Expression of SOD1 G93A or wild-type SOD1 in primary cultures of astrocytes down-regulates the glutamate transporter GLT-1: lack of involvement of oxidative stress

Glutamate excitotoxicity is implicated in the aetiology of amyotrophic lateral sclerosis (ALS) with impairment of glutamate transport into astrocytes a possible cause of glutamate-induced injury to motor neurons. It is possible that mutations of Cu/Zn superoxide dismutase (SOD1), responsible for about 20% of familial ALS, down-regulates glutamate transporters via oxidative stress. We transfected primary mouse astrocytes to investigate the effect of the FALS-linked mutant hSOD1(G93A) and wild-type SOD1 (hSOD1(wt)) on the glutamate uptake system. Using western blotting, immunocytochemistry and RT-PCR it was shown that expression of either hSOD1(G93A) or hSOD1(wt) in astrocytes produced down-regulation of the levels of a glutamate transporter GLT-1, without alterations in its mRNA level. hSOD1(G93A) or hSOD1(wt) expression caused a decrease of the monomeric form of GLT-1 without increasing oxidative multimers of GLT-1. The effects were selective to GLT-1, since another glutamate transporter GLAST protein and mRNA levels were not altered. Reflecting the decrease in GLT-1 protein, [H-3]D-aspartate uptake was reduced in cultures expressing hSOD1(G93A) or hSOD1(wt). The hSOD1-induced decline in GLT-1 protein and [H-3]D-aspartate uptake was not blocked by the antioxidant Trolox nor potentiated by antioxidant depletion using catalase and glutathione peroxidase inhibitors. Measurement of 2',7'-dichlorofluorescein (DCF)-induced fluorescence revealed that expression of hSOD1(G93A) or hSOD1(wt) in astrocytes does not lead to detectable increase of intracellular reactive oxygen species. This study suggests that levels of GLT-1 protein in astrocytes are reduced rapidly by overexpression of hSOD1, and is due to a property shared between the wild-type and G93A mutant form, but does not involve the production of intracellular oxidative stress.

Metabolism of the soyabean isoflavone glycoside genistin in vitro by human gut bacteria and the effect of prebiotics

The isoflavone genistein is found predominantly in soyabeans and is thought to possess various potent biological properties, including anticarcinogenic effects. Studies have shown that genistein is extensively degraded by the human gut microflora, presumably with a loss of its anti-carcinogenic action. The aim of the present study was to investigate the potential of a prebiotic to divert bacterial metabolism away from genistein breakdown: this may be of benefit to the host. Faecal samples were obtained from healthy volunteers and fermented in the presence of a source of soyabean isoflavones (Novasoy(TM) (10 g/l); ADM Neutraceuticals, Erith, Kent, UK). Bacterial genera of the human gut were enumerated using selective agars and genistein was quantified by HPLC. The experiment was repeated with the addition of glucose (10 g/l) or fructo-oligosaccharide (10 g/l; FOS) to the fermentation medium. The results showed most notably that counts of Bifidobacterium spp. and Lactobacillus spp. were significantly increased (P<0.05 and P<0.01 respectively) under steady-state conditions in the presence of FOS. Counts of Bacteroides spp. and Clostridium spp. were, however, both significantly reduced (P<0.05) during the fermentation. A decline in genistein concentration by about 52 and 56% over the 120h culture period was observed with the addition of glucose or FOS to the basal medium (P<0.01), compared with about 91% loss of genistein in the vessels containing Novasoy(TM) (ADM Neutraceuticals) only. Similar trends were obtained using a three-stage chemostat (gut model), in which once again the degradation of genistein was about 22% in vessel one, about 24% in vessel two and about 26% in vessel three in the presence of FOS, compared with a degradation of genistein of about 67% in vessel one, about 95% in vessel two and about 93% in vessel three in the gut model containing Novasoy(TM) (ADM Neutraceuticals) only. The present study has shown that the addition of excess substrate appeared to preserve genistein in vitro. In particular, the use of FOS not only augmented this effect, but also conferred an additional benefit in selectively increasing numbers of purportedly beneficial bacteria such as bifidobacteria and lactobacilli.

Description of a "Phoenix" phenomenon in the growth of Campylobacter jejuni at temperatures close to the minimum for growth

When Campylobacter jejuni cultures that had been grown in broth at 39degreesC were subcultured into fresh medium at 30degreesC, there was a transient period of growth followed by a decline in viable-cell numbers before growth resumed once more. We propose that this complex behavior is the net effect of the growth of inoculum cells followed by a loss of viability due to oxidative stress and the subsequent emergence of a spontaneously arising mutant population that takes over the culture.

Learning and memory in holocaust survivors with posttraumatic stress disorder

Background: Impairments in explicit memory have been observed in Holocaust survivors with posttraumatic stress disorder. Methods: To evaluate which memory components are preferentially affected, the California Verbal Learning Test was administered to Holocaust survivors with (n = 36) and without (n = 26) posttraumatic stress disorder, and subjects not exposed to the Holocaust (n = 40). Results: Posttraumatic stress disorder subjects showed impairments in learning and short-term and delayed retention compared to nonexposed subjects; survivors without posttraumatic stress disorder did not. Impairments in learning, but not retention, were retained after controlling fir intelligence quotient. Older age was associated with poorer learning and memory performance in the posttraumatic stress disorder group only. Conclusions: The most robust impairment observed in posttraumatic stress disorder was in verbal learning, which may be a risk factor for or consequence of chronic posttraumatic stress disorder. The negative association between performance and age may reflect accelerated cognitive decline in posttraumatic stress disorder.

Expression and regulation of 80K/MARCKS, a major substrate of protein kinase C, in the developing rat heart

Objective: Protein kinase C (PKC) plays a pivotal role in modulating the growth and differentiation of many cell types including the cardiac myocyte. However, little is known about molecules that act immediately downstream of PKC in the heart. In this study we have investigated the expression of 80K/MARCKS, a major PKC substrate, in whole ventricles and in cardiac myocytes from developing rat hearts. Methods: Poly A+ RNA was prepared from neonatal (2-day) and adult (42-day) cardiac myocytes and whole ventricular tissue and mRNA expression determined by reverse transcription-polymerase chain reaction (RT-PCR) using primers designed to identify a 420 bp fragment in the 80K/MARCKS gene. Protein extracts were prepared from either 2-day and 42-day cardiac myocytes or from whole ventricular tissue at 2, 5–11, 14, 17, 21, 28 and 42 days of age. Protein expression was determined by immunoblotting with an 80K/MARCKS antipeptide antibody and PKC activity was determined by measuring the amount of γ32P-ATP transferred to a specific peptide substrate. Results: RT-PCR analysis of 80K/MARCKS mRNA in neonatal (2-day) and adult (42-day) cardiac myocytes showed the expression of this gene in both cell types. Immunoblotting revealed maximum 80K/MARCKS protein expression in whole ventricular tissue at 5 days (a 75% increase above values at 2 days), followed by a transient decrease in expression during the 6–8-day period (61% of the protein expressed at 2 days for 8-day tissue) with levels returning to 5 day levels by 11 days of age. 80K/MARCKS protein was present in cardiac myocytes at 2 days of age whereas it was not detectable in adult cells. In addition, PKC activity levels increased to 160% of levels present at 2 days in 8-day-old ventricles with PKC activity levels returning to 5-day levels by 9 days of age. This was then followed by a steady decline in both 80K/MARCKS protein expression and PKC activity through to adulthood. Conclusions: Expression of the PKC substrate, 80K/MARCKS, in cardiac myocytes changes significantly during development and the transient loss of immunoreactive protein during the 6–8-day developmental period may reflect 80K/MARCKS phosphorylation and subsequent down-regulation as a result of the concomitant up-regulation of PKC activity at this time.

Mapping the human record in the British early Palaeolithic: evidence from the Solent River system

The lithic record from the Solent River and its tributaries is re-examined in the light of recent interpretations about the changing demography of Britain during the Lower and early Middle Palaeolithic. Existing models of the terrace stratigraphies in the Solent and its tributary areas are reviewed and the corresponding archaeological record (specifically handaxes) for each terrace is assessed to provide models for the relative changes in human occupation through time. The Bournemouth area is studied in detail to examine the effects of quarrying and urbanisation on collection history and on the biases it introduces to the record. In addition, the effects of reworking of artefacts from higher into lower terraces are assessed, and shown to be a significant problem. Although there is very little absolute dating available for the Solent area, a cautious interpretation of the results from these analyses would suggest a pre-Marine Isotope Stage (MIS) 12 date for the first appearance of humans, a peak in population between MIS 12 and 10, and a decline in population during MIS 9 and 8. Owing to poor contextual data and small sample sizes, it is not clear when Levallois technology was introduced. This record is compared and contrasted to that from the Thames Valley. It is suggested that changes in the palaeogeography of Britain, in particular land connections to the continent, might have contributed to differences in the archaeological records from the Solent and Thames regions.

Linking carbon and sulphur cycling during simulated drought cycles in peat from six sites across the UK

Water table draw-down is thought to increase peat decomposition and, therefore, DOC release. However, several studies have shown lower DOC concentrations during droughts relative to ‘normal’ periods with high water table. We carried out controlled incubation experiments at 10°C on 10x10 cm peat soil cores collected from six UK sites across a sulphur deposition gradient. Our aim was to quantify the balance between microbial consumption and chemical precipitation of DOC due to episodic acidification driven by sulphur redox reactions by comparing changes in soil water chemistry to microbial activity (i.e. soil respiration and trace gas fluxes). During dry periods, all sites showed a concurrent increase in SO4 and soil respiration and a decline in DOC. However, the magnitude of change in both DOC and SO4 varied considerably between sites according to historical sulphur deposition loads and the variation in acid/base chemistry.

De-agrarianization, re-agrarianization and local economic development: re-orientating livelihoods in African artisanal mining communities

This article contributes to the debate on livelihood diversification in rural sub-Saharan Africa, focusing specifically on the growing economic importance of artisanal and small-scale mining (ASM) in the region. The precipitous decline in the value of many export crops and the removal of subsidies on crucial inputs such as fertilizers have made smallholder production unviable, forcing many farmers to ‘branch out’ into non-farm activities to supplement their incomes. One of the more popular destinations for poor farmers is the low-tech ASM sector which, because of its low barriers to entry, has absorbed millions of rural Africans over the past two decades, the majority of whom are engaged in the extraction of near-surface mineral deposits located on concessions that have been demarcated to multinational corporations. The efforts made hitherto to control this illegal mining activity, both through force and regulation, however, have had little effect, forcing many of the region’s governments and private sector partners to ‘re-think’ their approaches. One strategy that has gained considerable attention throughout the region is intensified support for agrarian-orientated activities, many of which, despite the problems plaguing smallholder agricultural sector and challenges with making it more economically sustainable, are being lauded as appropriate ‘alternative’ sources of employment to artisanal mining. After examining where artisanal mining fits into the de-agrarianization ‘puzzle’ in sub-Saharan Africa, the article critiques the efficacy of ‘re-agrarianization’ as a strategy for addressing the region’s illegal mining problem. A case study of Ghana is used to shed further light on these issues.

The potential for bias in reporting of industry-sponsored clinical trials

Concerns about potentially misleading reporting of pharmaceutical industry research have surfaced many times. The potential for duality (and thereby conflict) of interest is only too clear when you consider the sums of money required for the discovery, development and commercialization of new medicines. As the ability of major, mid-size and small pharmaceutical companies to innovate has waned, as evidenced by the seemingly relentless decline in the numbers of new medicines approved by Food and Drug Administration and European Medicines Agency year-on-year, not only has the cost per new approved medicine risen: so too has the public and media concern about the extent to which the pharmaceutical industry is open and honest about the efficacy, safety and quality of the drugs we manufacture and sell. In 2005 an Editorial in Journal of the American Medical Association made clear that, so great was their concern about misleading reporting of industry-sponsored studies, henceforth no article would be published that was not also guaranteed by independent statistical analysis. We examine the precursors to this Editorial, as well as its immediate and lasting effects for statisticians, for the manner in which statistical analysis is carried out, and for the industry more generally.

Model inter-comparison between statistical and dynamic model assessments of the long-term stability of blanket peat in Great Britain (1940-2099)

We compared output from 3 dynamic process-based models (DMs: ECOSSE, MILLENNIA and the Durham Carbon Model) and 9 bioclimatic envelope models (BCEMs; including BBOG ensemble and PEATSTASH) ranging from simple threshold to semi-process-based models. Model simulations were run at 4 British peatland sites using historical climate data and climate projections under a medium (A1B) emissions scenario from the 11-RCM (regional climate model) ensemble underpinning UKCP09. The models showed that blanket peatlands are vulnerable to projected climate change; however, predictions varied between models as well as between sites. All BCEMs predicted a shift from presence to absence of a climate associated with blanket peat, where the sites with the lowest total annual precipitation were closest to the presence/absence threshold. DMs showed a more variable response. ECOSSE predicted a decline in net C sink and shift to net C source by the end of this century. The Durham Carbon Model predicted a smaller decline in the net C sink strength, but no shift to net C source. MILLENNIA predicted a slight overall increase in the net C sink. In contrast to the BCEM projections, the DMs predicted that the sites with coolest temperatures and greatest total annual precipitation showed the largest change in carbon sinks. In this model inter-comparison, the greatest variation in model output in response to climate change projections was not between the BCEMs and DMs but between the DMs themselves, because of different approaches to modelling soil organic matter pools and decomposition amongst other processes. The difference in the sign of the response has major implications for future climate feedbacks, climate policy and peatland management. Enhanced data collection, in particular monitoring peatland response to current change, would significantly improve model development and projections of future change.

Evidence that ice forms primarily in supercooled liquid clouds at temperatures > -27C

Using 4 years of radar and lidar observations of layer clouds from the Chilbolton Observatory in the UK, we show that almost all (95%) ice particles formed at temperatures >-20°C appear to originate from supercooled liquid clouds. At colder temperatures, there is a monotonic decline in the fraction of liquid-topped ice clouds: 50% at -27°C, falling to zero at -37°C (where homogeneous freezing of water droplets occurs). This strongly suggests that deposition nucleation plays a relatively minor role in the initiation of ice in mid-level clouds. It also means that the initial growth of the ice particles occurs predominantly within a liquid cloud, a situation which promotes rapid production of precipitation via the Bergeron-Findeison mechanism.

Local management and landscape drivers of pollination and biological control services in a Kenyan agro-ecosystem

Arthropods that have a direct impact on crop production (i.e. pests, natural enemies and pollinators) can be influenced by both local farm management and the context within which the fields occur in the wider landscape. However, the contributions and spatial scales at which these drivers operate and interact are not fully understood, particularly in the developing world. The impact of both local management and landscape context on insect pollinators and natural enemy communities and on their capacity to deliver related ecosystem services to an economically important tropical crop, pigeonpea was investigated. The study was conducted in nine paired farms across a gradient of increasing distance to semi-native vegetation in Kibwezi, Kenya. Results show that proximity of fields to semi-native habitats negatively affected pollinator and chewing insect abundance. Within fields, pesticide use was a key negative predictor of pollinator, pest and foliar active predator abundance. On the contrary, fertilizer application significantly enhanced pollinator and both chewing and sucking insect pest abundance. At a 1 km spatial scale of fields, there were significant negative effects of the number of semi-native habitat patches within fields dominated by mass flowering pigeonpea on pollinators abundance. For service provision, a significant decline in fruit set when insects were excluded from flowers was recorded. This study reveals the interconnections of pollinators, predators and pests with pigeonpea crop. For sustainable yields and to conserve high densities of both pollinators and predators of pests within pigeonpea landscapes, it is crucial to target the adoption of less disruptive farm management practices such as reducing pesticide and fertilizer inputs.

Causes of the rapid warming of the North Atlantic ocean in the mid-1990s

In the mid-1990s the subpolar gyre of the North Atlantic underwent a remarkable rapid warming, with sea surface temperatures increasing by around 1C in just 2 years. This rapid warming followed a prolonged positive phase of the North Atlantic Oscillation (NAO), but also coincided with an unusually negative NAO index in the winter of 1995/96. By comparing ocean analyses and carefully designed model experiments we show that this rapid warming can be understood as a delayed response to the prolonged positive phase of the NAO, and not simply an instantaneous response to the negative NAO index of 1995/96. Furthermore, we infer that the warming was partly caused by a surge, and subsequent decline, in the Meridional Overturning Circulation and northward heat transport of the Atlantic Ocean. Our results provide persuasive evidence of significant oceanic memory on multi-annual timescales, and are therefore encouraging for the prospects of developing skillful predictions.

Firm size and competition: a comparison of the housebuilding industries in Australia, the UK and the USA

Housebuilding is frequently viewed as an industry full of small firms. However, large firms exist in many countries. Here, a comparative analysis is made of the housebuilding industries in Australia, Britain and the USA. Housebuilding output is found to be much higher in Australia and the USA than in Britain when measured on a per capita basis. At the same time, the degree of market concentration in Australia and the USA is relatively low but in Britain it is far greater, with a few firms having quite substantial market shares. Investigation of the size distribution of the top 100 or so firms ranked by output also shows that the decline in firm size from the largest downwards is more rapid in Britain than elsewhere. The exceptionalism of the British case is put down to two principal reasons. First, the close proximity of Britain’s regions enables housebuilders to diversify successfully across different markets. The gains from such diversification are best achieved by large firms, because they can gain scale benefits in any particular market segment. Second, land shortages induced by a restrictive planning system encourage firms to takeover each other as a quick and beneficial means of acquiring land. The institutional rules of planning also make it difficult for new entrants to come in at the bottom end of the size hierarchy. In this way, concentration grows and a handful of large producers emerge. These conditions do not hold in the other two countries, so their industries are less concentrated. Given the degree of rivalry between firms over land purchases and takeovers, it is difficult to envisage them behaving in a long-term collusive manner, so that competition in British housebuilding is probably not unduly compromised by the exceptional degree of firm concentration. Reforms to lower the restrictions, improve the slow responsiveness and reduce the uncertainties associated with British planning systems’ role in housing supply are likely to greatly improve the ability of new firms to enter housebuilding and all firms’ abilities to increase output in response to rising housing demand. Such reforms would also probably lower overall housebuilding firm concentration over time.

Local space for local people? Trends in the provision and management of urban outdoor recreation in the UK

This paper examines the growing trend in the UK towards the effective privatisation of formerly public open space and the relationship of this trend to the recent shifts in public sector management. A case study of Reading, England, illustrates the growing cultural and spatial dysfunction, particularly in terms of the declining knowledge and use of the town's urban gardens by the local population. Where once the gardens were a focus of social activity, therefore, they are now a largely irrelevant site of urban decline. In contrast to central urban space, it is clear that other types of open space in other areas can still assume a significance in peoples' lives. In many cases the use of these areas illustrates a counter cultural position in which the consumerism of the city management is actively being resisted. The paper concludes that while there appear to be ways in which local space could be reclaimed for local people, the power to achieve this lies predominantly in the same hands as those responsible for appropriating central space to the imperative of the market in the first instance