Cold-Water Immersion and Lower Limb Muscle Oxygen Consumption as Measured by Near-Infrared Spectroscopy in Trained Endurance Athletes

CONTEXT

Cold-water immersion (CWI) has been reported to reduce tissue metabolism postimmersion, but physiological data are lacking regarding the muscle metabolic response to its application. Near-infrared spectroscopy (NIRS) is a noninvasive optical technique that can inform muscle hemodynamics and tissue metabolism.

OBJECTIVE

To investigate the effects of CWI at 2 water temperatures (10°C and 15°C) on NIRS-calculated measurements of muscle oxygen consumption (mVO2).

DESIGN

Crossover study.

SETTING

University sports rehabilitation center.

PATIENTS OR OTHER PARTICIPANTS

A total of 11 male National Collegiate Athletic Association Division II long-distance runners (age = 23.4 ± 3.4 years, height = 1.8 ± 0.1 m, mass = 68.8 ± 10.7 kg, mean adipose tissue thickness = 6.7 ± 2.7 mm).

INTERVENTION(S)

Cold-water immersion at 10°C and 15°C for 20 minutes.

MAIN OUTCOME MEASURE(S)

We calculated mVO2 preimmersion and postimmersion at water temperatures of 10°C and 15°C. Changes in tissue oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), total hemoglobin (tHb), hemoglobin difference (Hbdiff), and tissue saturation index (TSI %) were measured during the 20-minute immersion at both temperatures.

RESULTS

We observed a decrease in mVO2 after immersion at both 10°C and 15°C (F1,9 = 27.7801, P = .001). During the 20-minute immersion at both temperatures, we noted a main effect of time for O2Hb (F3,27 = 14.227, P = .001), HHb (F3,27 = 5.749, P = .009), tHb (F3,27 = 24.786, P = .001), and Hbdiff (F3,27 = 3.894, P = .020), in which values decreased over the course of immersion. Post hoc pairwise comparisons showed that these changes occurred within the final 5 minutes of immersion for tHb and O2Hb.

CONCLUSIONS

A 20-minute CWI at 10°C and 15°C led to a reduction in mVO2. This was greater after immersion at 10°C. The reduction in mVO2 suggests a decrease in muscle metabolic activity (ie, O2 use after CWI). Calculating mVO2 via the NIRS-occlusion technique may offer further insight into muscle metabolic responses beyond what is attainable from observing the NIRS primary signals.

An Evaluation of Service Provision and Novel Strength Assessment on Patient Outcomes in a UK-Based Pulmonary Rehabilitation Setting

This study's purpose was to (i) assess the impact of a 7-week pulmonary rehabilitation (PR) programme upon patient outcomes; incremental shuttle walk test (ISWT), COPD assessment tool (CAT), Clinical COPD Questionnaire (CCQ) and the Hospital Anxiety and Depression Scale (HADS); (ii) assess the impact of COPD severity on ISWT, psychological functioning and quality of life measures following PR; (iii) assess the feasibility of incorporating individually prescribed one repetition maximum (1RM) training loads into the existing strength training programme. Patients were people with COPD enrolled onto one of three versions (locations A, B and C) of a 7-week PR programme, which consisted of group exercise sessions and a social plus education element. Two locations incorporated individually prescribed training loads. Minimal clinically important changes (MCICs) are reported for the ISWT across all locations. Statistically significant changes in both CAT and the CCQ were found, with MCIC's evident for CAT score overall and individually at location B. MCIC's were not found for the CCQ. No statistically significant or MCICs were evident for the HADS. MCIC's were present only in patients with mild to moderate severity for the ISWT. For the CAT, moderate, severe and very severe patients with COPD experienced MCIC's. MCIC's and statistically significant increases in 1RM strength were seen at both locations. These findings evidence an effective PR service. Basic strength exercise programming and assessment are feasible and should be implemented in PR services to maximise patient outcomes.

Regular Doses of Nature: The Efficacy of Green Exercise Interventions for Mental Wellbeing

This study investigated the efficacy of medium-term Green Exercise (GE; being physically active within a natural environment) interventions for improving wellbeing, by pooling data collected at the start and end of participants' engagement with a range of GE interventions. Hypotheses were that (i) interventions would show good efficacy for improving wellbeing in the overall sample; (ii) compared to participants reporting 'average to high' wellbeing at the start of their project, participants with 'low' starting wellbeing would report greater improvements post-intervention; and (iii) improvements would significantly differ between age groups. The pooled dataset was categorized in line with UK norms (n = 318) and analyzed using a standardized meta-analysis approach. Effect size was large: g = 0.812 (95% CI [0.599, 1.025]), and differences in wellbeing changes associated with project duration, age or sex were not statistically significant. Compared to those reporting 'average-high' starting wellbeing, participants reporting 'low' starting wellbeing exhibited greater improvements (BCa 95% CI [-31.8, -26.5]), with 60.8% moving into the 'average-high' wellbeing category. GE can play an important role in facilitating wellbeing and can provide alternative pathways for health and social care practice. Public health commissioners should consider integrating such interventions for patients experiencing low wellbeing or associated comorbidities.

297Seeing is believing: the feasibility and acceptability of using wearable cameras to enhance self-management of heart failure

Introduction

For people with heart failure (HF), self-management (e.g., adhering to prescribed medication, management of fluid restrictions and daily weighing) and dietary management is critical for disease management. The rise of technologies (mobile phones, wearable cameras) for healthcare use offers potential support for people to better manage their disease. We aimed to test the feasibility and utility of wearable cameras for identifying self-management practices and to determine if these images can be used to enhance self-management in people with HF.

Methods

Participants wore the “narrative clip”, a small wearable camera for one month during waking hours; still images were taken every 30 seconds. Using state-of-the-art artificial intelligence techniques, we investigated automated image analysis of daily life activities to determine the potential of these systems to identify four categories of human activities: medication management, dietary intake, meal preparation and physical activity. Participants also completed a semi-structured questionnaire about acceptability and feasibility.

Results

30 participants (mean age 73.6 years, 60% male) with HF NYHA Class II-III were recruited. A total of 629,603 images were available for analysis. Higher order analyses were conducted to determine precision of identifying correct images for the pre-defined self-management categories. Precision of identifying the correct images was highest in dietary intake (average 49%, range 13–94%) followed by meal preparation (average 40%, range 1–99%) and physical activity (average 31%, range 0–95%). Medication management had the lowest precision (average 6%, range 6–22%). Manual review of images revealed substantial periods of sedentary time, typically paired with screen time (watching television, playing cards on a computer). All participants agreed the camera was easy to use and felt they had privacy when using the camera. The majority of participants felt comfortable wearing the camera (93%) and thought this technique will help people with HF in the future (93%).

Conclusions

Images from wearable cameras provided rich contextual data to better understand the lived experiences of people with HF and the device was acceptable to participants. Automated machine learning tools require more annotated data for training to enhance precision, which will be achieved via further annotation, fine-tuning and retraining the data analysis model. Despite these challenges, the data collected can be used as an adjunct to traditional data collection methods such as self-report. Once data analysis techniques are refined, objective data from wearable cameras may also prove useful for nurses to provide tailored education for self-management.

Acknowledgement/Funding

Heart Foundation Vanguard Grant, Australia (101348)

Constructed wetlands for steel slag leachate management: Partitioning of arsenic, chromium, and vanadium in waters, sediments, and plants

Constructed wetlands can treat highly alkaline leachate resulting from the weathering of steel slag before reuse (e.g. as aggregate) or during disposal in repositories and legacy sites. This study aimed to assess how metal(loid)s soluble at high pH, such as arsenic (As), chromium (Cr), and vanadium (V) are removed in constructed wetlands and how they accumulate in the sediments and the plants (Phragmites australis, common reed). The results show that reedbeds were very effective at removing calcium (98%), aluminium (81%), barium (98%), chromium (90%), gallium (80%), nickel (98%), and zinc (98%), and lowering pH and alkalinity. No statistical difference was found for As and V between leachate influent and wetland samples, showing that these metal(loid)s were not efficiently removed. As, Cr, and V were significantly higher in the reedbed sediments than in a reference site. However, sediment concentrations are not at levels that would pose a concern regarding reuse for agricultural purposes (average values of 39 ± 26 mg kg^-1 for As, 108 ± 15 mg kg^-1 for Cr, and 231 ± 34 mg kg^-1 for V). Also, there is no significant uptake of metals by the aboveground portions of the reeds compared to reference conditions. Results show statistically significant enrichment in metal(loid)s in rhizomes and also a seasonal effect on the Cr concentrations. The data suggest minimal risk of oxyanion-forming element uptake and cycling in wetlands receiving alkaline steel slag.

Can Simulated Green Exercise Improve Recovery From Acute Mental Stress?

This exploratory study enhances previous research into green exercise and addresses a gap in the research by exploring the contribution of individual and combined senses in the recovery of mood and stress after a psychological stressor, whilst rigorously controlling exercise intensity. The hypotheses were: (i) recovery of mood and stress from a state of psychological stress would be greater following simulated green exercise compared to rest, (ii) green exercise would facilitate better recovery than exercise alone, (iii) these effects would remain 10 min following intervention, and (iv) visual stimuli alone would enhance recovery from a state of psychological stress compared to sound. Fifty participants were randomly assigned to one of five groups: REST, exercise, exercise with nature sounds, exercise with nature visual and exercise with nature sound and visual. An initial visit to obtain predicted peak power output values and to familiarize participants with the equipment being used was followed by a second visit, where participants experienced one test condition. Baseline measures of heart rate, blood pressure, total mood disturbance (TMD), and perceived stress were taken, before participants completed a stressor based on the Trier Social Stress test. Measures of heart rate and blood pressure were recorded in the last 30 s of the stressor to assess efficacy of the stressor. Immediately post stressor, measures of mood and perceived stress were taken followed by the intervention assigned (one of five described above). Measures of mood and perceived stress were taken again immediately post intervention and 10 min post intervention. Results showed that green exercise improved mood and stress scores more than exercise alone or REST. For both TMD and perceived stress, improvements in all simulated nature conditions were significantly improved compared to REST or exercise alone immediately post intervention. There were no significant changes 10 min post intervention in either mood or perceived stress compared to immediately post intervention values in any of the groups. This study suggests that environmental exercise settings including nature sounds, visual or both combined should be considered as important in the use of exercise as a therapeutic activity or recovery from acute psychological stress.

Leaching behaviour of co-disposed steel making wastes: Effects of aeration on leachate chemistry and vanadium mobilisation

Steelmaking wastes stored in landfill, such as slag and spent refractory liners, are often enriched in toxic trace metals (including V). These may become mobile in highly alkaline leachate generated during weathering. Fresh steelmaking waste was characterised using XRD, XRF, and SEM-EDX. Batch leaching tests were performed under aerated, air-excluded and acidified conditions to determine the impact of atmospheric CO₂ and acid addition on leachate chemistry. Phases commonly associated with slag including dicalcium silicate, dicalcium aluminoferrite, a wüstite-like solid solution and free lime were identified, as well as a second group of phases including periclase, corundum and graphite which are representative of refractory liners. During air-excluded leaching, dissolution of free lime and dicalcium silicate results in a high pH, high Ca leachate in which the V concentration is low due to the constraint imposed by Ca₃(VO₄)₂ solubility limits. Under aerated conditions, carbonation lowers the leachate pH and provides a sink for aqueous Ca, allowing higher concentrations of V to accumulate. Below pH 10, leachate is dominated by periclase dissolution and secondary phases including monohydrocalcite and dolomite are precipitated. Storage of waste under saturated conditions that exclude atmospheric CO₂ would therefore provide the optimal environment to minimise V leaching during weathering.

Recovery of Al, Cr and V from steel slag by bioleaching: Batch and column experiments

Steel slag is a major by-product of the steel industry and a potential resource of technology critical elements. For this study, a basic oxygen furnace (BOF) steel slag was tested for bacterial leaching and recovery of aluminium (Al), chromium (Cr), and vanadium (V). Mixed acidophilic bacteria were adapted to the steel slag up to 5% (w/v). In the batch tests, Al, Cr, and V were bioleached significantly more from steel slag than in control treatments. No statistical difference was observed arising from the duration of the leaching (3 vs 6 d) in the batch tests. Al and Cr concentrations in the leachate were higher for the smaller particle size of the steel slag (<75 μm), but no difference was observed for V. In the column tests, no statistical difference was found for pH, Al, Cr and V between the live culture (one-step bioleaching) and the supernatant (two-step bioleaching). The results show that the culture supernatant can be effectively used in an upscaled industrial application for metal recovery. If bioleaching is used in the 170-250 million tonnes of steel slag produced per year globally, significant recoveries of metals (100% of Al, 84% of Cr and 8% of V) can be achieved, depending on the slag composition. The removal and recovery percentages of metals from the leachate with Amberlite^®IRA-400 are relatively modest (<67% and <5%, respectively), due to the high concentration of competing ions (SO₄^2-, PO₄^3-) in the culture medium. Other ion exchange resins can be better suited for the leachate or methods such as selective precipitation could improve the performance of the resin. Further research is needed to minimise interference and maximise metal recovery.

A microbial role in the construction of Mono Lake carbonate chimneys?

Lacustrine carbonate chimneys are striking, metre-scale constructions. If these were bioinfluenced constructions, they could be priority targets in the search for early and extraterrestrial microbial life. However, there are questions over whether such chimneys are built on a geobiological framework or are solely abiotic geomorphological features produced by mixing of lake and spring waters. Here, we use correlative microscopy to show that microbes were living around Pleistocene Mono Lake carbonate chimneys during their growth. A plausible interpretation, in line with some recent works by others on other lacustrine carbonates, is that benthic cyanobacteria and their associated extracellular organic material (EOM) formed tubular biofilms around rising sublacustrine spring vent waters, binding calcium ions and trapping and binding detrital silicate sediment. Decay of these biofilms would locally have increased calcium and carbonate ion activity, inducing calcite precipitation on and around the biofilms. Early manganese carbonate mineralisation was directly associated with cell walls, potentially related to microbial activity though the precise mechanism remains to be elucidated. Much of the calcite crystal growth was likely abiotic, and no strong evidence for either authigenic silicate growth or a clay mineral precursor framework was observed. Nevertheless, it seems likely that the biofilms provided initial sites for calcite nucleation and encouraged the primary organised crystal growth. We suggest that the nano-, micro- and macroscale fabrics of these Pleistocene Mono Lake chimneys were affected by the presence of centimetre-thick tubular and vertically stacked calcifying microbial mats. Such carbonate chimneys represent a promising macroscale target in the exploration for ancient or extraterrestrial life.

Hydration of dicalcium silicate and diffusion through neo-formed calcium-silicate-hydrates at weathered surfaces control the long-term leaching behaviour of basic oxygen furnace (BOF) steelmaking slag

Alkalinity generation and toxic trace metal (such as vanadium) leaching from basic oxygen furnace (BOF) steel slag particles must be properly understood and managed by pre-conditioning if beneficial reuse of slag is to be maximised. Water leaching under aerated conditions was investigated using fresh BOF slag at three different particle sizes (0.5-1.0, 2-5 and 10 × 10 × 20 mm blocks) and a 6-month pre-weathered block. There were several distinct leaching stages observed over time associated with different phases controlling the solution chemistry: (1) free-lime (CaO) dissolution (days 0-2); (2) dicalcium silicate (Ca₂SiO₄) dissolution (days 2-14) and (3) Ca-Si-H and CaCO₃ formation and subsequent dissolution (days 14-73). Experiments with the smallest size fraction resulted in the highest Ca, Si and V concentrations, highlighting the role of surface area in controlling initial leaching. After ~2 weeks, the solution Ca/Si ratio (0.7-0.9) evolved to equal those found within a Ca-Si-H phase that replaced dicalcium silicate and free-lime phases in a 30- to 150-μm altered surface region. V release was a two-stage process; initially, V was released by dicalcium silicate dissolution, but V also isomorphically substituted for Si into the neo-formed Ca-Si-H in the alteration zone. Therefore, on longer timescales, the release of V to solution was primarily controlled by considerably slower Ca-Si-H dissolution rates, which decreased the rate of V release by an order of magnitude. Overall, the results indicate that the BOF slag leaching mechanism evolves from a situation initially dominated by rapid hydration and dissolution of primary dicalcium silicate/free-lime phases, to a slow diffusion limited process controlled by the solubility of secondary Ca-Si-H and CaCO₃ phases that replace and cover more reactive primary slag phases at particle surfaces.

Hydraulic and biotic impacts on neutralisation of high-pH waters

The management of alkaline (pH11-12.5) leachate is an important issue associated with the conditioning, afteruse or disposal of steel slags. Passive in-gassing of atmospheric CO₂ is a low cost option for reducing Ca(OH)₂ alkalinity, as Ca(OH)₂ is neutralised by carbonic acid to produce CaCO₃. The relative effectiveness of such treatment can be affected by both the system geometry (i.e. stepped cascades versus settlement ponds) and biological colonization. Sterilized mesocosm experiments run over periods of 20days showed that, due to more water mixing and enhanced CO₂ dissolution at the weirs, the cascade systems (pH11.2→9.6) are more effective than settlement ponds (pH11.2→11.0) for lowering leachate alkalinity in all the tested conditions. The presence of an active microbial biofilm resulted in significantly more pH reduction in ponds (pH11.2→9.5), but had a small impact on the cascade systems (pH11.2→9.4). The pH variation in biofilm colonized systems shows a diurnal cycle of 1 to 1.5pH units due to CO₂ uptake and release associated with respiration and photosynthesis. The results demonstrate that, where gradient permits, aeration via stepped cascades are the best option for neutralisation of steel slag leachates, and where feasible, the development of biofilm communities can also help reduce alkalinity.

The importance of greenspace for mental health

There is an urgent global need for accessible and cost-effective pro-mental health infrastructure. Public green spaces were officially designated in the 19th century, informed by a belief that they might provide health benefits. We outline modern research evidence that greenspace can play a pivotal role in population-level mental health.

Green Mind Theory: How Brain-Body-Behaviour Links into Natural and Social Environments for Healthy Habits

We propose a Green Mind Theory (GMT) to link the human mind with the brain and body, and connect the body into natural and social environments. The processes are reciprocal: environments shape bodies, brains, and minds; minds change body behaviours that shape the external environment. GMT offers routes to improved individual well-being whilst building towards greener economies. It builds upon research on green exercise and nature-based therapies, and draws on understanding derived from neuroscience and brain plasticity, spiritual and wisdom traditions, the lifeways of original cultures, and material consumption behaviours. We set out a simple metaphor for brain function: a bottom brain stem that is fast-acting, involuntary, impulsive, and the driver of fight and flight behaviours; a top brain cortex that is slower, voluntary, the centre for learning, and the driver of rest and digest. The bottom brain reacts before thought and directs the sympathetic nervous system. The top brain is calming, directing the parasympathetic nervous system. Here, we call the top brain blue and the bottom brain red; too much red brain is bad for health. In modern high-consumption economies, life has often come to be lived on red alert. An over-active red mode impacts the gastrointestinal, immune, cardiovascular, and endocrine systems. We develop our knowledge of nature-based interventions, and suggest a framework for the blue brain-red brain-green mind. We show how activities involving immersive-attention quieten internal chatter, how habits affect behaviours across the lifecourse, how long habits take to be formed and hard-wired into daily practice, the role of place making, and finally how green minds could foster prosocial and greener economies. We conclude with observations on twelve research priorities and health interventions, and ten calls to action.

Removal and recovery of vanadium from alkaline steel slag leachates with anion exchange resins

Leachable vanadium (V) from steel production residues poses a potential environmental hazard due to its mobility and toxicity under the highly alkaline pH conditions that characterise these leachates. This work aims to test the efficiency of anion exchange resins for vanadium removal and recovery from steel slag leachates at a representative average pH of 11.5. Kinetic studies were performed to understand the vanadium sorption process. The sorption kinetics were consistent with a pseudo-first order kinetic model. The isotherm data cannot differentiate between the Langmuir and Freundlich models. The maximum adsorption capacity (Langmuir value q_max) was 27 mg V g^-1 resin. In column anion exchange, breakthrough was only 14% of the influent concentration after passing 90 L of steel slag leachate with 2 mg L^-1 V through the column. When eluting the column 57-72% of vanadium was recovered from the resin with 2 M NaOH. Trials on the reuse of the anion exchange resin showed it could be reused 20 times without loss of efficacy, and on average 69% of V was recovered during regeneration. The results document for the first time the use of anion exchange resins to remove vanadium from steel slag leachate. As an environmental contaminant, removal of V from leachates may be an obligation for long-term management requirements of steel slag repositories. Vanadium removal coupled with the recovery can potentially be used to offset long-term legacy treatment costs.

Vanadium removal and recovery from bauxite residue leachates by ion exchange

Bauxite residue is an important by-product of the alumina industry, and current management practices do not allow their full valorisation, especially with regard to the recovery of critical metals. This work aims to test the efficiency of ion exchange resins for vanadium (V) removal and recovery from bauxite residue leachates at alkaline pH (11.5 and 13). As an environmental pollutant, removal of V from leachates may be an obligation of bauxite residue disposal areas (BRDA) long-term management requirements. Vanadium removal from the leachate can be coupled with the recovery, and potentially can be used to offset long-term legacy treatment costs in legacy sites. Kinetics studies were performed to understand the adsorption process. The rate kinetics for the V adsorption was consistent with the pseudo-first-order kinetic model, with a higher adsorption rate for pH 11.5 (1.2 min^-1). Adsorption isotherm data fitted better to Freundlich equations than to the Langmuir model. The maximum adsorption capacity (Langmuir value q _max) was greatest for pH 13 (9.8 mg V g^-1 resin). In column tests, breakthrough was reached at 70 bed volumes with the red mud leachate at pH 13, while no breakthrough was achieved with the effluent at pH 11.5. In regeneration, 42 and 76 % of V were eluted from the resin with 2 M NaOH from the red mud leachate at pH 13 and 11.5, respectively. Further optimization will be needed to upscale the treatment.

Effects of the Visual Exercise Environments on Cognitive Directed Attention, Energy Expenditure and Perceived Exertion

Green exercise research often reports psychological health outcomes without rigorously controlling exercise. This study examines effects of visual exercise environments on directed attention, perceived exertion and time to exhaustion, whilst measuring and controlling the exercise component. Participants completed three experimental conditions in a randomized counterbalanced order. Conditions varied by video content viewed (nature; built; control) during two consistently-ordered exercise bouts (Exercise 1: 60% VO2peakInt for 15-mins; Exercise 2: 85% VO2peakInt to voluntary exhaustion). In each condition, participants completed modified Backwards Digit Span tests (a measure of directed attention) pre- and post-Exercise 1. Energy expenditure, respiratory exchange ratio and perceived exertion were measured during both exercise bouts. Time to exhaustion in Exercise 2 was also recorded. There was a significant time by condition interaction for Backwards Digit Span scores (F2,22 = 6.267, p = 0.007). Scores significantly improved in the nature condition (p < 0.001) but did not in the built or control conditions. There were no significant differences between conditions for either perceived exertion or physiological measures during either Exercise 1 or Exercise 2, or for time to exhaustion in Exercise 2. This was the first study to demonstrate effects of controlled exercise conducted in different visual environments on post-exercise directed attention. Via psychological mechanisms alone, visual nature facilitates attention restoration during moderate-intensity exercise.

A comparison of four typical green exercise environments and prediction of psychological health outcomes

Aims:

‘Green exercise’ (GE) is physical activity while simultaneously being exposed to nature. GE comprises three physical components: the individual, the exercise and the environment, and one processes component encompassing a range of psychological and physiological processes. Previous research has consistently shown affective benefits of GE compared to equivalent non-GE. Investigating the possibility of optimum GE environments may help maximise health benefits. The aim of this study was to compare affective outcomes of GE participation between four different typical GE environments (beach, grasslands, riverside, heritage), and further examine influences of several physical component–related variables and one processes component–related variable, on these outcomes.

Method:

Participants ( N = 331) completed questionnaires before and after a 5km run, at one of four parkrun event locations.

Results:

Self-esteem (Δ = 1.61, 95% confidence interval (CI) = (1.30, 1.93)), stress (Δ = −2.36, 95% CI = (−3.01, −1.71)) and mood (Δ = −5.25, 95% CI = (−7.45, −3.05)) all significantly improved from pre- to post-run ( p < .05). Improvements in these measures were not significantly different between environments. Several component-related variables significantly predicted these improvements, accounting for 9% of self-esteem improvement, 1.6% of perceived stress improvement, and 9.5% of mood improvement.

Conclusion:

GE offers accessible provision for improving acute psychological wellbeing. Although nature-based exercise environments can facilitate affective outcomes, the overall type of nature may be less critical. Other characteristics of the individual, exercise and environment can significantly influence attainment of psychological GE benefits. However, the results support a greater importance of the processes component in attaining previously reported affective outcomes.

Mine water geochemistry and metal flux in a major historic Pb-Zn-F orefield, the Yorkshire Pennines, UK

Recent studies have shown up to 6 % of rivers in England and Wales to be impacted by discharges from abandoned metal mines. Despite the large extent of impacts, there are still many areas where mine water impact assessments are limited by data availability. This study provides an overview of water quality, trace element composition and flux arising from one such area; the Yorkshire Pennine Orefield in the UK. Mine drainage waters across the orefield are characterised by Ca-HCO3-SO4-type waters, with moderate mineralization (specific electrical conductance: 160-525 μS cm(-1)) and enrichment of dissolved Zn (≤2003 μg L(-1)), Ba (≤971 μg L(-1)), Pb (≤183 μg L(-1)) and Cd (≤12 μg L(-1)). The major ion composition of the waters reflects the Carboniferous gritstone and limestone-dominated country rock, the latter of which is heavily karstified in parts of the orefield, while sulphate and trace element enrichment is a product of the oxidation of galena, sphalerite and barite mineralization. Contaminant flux measurements at discharge sites highlight the disproportionate importance of large drainage levels across the region, which generally discharge into first-order headwater streams. Synoptic metal loading surveys undertaken in the Hebden Beck sub-catchment of the river Wharfe highlight the importance of major drainage levels to instream baseflow contamination, with diffuse sources from identifiable expanses of waste rock becoming increasingly prominent as river flows increase.

Testing benthic foraminiferal distributions as a contemporary quantitative approach to biomonitoring estuarine heavy metal pollution

Biomonitoring of estuarine pollution is the subject of active research, and benthic foraminifera are an attractive group to use for these purposes due to their ubiquitous presence in saline water and wide diversity. Here, we describe a case study of biomonitoring using benthic foraminifera in the French Mediterranean lagoon, Bages-Sigean lagoon. In this case, the major pollutants of interest are heavy metals in the sediment, particularly contaminated by Cu and Cd derived from industrial and agricultural sources. The foraminiferal assemblages of the Bages-Sigean lagoon are typical of normal paralic environments, but unusually almost completely lack agglutinated forms. The density of benthic foraminifera was shown to be more influenced by the sediment characteristics rather than heavy metal pollution. However, the relative abundance of Quinqueloculina bicostata was shown to increase in the most polluted areas and we propose that this taxon may be used as an indicator of heavy metal pollution.

Inventory management

A critical aspect of blood transfusion is the timely provision of high quality blood products. This task remains a significant challenge for many blood services and blood systems reflecting the difficulty of balancing the recruitment of sufficient donors, the optimal utilization of the donor's gift, the increasing safety related restrictions on blood donation, a growing menu of specialized blood products and an ever-growing imperative to increase the efficiency of blood product provision from a cost perspective. As our industry now faces questions about our standard practices including whether or not the age of blood has a negative impact on recipients, it is timely to take a look at our collective inventory management practices. This International Forum represents an effort to get a snap shot of inventory management practices around the world, and to understand the range of different products provided for patients. In addition to sharing current inventory management practices, this Forum is intended to foster an exchange of ideas around where we see our field moving with respect to various issues including specialty products, new technologies, and reducing recipient risk from blood transfusion products.

In vitro investigations of the impact of different temperature and flow velocity conditions on tufa microfabric

A series of experiments on freshwater carbonates (tufas) involving biofilm colonization in both fast-flow and slow-flow mesocosms was carried out in order to assess the changing nature of biofilm and associated precipitates under contrasting conditions. A thin biofilm developed over 14 weeks during the ‘summer’ experimental run contained a basal calcite layer overlain by small calcite crystals suspended within the Extracellular Polymeric Substances (EPS). The ‘autumn’ biofilm, however, showed the development of multi-laminated calcite precipitates within the EPS despite constant environmental conditions throughout the run. The experiments also showed that the largest volume of calcite precipitate developed in the fast-flow flumes regardless of temperature control. Development of an extensive calcite layer at the base of EPS in conditions of complete darkness within the sump was also observed. This study provides increased weight for the concepts: (1) that fresh- and saltwater stromatolites appear to be highly comparable multi-laminated systems with precipitation strongly influenced by both phototrophic and heterotrophic microbes; and (2) that microbial precipitation may be more common within aphotic (including cave, lake bottom and soil) systems than has previously been considered.

Microbial influence on macroenvironment chemical conditions in alkaline (tufa) streams: perspectives from in vitro experiments

Tufas represent a palaeoclimatic archive of potentially global significance. However, uncertainty remains over the exact process of calcite precipitation from these systems, inhibiting our ability to decipher the precise meaning of geochemical records. For example, field studies of alkaline stream systems are unable to disentangle the influence of temperature and photosynthesis on ambient hydrochemistry on diurnal and annual timescales. This report describes a series of flume experiments in which temperature and light conditions are manipulated separately. These experiments reveal that precipitation of calcite occurs preferentially under conditions of rising pH, and consequently at the night–day transition. The amplitude of diurnal changes is regulated by the buffering capacity (i.e. alkalinity) of the ambient water and by the daytime balance of photosynthesis and respiration. Respiration is shown to be strongly affected by temperature, whereas photosynthesis is found to be limited by nutrient and/or DIC availability making temperature impacts minor. Consequently, macroenvironment pH during both day and night-time tend to be higher under lower temperatures, in contrast to expectation. These observations may have potential implications for the isotopic geochemistry of tufa carbonate, promoting slightly lower δ18O, due to the carbonate ion effect, and more significantly negative δ13C, due to incorporation of respired CO2 accumulated during the night. The observation that long periods of daylight are not necessarily needed for photosynthetically induced precipitation to occur confirm previous arguments that seasonal lamination requires either strong variability in ambient physicochemical activity or an ecological change in the microbial assemblage, and cannot be ascribed to reduced temperature and light intensity.

A humid corridor across the Sahara for the migration of early modern humans out of Africa 120,000 years ago

It is widely accepted that modern humans originated in sub-Saharan Africa approximately 150-200 thousand years ago (ka), but their route of dispersal across the currently hyperarid Sahara remains controversial. Given that the first modern humans north of the Sahara are found in the Levant approximately 120-90 ka, northward dispersal likely occurred during a humid episode in the Sahara within Marine Isotope Stage (MIS) 5e (130-117 ka). The obvious dispersal route, the Nile, may be ruled out by notable differences between archaeological finds in the Nile Valley and the Levant at the critical time. Further west, space-born radar images reveal networks of-now buried-fossil river channels that extend across the desert to the Mediterranean coast, which represent alternative dispersal corridors. These corridors would explain scattered findings at desert oases of Middle Stone Age Aterian lithic industries with bifacial and tanged points that can be linked with industries further to the east and as far north as the Mediterranean coast. Here we present geochemical data that demonstrate that water in these fossil systems derived from the south during wet episodes in general, and penetrated all of the way to the Mediterranean during MIS 5e in particular. This proves the existence of an uninterrupted freshwater corridor across a currently hyperarid region of the Sahara at a key time for early modern human migrations to the north and out of Africa.

End-stage renal disease: factors affecting referral decisions by family physicians in Canada, the United States, and Britain

The objective of this study is to determine how patient age, sex, creatinine level, and comorbidity affect referral decisions for the treatment of end-stage renal disease (ESRD) and whether these decisions are affected by physician characteristics in three countries: Canada, the United States, and Britain. A vignette-based questionnaire was mailed to a random sample of family physicians in Ontario, Canada (1,818 physicians); all family physicians in the state of New York (1,814 physicians); and a sample of general practitioners from the south of England (2,228 physicians) in 1996. Physicians were presented with clinical scenarios involving a patient with varying degrees of renal insufficiency and a complicating comorbidity, including angina, diabetes, cancer, mental illness, or socioeconomic circumstances. They were asked to indicate the likelihood of referral. Half the physicians received a questionnaire describing a male patient, and half, a female patient. Mean creatinine levels at which physicians would refer were 260 micromol/L for British physicians, 297 micromol/L for Canadian physicians, and 340 micromol/L for American physicians. No difference in referral rates was found based on the sex of the patient or physician. Sixty-five percent of American and Canadian physicians would refer regardless of patient age, but only 49% of British physicians would do so. Family physicians in the United States, Canada, and Britain function as gatekeepers for patients with ESRD. They are less likely to refer based on increasing severity of comorbid conditions. They also discriminate based on age, but not sex.

Tissue distribution of lipogenesis in vivo in the common murre (Uria aalge) and the domestic chicken (Gallus domesticus)

1. Total body lipogenesis was similar in the murre and the chicken. 2. The liver contributes 10.4% to whole body lipogenesis in fed murres when measured in vivo using 3H2O. 3. The liver contributes 28.0% to whole body lipogenesis in the fed chicken. 4. The lower contribution of the liver in the murre may be a consequence of the high fat diet of the murre relative to the chicken.

The effect of dietary fish oil on muscle and adipose tissue lipoprotein lipase

The activity of lipoprotein lipase (LPL) in the adipose tissue and skeletal muscle of rats fed glucose- or fructose-based diets containing fish oil, corn oil or tallow was examined. In addition, heart LPL activity was measured in rats fed a glucose-based diet containing either corn oil or fish oil. Adipose tissue LPL activity was unaffected by dietary fat. In both heart and skeletal muscle, LPL activity was higher in rats fed the fish oil diet. These results suggest that increased removal of triglyceride by muscle may contribute to the blood triglyceride lowering effect of dietary fish oil.

Hepatic fatty acid synthesis and triglyceride secretion in rats fed fructose- or glucose-based diets containing corn oil, tallow or marine oil

The effects of three dietary fats, corn oil (CO), tallow (T) and marine oil (MO), on serum triglycerides, hepatic lipogenic enzyme activity and lipogenesis in vivo using 3H2O were measured in fed and fasted rats that had been consuming diets in which the carbohydrate was either glucose or fructose. Hepatic triglyceride secretion was also measured in fasted rats fed the same diets. In both the fed and fasted state, hepatic enzyme activity and lipogenesis in vivo were greater in fructose-fed rats than in glucose-fed rats and less in both CO- and MO-fed rats than in T-fed rats. In rats fed glucose, serum triglycerides were lower in fasted rats fed MO than in fasted rats fed CO. In rats fed glucose or fructose, hepatic triglyceride secretion was lower in rats fed MO than in those fed CO or T.

Gluconeogenesis in liver and kidney of common murre (Uria aalge)

Phosphoenolpyruvate carboxykinase (PEPCK) in murre liver occurs in both cytoplasmic and mitochondrial forms. During a 3-day fast, hepatic PEPCK increases from 9.1 U/g with 19% cytosolic to 12.2 U/g with 35% cytosolic. The increase in activity is due almost entirely to increased cytosolic activity. PEPCK in murre kidney was present only in the mitochondrial compartment. Gluconeogenesis in vitro was determined in both hepatocytes and kidney tubules isolated from 3-day-fasted murres. In hepatocytes, lactate was the best substrate, but both pyruvate and alanine were good gluconeogenic substrates. This observation is consistent with the existence of a cytosolic form of PEPCK. In the kidney, glycerol was the best substrate but was only slightly better than lactate. Alanine and pyruvate were not as effective as gluconeogenic precursors, presumably because of the lack of cytosolic PEPCK. We propose that the major site of gluconeogenesis from amino acids in the murre is the liver, since this is a much larger organ than the kidney and has a cytosolic form of PEPCK necessary for gluconeogenesis from oxidized substrates.

Interaction of dietary carbohydrate and fat in the regulation of hepatic and extrahepatic lipogenesis in the rat

1. In order to examine the interaction of dietary fat and carbohydrate in the regulation of lipid metabolism, we have studied hepatic and extrahepatic lipogenesis, and adipose tissue lipoprotein lipase (EC 3.1.1.34) in rats fed on one of the following diets: a fructose-based diet containing 0 (F0) or 150 g maize oil (F15)/kg, or a glucose-based diet containing 0 (G0) or 150 g maize oil (G15)/kg. 2. The rats were meal-fed on the diets for 2 weeks after which the activities of a number of hepatic 'lipogenic' enzymes were measured and the activity of epididymal-fat-pad lipoprotein lipase. The activities of the lipogenic enzymes were: F0 greater than G0 greater than G15 greater than F15. Lipoprotein lipase activity was F0 = G0 = F15 = G15. The percentage of total body fatty acid synthesis which occurred in the liver was F0 greater than G0 greater than F15 greater than G15. 3. We conclude that fructose-induced hypertriglyceridaemia is primarily a result of the increased hepatic synthesis rather than decreased adipose-tissue lipoprotein lipase activity.

Use of alcohol oxidase to measure the methanol produced during the hydrolysis of D- and L-methyl-3-hydroxybutyric acid

An enzymatic assay for the measurement of methanol has been developed. The assay uses alcohol oxidase and peroxidase coupled to the oxidation of 2,2'-azino-di-(3-ethyl)-benzthiazoline-6-sulfonic acid as the chromogen. The assay is linear up to 50 nmol of methanol in a 200-microliters sample and sensitive; 1.25 nmol of methanol in a 200-microliters sample can be measured. The assay is rapid and measurements can be made at any convenient time between 15 min and 4 h after initiation of the reaction. The assay shows highest activity with methanol but significant activity with other primary alcohols up to 1-butanol. Little activity is shown with secondary alcohols and diols. We have used this assay to follow the hydrolysis of the two isomers of the methyl ester of 3-hydroxybutyric acid.

Hepatic lipogenesis in young rats given proteins of different quality

The effect of feeding casein, lactalbumin, soya-bean protein, gluten or gelatin on hepatic lipogenesis and the levels of hepatic fatty acid synthetase (FAS), glucose-6-phosphate dehydrogenase (EC 1.1.1.49; G6PD), malic enzyme (EC 1.1.1.40; ME) ATP-citrate lyase (EC 4.1.3.8; CL), acetyl CoA carboxylase (EC 6.4.1.2; ACCx) and glucokinase (EC 2.7.1.2; GK) was examined in young growing rats. The total activities of ACCx, FAS, CL, GK, G6PD, GK, ME and fatty acid synthesis in vivo were positively correlated with protein quality. The specific activities of ACCx, FAS, CL, G6PD and fatty acid synthesis in vivo were positively correlated with protein quality. The specific activities of GK and ME were unrelated to protein quality. The results demonstrate a dissociation between ME and hepatic lipogenesis and suggest a role for the NADPH generated by ME which is not related to the needs of fatty acid synthesis.

Interaction of the level of dietary fat and type of carbohydrate in the regulation of hepatic lipogenesis in the mouse

We have studied hepatic and extrahepatic lipogenesis in mice fed diets containing 0, 5, 10, or 15% corn oil in which the carbohydrate was one of fructose, sucrose, glucose, or wheat starch. Meal-fed animals were trained to eat a quantity of food such that at a given level of fat ail animals consumed the same amount of carbohydrate. Fatty acids synthesis in vivo, acetyl CoA carboxylase, fatty acid synthetase, ATP citrate lyase, glucose-6-phosphate dehydrogenase, and malic enzyme were determined. At 0 and 5% corn oil the values generally decreased in the order fructose > sucrose > glucose > wheat starch. At 10 and 15% corn oil differences due to the type of carbohydrate were less pronounced. The effect of dietary carbohydrate on glucokinase activity followed the reverse pattern with the values decreasing in the order wheat starch > glucose > sucrose > fructose. The results obtained demonstrate that hepatic lipogenesis was increased in mice consuming fructose or sucrose independent of carbohydrate intake or the level of dietary fat. However, total capacity for lipogenesis was greater in glucose-fed mice than those consuming wheat starch, fructose, or sucrose. Regardless of the carbohydrate in the diet, as dietary fat increased all the lipogenic parameters measured declined.Increasing corn oil from 0 to 15% caused a greater change in lipogenic capacity than the change due to the various carbohydrates. The percentage of total synthesis which occurred in liver was greater in mice fed fructose or sucrose. This increased contribution by the liver was unaltered by dietary fat which may contribute to the hypertriglyceridemia in such animals. Compared with diets based on glucose or wheat starch, diets based on fructose or sucrose do not cause increased lipogenesis in meal-fed mice if the diets contain more than 30 calorie percent fat. Our results suggest that when diets contain fat a a level similar to that in North American diets, the effects of the type of dietary carbohydrate on lipogenesis are minimal.

The role of dietary protein in hepatic lipogenesis in the young rat

1. The effect of varying dietary levels of casein (40-140 g/kg) on hepatic lipogenesis and the levels of hepatic fatty acid synthetase (FAS), glucose-6-phosphate dehydrogenase (EC 1.1.1.49; G6PD), malic enzyme (EC 1.1.1.40; ME), citrate cleavage enzyme (EC 4.1.3.8; CCE), acetyl CoA carboxylase (EC 6.4.1.2; AcCx), glucokinase (EC 2.7.1.2; GK), and pyruvate dehydrogenase (PDH) was examined in young, growing rats. 2. The activities of AcCx, FAS, G6PD and in vivo fatty acid synthesis were generally found to increase with increased dietary protein. 3. The levels of GK and PDH were not related to dietary protein. 4. ME decreased with increasing dietary protein. 5. The results demonstrate a dissociation between hepatic fatty acid synthesis and ME and suggest that when rats consume low-protein diets the NADPH needed for fatty acid synthesis is generated primarily by ME but that as the level of dietary protein is increased the contribution of ME is reduced while that of the phosphogluconate pathway becomes more important.