Porphyry copper enrichment linked to excess aluminium in plagioclase

PublishedPorphyry copper deposits provide around 75%, 50% and 20% of world copper, molybdenum and gold, respectively1. The deposits are mainly centred on calc-alkaline porphyry magmatic systems2, 3 in subduction zone settings1. Although calc-alkaline magmas are relatively common, large porphyry copper deposits are extremely rare and increasingly difficult to discover. Here, we compile existing geochemical data for magmatic plagioclase, a dominant mineral in calc-alkaline rocks, from fertile (porphyry-associated) and barren magmatic systems worldwide, barren examples having no associated porphyry deposit. We show that plagioclase from fertile systems is distinct in containing ‘excess’ aluminium. This signature is clearly demonstrated in a case study carried out on plagioclase from the fertile La Paloma and Los Sulfatos copper porphyry systems in Chile. Further, the presence of concentric zones of high excess aluminium suggests its incorporation as a result of magmatic processes. As excess aluminium has been linked to high melt water contents, the concentric zones may record injections of hydrous fluid or fluid-rich melts into the sub-porphyry magma chamber. We propose that excess aluminium may exclude copper from plagioclase, so enriching the remaining melts. Furthermore, this chemical signature can be used as an exploration indicator for copper porphyry deposits.The project would not have been possible without the financial and logistical support of Anglo American, including former and current staff: J. Coppard, V. Irarrazaval, M. Buchanan, E. Liebmann, R. Mattos Pino, E. Centino, J. Andronico, R. Mauricio, D. Fernando and J. Zamorano. J. Spratt (Natural History Museum, London) and S. Pendray (University of Exeter) are thanked for EPMA support and thin section preparation, respectively. K. Cashman (Bristol University), S. Hesselbo, J. Pickles and S. Broom-Fendley (University of Exeter), and reviewer J. Richards (University of Alberta), are gratefully acknowledged for comments on the manuscript

Association of Maximum Temperature With Sedentary Time in Older British Men.

BACKGROUND: Sedentary behaviour is very common in older adults and a risk factor for mortality. Understanding determinants of sedentary behaviour may help in defining strategies aimed to reduce the time spent sedentary. The degree of difference in sedentary time attributable to varying temperatures has not been yet estimated in older men. METHODS: Men aged 71-91 years participating in an established UK population-based cohort study were invited to wear an Actigraph GT3x accelerometer for one week in 2010-12. Outcome was sedentary time (<1.5 Metabolic Equivalent of Task) in minutes per day. Associations between daily outdoor maximum temperature and accelerometer-measured sedentary time were estimated using multilevel models. RESULTS: 43% (1361/3137) of invited men participated in the study and provided adequate data. Men spent on average 615 minutes in sedentary time per day (72% of the total accelerometer-wear time). After adjusting for covariates, men spent 26 minutes more per day (p<0.001) in sedentary time when temperatures were in the lowest (-3.5; 9.2°C) versus highest quintile (19.1; 29.5°C). CONCLUSIONS: Sedentary time in older adults is highest at lowest temperatures, typically recorded in winter. Findings are relevant for guidelines: interventions may consider targeting older men in winter providing recommendations for minimising sedentariness on daily basis

Estimation of country-specific and global prevalence of male circumcision.

BACKGROUND: Male circumcision (MC) status and genital infection risk are interlinked and MC is now part of HIV prevention programs worldwide. Current MC prevalence is not known for all countries globally. Our aim was to provide estimates for country-specific and global MC prevalence. METHODS: MC prevalence data were obtained by searches in PubMed, Demographic and Health Surveys, AIDS Indicator Surveys, and Behavioural Surveillance Surveys. Male age was ≥15 years in most surveys. Where no data were available, the population proportion whose religious faith or culture requires MC was used. The total number of circumcised males in each country and territory was calculated using figures for total males from (i) 2015 US Central Intelligence Agency (CIA) data for sex ratio and total population in all 237 countries and territories globally and (ii) 2015 United Nations (UN) figures for males aged 15-64 years. RESULTS: The estimated percentage of circumcised males in each country and territory varies considerably. Based on (i) and (ii) above, global MC prevalence was 38.7 % (95 % confidence interval [CI]: 33.4, 43.9) and 36.7 % (95 % CI: 31.4, 42.0). Approximately half of circumcisions were for religious and cultural reasons. For countries lacking data we assumed 99.9 % of Muslims and Jews were circumcised. If actual prevalence in religious groups was lower, then MC prevalence in those countries would be lower. On the other hand, we assumed a minimum prevalence of 0.1 % related to MC for medical reasons. This may be too low, thereby underestimating MC prevalence in some countries. CONCLUSIONS: The present study provides the most accurate estimate to date of MC prevalence in each country and territory in the world. We estimate that 37-39 % of men globally are circumcised. Considering the health benefits of MC, these data may help guide efforts aimed at the use of voluntary, safe medical MC in disease prevention programs in various countries

Associations of time of day with cardiovascular disease risk factors measured in older men: results from the British Regional Heart Study.

OBJECTIVE: We estimated associations of time of day with cardiovascular disease (CVD) risk factors measured in older men. METHODS: CVD risk factors (markers of inflammation and haemostasis, and cardiac markers) were measured on one occasion between 08:00 and 19:00 hours in 4252 men aged 60-79 years from the British Regional Heart Study. Linear models were used to estimate associations between time of day and risk factors. When an association was found, we examined whether the relationship between risk factors and cardiovascular mortality was affected by the adjustment for time of day using survival analyses. RESULTS: N-terminal pro-brain natriuretic peptide (NT-proBNP) levels increased by 3.3% per hour (95% CI 1.9% to 4.8%), interleukin-6 (IL-6) increased by 2.6% per hour (95% CI 1.8% to 3.4%), while tissue plasminogen activator (t-PA) decreased by 3.3% per hour (95% CI 3.7% to 2.9%); these associations were unaffected by adjustment for possible confounding factors. The percentages of variation in these risk factors attributable to time of day were less than 2%. In survival analyses, the association of IL-6, NT-proBNP and t-PA with cardiovascular mortality was not affected by the adjustment for time of day. C reactive protein, fibrinogen, D-dimer, von Willebrand factor and cardiac troponin T showed no associations with time of day. CONCLUSIONS: In older men, markers of inflammation (IL-6), haemostasis (t-PA) and a cardiac marker (NT-proBNP) varied by time of day. The contribution of time of day to variations in these markers was small and did not appear to be relevant for the CVD risk prediction

Does total volume of physical activity matter more than pattern for onset of CVD? A prospective cohort study of older British men.

AIMS: With increasing age, physical inactivity and sedentary behaviour levels increase, as does cardiovascular disease (CVD) incidence. We investigate how device-measured sedentary behaviour and physical activity (PA) are related to CVD onset in men aged 70+; whether the total volume of activity is more important than pattern. METHODS AND RESULTS: Prospective population-based cohort study of men recruited from 24 UK General Practices in 1978-80. In 2010-12, 3137 survivors were invited to complete questionnaires and wear an Actigraph GT3x accelerometer for 7 days. PA intensity was categorised as sedentary, light and moderate to vigorous (MVPA). Men were followed up for Myocardial Infarction, stroke and heart failure (ICD9 410-414, 430-438 and 428) morbidity and mortality from 2010 to 12 to June 2016. Hazard Ratios (HRs) for incident Cardiovascular Disease (CVD) were estimated. 1528/3137 (49%) men had sufficient accelerometer data. 254 men with pre-existing CVD were excluded. Participants' mean age was 78.4 (range 71-92) years. After median 4.9 years follow-up, 122 first CVD events occurred in 1181 men (22.7/1000 person-years) with complete data. For each additional 30 min in sedentary behaviour, light PA,10 min in MVPA, or 1000 steps/day, HRs for CVD were 1.09(95%CI 1.00, 1.19), 0.94(0.85, 1.04), 0.88(0.81, 0.96) and 0.86(0.78 to 0.95) respectively, adjusted for measurement-related factors, socio-demographics, health behaviours and disability. HRs for accumulating 150 min/week MVPA in bouts ≥1 min and bouts ≥10 min were 0.47(0.32 to 0.69), and 0.49(0.25, 0.98). CONCLUSIONS: In older men, high volume of steps or MVPA rather than MVPA bouts was associated with reduced CVD risk

Relationship between outdoor temperature and cardiovascular disease risk factors in older people.

Background Previous studies demonstrated that lower outdoor temperatures increase the levels of established cardiovascular disease risk factors, such as blood pressure and lipids. Whether or not low temperatures increase novel cardiovascular disease risk factors levels is not well studied. The aim was to investigate associations of outdoor temperature with a comprehensive range of established and novel cardiovascular disease risk factors in two large Northern European studies of older adults, in whom cardiovascular disease risk is increased. Design and methods Data came from the British Regional Heart Study (4252 men aged 60-79 years) and the Prospective Study of Pravastatin in the Elderly at Risk (5804 men and women aged 70-82 years). Associations between outdoor temperature and cardiovascular disease risk factors were quantified in each study and then pooled using a random effects model. Results With a 5℃ lower mean temperature, total cholesterol was 0.04 mmol/l (95% confidence interval (CI) 0.02-0.07) higher, low density lipoprotein cholesterol was 0.02 mmol/l (95% CI 0.01-0.05) higher and SBP was 1.12 mm Hg (95% CI 0.60-1.64) higher. Among novel cardiovascular disease risk factors, C-reactive protein was 3.3% (95% CI 1.0-5.6%) higher, interleukin-6 was 2.7% (95% CI 1.1-4.3%) higher, and vitamin D was 11.2% (95% CI 1.0-20.4%) lower. Conclusions Lower outdoor temperature was associated with adverse effects on cholesterol, blood pressure, circulating inflammatory markers, and vitamin D in two older populations. Public health approaches to protect the elderly against low temperatures could help in reducing the levels of several cardiovascular disease risk factors

Islet isolation assessment in man and large animals

Recent progress in islet isolation from the pancreas of large mammals including man, accentuated the need for the development of precise and reproducible techniques to assess islet yield. In this report both quantitative and qualitative criteria for islet isolation assessment were discussed, the main topics being the determination of number, volume, purity, morphologic integrity and in vitro and in vivo function tests of the final islet preparations. It has been recommended that dithizone should be used as a specific stain for immediate detection of islet tissue making it possible to estimate both the total number of islets (dividing them into classes of 50 μ diameter range increments) and the purity of the final preparation. Appropriate morphological assessment should include confirmation of islet identification, assessment of the morphological integrity and of the purity of the islet preparation. The use of fluorometric inclusion and exclusion dyes together have been suggested as a viability assay to simultaneously quantitate the proportion of cells that are intact or damaged. Perifusion of islets with glucose provides a dynamic profile of glucose-mediated insulin release and of the ability of the cells to down regulate insulin secretion after the glycemic challenge is interrupted. Although perifusion data provides a useful guide to islet viability the quantity and kinetics of insulin release do not necessarily predict islet performance after implantation. Therefore, the ultimate test of islet viability is their function after transplantation into a diabetic recipient. For this reason, in vivo models of transplantation of an aliquot of the final islet preparation into diabetic nude (athymic) rodents have been suggested. We hope that these general guidelines will be of assistance to standardize the assessment of islet isolations, making it possible to better interpret and compare procedures from different centers. © 1990 Casa Editrice il Ponte

Electrical stimulation devices for the prevention of venous thromboembolism: Preliminary studies of physiological efficacy and user satisfaction.

Introduction: Electrical stimulation could provide an alternative method for preventing venous thromboembolism in stroke patients. The purpose of this preliminary study was to explore the effects of electrical stimulation and intermittent pneumatic compression on enhancing lower limb venous return in healthy and chronic stroke patients and also to evaluate patient and nurse satisfaction. Methods: We investigated the effectiveness of two electrical stimulation devices: Geko (Firstkind Ltd, High Wycombe, UK) and Orthopaedic Microstim 2V2 (Odstock Medical Ltd, Salisbury, UK); and one intermittent pneumatic compression device: Huntleigh Flowstron Universal (Huntleigh Healthcare Ltd, Cardiff, UK). We recruited 12 healthy and 5 chronic stroke participants. The devices were fitted sequentially, and Doppler ultrasound measurements were taken. Eight patients and nurses were also recruited for a separate usability evaluation. Results: The electrical stimulation devices emulated the blood flow characteristics of intermittent pneumatic compression in both healthy and stroke participants provided that the intensity of electrical stimulation was sufficient. Patients and nurses also felt that the electrical stimulation devices were acceptable. Conclusions: Electrical stimulation may offer benefit as an alternative method for venous thromboembolism prevention in stroke patients. The apparent benefit is sufficient to warrant further investigation in a full powered randomised controlled trial

Genetic variation at CHRNA5-CHRNA3-CHRNB4 interacts with smoking status to influence body mass index

Cigarette smoking is associated with lower body mass index (BMI), and a commonly cited reason for unwillingness to quit smoking is a concern about weight gain. Common variation in the CHRNA5-CHRNA3-CHRNB4 gene region (chromosome 15q25) is robustly associated with smoking quantity in smokers, but its association with BMI is unknown. We hypothesized that genotype would accurately reflect smoking exposure and that, if smoking were causally related to weight, it would be associated with BMI in smokers, but not in never smokers

Association Between Genetic Variants on Chromosome 15q25 Locus and Objective Measures of Tobacco Exposure

Background: Two single-nucleotide polymorphisms, rs1051730 and rs16969968, located within the nicotinic acetylcholine receptor gene cluster on chromosome 15q25 locus, are associated with heaviness of smoking, risk for lung cancer, and other smoking-related health outcomes. Previous studies have typically relied on self-reported smoking behavior, which may not fully capture interindividual variation in tobacco exposure. / Methods: We investigated the association of rs1051730 and rs16969968 genotype (referred to as rs1051730–rs16969968, because these are in perfect linkage disequilibrium and interchangeable) with both self-reported daily cigarette consumption and biochemically measured plasma or serum cotinine levels among cigarette smokers. Summary estimates and descriptive statistical data for 12 364 subjects were obtained from six independent studies, and 2932 smokers were included in the analyses. Linear regression was used to calculate the per-allele association of rs1051730–rs16969968 genotype with cigarette consumption and cotinine levels in current smokers for each study. Meta-analysis of per-allele associations was conducted using a random effects method. The likely resulting association between genotype and lung cancer risk was assessed using published data on the association between cotinine levels and lung cancer risk. All statistical tests were two-sided. / Results: Pooled per-allele associations showed that current smokers with one or two copies of the rs1051730–rs16969968 risk allele had increased self-reported cigarette consumption (mean increase in unadjusted number of cigarettes per day per allele = 1.0 cigarette, 95% confidence interval [CI] = 0.57 to 1.43 cigarettes, P = 5.22 × 10−6) and cotinine levels (mean increase in unadjusted cotinine levels per allele = 138.72 nmol/L, 95% CI = 97.91 to 179.53 nmol/L, P = 2.71 × 10−11). The increase in cotinine levels indicated an increased risk of lung cancer with each additional copy of the rs1051730–rs16969968 risk allele (per-allele odds ratio = 1.31, 95% CI = 1.21 to 1.42). / Conclusions: Our data show a stronger association of rs1051730–rs16969968 genotype with objective measures of tobacco exposure compared with self-reported cigarette consumption. The association of these variants with lung cancer risk is likely to be mediated largely, if not wholly, via tobacco exposure