Mineral separation protocol for accurate and precise rhenium-osmium (Re-Os) geochronology and sulphur isotope composition of individual sulphide species.

A temporal framework for mineral deposits is essential when addressing the history of their formation and conceptualizing genetic models of their origin. This knowledge is critical to understand how crust-forming processes are related to metal accumulations at specific time and conditions of Earth evolution. To this end, high-precision absolute geochronology utilising the rhenium-osmium (Re-Os) radiometric system in specific sulphide minerals is becoming a method of choice. Here, we present a procedure to obtain mineral separates of individual sulphide species that may coexist within specific mineralized horizons in ore deposits. This protocol is based on preliminary petrographic and paragenetic investigations of sulphide and gangue minerals using reflected and transmitted light microscopy. Our approach emphasizes the key role of a stepwise use of a Frantz isodynamic separator to produce mineral separates of individual sulphide species that are subsequently processed for Re-Os and sulphur isotope geochemistry.•Detailed method and its graphical illustration modified from an original procedure introduced by [1], [2].•Quality control and validation of monophasic mineral separates made by microscopic investigations and qualitative analysis of aliquots embedded in epoxy mounts.•The present method, which contributed to the successful results presented in the co-publication by Saintilan et al. (2020), demonstrates why other studies reporting Re-Os isotope data for mixtures of sulphide minerals should be considered with caution.

Sulphide Re-Os geochronology links orogenesis, salt and Cu-Co ores in the Central African Copperbelt.

The origin of giant, sedimentary rock-hosted copper-cobalt (Cu-Co) provinces remains contentious, in part due to the lack of precise and reliable ages for mineralisation. As such, no consensus has been reached on the genetic model for ore formation, and the relationships between tectonism, palaeo-fluid circulation and mineralisation. Here, we link the timing of Cu-Co mineralisation in the Central African Copperbelt to compressional tectonics during the Lufilian Orogeny by using new ca. 609-473 Ma ages given by rhenium-osmium (Re-Os) isotope data for individual Cu-Co sulphides (carrolite and bornite) from the Cu-Co Kamoto deposit. The initial Os isotope composition of carrolite is compatible with the leaching of Os and Cu(-Co) from Mesoproterozoic Cu sulphide deposits hosted in fertile basement. In contrast, the ca. 473 Ma Cu-Au mineralisation stage, which is coeval with late- to post-compressional deformation, may be a distal expression of fluid flow and heat transfer caused by magmatic intrusions in the core of the collisional orogen. The Re-Os ages support a model for mineralisation driven by evaporite dissolution and percolation of large volumes of dense brines in the Katangan Basin during the Lufilian Orogeny.

Rhenium uptake and distribution in phaeophyceae macroalgae, Fucus vesiculosus.

Owing to Rhenium (Re) having no known biological role, it is not fully understood how Re is concentrated in oil kerogens. A commonly held assumption is that Re is incorporated into decomposing biomass under reducing conditions. However, living macroalgae also concentrate Re to several orders of magnitude greater than that of seawater. This study uses Fucus vesiculosus to assess Re uptake and its subsequent localization in the biomass. It is demonstrated that the Re abundance varies within the macroalgae and that Re is not located in one specific structure. In F. vesiculosus, the uptake and tolerance of Re was evaluated via tip cultures grown in seawater of different Re(VII) compound concentrations (0-7450 ng g(-1)). A positive correlation is shown between the concentration of Re-doped seawater and the abundance of Re accumulated in the tips. However, significant differences between Re(VII) compounds are observed. Although the specific cell structures where the Re is localized is not known, our findings suggest that Re is not held within chloroplasts or cytoplasmic proteins. In addition, metabolically inactivated F. vesiculosus does not accumulate Re, which indicates that Re uptake is via syn-life bioadsorption/bioaccumulation and that macroalgae may provide a source for Re phytomining and/or bioremediation.

Redox heterogeneity of subsurface waters in the Mesoproterozoic ocean.

A substantial body of evidence suggests that subsurface water masses in mid-Proterozoic marine basins were commonly anoxic, either euxinic (sulfidic) or ferruginous (free ferrous iron). To further document redox variations during this interval, a multiproxy geochemical and paleobiological investigation was conducted on the approximately 1000-m-thick Mesoproterozoic (Lower Riphean) Arlan Member of the Kaltasy Formation, central Russia. Iron speciation geochemistry, supported by organic geochemistry, redox-sensitive trace element abundances, and pyrite sulfur isotope values, indicates that basinal calcareous shales of the Arlan Member were deposited beneath an oxygenated water column, and consistent with this interpretation, eukaryotic microfossils are abundant in basinal facies. The Rhenium-Osmium (Re-Os) systematics of the Arlan shales yield depositional ages of 1414±40 and 1427±43 Ma for two horizons near the base of the succession, consistent with previously proposed correlations. The presence of free oxygen in a basinal environment adds an important end member to Proterozoic redox heterogeneity, requiring an explanation in light of previous data from time-equivalent basins. Very low total organic carbon contents in the Arlan Member are perhaps the key--oxic deep waters are more likely (under any level of atmospheric O2) in oligotrophic systems with low export production. Documentation of a full range of redox heterogeneity in subsurface waters and the existence of local redox controls indicate that no single stratigraphic section or basin can adequately capture both the mean redox profile of Proterozoic oceans and its variance at any given point in time.

Copper(II)-mediated thermolysis of alginates: a model kinetic study on the influence of metal ions in the thermochemical processing of macroalgae.

Thermochemical processing methods such as pyrolysis are of growing interest as a means of converting biomass into fuels and commodity chemicals in a sustainable manner. Macroalgae, or seaweed, represent a novel class of feedstock for pyrolysis that, owing to the nature of the environments in which they grow coupled with their biochemistry, naturally possess high metal contents. Although the impact of metals upon the pyrolysis of terrestrial biomass is well documented, their influence on the thermochemical conversion of marine-derived feeds is largely unknown. Furthermore, these effects are inherently difficult to study, owing to the heterogeneous character of natural seaweed samples. The work described in this paper uses copper(II) alginate, together with alginic acid and sodium alginate as model compounds for exploring the effects of metals upon macroalgae thermolysis. A thermogravimetric analysis-Fourier transform infrared spectroscopic study revealed that, unusually, Cu(2+) ions promote the onset of pyrolysis in the alginate polymer, with copper(II) alginate initiating rapid devolatilization at 143°C, 14°C lower than alginic acid and 61°C below the equivalent point for sodium alginate. Moreover, this effect was mirrored in a sample of wild Laminaria digitata that had been doped with Cu(2+) ions prior to pyrolysis, thus validating the use of alginates as model compounds with which to study the thermolysis of macroalgae. These observations indicate the varying impact of different metal species on thermochemical behaviour of seaweeds and offer an insight into the pyrolysis of brown macroalgae used in phytoremediation of metal-containing waste streams.

Developing a useful, user-friendly website for cancer patient follow-up: users' perspectives on ease of access and usefulness.

UK cancer survival has improved, leading to an increase in review patients and pressure on clinics. Use of the Internet for information exchange between patients and healthcare staff may provide a useful adjunct or alternative to traditional follow-up. This study aimed to develop and evaluate a website for use in follow-up cancer care in terms of usability, feasibility and acceptability. A website was developed and underwent iterative amendment following patient usability testing in focus groups. Patients on follow-up completed a Computer and Internet Usage Questionnaire. Internet users consented to a randomised crossover study to complete paper and online questionnaires, browse the website and participate in a website evaluation interview. Patient website use was tracked. Usability: Website changes were made following patient testing (n= 21). Patients would have liked a 'personalized' website with links to their clinical team, out with the scope of this study. Feasibility: The majority of participants (65%) had Internet access. Age remained a differentiating factor. Acceptability: Final evaluation (n= 103) was positive although many would like to maintain face-to-face hospital contact. User involvement in website design can ensure patient needs are met. A website model for follow-up will suit some patients but others will prefer clinical contact.

Predictors of survival in patients with non-curative stage IV cancer and malignant bowel obstruction.

PURPOSE: Malignant bowel obstruction (MBO) occurs in up to 15% of patients admitted to palliative care wards and management can be clinically challenging. Survival is generally poor with a reported median survival of 1-3 months; however, there are no studies describing predictors of survival for patients with MBO. PATIENTS AND METHODS: All patients admitted to a tertiary care hospital with a MBO were approached between March 1, 2006 and March 31, 2008 to enter the study. Demographic, clinical, laboratory, and radiographic information were prospectively collected from patient charts and the patient's functional status (Eastern Cooperative Oncology Group score, ECOG) at admission was recorded. Follow-up was until death or the end of the study (August 2008). Survival was estimated using Kaplan-Meier plots and Cox regression models were used to evaluate prognostic factors for survival. RESULTS: Thirty-five patients were recruited. Median patient age was 61% and 46% were female. Median survival of the cohort was 80 days (range 7-873). Median survival for patients with an ECOG performance status of 0-1 (n = 15) was 222 days, for ECOG 2 patients (n = 9), 63 days and for patients with an ECOG 3/4 score (n = 11) it was 27 days. ECOG status was the strongest predictor of survival on the multivariate analysis. In addition, a low blood urea nitrogen level or a high albumin on admission was also associated with prolonged survival. CONCLUSION: An ECOG score of 0/1 for patients with MBO in the setting of Stage IV non-curative cancer is the strongest predictor of overall survival.

Room for improvement? A quality-of-life assessment in patients with malignant bowel obstruction.

This prospective study followed 35 patients admitted to hospital with malignant bowel obstruction (MBO) to evaluate quality of life (QOL). Subjects completed the Edmonton Symptom Assessment Scale (ESAS) and Rotterdam Symptom Checklist (RSCL) at recruitment, and at one week, one month and three months.The highest ranked ESAS scores at recruitment (which was generally 18-36 hours post admission to hospital) included loss of appetite (median=7.5), fatigue (6.5) and overall well-being (6.0). The total ESAS score improved by 7.5, 11.5 and 11.0 points respectively at one week, one month and three months (p<0.05, p<0.01, NS).RSCL median scores for physical and psychological subscales were high at baseline (36.2, 42.9) and improved significantly at one week and one month (p<0.05). Psychological functioning appeared to be worsening by three months and at no time did activity level improve significantly. The overall QOL score was extremely poor at baseline (6.0 median) improving to 3.3 at one month (median fall=1.0, p<0.05) and 3.4 at three months.Further work should address the lack of improvement in activity and apparent deterioration in psychological functioning after one month.

Demographic profile and utilization statistics of a Canadian inpatient palliative care unit within a tertiary care setting.

BACKGROUND: Canadian data describing inpatient palliative care unit (PCU) utilization are scarce. In the present study, we performed a quality assessment of a 24-bed short-term PCU with a 3-months-or-less life expectancy policy in a tertiary care setting. METHODS: Using a retrospective chart review, we explored wait time (wt) for admission (May 2005 to April 2006), length of stay [los (February 2005 to January 2006)], and patient demographics. RESULTS: The wt data showed 508 referrals, with 242 resulting in admissions (92% malignant diagnoses) and 266 not (82% malignant). The most common malignancies in both groups were gastrointestinal, lung, and genitourinary. Median wt for admitted patients was 6 days, varying with referral source, such as the same hospital, home, or another hospital (6, 4, and 8.5 days respectively). Most admissions (93%) occurred in 21 or fewer days. Patient death (52%), admission to another PCU (25%), and declined offer (10%) were common reasons for no admission. Median los for 219 admitted patients was 19 days (range: 0-249 days). Most patients (94%) died in the PCU; a minority were discharged. CONCLUSIONS: Many patients requiring PCU services are admitted within a few days of referral, especially patients with the least available support: those at home. However, half of the non-admitted patients die while waiting-a potential area for improvement. The los for admitted patients complied with the 3-month "expected lifespan" PCU policy. Results are significant, because ensuring quality of life for palliative care patients includes timely PCU access and sufficient los to address end-of-life needs.

Anthropometric reference values in an Afro-Caribbean adolescent population.

Childhood and adolescent obesity is increasingly becoming a major public health issue in the Caribbean. In this study, we analyze patterns of growth in a population of Afro-Caribbean adolescents 12-18 years old and to compare these with those established for US adolescents. A cross-section of adolescent schoolchildren had weight and height measured using standardized procedures. In addition, percentage body fat (% BF) was measured using a foot-to-foot bioelectric impedance body fat analyzer (Tanita model 531). Selected age- and gender- specific percentiles of BMI, %BF, weight and height were derived and smoothed by cubic splines. These were compared with similar percentiles from US adolescent growth data. A total of 3,707 adolescents (1,585 males; 2,122 females) participated in the study. The age-specific correlation between BMI and %BF ranged from 0.75 to 0.87 in males and 0.79 to 0.87 in females. Females had significantly higher %BF than males in each age category. Overall, Tobagonian females were heavier and had higher BMI than their US counterparts especially levels above the median percentiles. Tobagonian males had similar height, weight, and BMI to their US counterparts over the range of percentiles. Overall, the pattern of growth in this group of adolescents suggests that they are growing at rates that are comparable to those seen in a more well-nourished population.

Prothrombin gene mutation uncommon in pulmonary embolism.

BACKGROUND: Venous thrombosis followed by pulmonary embolism is one of the most common causes of sudden death among middle-aged adults. Several inherited polymorphisms are associated with heightened risk of venous thrombosis, including mutation at position 20210 of the prothrombin gene and mutation at codon 506 of the factor V gene. METHODS: We studied mutation prevalence in 67 individuals who died of pulmonary embolism and were autopsied in a medical examiner's facility over a 5-year period. Mutations were identified by polymerase chain reaction followed by allele-specific endonuclease digestion. RESULTS: Traditional risk factors for pulmonary embolism (eg, immobility, oral contraceptive use, cancer) were identified in 75%. Heterozygous mutation of the prothrombin gene was found in 3/67 (4%), and heterozygous mutation of the factor V gene was identified in 3/66 (4%). No homozygotes or compound heterozygotes were identified. The prevalence of mutation was not significantly different from that of the general population. CONCLUSIONS: Individuals who die suddenly from pulmonary embolism are not often affected by prothrombin or factor V gene mutations. Therefore, medical examiners need not routinely test for these mutations in individuals who die of pulmonary embolism.

Plexiform neurofibroma of the penis in a child.

We report a case of a child with the stigmata of von Recklinghausen's disease and a plexiform neurofibroma arising from the penile shaft.

Expression of renal and vascular angiotensin II receptor subtypes in children.

Angiotensin II (Ang II) AT1 receptors modulate most of the known physiological functions of Ang II in the kidney and cardiovascular structures. In contrast, the physiological role of AT2 receptors, which are abundantly expressed in fetal tissues, is not clearly defined. The changes that occur in the expression and distribution of AT2 receptors in the kidney and arteries during the first 2 years of life have not been studied. We have localized and characterized the expression of Ang II receptor subtypes, AT1 and AT2, in the kidney, interlobular arteries, thoracic aorta, and middle cerebral artery, in children during their first 2 years of life, using quantitative autoradiography. Renal glomeruli and middle cerebral arteries expressed exclusively AT1 receptors. In contrast, more than 80% of the Ang II receptors expressed in thoracic aorta and interlobular arteries belonged to the AT2 subtype. These findings demonstrate that the expression of Ang II receptor subtypes in different vascular structures in young children varies according to the tissue.

Orthogonal acceleration time-of-flight mass spectrometry.

The principles and applications of time-of-flight mass spectrometry involving instruments with independent (orthogonal) axes for ion generation and mass analysis are reviewed. This approach, generally referred to as orthogonal acceleration time-of-flight mass spectrometry, has proved particularly advantageous for the combination of continuous ionization sources with time-of-flight mass spectrometry. The history of the technique is briefly discussed along with the instrumental principles pertaining to all the stages of the instrumentation from ion source to detector. The applications of commercial and customized instruments are discussed for several ionization methods including electrospray, matrix assisted laser desorption/ionization, electron ionization, and plasma ionization.

Muc-5/5ac mucin messenger RNA and protein expression is a marker of goblet cell metaplasia in murine airways.

Airway inflammation, hyperreactivity, increased number of goblet cells, and mucus overproduction characterize asthma. Respiratory challenge with ovalbumin (OVA) of sensitized mice has been shown by several laboratories to cause pulmonary pathology similar to that observed in human allergic asthma. Recently, interleukin (IL)-13 has been shown to be a central mediator in this process. Because the airways of healthy mice have few, if any, mucus-producing cells, an increase in the number of these cells likely reflects induction of mucin-gene expression. The purpose of this study was to identify mucin genes induced as a result of airway goblet-cell metaplasia (GCM) in mice sensitized and challenged with OVA or in mice treated with IL-13 alone. BALB/c mice were sensitized by intraperitoneal injection (Days 0, 4, 7, 11, and 14) and intranasal instillation (Day 14) of 100 microg of OVA in saline, and then challenged by intranasal instillation (Days 25, 26, and 27) of the same. IL-13-treated mice received 5 microg of IL-13 by intranasal instillation on three consecutive days. Control mice were given saline alone. All mice were studied 24 h after the last challenge. Histologic analysis of the lungs revealed both a striking peribronchial and perivascular lymphocytic and eosinophilic inflammation and airway GCM in OVA-treated mice, and also airway GCM without inflammation in IL-13-treated mice. Northern blot analysis of lung RNA demonstrated (1) expression of Muc-5/5ac messenger RNA (mRNA) in OVA-treated and IL-13-treated mice, but not in control mice; (2) expression of Muc-1 mRNA at comparable levels in all mice regardless of treatment; and (3) no expression of Muc-2 or Muc-3 mRNA in control or treated mice. Western blot analysis demonstrated the expression of Muc-5/5ac protein (both apomucin and glycosylated mucin) in lung lysates of OVA-treated (but not control) mice, and also the expression of Muc-5/5ac mucins in the bronchoalveolar lavage fluid of OVA-treated and IL-13-treated mice. These findings demonstrate that airway GCM is associated with the induction of pulmonary expression of Muc-5/5ac mRNA and mucin in murine models of allergic asthma.

Pancreatoblastoma: imaging findings in 10 patients and review of the literature.

PURPOSE: To describe the features of pancreatoblastoma at magnetic resonance (MR) imaging, computed tomography (CT), and ultrasonography (US). MATERIALS AND METHODS: Imaging and surgical findings in 10 patients (age range, 2-20 years; mean age, 6.8 years) with pathologically proved pancreatoblastoma were reviewed for tumor size, organ of origin, definition and quality of tumor margins, tumor heterogeneity, calcification, enhancement, ascites, biliary and/or pancreatic ductal dilatation, local invasion, adenopathy, vascular invasion, vascular encasement, metastases, and signal intensity on MR images. Results from 10 CT, seven US, and three MR imaging examinations were reviewed. RESULTS: Five of the 10 tumors were pancreatic; four others appeared to be pancreatic or hepatic. Most had well-defined margins (nine of 10), were heterogeneous (nine of 10), and enhanced (10 of 10). Other findings included calcification (two of 10), biliary and pancreatic ductal dilatation (one of 10), and ascites (three of 10). Hepatic (two patients) and pelvic (two patients) metastases were present. Adenopathy (two patients) and vascular invasion (one patient) were not identified radiologically. Tumors had low to intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. CONCLUSION: Pancreatoblastoma is typically a heterogeneous tumor with well-defined margins that may appear to arise from the pancreas or liver. It may behave aggressively, with localized vascular or bowel invasion or with widespread metastatic disease. Although it is rare, it should be considered in the differential diagnosis of an upper abdominal mass in a child.