Occipital Proton Magnetic Resonance Spectroscopy ((1)H-MRS) Reveals Normal Metabolite Concentrations in Retinal Visual Field Defects

BACKGROUND: Progressive visual field defects, such as age-related macular degeneration and glaucoma, prevent normal stimulation of visual cortex. We investigated whether in the case of visual field defects, concentrations of metabolites such as N-acetylaspartate (NAA), a marker for degenerative processes, are reduced in the occipital brain region. METHODOLOGY/PRINCIPAL FINDINGS: Participants known with glaucoma, age-related macular degeneration (the two leading causes of visual impairment in the developed world), and controls were examined by proton MR spectroscopic ((1)H-MRS) imaging. Absolute NAA, Creatine and Choline concentrations were derived from a single-voxel in the occipital region of each brain hemisphere. No significant differences in metabolites concentrations were found between the three groups. CONCLUSIONS/SIGNIFICANCE: We conclude that progressive retinal visual field defects do not affect metabolite concentration in visual brain areas suggesting that there is no ongoing occipital degeneration. We discuss the possibility that metabolite change is too slow to be detectable

Exploratory 7-Tesla magnetic resonance spectroscopy in Huntington’s disease provides in vivo evidence for impaired energy metabolism

Huntington’s disease (HD) is a neurodegenerative genetic disorder that affects the brain. Atrophy of deep grey matter structures has been reported and it is likely that underlying pathologic processes occur before, or in concurrence with, volumetric changes. Measurement of metabolite concentrations in these brain structures has the potential to provide insight into pathological processes. We aim to gain understanding of metabolite changes with respect to the disease stage and pathophysiological changes. We studied five brain regions using magnetic resonance spectroscopy (MRS) using a 7-Tesla MRI scanner. Localized proton spectra were acquired to obtain six metabolite concentrations. MRS was performed in the caudate nucleus, putamen, thalamus, hypothalamus, and frontal lobe in 44 control subjects, premanifest gene carriers and manifest HD. In the caudate nucleus, HD patients display lower NAA (p = 0.009) and lower creatine concentration (p = 0.001) as compared to controls. In the putamen, manifest HD patients show lower NAA (p = 0.024), lower creatine concentration (p = 0.027), and lower glutamate (p = 0.013). Although absolute values of NAA, creatine, and glutamate were lower, no significant differences to controls were found in the premanifest gene carriers. The lower concentrations of NAA and creatine in the caudate nucleus and putamen of early manifest HD suggest deficits in neuronal integrity and energy metabolism. The changes in glutamate could support the excitotoxicity theory. These findings not only give insight into neuropathological changes in HD but also indicate that MRS can possibly be applied in future clinical trails to evaluate medication targeted at specific metabolic processes

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Sequestration of Am3+ and Eu3+ into ionic liquid containing Aza-macrocycle based multiple-diglycolamide ligands: Extraction, complexation, luminescence and DFT studies

Extraction of Am3+ and Eu3+ was carried out into a room temperature ionic liquid, C8mim⋅Tf2N, using two multiple-diglycolamide extractants with three or four diglycolamide arms tethered to either a triaza- or tetraazamacrocyclic ligand termed as TAM-3-DGA and TAM-4-DGA, respectively. The metal ion extraction was highly efficient as only 5 × 10-4 M solutions of TAM-3-DGA resulted in D values of 680 and 845 for Am3+ and Eu3+, respectively, at pH 2.0, while the respective values with a five times lower concentration of TAM-4-DGA were 142 and 296, which is probably the best reported thus far. Though Eu3+ ion was preferentially extracted over Am3+, the selectivity was not as good as reported in molecular diluent-based extraction systems. The extracted species contained two units of the extractant and did not contain any nitrate ion suggesting a cation-exchange mechanism. Studies on the temperature effect on metal ion extraction were carried out to determine the thermodynamic parameters. Luminescence studies of the extracts were also performed which suggested strong complex formation with no inner-sphere water molecules. To understand the ligand coordination to Eu3+ and Am3+ and other bonding parameters, DFT studies were carried out

Sequestration of Np4+ and NpO22+ ions by using diglycolamide-functionalized azacrown ethers in C8mim·NTf2 ionic liquid: Extraction, spectroscopic, electrochemical and DFT studies

Complexation of Np4+ and NpO22+ ions was studied in a room temperature ionic liquid (C8mim•NTf2) using two multiple diglycolamide (DGA) ligands with three and four DGA arms tethered to the nitrogen atoms of the aza-9-crown-3 and -12-crown-4 scaffolds termed as LI and LII, respectively. The studies include solvent extraction, UV–visible spectrophotometry, cyclic voltammetry, and density functional theory (DFT). While the extraction of NpO22+ ion, as a function of the nitric acid concentration, resembled that of the ‘solvation’ mechanism, seen in case of neutral donor ligands in molecular diluent, an opposite trend was observed for the Np4+ ion suggesting a ‘cation-exchange’ mechanism often operating in the case of ionic liquid-based solvent systems. Slope analysis suggested formation of Np(NO3)]3+•L and NpO2(NO3)2•L extracted species for the extraction of Np4+ and NpO22+, respectively, in both the ligand systems. The complexation of the metal ions was supported by peak shifts in the UV–visible spectrophotometric as well as cyclic voltammetric studies. DFT studies were carried out to get structural information of the complexes