SPECIATION FEATURES OF GOLD IN ORES AND MINERALS OF THE NATALKINSKOE DEPOSIT (NORTH-EAST RUSSIA)

The distribution and speciation features of gold in ores and minerals of the Natalkinskoe gold deposit (North-East Russia) are studied using light microscopy (LM), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX), X-ray electron probe microanalysis (EPMA), "phase" chemical analysis with atomic absorption spectrometry (PCA-AAS) and atomic absorption spectrometry with analytical data selections for single crystals (AAS-ADSSC). The vein and streaky-vein ores are high-grade ores, whereas veinlet-disseminated ores are less rich and disseminated ores are poor in gold. Up to 85 % of the gold in the ores is in a free native state, associated with quartz and sulfide minerals. LM, SEM-EDX and EPMA reveal that the predominant gold grains are 0.01 to 2.00 mm in size and at a fineness of 720 to 900 ‰. The finely dispersed and submicron elemental gold particles (Au0) amounted to 20 % and are mainly enclosed into arsenopyrite and pyrite. According to PCA-AAS data, the highest Au concentrations (up to 1383 ppm) are recorded in arsenopyrite; lower contents are typical of pyrite (up to 158.2 ppm). In these sulfides, two non-mineral species of "invisible" Au are the structurally bound and surface-bound species recognized by AAS-ADSSC. The structural Au is included in the mineral structure. The surface-bounded Au prevails and is confined to nano-sized, non-autonomous phases (NAPs) on the sulfide surface. In common with "invisible" Au, the micro-sized particles of native gold are often observed on the surface and within the surface layers of sulfide crystals. This is consistent with the model of post-growth transformations of nano-sized NAPs, resulting in the formation of nano and micro-sized Au0 particles. It is expected that the major part of gold contained in arsenopyrite and pyrite as finely dispersed and submicron particles, as well as the surface-bound gold in NAPs, can be won with modified current schemes of gold concentration, which enhances the value of the gold ore mining

CD206-Targeted Liposomal Myelin Basic Protein Peptides in Patients with Multiple Sclerosis Resistant to First-Line Disease-Modifying Therapies: A First-in-Human, Proof-of-Concept Dose-Escalation Study

© 2016 The Author(s)Previously, we showed that CD206-targeted liposomal delivery of co-encapsulated immunodominant myelin basic protein (MBP) sequences MBP46–62, MBP124–139 and MBP147–170 (Xemys) suppressed experimental autoimmune encephalomyelitis in dark Agouti rats. The objective of this study was to assess the safety of Xemys in the treatment of patients with relapsing-remitting multiple sclerosis (MS) and secondary progressive MS, who failed to achieve a sustained response to first-line disease-modifying therapies. In this phase I, open-label, dose-escalating, proof-of-concept study, 20 patients with relapsing-remitting or secondary progressive MS received weekly subcutaneously injections with ascending doses of Xemys up to a total dose of 2.675 mg. Clinical examinations, including Expanded Disability Status Scale score, magnetic resonance imaging results, and serum cytokine concentrations, were assessed before the first injection and for up to 17 weeks after the final injection. Xemys was safe and well tolerated when administered for 6 weeks to a maximum single dose of 900 μg. Expanded Disability Status Scale scores and numbers of T2-weighted and new gadolinium-enhancing lesions on magnetic resonance imaging were statistically unchanged at study exit compared with baseline; nonetheless, the increase of number of active gadolinium-enhancing lesions on weeks 7 and 10 in comparison with baseline was statistically significant. During treatment, the serum concentrations of the cytokines monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, and interleukin-7 decreased, whereas the level of tumor necrosis factor-α increased. These results provide evidence for the further development of Xemys as an antigen-specific, disease-modifying therapy for patients with MS

CD206-Targeted Liposomal Myelin Basic Protein Peptides in Patients with Multiple Sclerosis Resistant to First-Line Disease-Modifying Therapies: A First-in-Human, Proof-of-Concept Dose-Escalation Study

© 2016, The Author(s).Previously, we showed that CD206-targeted liposomal delivery of co-encapsulated immunodominant myelin basic protein (MBP) sequences MBP46–62, MBP124–139 and MBP147–170 (Xemys) suppressed experimental autoimmune encephalomyelitis in dark Agouti rats. The objective of this study was to assess the safety of Xemys in the treatment of patients with relapsing-remitting multiple sclerosis (MS) and secondary progressive MS, who failed to achieve a sustained response to first-line disease-modifying therapies. In this phase I, open-label, dose-escalating, proof-of-concept study, 20 patients with relapsing-remitting or secondary progressive MS received weekly subcutaneously injections with ascending doses of Xemys up to a total dose of 2.675 mg. Clinical examinations, including Expanded Disability Status Scale score, magnetic resonance imaging results, and serum cytokine concentrations, were assessed before the first injection and for up to 17 weeks after the final injection. Xemys was safe and well tolerated when administered for 6 weeks to a maximum single dose of 900 μg. Expanded Disability Status Scale scores and numbers of T2-weighted and new gadolinium-enhancing lesions on magnetic resonance imaging were statistically unchanged at study exit compared with baseline; nonetheless, the increase of number of active gadolinium-enhancing lesions on weeks 7 and 10 in comparison with baseline was statistically significant. During treatment, the serum concentrations of the cytokines monocyte chemoattractant protein-1, macrophage inflammatory protein-1β, and interleukin-7 decreased, whereas the level of tumor necrosis factor-α increased. These results provide evidence for the further development of Xemys as an antigen-specific, disease-modifying therapy for patients with MS

ФОРМЫ НАХОЖДЕНИЯ ЗОЛОТА В РУДАХ И МИНЕРАЛАХ НАТАЛКИНСКОГО МЕСТОРОЖДЕНИЯ (СЕВЕРО-ВОСТОК РОССИИ)

The distribution and speciation features of gold in ores and minerals of the Natalkinskoe gold deposit (North-East Russia) are studied using light microscopy (LM), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX), X-ray electron probe microanalysis (EPMA), "phase" chemical analysis with atomic absorption spectrometry (PCA-AAS) and atomic absorption spectrometry with analytical data selections for single crystals (AAS-ADSSC). The vein and streaky-vein ores are high-grade ores, whereas veinlet-disseminated ores are less rich and disseminated ores are poor in gold. Up to 85 % of the gold in the ores is in a free native state, associated with quartz and sulfide minerals. LM, SEM-EDX and EPMA reveal that the predominant gold grains are 0.01 to 2.00 mm in size and at a fineness of 720 to 900 ‰. The finely dispersed and submicron elemental gold particles (Au0) amounted to 20 % and are mainly enclosed into arsenopyrite and pyrite. According to PCA-AAS data, the highest Au concentrations (up to 1383 ppm) are recorded in arsenopyrite; lower contents are typical of pyrite (up to 158.2 ppm). In these sulfides, two non-mineral species of "invisible" Au are the structurally bound and surface-bound species recognized by AAS-ADSSC. The structural Au is included in the mineral structure. The surface-bounded Au prevails and is confined to nano-sized, non-autonomous phases (NAPs) on the sulfide surface. In common with "invisible" Au, the micro-sized particles of native gold are often observed on the surface and within the surface layers of sulfide crystals. This is consistent with the model of post-growth transformations of nano-sized NAPs, resulting in the formation of nano and micro-sized Au0 particles. It is expected that the major part of gold contained in arsenopyrite and pyrite as finely dispersed and submicron particles, as well as the surface-bound gold in NAPs, can be won with modified current schemes of gold concentration, which enhances the value of the gold ore mining.С помощью оптической микроскопии (ОМ), сканирующей электронной микроскопии с энергодисперсионной спектрометрией (СЭМ-ЭДС), рентгеноспектрального микроанализа (РСМА), фазового химического анализа на основе атомно-абсорбционной спектрометрии (ФХА-ААС) и метода статистических выборок аналитических данных для монокристаллов с применением ААС (СВАДМ-ААС) проведено изучение особенностей распределения и форм нахождения (ФН) Au в рудах и минералах Наталкинского золоторудного месторождения (северо-восток России). К наиболее «богатым» здесь относят жильные и прожилково-жильные руды, к менее «богатым» – прожилково-вкрапленные, к «бедным» – вкрапленные. До 80–85 % Au в руде находится в свободном самородном состоянии в ассоциации с кварцем и сульфидными минералами. По данным ОМ, СЭМ-ЭДС и РСМА преобладают золотины размером 0.01–2.00 мм и пробностью 720–900 ‰. До 15–20 % приходится на долю тонкодисперсных и субмикронных частиц элементного золота (Au0), большая часть которых заключена в арсенопирите и пирите. По данным ФХА-ААС самые высокие концентрации Au отмечены в арсенопирите (до 1383 г/т), менее высокие – в пирите (до 158.2 г/т). С помощью метода СВАДМ-ААС в этих сульфидах установлены две неминеральные ФН «невидимого» Au – структурная и поверхностно-связанная. Первая входит в структуру минералов, вторая, преобладающая, приурочена к наноразмерным неавтономным фазам (НФ) на их поверхности. Наряду с «невидимым» Au часто на поверхности и в поверхностном слое сульфидов развиты микровключения самородного Au, что согласуется с моделью постростовых преобразований наноразмерных НФ, приводящих к возникновению нано- и микрочастиц Au0. Предполагается, что большую часть золота, находящегося в сульфидах в виде тонкодисперсных и субмикронных частиц, а также поверхностно-связанного золота в НФ можно извлечь при доработке уже имеющихся схем обогащения, что повышает ценность добываемого сырья и значительно увеличивает перспективы месторождения

Stream Sediments of the Pestrinsk Silver-Bearing System (Northeastern Russia)

The composition, structure, and formation features of the exogenous anomalous geochemical fields (AGCFs) identified through stream sediments (SSs) are considered here within the Pestrinsk silver-bearing system and the Goltsovy silver-polymetallic deposit. The research was performed in the southern part of the Balygychan-Sugoy trough (northeastern Russia). The exogenous AGCFs of the main indicator elements of ores, formed in cryolithogenesis zone conditions, were studied. We used the results of multi-scale areal geochemical surveys of SSs. A survey of SSs at 1:200,000 scale was found to be effective at the stage of regional forecasting. Indeed, it is characterized by simplicity and the possibility of obtaining information operatively regarding the metallogeny of the area. It was found that at the local forecast stage, when prospecting for mineralization, the most effective was a survey of SSs at 1:50,000 scale. The AGCFs identified during this survey were distinguished by a richer component composition, higher contrast, and closer relationship with ores. During the lithochemical sampling of the watercourse heads, where alluvial sediments were found to be almost completely absent, a positive result was obtained by the bryolithochemical method, which is based on moss sampling together with a fine fraction of alluvium held by a moss cushion. The method enabled the sampling of watercourse heads and thus yielded information about the presence or absence of anomalous concentration fields of ore elements

Lithochemical Stream Sediments of the Dukat Gold–Silver Ore-Forming System (North–East of Russia)

The composition, structure and formation features of the exogenous anomalous geochemical fields (AGFs) identified by lithochemical stream sediments (LSSs) are considered using the examples of the Dukat gold–silver ore-forming system and the deposit with the same name. The research was carried out in the Balygychan–Sugoy trough (Magadan region, north–east of Russia). Areal geochemical surveys on the 1:200,000 and 1:50,000 scales were conducted. Exogenous AGFs of basic element indicators of all known mineralization types were studied. It is shown that the surveys on the 1:200,000 scale are characterized by simplicity, relative depth and the possibility to obtain information operatively about the metallogeny of the area as a whole. At the same time, the anomalies were revealed as a result of surveys often making a relatively poor component composition and low contrast compared with ores. The violation of quantitative and sometimes qualitative relationships can be seen between elements, especially those related to gold–silver mineralization. In this situation, the most informative are surveys of LSSs on the 1:50,000 scale. The AGFs were revealed as a result of their performance to have a richer component composition and high contrast, conforming to different ore types. It is shown that, while prospecting for gold–silver mineralization with LSSs in cryolithogenesis zone conditions, the binding forms study of mineralization element indicators is effective. In watercourse heads, where alluvium is practically absent, mosses are proposed for sampling, as they hold the sandy silt material firmly. The obtained results are recommended for use at all stages of prospecting, not only in the north–east of Russia but also in other similar climatic regions

Platinum Group Elements in Arsenopyrites and Pyrites of the Natalkinskoe Gold Deposit (Northeastern Russia)

The peculiarities of the distribution and binding forms of platinum group elements (Pt, Pd, Ru, Rh, Os and Ir) in the arsenopyrites and pyrites of the Natalkinskoe gold ore deposit (Northeastern Russia) were examined using atomic absorption spectrometry with analytical data selections for single crystals (AAS-ADSSC), a “phase” chemical analysis (PCA) based on AAS of different size-fractions of minerals, scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The arsenopyrites and pyrites of the Natalkinskoe gold deposit were found to concentrate not only Au but also platinum group elements (PGEs) such as Pt, Pd, Ru and Rh. The PCA showed that the highest contents (in ppm) were found in the monofractions of arsenopyrite—Pt up to 128, Pd up to 20, Ru up to 86 and Rh up to 21—and comparably lower in monofractions of pyrite—Pt to 29, Pd to 15, Ru to 58 and Rh to 5.9. The AAS-ADSSC method revealed two forms of uniformly distributed Pt, Pd and Ru corresponding to the chemically bound element in the structure of the mineral and in the superficial non-autonomous phase (NAP). The superficially bound form dominates over the structural form and presumably exists in a very thin surface layer of the crystal (~100–500 nm). The maximum contents of these PGE, chemically bound in the structure of arsenopyrite, reached values of (in ppm) 48, 5.9 and 48; and in pyrite structure, 68, 5.2 and 34 for Pt, Pd and Ru respectively. The contents of Pt, Pd and Ru related to NAP on the surface of the crystal were significantly higher and amounted (in ppm) for arsenopyrite to 714, 114 and 1083; and for pyrite 890, 62 and 690 for Pt, Pd and Ru, respectively. Preliminary results for the Rh form in arsenopyrite crystals suggest that the surface-related form (154–678 ppm) is more abundant than the structural form (17–45 ppm). Data from studying the surfaces of sulphide minerals by SEM-EDX and LA-ICP-MS confirmed the presence of Pt, Pd, Ru and Rh on the surface of arsenopyrite and pyrite crystals. These methods generated primary data on the content of Os and Ir in arsenopyrite and pyrite in the surface layer. The maximum content of Os and Ir found in arsenopyrites was up to 0.7 wt%. PGE-enriched fluids (up to ~3 ppm Pt) may exist in the gold ore deposit. It is assumed that there is a common mechanism of impurities uptake associated with the active role of the crystal surface and surface defects for gold-bearing arsenopyrites and pyrites. The surface enrichment is due to peculiarities in the crystal growth mechanism through the medium of NAP and the dualism of the element distribution coefficient in the system of mineral–hydrothermal solution, which is higher for NAP, compared to the volume of the crystal. Although mineral forms of Pt, Pd, Ru, Rh, Os and Ir have not been found at the Natalkinskoe gold deposit, their existence in the form of nano-scale particles is not excluded. This follows from the evolutionary model of surficial NAPs, assuming their partial transformation and aggregation with the formation of nano- and micro-sized autonomous phases of trace elements. The presence of PGE in the ores and the possibility of their extraction significantly increase the quality and value of the extracted raw gold materials at the Natalkinskoe deposit, and adds to the list of known platiniferous ore formations

COVID-19 immunopathology and the central nervous system: Implication for multiple sclerosis and other autoimmune diseases with associated demyelination

In the frame of the coronavirus disease 2019 (COVID-19) pandemic, recent reports on SARS-CoV-2 potential neuroinvasion placed neurologists on increased alertness in order to assess early neurological manifestations and their potentially prognostic value for the COVID-19 disease. Moreover, the management of chronic neurological diseases, such as Multiple Sclerosis (MS), underwent guided modifications, such as an Extended Interval Dose (EID) of Disease-Modifying Treatment (DMT) administration, in order to minimize patients’ exposure to the health system, thus reducing the risk of SARS-CoV-2 infection. In this review, we summarize existing evidence of key immune pathways that the SARS-CoV-2 modifies during COVID-19 and the relevant implication for MS and other autoimmune diseases with associated demyelination (such as Systemic lupus erythematosus and Antiphospholipid syndrome), including the context of potential neuroinvasion by SARS-Cov-2 and the alterations that DMT induces to the immune system. Moreover we hereby aim to provide an overview of the possible consequences that COVID-19 may carry for the Central Nervous System (CNS) in People with MS (PwMS) and other demyelinating diseases, which are likely to pose challenges for treating Neurologists with respect to the long-term disease management of these diseases. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Contrasting Surficial Composition of Native Gold from Two Different Types of Gold Ore Deposits

Native gold grains sampled at two different gold ore deposits in Eastern Russia have been studied by the techniques of electron spectroscopy (X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES)), electron microprobe analysis (EMPA), and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX). The high-fineness gold of the deposit hosted by relatively high temperature gold-quartz-sulfide mesothermal ore formation contains no oxidized Au constituents on grain surfaces, whereas the less fine gold of the epithermal Au-Ag deposit contains gold oxidized to the Au (I) state, or higher, in half of the cases. At this deposit the surface of native Au consists of a thin layer (~15 nm) with elevated Ag and S contents and an underlying SiO2–containing layer ~30–60 nm thick. Such a composite coating can perform a protective function and prevent the gold-silver sulfides in surficial parts of AuAg grains from oxidation. The sulfur-enriched marginal parts of native gold particles do not always correlate with the stoichiometry of well-known binary AuAg-sulfides and have a variable composition. This may be due to the existence of solid solutions, Ag2−xAuxS, if there is enough S or S adsorption-stabilized cluster agglomerates, AgnAumS, under sulfur deficit. The effect of the formation of nano-scale surficial zonality on the surface of native gold is quite common in nature and applicable to geological exploration and technology of gold-ore processing. It can facilitate establishing the geochemical environment and genetic type of Au mineralization

DIAGNOSTIC AND PROGNOSTIC SIGNIFICANCE OF INTRATHECAL SYNTHESIS OF IMMUNOGLOBULIN FREE LIGHT CHAINS IN MULTIPLE SCLEROSIS

Increased intrathecal synthesis and oligoclonal banding of immunoglobulins (Ig) in cerebrospinal fluid (CSF) are major immunological findings in multiple sclerosis. Free light chains are fragments of Ig molecules that are produced in parallel to oligoclonal Ig, and their production reflects total Ig synthesis within central nervous system. Assessment of intrathecal kappaand lambda free light chain production within CNS compartment will help to improve diagnosis and prediction of outcomes in multiple sclerosis. Concentrations of kappa and lambda free light chains and clonality of immunoglobulin pattern synthesis were studied in paired CSF and serum samples of 151 patients, including 92 patients with multiple sclerosis, and 33 patients with clinically isolated syndrome which later was transformed into the definite multiple sclerosis. A control group consisted of 26 patients with other inflammatory diseases of central nervous system. Several Ig parameters have been determined in the patients, i.e., Ig clonality in CSF; concentrations of free light chains (both kappaand lambda-) in CSF; as well as their indexes and ratios. It was established that synthesis of kappa free light chains were significantly elevated in patients with multiple sclerosis. Moreover, the amounts of free light Ig chains in patients with positive oligoclonality test were significantly higher than in cases without intrathecal oligoclonal synthesis. With respect to diagnostic significance, the kappa quotient proved the best available option for diagnosis of multiple sclerosis. Its combination with Ig oligoclonality assays caused a decrease in false-negative diagnostics by 42%. Diagnostic benefit of the kappa quotient could be also confirmed by the data of ROC analysis. Also concentration of lambda free light chains in cerebrospinal fluid showed a negative correlation with conversion terms of clinically isolated syndrome to evident multiple sclerosis. Therefore, the indexes of free Ig light chains enables more precise diagnostics, like as more efficient severity evaluation of multiple sclerosis