Spectroscopic and Mechanistic Studies of Heterodimetallic Forms of Metallo-β-lactamase NDM-1

In an effort to characterize the roles of each metal ion in metallo-β-lactamase NDM-1, heterodimetallic analogues (CoCo-, ZnCo-, and CoCd-) of the enzyme were generated and characterized. UV–vis, 1H NMR, EPR, and EXAFS spectroscopies were used to confirm the fidelity of the metal substitutions, including the presence of a homogeneous, heterodimetallic cluster, with a single-atom bridge. This marks the first preparation of a metallo-β-lactamase selectively substituted with a paramagnetic metal ion, Co(II), either in the Zn1 (CoCd-NDM-1) or in the Zn2 site (ZnCo-NDM-1), as well as both (CoCo-NDM-1). We then used these metal-substituted forms of the enzyme to probe the reaction mechanism, using steady-state and stopped-flow kinetics, stopped-flow fluorescence, and rapid-freeze-quench EPR. Both metal sites show significant effects on the kinetic constants, and both paramagnetic variants (CoCd- and ZnCo-NDM-1) showed significant structural changes on reaction with substrate. These changes are discussed in terms of a minimal kinetic mechanism that incorporates all of the data

Modeling the Influence of Local Environmental Factors on Malaria Transmission in Benin and Its Implications for Cohort Study

Malaria remains endemic in tropical areas, especially in Africa. For the evaluation of new tools and to further our understanding of host-parasite interactions, knowing the environmental risk of transmission—even at a very local scale—is essential. The aim of this study was to assess how malaria transmission is influenced and can be predicted by local climatic and environmental factors

Plant-mediated effects on mosquito capacity to transmit human malaria

The ecological context in which mosquitoes and malaria parasites interact has received little attention, compared to the genetic and molecular aspects of malaria transmission. Plant nectar and fruits are important for the nutritional ecology of malaria vectors, but how the natural diversity of plant-derived sugar sources affects mosquito competence for malaria parasites is unclear. To test this, we infected Anopheles coluzzi, an important African malaria vector, with sympatric field isolates of Plasmodium falciparum, using direct membrane feeding assays. Through a series of experiments, we then examined the effects of sugar meals from Thevetia neriifolia and Barleria lupilina cuttings that included flowers, and fruit from Lannea microcarpa and Mangifera indica on parasite and mosquito traits that are key for determining the intensity of malaria transmission. We found that the source of plant sugar meal differentially affected infection prevalence and intensity, the development duration of the parasites, as well as the survival and fecundity of the vector. These effects are likely the result of complex interactions between toxic secondary metabolites and the nutritional quality of the plant sugar source, as well as of host resource availability and parasite growth. Using an epidemiological model, we show that plant sugar source can be a significant driver of malaria transmission dynamics, with some plant species exhibiting either transmission-reducing or -enhancing activities

Monitoring land use and soil salinity changes in coastal landscape: a case study from Senegal

Soil salinity is a major issue causing land degradation in coastal areas. In this study, we assessed the land use and soil salinity changes in Djilor district (Senegal) using remote sensing and field data. We performed land use land cover changes for the years 1984, 1994, 2007, and 2017. Electrical conductivity was measured from 300 soil samples collected at the study area; this, together with elevation, distance to river, Normalized Difference Vegetation Index (NDVI), Salinity Index (SI), and Soil-Adjusted Vegetation Index (SAVI), was used to build the salinity model using a multiple regression analysis. Supervised classification and intensity analysis were applied to determine the annual change area and the variation of gains and losses. The results showed that croplands recorded the highest gain (17%) throughout the period 1984–2017, while forest recorded 3%. The fastest annual area of change occurred during the period 1984–1994. The salinity model showed a high potential for mapping saline areas (R² = 0.73 and RMSE = 0.68). Regarding salinity change, the slightly saline areas (2 < EC < 4 dS/m) increased by 42% whereas highly saline (EC > 8 dS/m) and moderately saline (4 < EC < 8 dS/m) areas decreased by 23% and 26%, respectively, in 2017. Additionally, the increasing salt content is less dominant in vegetated areas compared with non-vegetated areas. Nonetheless, the highly concentrated salty areas can be restored using salt-resistant plants (e.g., Eucalyptus sp., Tamarix sp.). This study gives more insights on land use planning and salinity management for improving farmers’ resilience in coastal regions

Tomato pomace as a source of valuable functional ingredients for improving physicochemical and sensory properties and extending the shelf life of foods: A review

Due to its nutritional and bioactive content, tomato pomace (TP) remains among the world's richest fruits and vegetables. Tomatoes and TP (generated coproduct) are a very rich source of lycopene and other carotenoid compounds and contain an essential amount of polyphenols, policosanol, phytosterols, organic acids, dietary fibers, minerals, and vitamins. TP is a promising source of significant bioactive compounds with antioxidant and antimicrobial potential. Therefore, their consumption is known to be effective in preventing certain chronic diseases. For example, lycopene prevents prostate cancer and acts as a hepatoprotector and genoprotector against mycotoxins, pesticide residues, and heavy metals. Thus, the valorization of TP as a food ingredient can be of great health, economic and environmental interest and contribute to improving nutrition and food security. During the last decades, considerable efforts have been made to valorize TP as a crucial functional ingredient in improving: (i) the nutritional and functional properties, (ii) sensory characteristics and (iii) the shelf life of many foods. The current review aims to update and summarize the knowledge on the recent food applications of TP, particularly its use as a functional ingredient to improve the functional properties and shelf life of foods

Implementation of community-based cattle breeding programs in Burkina Faso

Community-based breeding programs (CBBP), are being implemented in the South-West of Burkina Faso. CBBP are participatory programs that involve all local stakeholders in all steps, from designing and planning of the breeding program, all the way to the selection of the breeding stock. They aim to improve local cattle breeds. The breeding program has been implemented in three sites. Cattle types included in the program are the pure Lobi (Baoulé) cattle in one site and Lobi x Zebu crossbreds in the other two. The program pursues the main interest of farmers to have bigger animals which are tolerant to trypanosomosis. In the he first round of selection, young bulls, aged three to five years, were recorded twice, at an interval of 6 months. The project team grouped bulls into three groups (top, medium, inferior) based on an index combining current body weight and growth. Selection committees consisting of male and female cattle owners made their choice of best young bulls based on this information and their own criteria. The three best bulls selected by the committees were only partly from the top groups based on preliminary grouping of the project team. Decision was taken by the farmers which bulls to keep for breeding and which ones to castrate or sell out, to avoid undesired mating. Joint use of bulls and bull exchange are still being negotiated by farmers, as it is not a customary practice in the region. Farmers were open and appreciated the concept very much. They understood that CBBP are long term and committed their efforts and participation

Practicing medicine without borders: tele-consultations and tele-mentoring for improving paediatric care in a conflict setting in Somalia?

OBJECTIVES: In a district hospital in conflict-torn Somalia, we assessed (i) the impact of introducing telemedicine on the quality of paediatric care, and (ii) the added value as perceived by local clinicians. METHODS: A 'real-time' audio-visual exchange of information on paediatric cases (Audiosoft Technologies, Quebec, Canada) took place between clinicians in Somalia and a paediatrician in Nairobi. The study involved a retrospective analysis of programme data, and a perception study among the local clinicians. RESULTS: Of 3920 paediatric admissions, 346 (9%) were referred for telemedicine. In 222 (64%) children, a significant change was made to initial case management, while in 88 (25%), a life-threatening condition was detected that had been initially missed. There was a progressive improvement in the capacity of clinicians to manage complicated cases as demonstrated by a significant linear decrease in changes to initial case management for meningitis and convulsions (92-29%, P = 0.001), lower respiratory tract infection (75-45%, P = 0.02) and complicated malnutrition (86-40%, P = 0.002). Adverse outcomes (deaths and lost to follow-up) fell from 7.6% in 2010 (without telemedicine) to 5.4% in 2011 with telemedicine (30% reduction, odds ratio 0.70, 95% CI: 0.57-0.88, P = -0.001). The number needed to be treated through telemedicine to prevent one adverse outcome was 45. All seven clinicians involved with telemedicine rated it to be of high added value. CONCLUSION: The introduction of telemedicine significantly improved quality of paediatric care in a remote conflict setting and was of high added value to distant clinicians

Pressure and momentum field investigation of a centrifugal pump through dynamic loading of a semi-open impeller

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references: p. 58-59.Issued also on microfiche from Lange Micrographics.A study was performed to investigate the variation in the forces and moments acting on the front and back sides of a semi-open impeller. Three rotational speeds and five volumetric flow rates for each speed were identified as the operating conditions for the pump after generating performance curves. The pressure distribution inside the pump housing was measured through pressure taps drilled in the front and back housing. These pressure measurements were obtained for distinct geometric configurations comprising of varying positions of the impeller and the front housing. Pressure contour plots were generated for all the operating conditions and an asymmetric pressure distribution was observed in the pump housing. Higher pressures were witnessed near the volute tongue. Forces acting on the impeller were calculated by integrating the pressures acting on it as measured by the pressure taps. A net axial thrust on the impeller, trying to push it towards the suction side, was observed, which decreased in magnitude with increasing back clearance for a certain fixed value of the front clearance. Moments acting on the front and back sides of the impeller were noticed to approach smaller magnitudes for higher volumetric flow rates. A geometric configuration was identified for better overall performance of the pump