Capacity and mechanisms of uptake of silver by jarosite family minerals

Jarosite is a family of iron-hydroxysulphate minerals that commonly occur in acidic, sulphate-rich environments and in ore processing wastes. Jarosite precipitation is used in hydrometallurgy to control Fe and other impurities. End-member jarosite sensu stricto contains potassium and has the chemical formula KFe3(SO4)2(OH)6, but extensive element substitution takes place in the crystal structure. Silver can be taken up by jarosite minerals and, in theory, Ag can form solid-solution series with K, Na and Pb in jarosite. This study carried out synthesis experiments, using a variety of sulphate starting solutions and temperatures, to form K-jarosite, Na-jarosite and Pbjarosite minerals and determined their capacity for Ag by investigating them using powder X-ray diffraction (XRD), Rietveld refinement, electron microprobe analysis and inductively coupled plasma-atomic emission spectroscopy. Solid solution was found between Ag-jarosite and separately K-jarosite, Na-jarosite and Pb-jarosite, but with substantial hydronium (H3O) content and vacancies in the Fe site. The average relative partitioning coefficients for Ag were 0.9 in K-jarosite, 1.3 in Na-jarosite and 1.17 in Pb-jarosite. Powder XRD analysis showed that, in the K-Ag-H3O and Pb-Ag- H3O-jarosite series, d-spacing values for the hkl 003 and 006 peaks indicated the unitcell c-axis parameter decreased as Ag content increased. Rietveld refinement showed that, in K-Ag-H3O-jarosite and Na-Ag-H3O-jarosite, there were trends of increasing unit-cell a-axis parameters and decreasing c-axis parameters as Ag content increased. Rietveld refinement indicated decreasing K,Ag-O2 and K,Ag-O3 bond lengths as Ag content increased in K-Ag-H3O-jarosite. Raman spectroscopic analysis showed the assigned v1SO4 and v3SO4 vibrational modes in some K-Ag-H3O-jarosite series had higher wavenumbers (cm-1), indicating higher bonding energies, as Ag content increased. The XRD, Rietveld refinement and Raman data from this project will inform the evaluation of the Ag composition of jarosite minerals in complex natural mineral assemblages using these same techniques

Human and animal models for translational research on neurodegeneration: Challenges and opportunities from South America

Facing the alarming growth of dementia and neurodegenerative conditions has become a critical priority across the globe (Alzheimer´s Disease International, 2009;Lancet, 2015;Shah et al., 2016;Parra et al., 2018). Neurodegenerative diseases are the most frequent cause of dementia, representing a burden for public health systems (especially in middle and middle-high income countries). Although most research on this subject is concentrated in first-world centers, growing efforts in South American countries (SACs) are affording important breakthroughs. This emerging agenda poses not only new challenges for the region, but also new opportunities for the field at large. SACs have witnessed a promising development of relevant research in humans and animals, giving rise to new regional challenges. As highlighted in a recent experts? consensus paper Latin-American countries (LAC), and SACs in particular (Parra et al., 2018), face a critical situation. Higher demographic rates and the predicted prevalence of dementia have reached and even exceeded those of developing countries. In SACs, low- and middle-income countries (e.g., Bolivia, Paraguay), the prevalence of dementia will double that of high-income countries, while upper-middle-income countries in the region (e.g., Argentina, Brazil, Chile, Colombia, Peru, Uruguay, and Venezuela) will experience the greatest impact of dementia. The WHO estimated that the standardized prevalence of dementia in Latin America was 8.5%, but multiple SACs have been underrepresented or underestimated in such a calculation (Parra et al., 2018). Moreover, raw prevalence rates across studies are characterized by high variability within and between countries (e.g., Argentina: 8.3; Brazil: 7.1-2.0; Chile: 4.4-7.0; Colombia: 6.0; Peru: 6.72-9.3; Uruguay: 3.1; Venezuela: 5.7-13,7) (Parra et al., 2018). In addition, most of these studies are undermined by various limitations and methodological problems. Even considering these data, SACs possess the highest global prevalence of dementia after North Africa/Middle East in people above the age of 60 (Parra et al., 2018). Moreover, the harmonization of global strategies against dementia in these contexts is hindered not only by reduced epidemiological data, but also by the lack of standardized clinical practice, insufficient training of physicians, limited resources, and poor governmental support, let alone poverty and more general cultural barriers and stigmas. All of these factors have impacted the type and amount of research conducted in SACs. A regional network, based on multiinstitutional actors from research, governmental, and private sectors is fundamental to overcome these challenges (Parra et al., 2018).Fil: Ibanez Barassi, Agustin Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Instituto de Neurología Cognitiva. Laboratorio de Psicología Experimental y Neurociencia; Argentina. Universidad Autónoma del Caribe; Colombia. Universidad Adolfo Ibañez; ChileFil: Sedeño, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Instituto de Neurología Cognitiva. Laboratorio de Psicología Experimental y Neurociencia; ArgentinaFil: García, Adolfo Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Instituto de Neurología Cognitiva. Laboratorio de Psicología Experimental y Neurociencia; Argentina. Universidad Nacional de Cuyo. Facultad de Educación Elemental y Especial; ArgentinaFil: Deacon, Robert. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Instituto de Neurología Cognitiva. Laboratorio de Psicología Experimental y Neurociencia; Argentina. Universidad de Chile; ChileFil: Cogram, Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Neurociencia Cognitiva. Fundación Favaloro. Instituto de Neurociencia Cognitiva; Argentina. Instituto de Neurología Cognitiva. Laboratorio de Psicología Experimental y Neurociencia; Argentina. Universidad de Chile; Chil

Inositol and protein kinase C in the prevention of neural tube defects.

A number of mouse genetic mutants develop neural tube defects (NTDs). In some cases, defects can be prevented by administration of folic acid during pregnancy, whereas in other mutants there is no response. This parallels the human situation in which a proportion of NTDs appear resistant to folic acid therapy. Curly tail is the best characterised mouse model of folic acid-resistant NTDs. Previously it was shown that the incidence of spina bifida in curly tail mice can be reduced by administration of inositol during embryonic development. In this thesis, I compared the effectiveness of two isomers, myo- and D-chiro-inositol, with administration either directly to embryos in vitro, or to pregnant females by subcutaneous or oral routes. Although both inositols exerted a preventive effect on spina bifida, by all routes of administration, D-chiro-inositol consistently exhibited greater potency than myo-inositol. The protective effect of inositol has been shown previously to be mediated through the activity of the inositol/lipid cycle and to depend on downstream activation of protein kinase C (PKC). In the studies decscribed in this thesis, I examined the role of PKC in more detail. The expression of PKC isoforms was first examined by irrmiunohistochemistry, Broad spectrum chemical inhibitors were then used in whole embryo culture to confirm that one or more PKC isoforms are indispensable for normalisation of neural tube closure by inositol. Specific peptide inhibitors were then applied, and revealed that PKC beta I, gamma and zeta are most important in the protective pathway. Finally, I demonstrated that inositol stimulates cell proliferation in the hindgut of curly tail embryos, reversing the imbalance of cell proliferation that is known to lead, via enhanced ventral curvature of the caudal region, to delay or failure of neural tube closure

Uptake of silver by jarosite and natrojarosite family compounds at 22 °C, 97 °C and 140 °C

This is the final version. Available from MDPI via the DOI in this record. Data Availability Statement: Data for this paper can be found in this article and at https://eprints. bbk.ac.uk/id/eprint/40262/The jarosite family of minerals are part of the alunite supergroup with the general formula AB3(TO4)2(OH)6. Jarosite family minerals are known to incorporate silver (Ag), but the extent to which this occurs, and at what temperature range, is not well constrained. To address this knowledge gap, jarosite compounds with the A site filled with K, Na, Ag and H3O were synthesised at 22 °C, 97 °C and 140 °C to simulate low-, moderate- and high-temperature environments, respectively. The compounds were characterised by XRD, SEM, chemical analysis and Raman spectroscopy. All of the synthesised compounds took up Ag. In general, higher temperatures of synthesis increased alkali and Ag occupancy of the A site of the products. Silver contents increased with the increasing concentration of Ag in the starting solutions at all temperatures. The order of preference for occupancy of the A site in the synthesised solids is K > Na > H3O > Ag at all temperatures, which is consistent with the reported order of ΔGf of −3309 kJ/mol, −3270 kJ/mol, −3247 kJ/mol and −2948 kJ/mol for jarosite, natrojarosite, hydroniumjarosite and argentojarosite, respectively. The results of this study show that Ag can be incorporated in jarosite and natrojarosite at low-to-high temperatures, and therefore, jarosite family minerals can be important stores of Ag in in natural and engineered environments.Birkbeck, University of Londo

Spatial maps and oscillations in the healthy hippocampus of Octodon degus, a natural model of sporadic Alzheimer’s disease

The Octodon degus is a South American rodent that is receiving increased attention as a potential model of aging and sporadic late-onset Alzheimer’s disease (AD). Impairments in spatial memory tasks in Octodon degus have been reported in relation to either advanced AD-like disease or hippocampal lesion, opening the way to investigate how the function of hippocampal networks affects behavior across AD stages. However, no characterization of hippocampal electrophysiology exists in this species. Here we describe in young, healthy specimens the activity of neurons and local field potential rhythms during spatial navigation tasks with and without objects. Our findings show similarities between the Octodon degus and laboratory rodents. First, place cells with characteristics similar to those found in rats and mice exist in the CA1 subfield of the Octodon degus. Second, the introduction of objects elicits novelty-related exploration and an increase in activity of CA1 cells, with location specific and unspecific components. Third, oscillations of the local field potential are organized according to their spectral content into bands similar to those found in laboratory rodents. These results suggest a common framework of underlying mechanisms, opening the way to future studies of hippocampal dysfunction in this species associated to aging and disease.Fil: Mugnaini, Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Polania, Diana. Universidad de Chile; ChileFil: Díaz, Yannina Constanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; ArgentinaFil: Ezquer, Marcelo. Universidad del Desarrollo; ChileFil: Ezquer, Fernando. Universidad del Desarrollo; ChileFil: Deacon, Robert M. J.. Universidad de Chile; ChileFil: Cogram, Patricia. Universidad de Chile; Chile. University of California at Irvine; Estados UnidosFil: Kropff, Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Bioquímicas de Buenos Aires. Fundación Instituto Leloir. Instituto de Investigaciones Bioquímicas de Buenos Aires; Argentin

Using digital and hand printing techniques to compensate for loss: re-establishing colour and texture in historic textiles

Conservators use a range of 'gap filling' techniques to improve the structural stability and presentation of objects. Textile conservators often use fabric supports to provide reinforcement for weak areas of a textile and to provide a visual infill in missing areas. The most common technique is to use dyed fabrics of a single colour but while a plain dyed support provides good reinforcement, it can be visually obtrusive when used with patterned or textured textiles. Two recent postgraduate dissertation projects at the Textile Conservation Centre (TCC) have experimented with hand printing and digital imaging techniques to alter the appearance of support fabrics so that they are less visually obtrusive and blend well with the colour and texture of the textile being supported. Case studies demonstrate the successful use of these techniques on a painted hessian rocking horse and a knitted glove from an archaeological context

Dementia in Latin America:Assessing the present and envisioning the future

The demographic structure of Latin American countries (LAC) is fast approaching that of developing countries, and the predicted prevalence of dementia in the former already exceeds the latter. Dementia has been declared a global challenge, yet regions around the world show differences in both the nature and magnitude of such a challenge. This article provides evidence and insights on barriers which, if overcome, would enable the harmonization of strategies to tackle the dementia challenge in LAC. First, we analyze the lack of available epidemiologic data, the need for standardizing clinical practice and improving physician training, and the existing barriers regarding resources, culture, and stigmas. We discuss how these are preventing timely care and research. Regarding specific health actions, most LAC have minimal mental health facilities and do not have specific mental health policies or budgets specific to dementia. In addition, local regulations may need to consider the regional context when developing treatment and prevention strategies. The support needed nationally and internationally to enable a smooth and timely transition of LAC to a position that integrates global strategies is highlighted. We focus on shared issues of poverty, cultural barriers, and socioeconomic vulnerability. We identify avenues for collaboration aimed to study unique populations, improve valid assessment methods, and generate opportunities for translational research, thus establishing a regional network. The issues identified here point to future specific actions aimed at tackling the dementia challenge in LAC.Alzheimer's Society UK grants AS-R42303 AS-SF-14-008 CONICYT-Fondecyt 117001

The Genetic Background of the Curly Tail Strain Confers Susceptibility to Folate-Deficiency-Induced Exencephaly

BACKGROUND: Suboptimal maternal folate status is considered a risk factor for neural tube defects (NTDs). However, the relationship between dietary folate status and risk of NTDs appears complex, as experimentally induced folate deficiency is insufficient to cause NTDs in nonmutant mice. In contrast, folate deficiency can exacerbate the effect of an NTD-causing mutation, as in splotch mice. The purpose of the present study was to determine whether folate deficiency can induce NTDs in mice with a permissive genetic background which do not normally exhibit defects. METHODS: Folate deficiency was induced in curly tail and genetically matched wild-type mice, and we analyzed the effect on maternal folate status, embryonic growth and development, and frequency of NTDs. RESULTS: Folate-deficient diets resulted in reduced maternal blood folate, elevated homocysteine, and a diminished embryonic folate content. Folate deficiency had a deleterious effect on reproductive success, resulting in smaller litter sizes and an increased rate of resorption. Notably, folate deficiency caused a similar-sized, statistically significant increase in the frequency of cranial NTDs among both curly tail (Grhl3 mutant) embryos and background-matched embryos that are wild type for Grhl3. The latter do not exhibit NTDs under normal dietary conditions. Maternal supplementation with myo-inositol reduced the incidence of NTDs in the folate-deficient wild-type strain. CONCLUSIONS: Dietary folate deficiency can induce cranial NTDs in nonmutant mice with a permissive genetic background, a situation that likely parallels gene-nutrient interactions in human NTDs. Our findings suggest that inositol supplementation may ameliorate NTDs resulting from insufficient dietary folate. Birth Defects Research (Part A), 2010. © 2009 Wiley-Liss, Inc

Dementia in Latin America : paving the way towards a regional action plan

Regional challenges faced by Latin American and Caribbean countries (LACs) to fight dementia, such as heterogeneity, diversity, political instabilities, and socioeconomic disparities, can be addressed more effectively grounded in a collaborative setting based on the open exchange of knowledge. In this work, the Latin American and Caribbean Consortium on Dementia (LAC-CD) proposes an agenda for integration to deliver a Knowledge to Action Framework (KtAF). First, we summarize evidence-based strategies (epidemiology, genetics, biomarkers, clinical trials, nonpharmacological interventions, networking and translational research) and align them to current global strategies to translate regional knowledge into actions with transformative power. Then, by characterizing genetic isolates, admixture in populations, environmental factors, and barriers to effective interventions and mapping these to the above challenges, we provide the basic mosaics of knowledge that will pave the way towards a KtAF. We describe strategies supporting the knowledge creation stage that underpins the translational impact of KtAF