bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of sugar cane policosanol on lipid profile in primary hypercholesterolemia
Authors: Francini‐Pesenti F. , Beltramolli D. , Dall'Acqua S. , Brocadello F.
Published: December 2007

Policosanol, a mixture of long‐chain aliphatic primary alcohols, is used as a cholesterol‐lowering supplement. The effectiveness of policosanol is still questionable. To determine the lipoprotein‐lowering effects of Cuban sugar cane‐derived policosanol a double‐blind, randomized, placebo controlled trial was performed. Sixty‐eight primary hypercholesterolemic subjects were enrolled and randomly assigned to the treatment or to the control group. The first group received sugar cane policosanol 20 mg daily for 8 weeks, while the control group was treated with placebo. All subjects followed a normocaloric diet. The content of policosanol in the supplement tablets was assessed by gas chromatography. A total of 32 subjects in the policosanol group and 31 subjects in the control group completed the study. Body mass index, total cholesterol, HDL‐cholesterol, LDL‐cholesterol and triglyceride plasma levels did not change significantly in either group. In conclusion, sugar cane policosanol at doses of 20 mg daily showed no lipid lowering effects in subjects with primary hypercholesterolemia. Copyright © 2007 John Wiley & Sons, Ltd.
Glycation inhibitory activity and the identification of an active compound in Plantago asiatica extract
Authors: Choi Soo‐Youn , Jung Sung‐Hoon , Lee Hyun‐Sun , Park Kwen‐Woo , Yun Bong‐Sik , Lee Kwang‐Won
Published: December 2007

The glycation reaction involves a series of non‐enzymatic reactions between the carbonyl group on reducing sugars and the amino group on proteins leading to the formation of advanced glycation end‐products (AGEs), which are acknowledged to be involved in the pathogenesis of diabetic and aging‐related complications. Consequently, the development of AGE inhibitors is considered to have therapeutic potential in patients with diabetes or age‐related diseases. The preliminary results showed that a methanol extract (PAE) of Plantago asiatica, which is traditionally used as a folk medicine in Asian countries to treat fever, cough, wound etc., had strong glycation inhibitory activity. The effects of the extract on AGE fluorescence were dose‐dependent, reaching 41% inhibition at 0.1 µg/mL of extract. The purified principle from PAE was identified as plantamajoside. As well as antioxidant activities, in vitro glycation inhibitory activities with 10 and 25 mm plantamajoside were higher than those with 10 and 25 mm aminoguanidine. The results demonstrate that PAE and plantamajoside had significant effects on in vitro AGE formation, and the glycation inhibitory activity and antioxidant activity of plantamajoside were comparable to those obtained using millimolar concentrations of the standard antiglycation agent aminoguanidine, and the antioxidant ascorbate, respectively. Copyright © 2007 John Wiley & Sons, Ltd.
Immunomodulatory activity of biopolymeric fraction BOS 2000 from Boswellia serrata
Authors: Khajuria Anamika , Gupta Amit , Suden Pankaj , Singh Surjeet , Malik Fayaz , Singh Jaswant , Gupta B. D. , Suri K. A. , Srinivas V. K. , Ella Krishna , Qazi G. N.
Published: December 2007

Oral administration of BOS 2000 (1–10 mg/kg) elicited a dose related increase in the delayed hypersensitivity reaction (early 24 h and delayed 48 h) in mice. It also stimulated the IgM and IgG titre expressed in the form of plaques (PFC) and complement fixing antibody titre. The concentration of cytokines (IL‐4, IFN‐γ and TNF‐α) in serum with respect to T cell interactions, i.e. (CD4/CD8) and the proliferation of lymphocytes were significantly increased at 10 mg/kg compared with the control. The results in these studies demonstrated the immunostimulatory effect of BOS 2000 in a dose‐dependent manner with respect to the macrophage activation possibly expressing the phagocytosis and nitrite production by the enhancement of TNF‐α and IFN‐γ production as a mode of action. Copyright © 2007 John Wiley & Sons, Ltd.
Estradiol‐antagonistic activity of phenolic compounds from leguminous plants
Authors: Pinto B. , Bertoli A. , Noccioli C. , Garritano S. , Reali D. , Pistelli L.
Published: December 2007

Natural flavonoids are currently receiving much attention because of their estrogenic and antiestrogenic properties. Six isoflavones (isoprunetin, isoprunetin 7‐O‐β‐d‐glucopyranoside, isoprunetin 4′,7‐di‐O‐β‐d‐glucopyranoside, genistein, genistein 7‐O‐β‐d‐glucopyranoside, daidzein), four flavones (luteolin, luteolin 7‐O‐β‐d‐glucopyranoside, luteolin 4′‐O‐β‐d‐glucopyranoside, licoflavone C), isolated from Genista morisii and G. ephedroides (two Leguminosae plants of the Mediterranean area) together with two structurally related pterocarpans, bitucarpin A and erybraedyn C, isolated from Bituminaria bituminosa (Leguminosae), were tested for the antagonist activity by a yeast based estrogen receptor assay (Saccharomyces cerevisiae RMY326 ER‐ERE). Most compounds inhibited the estradiol‐induced transcriptional activity in a concentration dependent manner. In particular, for the flavone luteolin 77% inhibition of the induced β‐galactosidase activity was observed. Interestingly, licoflavone C exhibited a dose‐dependent antagonistic activity at concentrations up to 10−4 m, but stimulated β‐galactosidase expression at higher concentrations resulting in a U‐shaped‐like dose‐response curve. Copyright © 2007 John Wiley & Sons, Ltd.
In vitro antioxidant, antimutagenic and genoprotective activity of Rosa roxburghii fruit extract
Authors: van der Westhuizen Francois H. , van Rensburg Catharina S. Janse , Rautenbach George S. , Marnewick Jeanine L. , Loots Du Toit , Huysamen Cristal , Louw Roan , Pretorius Pieter J. , Erasmus Elardus
Published: December 2007

The antioxidant properties of the fruit of the Rosa roxburghii (RR) plant have been associated with several putative health promoting effects. The possible cytotoxic, mutagenic/antimutagenic and genotoxic effects of RR fruit extract were investigated. The effect on antioxidant status and protection against induced oxidative stress were also investigated using primary rat hepatocytes. A RR fruit extract containing 45 g/L total ascorbic acid and 65 g/L total polyphenols was used in this study. Dilutions up to 0.08% (v/v) increased significantly the antioxidant status in primary rat hepatocytes. The glutathione redox state was decreased with RR treatment but was increased in Chang liver cells and MT‐2 lymphoblast. No cyto‐ or genotoxicity were observed at levels of up to 5% (v/v) of the fruit extract. In addition, a significant protection against t‐BHP induced oxidative stress was observed in primary rat hepatocytes. The Ames test revealed no mutagenic activity using the Salmonella typhimurium strains TA98, TA100 and TA102. A significant antimutagenic effect of the extract was observed against the metabolic activated mutagens 2‐acetylaminofluorene and aflatoxin B1 and to a lesser extent against methyl methanesulfonate. It is concluded that these results support the associated health promoting potential of Rosa Roxburghii fruit and in particular against oxidative stress. Copyright © 2007 John Wiley & Sons, Ltd.
Antimutagenic in vitro activity of plant polyphenols: Pycnogenol® and Ginkgo biloba extract (EGb 761)
Authors: Križková Lívia , Chovanová Zuzana , Ďuračková Zdenka , Krajčovič Juraj
Published: December 2007

Ofloxacin (15 µg/mL) and acridine orange (5 µg/mL) induce mutagenicity by different mechanisms in the photosynthetic flagellate Euglena gracilis. The present study examined whether Pycnogenol® (PYC; 5–100 µg/mL) or Ginkgo biloba extract (EGb 761; 5–100 µg/mL) could protect against the mutagenic effects of each of the mutagens and the potential mechanisms underlying such protection. The highest concentration of PYC and EGb 761 effectively reduced the mutagenic activity of both ofloxacin and acridine orange by more than 99% (p < 0.001). Using luminol‐dependent photochemical methodology it was demonstrated that EGb 761 and PYC were effective antioxidants. In addition, as determined by spectrophotometry, PYC and EGb 761 bound acridine orange. Both PYC and EGb 761 have been shown to produce dual antimutagenic effects, as evidenced by both antioxidant and physicochemical properties. The findings suggest that EGb 761 and PYC would thus be suitable for future study, not only as antioxidants, but also as antimutagenic agents. Copyright © 2007 John Wiley & Sons, Ltd.
Antileishmanial activity of piceatannol isolated from Euphorbia lagascae seeds
Authors: Duarte Noélia , Kayser Oliver , Abreu Pedro , Ferreira Maria‐José U.
Published: December 2007

In the search for biologically active compounds from Euphorbia lagascae Spreng, an herbaceous plant native to southeast of Iberic Peninsula, a stilbene, two coumarins and two 12‐deoxyphorbol diterpene esters were isolated by chromatographic methods, from the methanol extracts of its defatted seeds. The structures of these compounds were elucidated by a combination of physical and spectral data (IR, MS and high‐resolution 1H‐NMR and 13C‐NMR spectroscopy utilizing COSY, HMBC, HMQC and NOESY experiments). The stilbene, piceatannol, was screened for its antileishmanial activity against promastigotes as an extracellular form of Leishmania donovani, Leishmania infantum and Leishmania major, and amastigotes of Leishmania donovani as an intracellular form. Pentostan® (sodium stibogluconate), the first line clinical drug, was used as a standard reference. Piceatannol was moderately active against the extracellular forms of the three tested Leishmania species, and more active than the reference compound against the intracellular form of Leishmania donovani. Copyright © 2007 John Wiley & Sons, Ltd.
The inhibitory effects of naringin on the growth of periodontal pathogens in vitro
Authors: Tsui V. W. K. , Wong R. W. K. , Rabie A‐Bakr M.
Published: December 2007

Naringin is a flavonoid that is commonly found in grapefruits. The objective of this study was to evaluate the effects of naringin on the growth of periodontal pathogens such as A. actinomycetemcomitans and P. gingivalis in vitro. For comparison, the effects of naringin on several oral microbes were also studied.

Different concentrations of naringin solution were added to calibrated suspensions of A. actinomycetemcomitans and P. gingivalis. All the suspensions were incubated for 3, 6 and 24 h in an anaerobic chamber at 37 °C. At each time point, selected dilutions from each culture broth were plated on blood agar plates. Colonies recovered on blood agar were visually counted on days 3 and 5, respectively.

A. actinomycetemcomitans showed a significant decrease (p < 0.05) in viable counts after 3 h when naringin was added at baseline. P. gingivalis also showed a marked growth reduction in the presence of naringin, and no colony forming units could be observed after 24 h. Naringin also had an inhibitory effect against all bacteria and yeasts tested.

The results suggest that naringin possesses significant antimicrobial properties on periodontal pathogens in vitro. It also has an inhibitory effect on some common oral microorganisms in low concentrations. Copyright © 2007 John Wiley & Sons, Ltd.
Growth inhibition and induction of apoptosis in human oral squamous cell carcinoma Tca‐8113 cell lines by shikonin was partly through the inactivation of NF‐κB pathway
Authors: Ruan Min , Ji Tong , Yang Wenjun , Duan Wenhu , Zhou Xiaojian , He Jiacai , Zhou Jian , Chen Wantao , Zhang Chenping
Published: December 2007

Shikonin, a naphthoquinone pigment isolated from the Chinese herbal therapeutic, Zicao, has been shown to exhibit antioxidant and anticancer effects. In this study, its ability to induce apoptosis in cultured Tca‐8113 oral cancer cells was studied. Treatment of the Tca‐8113 cells with a variety of concentrations of Shikonin (10–40 µm) resulted in dose‐ and time‐dependent sequences of events marked by apoptosis, as shown by the loss of cell viability, chromatin condensation, internucleosomal DNA fragmentation and sub‐G1 phase accumulation. Furthermore, apoptosis in the Tca‐8113 cells was accompanied by the activation of protease caspase‐8, ‐9, ‐3 and low expression of Bcl‐2 protein. Interestingly, inactivation of the NF‐κB pathway was found in shikonin‐induced apoptosis in Tca‐8113 cells. These results raise the possibility that the anti‐tumor effects of Shikonin in Tca‐8113 cells are at least partly through the inactivation of the NF‐κB pathway and subsequent activation of protease caspase family. Pharmacological inhibition of the NF‐κB activity by Shikonin might be a powerful treatment option for OSCC in which activation of NF‐κB plays a critical role in tumor growth and progression. Copyright © 2007 John Wiley & Sons, Ltd.
Validation of therapeutic claims of Tinospora cordifolia: a review
Authors: Panchabhai T. S. , Kulkarni U. P. , Rege N. N.
Published: December 2007

This review article attempts to correlate Ayurvedic pharmacology and therapeutic claims for Tinospora cordifolia (Tc) with the evidence generated using scientific research methodology. In the present paper, a brief description of Ayurvedic pharmacology of the plant is presented. The work carried out by researchers using extracts of Tc in various areas such as diabetes, liver damage, free radical mediated injury, infections, stress and cancer have been reviewed. Also discussed are the immunomodulatory, diuretic, antiinflammatory, analgesic, anticholinesterase and gastrointestinal protective effects. An attempt has been made to provide the readers with the array of outcome variables, which can be further worked upon in clinical studies. Finally, this paper puts forth issues that need to be addressed by researchers in the future. Copyright © 2007 John Wiley & Sons, Ltd.
Coping with hydrogeomorphic variations in a prairie river: resiliency in young‐of‐the‐year fishes
Authors: Moore S. L. , Thorp J. H.
Published: December 2007

Young‐of‐the‐year (YOY) fish in sand‐bed rivers of grassland ecoregions frequently encounter dynamic habitat conditions produced by highly variable flow and resulting changes in geomorphic complexity of the river. How these vulnerable life history stages cope with changes in habitat condition and location is largely unknown. Therefore, we examined biodiversity and abundance of YOY fish (larvae and juveniles) at two spatiotemporal scales in response to dynamic flow conditions in the Kansas River. During the summer of 2004, we collected and identified 13 745 YOY fish from various moderate to zero‐flow habitats. Patterns of community structure through time were compared with the river's hydrogeomorphic characteristics, as determined by aerial photographs and measurements of instream flow rate and other water quality characteristics.

Our initial hypothesis was that species richness and total YOY abundance would be maximized in larger and longer‐lived slackwater habitats. In contrast, our data suggest that dominant fishes in these highly dynamic ecosystems have adapted to hydrological variations with a more generalist lifestyle by either: (i) temporarily using higher flow habitats (except possibly the thalweg) to cope with intermittent loss of prime habitat; or (ii) extending spawning through favourable and demanding conditions. In contrast to current theories, our results suggest that conditions for YOY success are optimized in dynamic prairie rivers during the intermediate flows that maximize habitat heterogeneity and availability. Copyright © 2007 John Wiley & Sons, Ltd.
Effects of grade control structures on the macroinvertebrate assemblage of an agriculturally impacted stream
Authors: Litvan M. E. , Stewart T. W. , Pierce C. L. , Larson C. J.
Published: December 2007

Nearly 400 rock rip‐rap grade control structures (hereafter GCS) were recently placed in streams of western Iowa, USA to reduce streambank erosion and protect bridge infrastructure and farmland. In this region, streams are characterized by channelized reaches, highly incised banks and silt and sand substrates that normally support low macroinvertebrate abundance and diversity. Therefore, GCS composed of rip‐rap provide the majority of coarse substrate habitat for benthic macroinvertebrates in these streams. We sampled 20 sites on Walnut Creek, Montgomery County, Iowa to quantify macroinvertebrate assemblage characteristics (1) on GCS rip‐rap and at sites located (2) 5–50 m upstream of GCS, (3) 5–50 m downstream of GCS and (4) at least 1 km from any GCS (five sites each). Macroinvertebrate biomass, numerical densities and diversity were greatest at sites with coarse substrates, including GCS sites and one natural riffle site and relatively low at remaining sites with soft substrates. Densities of macroinvertebrates in the orders Ephemeroptera, Trichoptera, Diptera, Coleoptera and Acariformes were abundant on GCS rip‐rap. Increases in macroinvertebrate biomass, density and diversity at GCS may improve local efficiency of breakdown of organic matter and nutrient and energy flow, and provide enhanced food resources for aquatic vertebrates. However, lack of positive macroinvertebrate responses immediately upstream and downstream of GCS suggest that positive effects might be restricted to the small areas of streambed covered by GCS. Improved understanding of GCS effects at both local and ecosystem scales is essential for stream management when these structures are present. Copyright © 2007 John Wiley & Sons, Ltd.
A combined organic‐inorganic sea‐spray source function
Authors: O'Dowd Colin D. , Langmann Baerbel , Varghese Saji , Scannell Claire , Ceburnis Darius , Facchini Maria Cristina
Published: December 2007

This study presents a novel approach to develop a combined organic‐inorganic sub‐micron sea‐spray source function for inclusion in large‐scale models. It requires wind speed and surface ocean chlorophyll‐a concentration as input parameters. The combined organic‐inorganic source function is implemented in the REMOTE regional climate model and sea‐spray fields are predicted with particular focus on the North East Atlantic. The model predictions using the new source functions compare well with observations of total sea‐spray mass and organic carbon fraction in sea‐spray aerosol. During winter (periods of low oceanic biological activity), sea‐salt dominates the sea‐spray mass while in summer (when biological activity is high), water soluble organic carbon contributes between 60–90% of the submicron sea‐spray mass.
A new, global, multi‐annual (2000–2007) burnt area product at 1 km resolution
Authors: Tansey Kevin , Grégoire Jean‐Marie , Defourny Pierre , Leigh Roland , Pekel Jean‐François , van Bogaert Eric , Bartholomé Etienne
Published: December 2007

This paper reports on the development and validation of a new, global, burnt area product. Burnt areas are reported at a resolution of 1 km for seven fire years (2000 to 2007). A modified version of a Global Burnt Area (GBA) 2000 algorithm is used to compute global burnt area. The total area burnt each year (2000–2007) is estimated to be between 3.5 million km2 and 4.5 million km2. The total amount of vegetation burnt by cover type according to the Global Land Cover (GLC) 2000 product is reported. Validation was undertaken using 72 Landsat TM scenes was undertaken. Correlation statistics between estimated burnt areas are reported for major vegetation types. The accuracy of this new global data set depends on vegetation type.
Interface locking along the subduction megathrust from b‐value mapping near Nicoya Peninsula, Costa Rica
Authors: Ghosh Abhijit , Newman Andrew V. , Thomas Amanda M. , Farmer Grant T.
Published: December 2007

To understand controlling factors for seismogenesis and strain‐accumulation in subduction megathrusts we examine seismicity patterns across Nicoya, Costa Rica, to determine the overall and spatial variability in the earthquake frequency‐magnitude distribution along the interface. The mean reduction in earthquake activity with magnitude, b‐value, is higher (1.06) than global subduction zone averages (0.6–0.8), suggesting the interface here is weakly coupled. Strong spatial variations in b are anticorrelated (−0.53) with geodetic estimates of interface locking of E. Norabuena et al. (2004). High b prevails in two regions, including the subducted Fisher seamount chain. A broad zone of reduced b is observed at and offshore the central Nicoya coast; extending towards an imaged locked patch. These results suggest b‐value studies may be useful in identifying regions of increased interface locking in subduction zones, which may indicate regions capable of large slip in future large earthquakes.
Velocity contrast along the Calaveras fault from analysis of fault zone head waves generated by repeating earthquakes
Authors: Zhao Peng , Peng Zhigang
Published: December 2007

We systematically investigate the velocity contrast along the Calaveras fault that ruptured during the 1984 Morgan Hill earthquake using fault zone head waves (FZHW) that refract along the fault interface. We stack waveforms in 353 sets of repeating clusters, and align the peaks or troughs of the direct P waves assuming right‐lateral strike‐slip focal mechanisms. The obtained velocity contrasts are 2–3% and 12–14% NW and SE of station CCO, respectively. The FZHW and the fault plane outlined by the relocated seismicity SE of CCO are more complicated than those NW of CCO. The results can be explained by a relatively simple and sharp fault interface in the NW, and a complicated fault structure with a presence of a low‐velocity zone in the SE. The along‐strike variations in the strength of the velocity contrast are consistent with surface geological mapping and recent 3D tomography studies in this region.
Integrated impact of tropical cyclones on sea surface chlorophyll in the North Atlantic
Authors: Hanshaw Maiana N. , Lozier M. Susan , Palter Jaime B.
Published: December 2007

Past studies have shown that surface chlorophyll‐a concentrations increase in the wake of hurricanes. Given the reported increase in the intensity of North Atlantic hurricanes in recent years, increasing chlorophyll‐a concentrations, perhaps an indication of increasing biological productivity, would be an expected consequence. However, in order to understand the impact of variable hurricane activity on ocean biology, the magnitude of the hurricane‐induced chlorophyll increase relative to other events that stir or mix the upper ocean must be assessed. This study investigates the upper ocean biological response to tropical cyclones in the North Atlantic from 1997–2005. Specifically, we quantitatively compare the anomalous chlorophyll‐a concentrations created by cyclone activity to the total distribution of anomalies in the subtropical waters. We show that the cyclone‐induced chlorophyll‐a increase has minimal impact on the integrated biomass budget, a result that holds even when taking into consideration the lagged and asymmetrical response of ocean color.
Glacial cycles and carbon dioxide: A conceptual model
Authors: Hogg Andrew McC.
Published: December 2007

The correlation between Antarctic temperature and atmospheric carbon dioxide concentration is a key feature of Quaternary climate cycles. The cycle is characterised by pronounced temporal asymmetry; with rapid increase in both temperature and CO2 at the glacial termination. Here I compare observed climate cycles with results from a simple model which predicts the evolution of global temperature and carbon dioxide over the glacial‐interglacial cycle. The model includes a term which parameterises deep ocean release of CO2 in response to warming, and thereby amplifies the glacial cycle. In this model, temperature rises lead CO2 increases at the glacial termination, but it is the feedback between these two quantities that drives the abrupt warming during the transition from glacial to interglacial periods.
Forward modeling of ice topography on Mars to infer basal shear stress conditions
Authors: Banks M. E. , Pelletier J. D.
Published: December 2007

Understanding the history of ice caps on Mars could reveal important information about Martian geologic and climatic history. To do this, an ice reconstruction model is needed that operates over complex topography and can be constrained with a limited number of free parameters. In this study we developed a threshold‐sliding model for ice cap morphology based on the classic model of Nye later incorporated into the models of Reeh and colleagues. We have updated the Nye‐Reeh model with a new numerical algorithm. Although the model was originally developed to model perfectly plastic deformation, it is applicable to any ice body that deforms when a threshold basal shear stress is exceeded. The model requires three inputs: a digital elevation model of bed topography, a “mask” grid that defines the position of the ice terminus, and a function defining the threshold basal shear stress. To test the robustness of the model, the morphology of the Greenland ice sheet is reconstructed using an empirical equation between threshold basal shear stress and ice surface slope. The model is then used to reconstruct the morphology of ice draping impact craters on the margins of the south polar layered deposits using an inferred constant basal shear stress of ∼0.6 bar for the majority of the examples. This inferred basal shear stress value is almost 1/3 of the average basal shear stress calculated for the Greenland ice sheet. What causes this lower basal shear stress value on Mars is unclear but could involve the strain‐weakening behavior of ice.
Applying Bayesian Maximum Entropy to extrapolating local‐scale water consumption in Maricopa County, Arizona
Authors: Lee Seung‐Jae , Wentz Elizabeth A.
Published: December 2007

Understanding water use in the context of urban growth and climate variability requires an accurate representation of regional water use. It is challenging, however, because water use data are often unavailable, and when they are available, they are geographically aggregated to protect the identity of individuals. The present paper aims to map local‐scale estimates of water use in Maricopa County, Arizona, on the basis of data aggregated to census tracts and measured only in the City of Phoenix. To complete our research goals we describe two types of data uncertainty sources (i.e., extrapolation and downscaling processes) and then generate data that account for the uncertainty sources (i.e., soft data). Our results ascertain that the Bayesian Maximum Entropy (BME) mapping method of modern geostatistics is a theoretically sound approach for assimilating the soft data into mapping processes. Our results lead to increased mapping accuracy over classical geostatistics, which does not account for the soft data. The confirmed BME maps therefore provide useful knowledge on local water use variability in the whole county that is further applied to the understanding of causal factors of urban water demand.
Petro-Insurgency or Criminal Syndicate? Conflict & Violence in the Niger Delta
Authors: Watts Michael
Published: December 2007

The volatility of world oil markets, and the grumbling of American consumers over rising gas and heating oil prices over the last year, has highlighted a number of key trends in world oil markets: the rapidly growing demand for oil by China and India, the questionable status of some of the mega-oilfields in the Gulf, the aggressive nationalism of Hugo Chavez in Venezuela and President Ahmadinejad in Iran, and not least the spill-over effects of the Iraqi insurgency across the Gulf. But there has been another presence contributing to this volatility, namely the deepening conflicts across, indeed the increasing ungovernability of the oil fields of the Niger Delta in Nigeria. A spectacular escalation in violent attacks on oil installations and abduction of oil workers beginning in December 2005 and January-February 2006 by a shadowy and largely unknown militant group MEND (the Movement for the Emancipation of the Niger Delta), have thrown into dramatic relief the enormous fragility of the Nigeria's oil economy. Among MEND's demands were the release of two key Ijaw leaders but as their operations became more brazen and daring so did their political demands. MEND claimed a goal of cutting Nigerian output by 30 per cent. Within the first three months of 2006, $1 billion in oil revenues had been lost and over 29 Nigerian military had been killed in the uprising. By early July 2007, 700,000 barrels per day were shut (deferred) by growing political instability and insurgent attacks. The situation across the oilfields is now as fraught as at any time since the onset of civil war in 1967. How did this instability and political order arise and does it reflect, as some have suggested, an oil insurgency draped in the garb of organised crime?
South Africa: The End of Apartheid & the Emergence of the ‘BEE Elite’
Authors: Freund Bill
Published: December 2007

Recent South African policy making at the highest level has used the language of the developmental state. It has been used as a means of understanding and defining the purpose of ANC government. This article interrogates that concept, especially using the formation of an elite transcending the publicprivate sector divide and considering the concept of an ‘embedded elite’. In this light, the evolution of Black Economic Empowerment (BEE) policies are drawn out and specific comparisons made between South Africa and Malaysia. While creating an elite may involve enriching a small number of black ANC supporters, it is probably a necessity given the propensities of what remains of the established ‘embedded elites’ of the past. It is questionable however, whether this new elite has the sense of direction in pursuit of an industrialising economic model or a broad social model to carry through envisioned changes. Nor are its instincts necessarily democratic. While under the direction of the ANC the South African social structure is shifting in important ways and different sectors of the black population clearly benefit, the majority are not actively involved in a process of transformation that would offer the possibility of radical improvements.
Between Socialism & Neo-Liberalism: Mafia Island, Tanzania, 1965-2004
Authors: Caplan Pat
Published: December 2007

This article considers local perceptions of changes which have taken place on Mafia Island, Coast Region, Tanzania over a period of 40 years during which the state has moved from a policy of socialism to one of neo-liberalism. It begins by examining the apparent paradox that, while Tanzania has won plaudits from multilateral agencies for its economic policies, many ordinary people on Mafia consider that their well-being has actually worsened. The paper examines people's perceptions of equality, inequality and poverty, with particular emphasis on the comparisons made between previous eras and the present, and between themselves and various others, as well as their views of their entitlements both as citizens and human beings.
Filling in the Blanks: The Potency of Fragmented Imageries of the State
Authors: Nielsen Morten
Published: December 2007

Recent neo-patrimonial approaches to the state see the sub-Saharan state as a façade that serves – with different degrees of effectiveness – to disguise the play of clientalistic relations and the interests of kin and kith. Drawing on an analysis of how ideas are reproduced in peri-urban areas of Maputo, Mozambique, this article argues that no pre-given causality exists between encounters with a dysfunctional state apparatus and subjectively held understandings of ordinary people. We cannot a priori determine that incoherent and partial state practices necessarily lead individuals to perceive the state as devoid of legitimate moral value. On the contrary, locally situated individuals use ideas associated with the state to define entitlements and create standards for evaluating state-defined programmes or international donor-driven initiatives. Ideas of the state can thus be a basis for social action; even when the reality of state dysfunction is widely accepted, ‘ordinary people’ continue to invest themselves in these ideas.
Debates
Authors: Mittelman James
                      H.
Published: December 2007

The following remarks were delivered at a plenary session on 19 October 2007 in New York City at the 50th meeting of the African Studies Association. This was, for an ASA, an extremely animated plenary attended by over 400. The question and answer session that followed indicated the huge concern of all those present.

For instance, one suggested that the ‘US is not interested in development or democracy; it is focused only on the“war on terror“ and placing the Bureau of Homeland Security into as many states in Africa as possible’.

Another suggested that ‘the trend in Africa is militarising the continenet, creating terror in order to have a “war on terror“ and suggested that the US was establishing military bases across the continent – a discussion we've had here in the pages of ROAPE about the use of language, i.e. when is a base not a base? when it's a facility run by privatised military or Bureau of Homeland Security.

ROAPE asked the plenary partcipants to rise to the challenge once again and put pen to paper; they were given a very short time to do this. Mahmood Mamdani was not well afterwards and wasn't able to contribute in time and the US Ambassador to the AU, Cindy Courville, had at first agreed but then withdrew at the last moment.
Anthony Hyman: From unlikely scientist to Royal Society Fellow
Authors: Williams Ruth
Published: December 2007

Hyman tinkers with cellular machines in his Dresden workshop
Retinoblastoma tumor suppressor protein–dependent methylation of histone H3 lysine 27 is associated with irreversible cell cycle exit
Authors: Blais Alexandre , van Oevelen Chris J.C. , Margueron Raphaël , Acosta-Alvear Diego , Dynlacht Brian David
Published: December 2007

The retinoblastoma tumor suppressor protein (pRb) is involved in mitotic exit, promoting the arrest of myoblasts, and myogenic differentiation. However, it is unclear how permanent cell cycle exit is maintained in differentiated muscle. Using RNA interference, expression profiling, and chromatin immunoprecipitations, we show that pRb is essential for cell cycle exit and the differentiation of myoblasts and is also uniquely required to maintain this arrest in myotubes. Remarkably, we also uncover a function for the pRb-related proteins p107 and p130 as enforcers of a G2/M phase checkpoint that prevents progression into mitosis in cells that have lost pRb. We further demonstrate that pRb effects permanent cell cycle exit in part by maintaining trimethylation of histone H3 lysine 27 (H3K27) on cell cycle genes. H3K27 trimethylation silences other genes, including Cyclin D1, in a pRb-independent but polycomb-dependent manner. Thus, our data distinguish two distinct chromatin-based regulatory mechanisms that lead to terminal differentiation.
DIAP2 functions as a mechanism-based regulator of drICE that contributes to the caspase activity threshold in living cells
Authors: Ribeiro Paulo S. , Kuranaga Erina , Tenev Tencho , Leulier François , Miura Masayuki , Meier Pascal
Published: December 2007

In addition to their well-known function in apoptosis, caspases are also important in several nonapoptotic processes. How caspase activity is restrained and shut down under such nonapoptotic conditions remains unknown. Here, we show that Drosophila melanogaster inhibitor of apoptosis protein 2 (DIAP2) controls the level of caspase activity in living cells. Animals that lack DIAP2 have higher levels of drICE activity. Although diap2-deficient cells remain viable, they are sensitized to apoptosis following treatment with sublethal doses of x-ray irradiation. We find that DIAP2 regulates the effector caspase drICE through a mechanism that resembles the one of the caspase inhibitor p35. As for p35, cleavage of DIAP2 is required for caspase inhibition. Our data suggest that DIAP2 forms a covalent adduct with the catalytic machinery of drICE. In addition, DIAP2 also requires a functional RING finger domain to block cell death and target drICE for ubiquitylation. Because DIAP2 efficiently interacts with drICE, our data suggest that DIAP2 controls drICE in its apoptotic and nonapoptotic roles.
Real-time imaging reveals that noninvasive mammary epithelial acini can contain motile cells
Authors: Pearson Gray W. , Hunter Tony
Published: December 2007

To determine how extracellular signal–regulated kinases (ERK) 1/2 promote mammary tumorigenesis, we examined the real-time behavior of cells in an organotypic culture of the mammary glandular epithelium. Inducible activation of ERK1/2 in mature acini elicits cell motility and disrupts epithelial architecture in a manner that is reminiscent of ductal carcinoma in situ; however, motile cells do not invade through the basement membrane and branching morphogenesis does not take place. ERK1/2-induced motility causes cells to move both within the cell monolayer that contacts the basement membrane surrounding the acinus and through the luminal space of the acinus. E-cadherin expression is reduced after ERK1/2 activation, but motility does not involve an epithelial–mesenchymal transition. Cell motility and the disruption of epithelial architecture require a Rho kinase– and myosin light chain kinase–dependent increase in the phosphorylation of myosin light chain 2. Our results identify a new mechanism for the disruption of architecture in epithelial acini and suggest that ERK1/2 can promote noninvasive motility in preinvasive mammary tumors.
The histone methyltransferase SET8 is required for S-phase progression
Authors: Jørgensen Stine , Elvers Ingegerd , Trelle Morten Beck , Menzel Tobias , Eskildsen Morten , Jensen Ole Nørregaard , Helleday Thomas , Helin Kristian , Sørensen Claus Storgaard
Published: December 2007

Chromatin structure and function is influenced by histone posttranslational modifications. SET8 (also known as PR-Set7 and SETD8) is a histone methyltransferase that monomethylates histonfe H4-K20. However, a function for SET8 in mammalian cell proliferation has not been determined. We show that small interfering RNA inhibition of SET8 expression leads to decreased cell proliferation and accumulation of cells in S phase. This is accompanied by DNA double-strand break (DSB) induction and recruitment of the DNA repair proteins replication protein A, Rad51, and 53BP1 to damaged regions. SET8 depletion causes DNA damage specifically during replication, which induces a Chk1-mediated S-phase checkpoint. Furthermore, we find that SET8 interacts with proliferating cell nuclear antigen through a conserved motif, and SET8 is required for DNA replication fork progression. Finally, codepletion of Rad51, an important homologous recombination repair protein, abrogates the DNA damage after SET8 depletion. Overall, we show that SET8 is essential for genomic stability in mammalian cells and that decreased expression of SET8 results in DNA damage and Chk1-dependent S-phase arrest.
Apoptosis induction by Bid requires unconventional ubiquitination and degradation of its N-terminal fragment
Authors: Tait Stephen W.G. , de Vries Evert , Maas Chiel , Keller Anna M. , D'Santos Clive S. , Borst Jannie
Published: December 2007

Bcl-2 family member Bid is subject to autoinhibition; in the absence of stimuli, its N-terminal region sequesters the proapoptotic Bcl-2 homology 3 (BH3) domain. Upon proteolytic cleavage in its unstructured loop, Bid is activated, although structural data reveal no apparent resulting conformational change. We found that, upon Bid cleavage, the N-terminal fragment (tBid-N) is ubiquitinated and degraded, thus freeing the BH3 domain in the C-terminal fragment (tBid-C). Ubiquitination of tBid-N is unconventional because acceptor sites are neither lysines nor the N terminus. Chemical approaches implicated thioester and hydroxyester linkage of ubiquitin and mutagenesis implicated serine and possibly threonine as acceptor residues in addition to cysteine. Acceptor sites reside predominantly but not exclusively in helix 1, which is required for ubiquitination and degradation of tBid-N. Rescue of tBid-N from degradation blocked Bid's ability to induce mitochondrial outer membrane permeability but not mitochondrial translocation of the cleaved complex. We conclude that unconventional ubiquitination and proteasome-dependent degradation of tBid-N is required to unleash the proapoptotic activity of tBid-C.
Regulation of translation is required for dendritic cell function and survival during activation
Authors: Lelouard Hugues , Schmidt Enrico K. , Camosseto Voahirana , Clavarino Giovanna , Ceppi Maurizio , Hsu Hsiang-Ting , Pierre Philippe
Published: December 2007

In response to inflammatory stimulation, dendritic cells (DCs) have a remarkable pattern of differentiation (maturation) that exhibits specific mechanisms to control antigen processing and presentation. Here, we show that in response to lipopolysaccharides, protein synthesis is rapidly enhanced in DCs. This enhancement occurs via a PI3K-dependent signaling pathway and is key for DC activation. In addition, we show that later on, in a manner similar to viral or apoptotic stress, DC activation leads to the phosphorylation and proteolysis of important translation initiation factors, thus inhibiting cap-dependent translation. This inhibition correlates with major changes in the origin of the peptides presented by MHC class I and the ability of mature DCs to prevent cell death. Our observations have important implications in linking translation regulation with DC function and survival during the immune response.
Molecular basis of synaptic vesicle cargo recognition by the endocytic sorting adaptor stonin 2
Authors: Jung Nadja , Wienisch Martin , Gu Mingyu , Rand James B. , Müller Sebastian L. , Krause Gerd , Jorgensen Erik M. , Klingauf Jürgen , Haucke Volker
Published: December 2007

Synaptic transmission depends on clathrin-mediated recycling of synaptic vesicles (SVs). How select SV proteins are targeted for internalization has remained elusive. Stonins are evolutionarily conserved adaptors dedicated to endocytic sorting of the SV protein synaptotagmin. Our data identify the molecular determinants for recognition of synaptotagmin by stonin 2 or its Caenorhabditis elegans orthologue UNC-41B. The interaction involves the direct association of clusters of basic residues on the surface of the cytoplasmic domain of synaptotagmin 1 and a β strand within the μ–homology domain of stonin 2. Mutation of K783, Y784, and E785 to alanine within this stonin 2 β strand results in failure of the mutant stonin protein to associate with synaptotagmin, to accumulate at synapses, and to facilitate synaptotagmin internalization. Synaptotagmin-binding–defective UNC-41B is unable to rescue paralysis in C. elegans stonin mutant animals, suggesting that the mechanism of stonin-mediated SV cargo recognition is conserved from worms to mammals.
The expanding role of the ER translocon in membrane protein folding
Authors: Skach William R.
Published: December 2007

Eukaryotic polytopic membrane proteins are cotranslationally inserted into the ER membrane by a multisubunit protein-conducting channel called the Sec61 translocon. Although most major translocon components have been identified and reconstituted, their stoichiometry and functional organization remain unknown. This has led to speculative and sometimes conflicting models describing how multiple transmembrane (TM) segments might be oriented and integrated during nascent polytopic protein biogenesis. Kida et al. (see p. 1441 of this issue) shed new insight into this area by demonstrating that functional translocons exhibit a remarkable flexibility by simultaneously accommodating at least two hydrophilic translocating peptides that are separated by multiple hydrophobic TMs. These surprising findings support an expanded role for the translocon in membrane protein biogenesis and require reassessment of current views based on a single small functional pore.
Structural Determinants of Water Permeability through the Lipid Membrane
Authors: Mathai John C. , Tristram-Nagle Stephanie , Nagle John F. , Zeidel Mark L.
Published: December 2007

Despite intense study over many years, the mechanisms by which water and small nonelectrolytes cross lipid bilayers remain unclear. While prior studies of permeability through membranes have focused on solute characteristics, such as size, polarity, and partition coefficient in hydrophobic solvent, we focus here on water permeability in seven single component bilayers composed of different lipids, five with phosphatidylcholine headgroups and different chain lengths and unsaturation, one with a phosphatidylserine headgroup, and one with a phosphatidylethanolamine headgroup. We find that water permeability correlates most strongly with the area/lipid and is poorly correlated with bilayer thickness and other previously determined structural and mechanical properties of these single component bilayers. These results suggest a new model for permeability that is developed in the accompanying theoretical paper in which the area occupied by the lipid is the major determinant and the hydrocarbon thickness is a secondary determinant. Cholesterol was also incorporated into DOPC bilayers and X-ray diffuse scattering was used to determine quantitative structure with the result that the area occupied by DOPC in the membrane decreases while bilayer thickness increases in a correlated way because lipid volume does not change. The water permeability decreases with added cholesterol and it correlates in a different way from pure lipids with area per lipid, bilayer thickness, and also with area compressibility.
Theory of Passive Permeability through Lipid Bilayers
Authors: Nagle John F. , Mathai John C. , Zeidel Mark L. , Tristram-Nagle Stephanie
Published: December 2007

Recently measured water permeability through bilayers of different lipids is most strongly correlated with the area per lipid A rather than with other structural quantities such as the thickness. This paper presents a simple three-layer theory that incorporates the area dependence in a physically realistic way and also includes the thickness as a secondary modulating parameter. The theory also includes the well-known strong correlation of permeability upon the partition coefficients of general solutes in hydrocarbon environments (Overton's rule). Two mathematical treatments of the theory are given; one model uses discrete chemical kinetics and one model uses the Nernst-Planck continuum equation. The theory is fit to the recent experiments on water permeability in the accompanying paper.