Quantitative mineral resource assessment of undiscovered porphyry copper resources in South America

A quantitative resource assessment to be published this fall identifies and evaluates 26 tracts in South America where the geology isconsidered permissive for the occurrence of porphyry copper deposits. For each tract, information is provided on: (1) the rationale fordelineating the tract, (2) examples of important deposits in the tract, (3) the rationale for choosing the mineral deposit model used forthe assessment, (4) exploration history, and (5) expected spatial distribution of undiscovered deposits in the tract. The scale used toevaluate geologic information and define tracts is 1:1,000,000. There are about 600 million tonnes of copper in known porphyry copper deposits in South America. This study estimates there areapproximately 720 million tonnes of additional copper in undiscovered porphyry copper deposits, yielding a combined endowment ofabout 1.3 billion tonnes of copper. There are about 69 known porphyry copper deposits using the criteria adopted here to define a well-explored deposit. This study estimates that a mean of about 140 deposits remain to be found. In other words, about twice as manynew deposits might be found as have already been found. Overall, deposit densities in South America are comparable to those in therest of the world but differ in important details that are reflected in mapped distributions of deposits, metal densities, and percentagesof undiscovered deposits in each tract. The deposits in the tracts that include Chuquicamata and El Teniente are significantly larger intonnage and grade and are reported in a separate model that is more representative of their characteristics. The results of theassessment afirm that not all porphyry copper deposits in South America are located in the Andes. Geologic indications support thepresence of undiscovered deposits in Patagonia as well as the Amazon of Brazil. A preliminary 1:4,000,000 map of the 26 tracts will bedisplayed

Pan-American quantitative mineral resource assessment of copper, molybdenum, gold, and silver in undiscovered porphyry copper deposits in the Andes mountains, South America

Working together, the geological surveys of Argentina, Chile, Colombia, Peru, and the United States used the U. S. Geological Survey three-part mineral resource assessment methodology (Singer, 1993) to delineate the regional locations and make probabilistic estimates of the amounts of copper, molybdenum, silver, and gold in undiscovered porphyry copper deposits in the Andes. Quantitative information on the probable locations and amounts of undiscovered mineral resources of the world is important to exploration managers, land-use and environmental planners, economists, and policy makers

The transcriptional landscape of age in human peripheral blood

Disease incidences increase with age, but the molecular characteristics of ageing that lead to increased disease susceptibility remain inadequately understood. Here we perform a whole-blood gene expression meta-analysis in 14,983 individuals of European ancestry (including replication) and identify 1,497 genes that are differentially expressed with chronological age. The age-associated genes do not harbor more age-associated CpG-methylation sites than other genes, but are instead enriched for the presence of potentially functional CpG-methylation sites in enhancer and insulator regions that associate with both chronological age and gene expression levels. We further used the gene expression profiles to calculate the 'transcriptomic age' of an individual, and show that differences between transcriptomic age and chronological age are associated with biological features linked to ageing, such as blood pressure, cholesterol levels, fasting glucose, and body mass index. The transcriptomic prediction model adds biological relevance and complements existing epigenetic prediction models, and can be used by others to calculate transcriptomic age in external cohorts.Peer reviewe

Common Data Elements Reported in Mechanical Thrombectomy for Acute Ischemic Stroke: A Systematic Review of Active Clinical Trials

Background: New trials are planned regularly to provide the highest quality of evidence and invade new occlusion territories, which requires a pre-defined reporting strategy with consistent, common data elements for more straightforward collective evidence synthesis. We sought to review all active endovascular thrombectomy trials to investigate their patient selection criteria, intervention description, and reported outcomes. Methods: A literature search was systematically conducted on clinicaltrials.gov for active trials and all intervention, inclusion criteria, and outcomes reported were extracted. A qualitative synthesis of the frequency of study design types and data elements are graphically and narratively presented. Results: A total of 32 studies were tagged and included in the final qualitative analysis. The inclusion criteria were highly variable, including different cut-offs for the last well-known baseline National Institutes of Health Stroke Scale, Alberta Stroke Program Early CT Score, and modified Rankin scale (mRS). Half of the studies (16/32) mentioned “thrombectomy” without defining which technique or device was used, and the final thrombolysis in cerebral infarction scale was provided in 19 (59.4%) studies. Heterogeneity was also present among the studies reporting a first-pass effect, both in how studies defined the outcome and in used ranges for mRS. Mortality and intracerebral hemorrhage (ICH) were more homogenous in their presentation and follow-up. Conclusions: There is a great degree of heterogeneity in the active thrombectomy trials concerning inclusion criteria, interventions used, and how outcomes are being reported

Quantitative Mineral Resource Assessment of Copper, Molybdenum, Gold, and Silver in Undiscovered Porphyry Copper Deposits in the Andes Mountains of South America

Quantitative information on the general locations and amounts of undiscovered porphyry copperresources of the world is important to exploration managers, land-use and environmental planners, economists, and policymakers. This publication contains the results of probabilistic estimates of theamounts of copper (Cu), molybdenum (Mo), silver (Ag), and gold (Au) in undiscovered porphyry copperdeposits in the Andes Mountains of South America. The methodology used to make these estimates is called the "Three-Part Form.” It was developed to explicitly express estimates of undiscovered resourcesand associated uncertainty in a form that allows economic analysis and is useful to decisionmakers. The three-part form of assessment includes: (1) delineation of tracts of land where the geology ispermissive for porphyry copper deposits to form; (2) selection of grade and tonnage models appropriatefor estimating grades and tonnages of the undiscovered porphyry copper deposits in each tract; and (3)estimation of the number of undiscovered porphyry copper deposits in each tract consistent with the gradeand tonnage model. A Monte Carlo simulation computer program (EMINERS) was used to combine theprobability distributions of the estimated number of undiscovered deposits, the grades, and the tonnages ofthe selected model to obtain the probability distributions for undiscovered metals in each tract. Thesedistributions of grades and tonnages then can be used to conduct economic evaluations of undiscovered resources in a format usable by decisionmakers. Economic evaluations are not part of this report. The results of this assessment are presented in two principal parts. The first part identifies 26 regional tracts of land where the geology is permissive for the occurrence of undiscovered porphyrycopper deposits of Phanerozoic age to a depth of 1 km below the Earth’s surface. These tracts are believed to contain most of South America's undiscovered resources of copper. The second part presentsprobabilistic estimates of the amounts of copper, molybdenum, gold, and silver in undiscovered porphyry copper deposits in each tract. The study also provides tables showing the location, tract number, and age (if available) of discovered deposits and prospects. For each of the 26 permissive tracts delineated in thisstudy, summary information is provided on: (1) the rationale for delineating the tract; (2) the rational for choosing the mineral deposit model used to assess the tract; (3) discovered deposits and prospects; (4) exploration history; and (5) the distribution of undiscovered deposits in the tract. The scale used toevaluate geologic information and draw tracts is 1:1,000,000. There are 69 known porphyry copper deposits in the Andes using criteria adopted herein to definea deposit. This assessment estimates that about 145 undiscovered deposits remain. In other words, abouttwice as many new deposits might be found as have already been found. Not only have large quantities ofcopper been discovered, but also even larger quantities of undiscovered copper remain. About 590 million metric tons of copper have been discovered. About 190 million tons of this amount are in 57 deposits of the general porphyry copper type whereas nearly 400 million metric tons are in an additional 12 giantdeposits. This study estimates that there are approximately 750 million metric tons of copper in undiscovered deposits of these two types in the Andes. This undiscovered copper resource is the sum ofthe mean estimated copper in each of 26 tracts. About 470 million metric tons of this copper are estimated to occur in 137 undiscovered deposits in 24 tracts of the general porphyry copper type, plus another 280 million metric tons estimated in 8 undiscovered deposits in 2 tracts of the giant porphyry copper type. Thetotal discovered, mined, and undiscovered copper amounts to an endowment, or grand total, of about 1.3 billion metric tons. The estimates suggest there may be almost 1.3 times as much copper to be found in porphyry copper deposits of the Andes as has already been found. In addition to copper, the undiscovered deposits also contain large estimated amounts ofmolybdenum (20,000,000 metric tons), gold (13,000 tons), and silver (250,000 tons). The estimated undiscovered copper is equivalent to about 80 percent of the world reserve base; molybdenum, 105 percent; gold, 14 percent; and silver, 44 percent. Not all of these undiscovered mineral resources are likely to be available for discovery anddevelopment. Commonly, a significant amount of land delineated as permissive or even favorable for theoccurrence of undiscovered mineral deposits is not available for mineral exploration, discovery, and development because it consists of urban areas, transportation corridors, forest and wildlife preserves,sensitive ecosystems, protected biodiversity areas, sensitive and threatened surface and groundwatersupplies, wilderness areas, national parks, private land where mining is not desired, and many other reasons. Global inventory and analysis are needed of such restrictions and their probable impact on futuremineral supply and costs. The porphyry copper resources reported herein are not evenly distributed throughout the Andesregion. The Chuquicamata tract (SA10a,bPC) and the El Teniente tract (SA14bPC) are remarkable incontaining exceptionally large deposits of discovered, mined, and estimated undiscovered copper that do not conform to grade and tonnage characteristics of the general porphyry copper model appropriate forother Andean tracts. The deposits in these two tracts being significantly larger in tonnage and higher in grade necessitated a new giant model that is more representative of their characteristics. The greatest premining endowment of copper is in Eocene-Oligocene tract SA10a,bPC with about 460 million metric tons, followed by late Miocene-early Pliocene tract SA14bPC with about 220 million metric tons. Thenext largest endowments are in tract SA8PC (a Paleocene–Eocene tract of Chile-southern Peru) containing an endowment of about 98 million metric tons and in tract SA6PC (the middle–late Miocene tract of Peru-Ecuador) with an endowment of about 96 million metric tons. The undiscovered copper remaining to be found in these four tracts is estimated to be: tract SA10a,bPC, 210 million metric tons; tract SA14bPC, 69 million; tract SA6PC, 49 million; and tract SA8PC, 43 million. Density of estimated undiscovered metal in tracts was examined as mean metric tons of metal per km2 in undiscovered deposits. Giant tracts SA10a,bPC and SA14bPC have the highest copper densitieswith about 8,200 and 7,400 metric tons per km2, respectively. The next richest tracts, with just over 2,000 metric tons per km2, are tracts SA12PC and SA14dPC. About 90 percent of the total discovered and estimated undiscovered copper resources in Andean porphyry copper deposits is of Cenozoic age; the remainder is Cretaceous (4%), Jurassic (5%), andPermian (2%) in age. The Cenozoic resources are in tracts with host rock ages of Eocene–Oligocene (39%), Miocene–Pliocene (29%), Paleocene–Eocene (12%), and Miocene (11%). The Eocene–Oligocene and Miocene–Pliocene tracts are dominated by giant tracts SA10a,bPC (includes Chuquicamata deposit) and SA14bPC (includes El Teniente deposit). There appear to have been three approximately 16-million-year-long episodes of porphyry copper deposit formation in the Andes during Cenozoic time: Paleocene–early Eocene, late Eocene–early Oligocene; and middle Miocene–early Pliocene. These three episodes appear to be separated by twointervening quiescent periods of 5 to 9 million years duration in the middle Eocene (44-49 Ma) and late Oligocene–early Miocene (20-29 Ma). These two periods correspond to times of change in Pacific plateboundaries, geometries, and directions and rates of spreading and convergence. There are variations in the geographic trends of magmatic arcs in the southern Andes. Tract SA14cPC, for example, follows a transverse SE-trending band of late Miocene–early Pliocene volcanicrocks and associated upper Miocene porphyry copper deposits, prospects, and other areas of altered and mineralized rocks. The parent magmatic source is approximately perpendicular to the grain of the fault-controlled outcrops of metamorphic basement rocks that reflect the surface geology and could becontrolled by a tear fault in a subducted plate. Southeast-trending tract SA19PC, which extends from theAndes south southeasterly across the Patagonia of Argentina to the Atlantic Ocean, and contains the Bajo de la Leona prospect, also shows that Mesozoic porphyry copper ore-forming processes occurred outside of the present-day trend of the Andes. The results of this assessment study are likely to spur research and exploration activities in theAndes and adjacent regions, which in turn will enable the evaluation and update of regional assessmentsof porphyry copper resources in the future

Missense mutations in COL8A2, the gene encoding the alpha2 chain of type VIII collagen, cause two forms of corneal endothelial dystrophy

Corneal clarity is maintained by its endothelium, which functions abnormally in the endothelial dystrophies, leading to corneal opacification. This group of conditions includes Fuchs' endothelial dystrophy of the cornea (FECD), one of the commonest indications for corneal transplantation performed in developed countries, posterior polymorphous dystrophy (PPCD) and the congenital hereditary endothelial dystrophies (CHED). A genome-wide search of a three-generation family with early-onset FECD demonstrated significant linkage with D1S2830 (Z(max) = 3.72, theta = 0.0). Refinement of the critical region defined a 6-7 cM interval of chromosome 1p34.3-p32 within which lies the COL8A2 gene. This encodes the 703 amino acid alpha2 chain of type VIII collagen, a short-chain collagen which is a component of endothelial basement membranes and which represented a strong candidate gene. Analysis of its coding sequence defined a missense mutation (gln455lys) within the triple helical domain of the protein in this family. Mutation analysis in patients with FECD and PPCD demonstrated further missense substitutions in familial and sporadic cases of FECD as well as in a single family with PPCD. This is the first description of the molecular basis of any of the corneal endothelial dystrophies or of mutations in type VIII collagen in association with human disease. This suggests that the underlying pathogenesis of FECD and PPCD may be related to disturbance of the role of type VIII collagen in influencing the terminal differentiation of the neural crest derived corneal endothelial cell

Missense mutations in COL8A2, the gene encoding the α2 chain of type VIII collagen, cause two forms of corneal endothelial dystrophy

Corneal clarity is maintained by its endothelium, which functions abnormally in the endothelial dystrophies, leading to corneal opacification. This group of conditions includes Fuchs' endothelial dystrophy of the cornea (FECD), one of the commonest indications for corneal transplantation performed in developed countries, posterior polymorphous dystrophy (PPCD) and the congenital hereditary endothelial dystrophies (CHED). A genome-wide search of a three-generation family with early-onset FECD demonstrated significant linkage with D1S2830 (Zmax = 3.72, θ = 0.0). Refinement of the critical region defined a 6-7 cM interval of chromosome 1p34.3-p32 within which lies the COL8A2 gene. This encodes the 703 amino acid α2 chain of type VIII collagen, a short-chain collagen which is a component of endothelial basement membranes and which represented a strong candidate gene. Analysis of its coding sequence defined a missense mutation (gln455lys) within the triple helical domain of the protein in this family. Mutation analysis in patients with FECD and PPCD demonstrated further missense substitutions in familial and sporadic cases of FECD as well as in a single family with PPCD. This is the first description of the molecular basis of any of the corneal endothelial dystrophies or of mutations in type VIII collagen in association with human disease. This suggests that the underlying pathogenesis of FECD and PPCD may be related to disturbance of the role oftype VIII collagen in influencing the terminal differentiation of the neural crest derived corneal endothelial cel

Absence of effects of Sir2 overexpression on lifespan in C. elegans and Drosophila

Overexpression of sirtuins (NAD(+)-dependent protein deacetylases) has been reported to increase lifespan in budding yeast (Saccharomyces cerevisiae), Caenorhabditis elegans and Drosophila melanogaster. Studies of the effects of genes on ageing are vulnerable to confounding effects of genetic background. Here we re-examined the reported effects of sirtuin overexpression on ageing and found that standardization of genetic background and the use of appropriate controls abolished the apparent effects in both C. elegans and Drosophila. In C. elegans, outcrossing of a line with high-level sir-2.1 overexpression abrogated the longevity increase, but did not abrogate sir-2.1 overexpression. Instead, longevity co-segregated with a second-site mutation affecting sensory neurons. Outcrossing of a line with low-copy-number sir-2.1 overexpression also abrogated longevity. A Drosophila strain with ubiquitous overexpression of dSir2 using the UAS-GAL4 system was long-lived relative to wild-type controls, as previously reported, but was not long-lived relative to the appropriate transgenic controls, and nor was a new line with stronger overexpression of dSir2. These findings underscore the importance of controlling for genetic background and for the mutagenic effects of transgene insertions in studies of genetic effects on lifespan. The life-extending effect of dietary restriction on ageing in Drosophila has also been reported to be dSir2 dependent. We found that dietary restriction increased fly lifespan independently of dSir2. Our findings do not rule out a role for sirtuins in determination of metazoan lifespan, but they do cast doubt on the robustness of the previously reported effects of sirtuins on lifespan in C. elegans and Drosophila