligonucleotide synthesis is an important parameter in large-scale manufacturing of oligonucleotides. Several key process parameters are dependent on the substitution of the solid support, including the number of phosphoramidite nucleoside equivalents used in the coupling step. For dimethoxytrityl (DMTr)-loaded solid supports, the substitution of the resin is determined by quantitatively cleaving the DMTr protecting group from the resin under acidic conditions and then analyzing the DMTr cation extinction by UV/vis spectroscopy. The spectrometric measurement can be performed at 409 nm or the global extinction maximum of 510 nm. The substitution is then calculated based on the Lambert-Beer law analogously to the substitution determination of Fmoc-substituted resins. Below, the determination of the molar extinction coefficient at 510 nm in a solution of 10% dichloroacetic acid in toluene and subsequent determination of the DMTr loading of DMTr-substituted resins is reported. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Determination of the molar extinction coefficient at 510 nm in DCA Deblock solution Basic Protocol 2: Substitution determination of DMTr-substituted resins by cleavage of the DMTr cation.

Severity of white matter microstructural damage in a Brazilian relapsing-remitting multiple sclerosis cohort: A possible window to optimize treatment.

BACKGROUND: Multiple sclerosis (MS) is an important cause of acquired neurological disability in young adults, characterized by multicentric inflammation, demyelination, and axonal damage. OBJECTIVE: The objective is to investigate white matter (WM) damage progression in a Brazilian MS patient cohort, using diffusion tensor imaging (DTI) post-processed by tract-based spatial statistics (TBSS). METHODS: DTI scans were acquired from 76 MS patients and 37 sex-and-age matched controls. Patients were divided into three groups based on disease duration. DTI was performed along 30 non-collinear directions by using a 1.5T imager. For TBSS analysis, the WM skeleton was created, and a 5000 permutation-based inference with a threshold of p < .05 was used, to enable the identification of abnormalities in fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD). RESULTS: Decreased FA and increased RD, MD, and AD were seen in patients compared to controls and a decreased FA and increased MD and RD were seen, predominantly after the first 5 years of disease, when compared between groups. CONCLUSION: Progressive WM deterioration is seen over time with a more prominent pattern after 5 years of disease onset, providing evidence that the early years might be a window to optimize treatment and prevent disability.

A model for colour preference behaviour of spring migrant aphids.

Aphids are economically and ecologically important herbivorous insects. A critical step in their life cycle is the visually guided host finding behaviour. To elucidate the role of colour in host finding of aphid spring migrants we conducted large colour trap experiments in the field and analysed aphid catch data, using trap spectral reflectance data as input. Based on known and putative photoreceptor sensitivities we developed and optimized a simple empirical colour choice model for spring migrants of different aphid species which confirmed and explained the yellow preference of these insects. In a further step, we applied multivariate statistical methods to behavioural and reflectance data, but without data on photoreceptor sensitivities, to find the wavelengths of greatest importance for the aphids' behavioural responses. This analysis confirmed the position of the green photoreceptor peak previously obtained independently with electrophysiological methods. In a final step, we applied the colour preference model to a dataset of leaf spectra. This showed that aphid visual preference would be dependent on the plants' nutritional status, with lower nitrogen input being associated with stronger preference, despite known benefits of high nitrogen levels for aphid reproduction and fitness. Ecological and evolutionary implications of these results are discussed. This article is part of the theme issue 'Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods'.

Mixture × Genotype Effects in Cereal/Legume Intercropping.

Cropping system diversification through annual intercropping provides a pathway for agricultural production with reduced inputs of fertilizer and pesticides. While several studies have shown that intercrop performance depends on the genotypes used, the available evidence has not been synthesized in an overarching analysis. Here, we review the effects of genotypes in cereal/legume intercropping systems, showing how genotype choice affects mixture performance. Furthermore, we discuss the mechanisms underlying the interactions between genotype and cropping system (i.e., sole cropping vs. intercropping). Data from 69 articles fulfilling inclusion criteria were analyzed, out of which 35 articles reported land equivalent ratio (LER), yielding 262 LER data points to be extracted. The mean and median LER were 1.26 and 1.24, respectively. The extracted genotype × cropping system interaction effects on yield were reported in 71% out of 69 publications. Out of this, genotype × cropping system interaction effects were significant in 75%, of the studies, whereas 25% reported non-significant interactions. The remaining studies did not report the effects of genotype × cropping system. Phenological and morphological traits, such as differences in days to maturity, plant height, or growth habit, explained variations in the performance of mixtures with different genotypes. However, the relevant genotype traits were not described sufficiently in most of the studies to allow for a detailed analysis. A tendency toward higher intercropping performance with short cereal genotypes was observed. The results show the importance of genotype selection for better in cereal/legume intercropping. This study highlights the hitherto unrevealed aspects of genotype evaluation for intercropping systems that need to be tackled. Future research on genotype effects in intercropping should consider phenology, root growth, and soil nutrient and water acquisition timing, as well as the effects of weeds and diseases, to improve our understanding of how genotype combination and breeding may help to optimize intercropping systems.

Remineralizing soils? The agricultural usage of silicate rock powders: A review.

Soil nutrient depletion threatens global food security and has been seriously underestimated for potassium (K) and several micronutrients. This is particularly the case for highly weathered soils in tropical countries, where classical soluble fertilizers are often not affordable or not accessible. One way to replenish macro- and micronutrients are ground silicate rock powders (SRPs). Rock forming silicate minerals contain most nutrients essential for higher plants, yet slow and inconsistent weathering rates have restricted their use in the past. Recent findings, however, challenge past agronomic objections which insufficiently addressed the factorial complexity of the weathering process. This review therefore first presents a framework with the most relevant factors for the weathering of SRPs through which several outcomes of prior studies can be explained. A subsequent analysis of 48 crop trials reveals the potential as alternative K source and multi-nutrient soil amendment for tropical soils, whereas the benefits for temperate soils are currently inconclusive. Beneficial results prevail for mafic and ultramafic rocks like basalts and rocks containing nepheline or glauconite. Several rock modifications are highly efficient in increasing the agronomic effectiveness of SRPs. Enhanced weathering of SRPs could additionally sequester substantial amounts of CO2 from the atmosphere and silicon (Si) supply can induce a broad spectrum of plant biotic and abiotic stress resistance. Recycling massive amounts of rock residues from domestic mining industries could furthermore resolve serious disposal challenges and improve fertilizer self-sufficiency. In conclusion, under the right circumstances, SRPs could not only advance low-cost and regional soil sustaining crop production but contribute to various sustainable development goals.

Upper limits to sustainable organic wheat yields.

Current use of mineral nitrogen (N) fertilizers is unsustainable because of its high fossil energy requirements and a considerable enrichment of the biosphere with reactive N. Biological nitrogen fixation (BNF) from leguminous crops is the most important renewable primary N source, especially in organic farming. However, it remains unclear to which degree BNF can sustainably replace mineral N, overcome the organic to conventional (O:C) yield gap and contribute to food security. Using an agronomic modelling approach, we show that in high-yielding areas farming systems exclusively based on BNF are unlikely to sustainably reach yield levels of mineral-N based systems. For a high reference wheat yield (7.5 t ha-1) and a realistic proportion of fodder legumes in the rotation (33%) even optimistic levels of BNF (282 kg N ha-1), resulted in an O:C ratio far below parity (0.62). Various constraints limit the agricultural use of BNF, such as arable land available for legumes and highly variable performance under on-farm conditions. Reducing the O:C yield gap through legumes will require BNF performance to be increased and N losses to be minimised, yet our results show that limits to the productivity of legume-based farming systems will still remain inevitable.

Effects of mixing two legume species at seedling stage under different environmental conditions.

While intercropping is known to have positive effects on crop productivity, it is unclear whether the effects of mixing species start at the early plant stage, that is, during germination. We tested whether the germination of two legume species, alsike clover and black medic, characterized by a contrasting response to water availability and temperature is affected by mixing. We set up four experiments in each of which we compared a 1:1 mixture against the two monocultures, and combined this with various other experimental factors. These additional factors were (i) varied seed densities (50%, 100% and 150% of a reference density) in two field trials in 2016 and 2017, (ii) varied seed densities (high and low) and water availability (six levels, between 25% and 100% of water holding capacity (WHC)) in a greenhouse pot trial, (iii) varied seed spacing in a climate chamber, and (iv) varied temperatures (12 °C, 20 °C and 28 °C) and water availability (four levels between 25% and 100% of WHC) in a climate chamber. Across all experiments, the absolute mixture effects (AME) on germination ranged between -9% and +11%, with a median of +1.3%. Within experiments, significant mixture effects were observed, but the direction of these effects was inconsistent. In the field, AME on germination was significantly negative at some of the tested seed densities. A positive AME was observed in the climate chamber at 12 °C, and the mean AME decreased with increasing temperature. Higher density was associated with decreased germination in the field, indicating negative interaction through competition or allelopathy, among seedlings. Our findings indicate that interaction among seeds in species mixtures may be ongoing during germination, but that the direction of the mixture effect is affected by complex interactions with abiotic and biotic factors.

[Corona Financial Aid from the Federal Government to Ease the Burden on Municipalities]. / Corona-Finanzhilfen des Bundes zur Entlastung der Kommunen.

The Corona crisis has led to unforeseeable additional expenses as well as significant losses of tax income for local governments. In order to stabilise public finances at the local level, the German federal government has passed two new bills. One of the bills basically provides for a permanent expansion of the federal government's financial contribution towards the cost of housing and heating as part of the guaranteed minimum income for job seekers. The federal government also singularly compensates - in cooperation with the state governments - local governments for the significant crisis-related decline in local business tax revenue through a lump sum payment in 2020. However, these two measures will affect short-term intervention to cope with the fiscal problems of the Corona crisis as well as the fundamental need to reform public finances at local government level.

Crop Resilience to Drought With and Without Response Diversity.

In the face of increasingly frequent droughts threatening crop performance, ecological theory suggests that higher species diversity may help buffering productivity by making systems more resistant through resource complementarity and more resilient through higher response diversity. However, empirical evidence for these diversity effects under drought stress has remained patchy. In two pot experiments, we explored whether mixing two legume species with a contrasting response to water availability, alsike clover (AC) and black medic (BM), promotes resistance to cumulative drought stress, and resilience of aboveground crop biomass to a transient drought event. The mixture was more productive than the average of the sole crops, and this mixture effect was higher in the non-stressed than in the drought-stressed plants. However, with six levels of constant drought intensities, the mixture effect was not consistently affected by drought level. Response diversity was evident as asynchrony of growth in the two species after the drought event, with BM re-growing faster than AC. Significant resilience to drought was observed in sole AC, i.e., without response diversity. Resilience was larger in AC than in BM and increased from 44 to 72 days after sowing (DAS). The mixture was more resilient than the average resilience of the sole crops at 72 DAS, but it was never more resilient than AC, indicating that resilience is promoted by, but not dependent on response diversity. We conclude that crop diversity may contribute to drought resilience through growth asynchrony, but that species identity plays a crucial role in making systems more drought-resilient.

Natural Selection Towards Wild-Type in Composite Cross Populations of Winter Wheat.

Most of our crops are grown in monoculture with single genotypes grown over wide acreage. An alternative approach, where segregating populations are used as crops, is an exciting possibility, but outcomes of natural selection upon this type of crop are not well understood. We tracked allelic frequency changes in evolving composite cross populations of wheat grown over 10 generations under organic and conventional farming. At three generations, each population was genotyped with 19 SSR and 8 SNP markers. The latter were diagnostic for major functional genes. Gene diversity was constant at SSR markers but decreased over time for SNP markers. Population differentiation between the four locations could not be detected, suggesting that organic vs. non-organic crop management did not drive allele frequency changes. However, we did see changes for genes controlling plant height and phenology in all populations independently and consistently. We interpret these changes as the result of a consistent natural selection towards wild-type. Independent selection for alleles that are associated with plant height suggests that competition for light was central, resulting in the predominance of stronger intraspecific competitors, and highlighting a potential trade-off between individual and population performance.

Widespread white matter DTI alterations in mesial temporal sclerosis independent of disease side.

PURPOSE: The aim of this study was to evaluate white matter (WM) integrity in vivo in patients with unilateral mesial temporal sclerosis (MTS). METHODS: Diffusion tensor imaging (DTI) findings from patients with left-sided MTS (L-MTS; N = 14) and right-sided MTS (R-MTS; N = 13), all taking antiepileptic medication, were compared with those from gender- and age-matched controls; DTI was performed along 30 noncollinear directions in a 1.5-T scanner. Tract-based spatial statistics (TBSS) analysis was performed by creating a WM skeleton; 5000-permutation-based inference (threshold, p < 0.05) was used to identify fractional anisotropy (FA) abnormalities. Mean (MD), radial (RD), and axial diffusivities (AD) were projected onto the mean FA skeleton. RESULTS: Compared with the control groups, patients with MTS had decreased FA affecting widespread WM tracts as well as extensive areas with increased RD, bilaterally and independent of the disease side. Areas with decreased FA and increased RD overlapped substantially. There were no significant differences in DTI parameters between L-MTS and R-MTS patients. CONCLUSION: Diffusion tensor imaging abnormalities were observed within and beyond the temporal lobe in patients with MTS. Patients with R- and L-MTS had extensive bilateral abnormalities in comparison to controls. These findings suggest that MTS pathobiology involves diffuse dysfunction of WM tracts, even in areas with no direct connections to the hippocampus.

White-matter integrity in patients with systemic lupus erythematosus and memory deficits.

PURPOSE: Cognitive dysfunction is common in neuropsychiatric systemic lupus erythematosus (SLE). Memory is a commonly affected cognitive domain. Clinically, however, it is difficult to detect memory deficits. The objective of this study is to evaluate whether normal controls and SLE patients with and without memory deficit differ in terms of white-matter integrity. METHODS: Twenty SLE patients with memory deficit were compared to 47 SLE patients without memory deficit and 22 sex-, age-, and education-matched control individuals. Diffusion tensor imaging (DTI) was performed in a 1.5-Tesla scanner. For tract-based spatial statistics analysis, a white-matter skeleton was created. A permutation-based inference with 5000 permutations with a threshold of p < 0.05 was used to identify abnormalities in fractional anisotropy (FA). The mean diffusivity (MD), radial diffusivity (RD) and axial diffusivity (AD) were also projected onto the mean FA skeleton. RESULTS: Compared to controls, SLE patients with and without memory deficit had decreased FA in: bilateral anterior thalamic radiation, inferior fronto-occipital fasciculus, superior longitudinal fasciculus, uncinate fasciculus, corticospinal tract, genu, and body of the corpus callosum. SLE patients with and without memory deficit also presented increased MD and RD values compared to controls in these areas. Comparison between SLE patients with and without memory deficit did not present significant differences in DTI parameters. CONCLUSION: DTI can detect extensive abnormalities in the normal-appearing white matter of SLE patients with and without memory deficit, compared to controls. However, there was no difference, in terms of white-matter integrity, between the groups of SLE patients.

Grain legume yields are as stable as other spring crops in long-term experiments across northern Europe.

Grain legumes produce high-quality protein for food and feed, and potentially contribute to sustainable cropping systems, but they are grown on only 1.5% of European arable land. Low temporal yield stability is one of the reasons held responsible for the low proportion of grain legumes, without sufficient quantitative evidence. The objective of this study was to compare the yield stability of grain legumes with other crop species in a northern European context and accounting for the effects of scale in the analysis and the data. To avoid aggregation biases in the yield data, we used data from long-term field experiments. The experiments included grain legumes (lupin, field pea, and faba bean), other broad-leaved crops, spring, and winter cereals. Experiments were conducted in the UK, Sweden, and Germany. To compare yield stability between grain legumes and other crops, we used a scale-adjusted yield stability indicator that accounts for the yield differences between crops following Taylor's Power Law. Here, we show that temporal yield instability of grain legumes (30%) was higher than that of autumn-sown cereals (19%), but lower than that of other spring-sown broad-leaved crops (35%), and only slightly greater than spring-sown cereals (27%). With the scale-adjusted yield stability indicator, we estimated 21% higher yield stability for grain legumes compared to a standard stability measure. These novel findings demonstrate that grain legume yields are as reliable as those of other spring-sown crops in major production systems of northern Europe, which could influence the current negative perception on grain legume cultivation. Initiatives are still needed to improve the crops agronomy to provide higher and more stable yields in future.

Is there sufficient Ensifer and Rhizobium species diversity in UK farmland soils to support red clover (Trifolium pratense), white clover (T. repens), lucerne (Medicago sativa) and black medic (M. lupulina)?

Rhizobia play important roles in agriculture owing to their ability to fix nitrogen through a symbiosis with legumes. The specificity of rhizobia-legume associations means that underused legume species may depend on seed inoculation with their rhizobial partners. For black medic (Medicago lupulina) and lucerne (Medicago sativa) little is known about the natural prevalence of their rhizobial partner Ensifer meliloti in UK soils, so that the need for inoculating them is unclear. We analysed the site-dependence of rhizobial seed inoculation effects on the subsequent ability of rhizobial communities to form symbioses with four legume species (Medicago lupulina, M. sativa, Trifolium repens and T. pratense). At ten organic farms across the UK, a species-diverse legume based mixture (LBM) which included these four species was grown. The LBM seed was inoculated with a mix of commercial inocula specific for clover and lucerne. At each site, soil from the LBM treatment was compared to the soil sampled prior to the sowing of the LBM (the control). From each site and each of the two treatments, a suspension of soils was applied to seedlings of the four legume species and grown in axenic conditions for six weeks. Root nodules were counted and their rhizobia isolated. PCR and sequencing of a fragment of the gyrB gene from rhizobial isolates allowed identification of strains. The number of nodules on each of the four legume species was significantly increased when inoculated with soil from the LBM treatment compared to the control. Both the proportion of plants forming nodules and the number of nodules formed varied significantly by site, with sites significantly affecting the Medicago species but not the Trifolium species. These differences in nodulation were broadly reflected in plant biomass where site and treatment interacted; at some sites there was a significant advantage from inoculation with the commercial inoculum but not at others. In particular, this study has demonstrated the commercial merit of inoculation of lucerne with compatible rhizobia.

Longitudinal evaluation of resting-state connectivity, white matter integrity and cortical thickness in stable HIV infection: Preliminary results.

Purpose The objectives of this study were to determine if HIV-infected patients treated with highly active antiretroviral therapy (HAART), without dementia, suffer from longitudinal gray matter (GM) volume loss, changes in white matter (WM) integrity and deterioration in functional connectivity at rest, in an average interval of 30 months. Methods Clinically stable HIV-positive patients (on HAART, CD4 + T lymphocyte > 200 cells/µl, and viral loads <50 copies/µl) were recruited. None of them had HIV-associated dementia. Each patient underwent two scans, performed in a 1.5-T magnetic resonance imaging (MRI) scanner. FreeSurfer was used to perform cortical volumetric reconstruction and segmentation of GM structures. WM integrity was assessed using tract-based spatial statistics to post-process diffusion tensor imaging data, and FMRIB's Software Library tools were used to post-process resting-state functional magnetic resonance imaging (RS-fMRI). Results There were no significant differences in cortical thickness, deep GM volumes, or diffusivity parameters between the scans at the two time points. Five resting-state networks were identified in our patients. In the second MRI, HIV-positive patients presented increased areas of functional connectivity in visual pathways, frontoparietal and cerebellar networks, compared with the first MRI (considering p < 0.05). Conclusions RS-fMRI revealed potentially compensatory longitudinal alterations in the brains of HIV-positive patients, attempting to compensate for brain damage related to the infection.

Diffusion tensor imaging of brain white matter in Huntington gene mutation individuals.

OBJECTIVE: To evaluate the role of the involvement of white matter tracts in huntingtin gene mutation patients as a potential biomarker of the progression of the disease. METHODS: We evaluated 34 participants (11 symptomatic huntingtin gene mutation, 12 presymptomatic huntingtin gene mutation, and 11 controls). We performed brain magnetic resonance imaging to assess white matter integrity using diffusion tensor imaging, with measurement of fractional anisotropy. RESULTS: We observed a significant decrease of fractional anisotropy in the cortical spinal tracts, corona radiate, corpus callosum, external capsule, thalamic radiations, superior and inferior longitudinal fasciculus, and inferior frontal-occipital fasciculus in the Huntington disease group compared to the control and presymptomatic groups. Reduction of fractional anisotropy is indicative of a degenerative process and axonal loss. There was no statistically significant difference between the presymptomatic and control groups. CONCLUSION: White matter integrity is affected in huntingtin gene mutation symptomatic individuals, but other studies with larger samples are required to assess its usefulness in the progression of the neurodegenerative process.

Diffusion tensor imaging of brain white matter in Huntington gene mutation individuals / Imagem por tensor de difusão em indivíduos com mutação do gene da doença de Huntington

ABSTRACT Objective To evaluate the role of the involvement of white matter tracts in huntingtin gene mutation patients as a potential biomarker of the progression of the disease. Methods We evaluated 34 participants (11 symptomatic huntingtin gene mutation, 12 presymptomatic huntingtin gene mutation, and 11 controls). We performed brain magnetic resonance imaging to assess white matter integrity using diffusion tensor imaging, with measurement of fractional anisotropy. Results We observed a significant decrease of fractional anisotropy in the cortical spinal tracts, corona radiate, corpus callosum, external capsule, thalamic radiations, superior and inferior longitudinal fasciculus, and inferior frontal-occipital fasciculus in the Huntington disease group compared to the control and presymptomatic groups. Reduction of fractional anisotropy is indicative of a degenerative process and axonal loss. There was no statistically significant difference between the presymptomatic and control groups. Conclusion White matter integrity is affected in huntingtin gene mutation symptomatic individuals, but other studies with larger samples are required to assess its usefulness in the progression of the neurodegenerative process.

RESUMO Objetivo Avaliar o envolvimento da substância branca (SB) cerebral em indivíduos com mutação do gene da huntingtina. Métodos Foram avaliados 34 indivíduos: 11 com mutação do gene da huntingtina sintomática, 12 assintomáticos com mutação do gene da huntingtina e 11 indivíduos controles. Realizamos ressonância magnética cerebral para avaliar a integridade da SB usando o tensor de difusão (DTI), com medição da anisotrofia fracionada (FA). Resultados Observamos uma diminuição da FA no trato corticoespinhal, coroa radiada, corpo caloso (joelho, corpo e esplênio), cápsula externa, radiações talâmicas, fascículo longitudinal superior e inferior, e fascículo frontal-occipital inferior no grupo dos indivíduos com mutação sintomática. A redução da FA é indicativa de processo degenerativo e perda axonal. Não houve diferença estatística entre os grupos controle e pré-sintomático. Conclusão Houve comprometimento da integridade da SB em indivíduos com mutação no gene da Huntingtina sintomática, mas outros estudos são necessários para avaliar a sua utilidade na progressão do processo neurodegenerativo.

Boxwood Borer Heterobostrychus brunneus (Coleoptera: Bostrichidae) Infesting Dried Cassava: A Current Record from Southern Ethiopia.

Insect specimens of adult beetles and larvae of 7-9 and 9-10 mm length, respectively were collected from infested dry cassava at two locations from multiple stores in southern Ethiopia. The specimens were identified as Heterobostrychus brunneus (Murray, 1867) commonly known as boxwood borer and auger beetle. The study presents a current record of H. brunneus in Ethiopia, particularly in the context of infesting food products. Additionally, a wide geographical distribution of the pest was reviewed and presented in this article. Current evidence suggests that H. brunneus is a serious pest of forest wood, structural timbers, and dried food products and that it carries a risk to be introduced into various other parts of the world via global trade.

Quantitative Susceptibility Mapping Indicates a Disturbed Brain Iron Homeostasis in Neuromyelitis Optica - A Pilot Study.

Dysregulation of brain iron homeostasis is a hallmark of many neurodegenerative diseases and can be associated with oxidative stress. The objective of this study was to investigate brain iron in patients with Neuromyelitis Optica (NMO) using quantitative susceptibility mapping (QSM), a quantitative iron-sensitive MRI technique. 12 clinically confirmed NMO patients (6 female and 6 male; age 35.4y±14.2y) and 12 age- and sex-matched healthy controls (7 female and 5 male; age 33.9±11.3y) underwent MRI of the brain at 3 Tesla. Quantitative maps of the effective transverse relaxation rate (R2*) and magnetic susceptibility were calculated and a blinded ROI-based group comparison analysis was performed. Normality of the data and differences between patients and controls were tested by Kolmogorov-Smirnov and t-test, respectively. Correlation with age was studied using Spearman's rank correlation and an ANCOVA-like analysis. Magnetic susceptibility values were decreased in the red nucleus (p<0.01; d>0.95; between -15 and -22 ppb depending on reference region) with a trend toward increasing differences with age. R2* revealed significantly decreased relaxation in the optic radiations of five of the 12 patients (p<0.0001; -3.136±0.567 s(-1)). Decreased relaxation in the optic radiation is indicative for demyelination, which is in line with previous findings. Decreased magnetic susceptibility in the red nucleus is indicative for a lower brain iron concentration, a chemical redistribution of iron into less magnetic forms, or both. Further investigations are necessary to elucidate the pathological cause or consequence of this finding.

Longitudinal assessment of subcortical gray matter volume, cortical thickness, and white matter integrity in HIV-positive patients.

PURPOSE: To longitudinally evaluate the cortical thickness and deep gray matter structures volume, measured from T1 three-dimensional (3D) Gradient echo-weighted imaging, and white matter integrity, assessed from diffusion tensor imaging (DTI) of HIV-positive patients. MATERIALS AND METHODS: Twenty-one HIV-positive patients on stable highly active antiretroviral therapy (HAART) with CD4+ T lymphocytes count >200 cells/mL and viral load <50 copies/mL underwent two magnetic resonance imaging (MRI) scans with a median interval of 26.6 months. None of the patients had HIV-related dementia. T1 3D magnetization prepared rapid gradient echo-weighted imaging and DTI along 30 noncolinear directions were performed using a 1.5 Tesla MR scanner. FreeSurfer was used to perform cortical volumetric reconstruction and segmentation of deep gray matter structures. For tract-based spatial statistics analysis, a white matter skeleton was created, and a permutation-based inference with 5000 permutations, with a threshold of P < 0.05 was used to identify abnormalities in fractional anisotropy (FA). The median, radial, and axial diffusivities were also projected onto the mean FA skeleton. RESULTS: There were no significant differences in cortical thickness, deep gray matter structures volumes or diffusivity parameters between scans at the two time points (considering P < 0.05). CONCLUSION: No longitudinal differences in cortical thickness, deep gray matter volumes, or white matter integrity were observed in an HIV-positive population on stable HAART, with undetectable viral load and high CD4+ T lymphocytes count. J. Magn. Reson. Imaging 2016;44:1262-1269.