Vegetation Controls on Weathering Intensity During the Last Deglacial Transition in Southeast Africa

Tropical climate is rapidly changing, but the effects of these changes on the geosphere are unknown, despite a likelihood of climatically-induced changes on weathering and erosion. The lack of long, continuous paleo-records prevents an examination of terrestrial responses to climate change with sufficient detail to answer questions about how systems behaved in the past and may alter in the future. We use high-resolution records of pollen, clay mineralogy, and particle size from a drill core from Lake Malawi, southeast Africa, to examine atmosphere-biosphere-geosphere interactions during the last deglaciation (~ 18-9 ka), a period of dramatic temperature and hydrologic changes. The results demonstrate that climatic controls on Lake Malawi vegetation are critically important to weathering processes and erosion patterns during the deglaciation. At 18 ka, afromontane forests dominated but were progressively replaced by tropical seasonal forest, as summer rainfall increased. Despite indication of decreased rainfall, drought-intolerant forest persisted through the Younger Dryas (YD) resulting from a shorter dry season. Following the YD, an intensified summer monsoon and increased rainfall seasonality were coeval with forest decline and expansion of drought-tolerant miombo woodland. Clay minerals closely track the vegetation record, with high ratios of kaolinite to smectite (K/S) indicating heavy leaching when forest predominates, despite variable rainfall. In the early Holocene, when rainfall and temperature increased (effective moisture remained low), open woodlands expansion resulted in decreased K/S, suggesting a reduction in chemical weathering intensity. Terrigenous sediment mass accumulation rates also increased, suggesting critical linkages among open vegetation and erosion during intervals of enhanced summer rainfall. This study shows a strong, direct influence of vegetation composition on weathering intensity in the tropics. As climate change will likely impact this interplay between the biosphere and geosphere, tropical landscape change could lead to deleterious effects on soil and water quality in regions with little infrastructure for mitigation

Position-specific ^(13)C distributions within propane from experiments and natural gas samples

Site-specific carbon isotope measurements of organic compounds potentially recover information that is lost in a conventional, ‘bulk' isotopic analysis. Such measurements are useful because isotopically fractionating processes may have distinct effects at different molecular sites, and thermodynamically equilibrated populations of molecules tend to concentrate heavy isotopes in one molecular site versus another. Most recent studies of site-specific ^(13)C in organics use specialized Nuclear Magnetic Resonance (NMR) techniques or complex chemical degradations prior to mass spectrometric measurements. Herein we present the first application of a new mass spectrometric technique that reconstructs the site-specific carbon isotope composition of propane based on measurements of the ^(13)C/^(12)C ratios of two or more fragment ions that sample different proportions of the terminal and central carbon sites. We apply this method to propane from laboratory experiments and natural gas samples to explore the relationships between site-specific carbon isotope composition, full-molecular δ^(13)C, thermal maturity, and variation in organic matter precursors. Our goal is to advance the understanding of the sources and histories of short-chain alkanes within geologic systems. Our findings suggest that propane varies in its site-specific carbon isotope structure, which is correlated with increasing thermal maturity, first increasing in terminal position δ^(13)C and then increasing in both center and terminal position δ^(13)C. This pattern is observed in both experimental and natural samples, and is plausibly explained by a combination of site-specific, temperature-dependent isotope effects associated with conversion of different precursor molecules (kerogen, bitumen, and/or oil) to propane, differences in site-specific isotopic contents of those precursors, and possibly distillation of reactive components of those precursors with increasing maturity. We hypothesize that the largest changes in site-specific isotopic content of propane occur when bitumen and/or oil replace kerogen as the dominant precursors. If correct, this phenomenon could have significant utility for understanding gas generation in thermogenic petroleum systems

Kidney after nonrenal transplantation-the impact of alemtuzumab induction

BACKGROUND.: Calcineurin inhibitor nephrotoxicity in nonrenal allograft recipients can lead to end-stage renal disease and the need for kidney transplantation. We sought to evaluate the role of alemtuzumab induction in this population. PATIENTS AND METHODS.: We evaluated 144 patients undergoing kidney transplantation after nonrenal transplantation between May 18, 1998, and October 8, 2007. Seventy-two patients transplanted between January 15, 2003, and October 8, 2007, received alemtuzumab induction and continued their pretransplant immunosuppression. Seventy-two patients transplanted between May 18, 1998, and July 21, 2007, did not receive alemtuzumab induction, but received additional steroids and maintenance immunosuppression. Donor and recipient demographics were comparable. RESULTS.: Overall, 1-and 3-year patient survival and renal function were comparable between the two groups. One-and 3-year graft survival was 93.0% and 75.3% in the alemtuzumab group and 83.3% and 68.7% in the no alemtuzumab group, respectively (P=0.051). The incidence of acute rejection was lower in the alemtuzumab group, 15.3%, than in the no alemtuzumab group, 41.7% (P=0.0001). The incidence of delayed graft function was lower in the alemtuzumab group, 9.7%, than in the no alemtuzumab group, 25.0% (P=0.003). The incidence of viral complications was comparable. CONCLUSION.: Alemtuzumab induction with simple resumption of baseline immunosuppression in patients undergoing kidney transplantation after nonrenal transplantation represents a reasonable immunosuppressive strategy. Copyright © 2009 by Lippincott Williams & Wilkins

RASSF2 Is a Novel K-Ras-specific Effector and Potential Tumor Suppressor

Ras proteins regulate a wide range of biological processes by interacting with a broad assortment of effector proteins. Although activated forms of Ras are frequently associated with oncogenesis, they may also provoke growth-antagonistic effects. These include senescence, cell cycle arrest, differentiation, and apoptosis. The mechanisms that underlie these growth-inhibitory activities are relatively poorly understood. Recently, two related novel Ras effectors, NORE1 and RASSF1, have been identified as mediators of apoptosis and cell cycle arrest. Both of these proteins exhibit many of the properties normally associated with tumor suppressors. We now identify a novel third member of this family, designated RASSF2. RASSF2 binds directly to K-Ras in a GTP-dependent manner via the Ras effector domain. However, RASSF2 only weakly interacts with H-Ras. Moreover, RASSF2 promotes apoptosis and cell cycle arrest and is frequently down-regulated in lung tumor cell lines. Thus, we identify RASSF2 as a new member of the RASSF1 family of Ras effectors/tumor suppressors that exhibits a specificity for interacting with K-Ras

Position-specific ^(13)C distributions within propane from experiments and natural gas samples

Site-specific carbon isotope measurements of organic compounds potentially recover information that is lost in a conventional, ‘bulk' isotopic analysis. Such measurements are useful because isotopically fractionating processes may have distinct effects at different molecular sites, and thermodynamically equilibrated populations of molecules tend to concentrate heavy isotopes in one molecular site versus another. Most recent studies of site-specific ^(13)C in organics use specialized Nuclear Magnetic Resonance (NMR) techniques or complex chemical degradations prior to mass spectrometric measurements. Herein we present the first application of a new mass spectrometric technique that reconstructs the site-specific carbon isotope composition of propane based on measurements of the ^(13)C/^(12)C ratios of two or more fragment ions that sample different proportions of the terminal and central carbon sites. We apply this method to propane from laboratory experiments and natural gas samples to explore the relationships between site-specific carbon isotope composition, full-molecular δ^(13)C, thermal maturity, and variation in organic matter precursors. Our goal is to advance the understanding of the sources and histories of short-chain alkanes within geologic systems. Our findings suggest that propane varies in its site-specific carbon isotope structure, which is correlated with increasing thermal maturity, first increasing in terminal position δ^(13)C and then increasing in both center and terminal position δ^(13)C. This pattern is observed in both experimental and natural samples, and is plausibly explained by a combination of site-specific, temperature-dependent isotope effects associated with conversion of different precursor molecules (kerogen, bitumen, and/or oil) to propane, differences in site-specific isotopic contents of those precursors, and possibly distillation of reactive components of those precursors with increasing maturity. We hypothesize that the largest changes in site-specific isotopic content of propane occur when bitumen and/or oil replace kerogen as the dominant precursors. If correct, this phenomenon could have significant utility for understanding gas generation in thermogenic petroleum systems

Qualitative study of system-level factors related to genomic implementation

PURPOSE: Research on genomic medicine integration has focused on applications at the individual level, with less attention paid to implementation within clinical settings. Therefore, we conducted a qualitative study using the Consolidated Framework for Implementation Research (CFIR) to identify system-level factors that played a role in implementation of genomic medicine within Implementing GeNomics In PracTicE (IGNITE) Network projects. METHODS: Up to four study personnel, including principal investigators and study coordinators from each of six IGNITE projects, were interviewed using a semistructured interview guide that asked interviewees to describe study site(s), progress at each site, and factors facilitating or impeding project implementation. Interviews were coded following CFIR inner-setting constructs. RESULTS: Key barriers included (1) limitations in integrating genomic data and clinical decision support tools into electronic health records, (2) physician reluctance toward genomic research participation and clinical implementation due to a limited evidence base, (3) inadequate reimbursement for genomic medicine, (4) communication among and between investigators and clinicians, and (5) lack of clinical and leadership engagement. CONCLUSION: Implementation of genomic medicine is hindered by several system-level barriers to both research and practice. Addressing these barriers may serve as important facilitators for studying and implementing genomics in practice

Sodium Stibogluconate (SSG) & Paromomycin Combination Compared to SSG for Visceral Leishmaniasis in East Africa: A Randomised Controlled Trial

Visceral leishmaniasis (VL) is a parasitic disease with about 500,000 new cases each year and is fatal if untreated. The current standard therapy involves long courses, has toxicity and there is evidence of increasing resistance. New and better treatment options are urgently needed. Recently, the antibiotic paromomycin (PM) was tested and registered in India to treat this disease, but the same dose of PM monotherapy evaluated and registered in India was not efficacious in Sudan. This article reports the results of a clinical trial to test the effectiveness of injectable PM either alone (in a higher dose) or in combination with sodium stibogluconate (SSG) against the standard SSG monotherapy treatment in four East African countries—Sudan, Kenya, Ethiopia and Uganda. The study showed that the combination of SSG &PM was as efficacious and safe as the standard SSG treatment, with the advantages of being cheaper and requiring only 17 days rather than 30 days of treatment. In March 2010, a WHO Expert Committee recommended the use of the SSG & PM combination as a first line treatment for VL in East Africa

Institutional legacies and HRM: similarities and differences in HRM practices in Portugal and Mozambique

This is a study of institutional change and continuity, comparing the trajectories followed by Mozambique and its formal colonial power Portugal in HRM, based on two surveys of firm level practices. The colonial power sought to extend the institutions of the metropole in the closing years of its rule, and despite all the adjustments and shocks that have accompanied Mozambique’s post-independence years, the country continues to retain institutional features and associated practices from the past. This suggests that there is a post-colonial impact on human resource management. The implications for HRM theory are that ambitious attempts at institutional substitution may have less dramatic effects than is commonly assumed. Indeed, we encountered remarkable similarities between the two countries in HRM practices, implying that features of supposedly fluid or less mature institutional frameworks (whether in Africa or the Mediterranean world) may be sustained for protracted periods of time, pressures to reform notwithstanding. This highlights the complexities of continuities which transcend formal rules; as post-colonial theories alert us, informal conventions and embedded discourse may result in the persistence of informal power and subordination, despite political and legal changes