Impact of solid surface hydrophobicity and micrococcal nuclease production on Staphylococcus aureus Newman biofilms

Staphylococcus aureus is commonly associated with biofilm-related infections and contributes to the large financial loss that accompany nosocomial infections. The micrococcal nuclease Nuc1 enzyme limits biofilm formation via cleavage of eDNA, a structural component of the biofilm matrix. Solid surface hydrophobicity influences bacterial adhesion forces and may as well influence eDNA production. Therefore, it is hypothesized that the impact of Nuc1 activity is dependent on surface characteristics of solid surfaces. For this reason, this study investigated the influence of solid surface hydrophobicity on S. aureus Newman biofilms where Nuc1 is constitutively produced. To this end, biofilms of both a wild-type and a nuc1 knockout mutant strain, grown on glass, salinized glass and Pluronic F-127-coated silanized glass were analysed. Results indicated that biofilms can grow in the presence of Nuc1 activity. Also, Nuc1 and solid surface hydrophobicity significantly affected the biofilm 3D-architecture. In particular, biofilm densities of the wild-type strain on hydrophilic surfaces appeared higher than of the mutant nuc1 knockout strain. Since virulence is related to bacterial cell densities, this suggests that the virulence of S. aureus Newman biofilms is increased by its nuclease production in particular on a hydrophilic surface

Comparing productivity of millet-based cropping systems in unstable environments of the Sahel: possibilities and challenges

Falling per capita food production, increasing population pressure on arable land and soil nutrient mining that occurs under traditional cropping systems in West Africa have generated a strong demand for more productive yet sustainable cropping systems. Total factor productivity methodology was used to analyse millet (Pennisetum glaucum)-based cropping systems developed for the Sahel. The traditional cropping system uses low plant densities of intercropped millet and cowpeas, with manual cultivation and no applied P, while non-traditional systems tested in trials in Niger included P application and higher plant densities of sole- or intercropped millet grown with animal or manual tillage. Interspatial total factor productivity comparisons indicate that the new cropping systems were more profitable than the traditional cropping system. However, the determination of the sustainability of the tested systems was constrained by lack of appropriate time series data to cope with environmental instability in the Sahel and changes in resource stocks. In designing new cropping system technologies for areas prone to degradation, a multidisciplinary research strategy is needed to identify and measure resource stock changes that affect productivity. It is also imperative to use crops and system models, particularly in unstable climatic environments, to generate adequate time series data for the measurement of sustainability. Finally, cropping systems evaluated should include both packages and components. This will permit the formulation of recommendations that fit resources or preferences of different farmer

Preliminary Evaluation of Indoor Radon Exposure Levels in Students' Halls of Residence at the Northern Campus (New Site) of the University of Cape Coast, Ghana

Abstract: The study seeks to present Radon exposure levels in some rooms within halls of residence at the New Site of the University of Cape Coast, Ghana determined using LR-115 TypeII Solid State Nuclear Track Detector (SSNTD) and E-PERM detecting systems. Pieces of the plastic LR-115 detectors were covered with aluminium foil and fixed in plastic holder such that the active part (coated part) of the detector was exposed (bare), facing downwards and together with the E-PERM were placed at a location in each of the selected rooms in the halls of residence for 30 days. The voltages of the E-PERMs were taken using the SPER-1 Reader whilst the LR-115 was chemically etched to reveal the alpha tracks. The mean radon exposure level for LR-115 was 6.8 mSv (range: 3.1-9.1 mSv) whiles the mean exposure for the E-PERM was 3.6 mSv (range: 1.7-5.3 mSv). The results obtained also indicated that the exposure levels measured by both the E-PERM and the LR-115 detectors were generally below the Environmental Protection Agency (US-EPA) guideline limit of 8 mSv. However, some rooms had their exposure levels (measured with the LR-115 detector) above the remedial guideline limit of 8 mSv, but far below the immediate action limit of 20 mSv. Most of a student time is spent indoors. There is therefore the need to have a fair idea the radon concentration and exposure levels in rooms since radon has been identified as a carcinogenic gas

Nutrients and bioactive compounds content of Baillonella toxisperma, Trichoscypha abut and Pentaclethra macrophylla from Cameroon

Baillonella toxisperma, Pentaclethra macrophylla and Trichoscypha abut are important foods for communities living around forests in Cameroon. Information on the nutritional value and bioactive content of these foods is required to establish their contribution to the nutrition and health of the communities. Samples of the three foods were obtained from four villages in east and three villages in south Cameroon. The foods were analyzed for proximate composition, minerals and bioactive content using standard chemical analysis methods. T. abut was found to be an excellent source of bioactive compounds; flavonoids (306 mg/100 g), polyphenols (947 mg/100 g), proanthocyanins (61.2 mg/100 g), vitamin C (80.05 mg/100 g), and total oxalates (0.6 mg/100 g). P. macrophylla was found to be a rich source of total fat (38.71%), protein (15.82%) and total fiber (17.10%) and some bioactive compounds; vitamin E (19.4 mg/100 g) and proanthocyanins (65.0 mg/100 g). B. toxisperma, was found to have high content of carbohydrates (89.6%), potassium (27.5 mg/100 g) and calcium (37.5 mg/100 g). Flavonoids, polyphenols, vitamins C and E are the main bioactive compounds in these forest foods. The daily consumption of some of these fruits may coffer protection against some ailments and oxidative stress. Approximately 200 g of either B. toxisperma or P. macrophylla, can supply 100% iron and zinc RDAs for children aged 1–3 years, while 300 g of the two forest foods can supply about 85% iron and zinc RDAs for non-pregnant non-lactating women. The three foods provide 100% daily vitamins C and E requirements for both adults and children. The results of this study show that Baillonella toxisperma, Pentaclethra macrophylla and Trichoscypha abut can considerably contribute towards the human nutrient requirements. These forest foods also contain substantial levels of health promoting phytochemicals notably flavonoids, polyphenols, vitamins C and E. These foods therefore have potential to promote nutrition and health, especially among forest dependent communities who consume them in substantial amounts

Micrococcal Nuclease stimulates Staphylococcus aureus Biofilm Formation in a Murine Implant Infection Model

Advancements in contemporary medicine have led to an increasing life expectancy which has broadened the application of biomaterial implants. As each implant procedure has an innate risk of infection, the number of biomaterial-associated infections keeps rising. Staphylococcus aureus causes 34% of such infections and is known as a potent biofilm producer. By secreting micrococcal nuclease S. aureus is able to escape neutrophil extracellular traps by cleaving their DNA-backbone. Also, micrococcal nuclease potentially limits biofilm growth and adhesion by cleaving extracellular DNA, an important constituent of biofilms. This study aimed to evaluate the impact of micrococcal nuclease on infection persistence and biofilm formation in a murine biomaterial-associated infection-model with polyvinylidene-fluoride mesh implants inoculated with bioluminescent S. aureus or its isogenic micrococcal nuclease deficient mutant. Supported by results based on in-vivo bioluminescence imaging, ex-vivo colony forming unit counts, and histological analysis it was found that production of micrococcal nuclease enables S. aureus bacteria to evade the immune response around an implant resulting in a persistent infection. As a novel finding, histological analysis provided clear indications that the production of micrococcal nuclease stimulates S. aureus to form biofilms, the presence of which extended neutrophil extracellular trap formation up to 13 days after mesh implantation. Since micrococcal nuclease production appeared vital for the persistence of S. aureus biomaterial-associated infection, targeting its production could be a novel strategy in preventing biomaterial-associated infection

Partners in Impact Assessment Summary Proceedings of the ICRISAT/NARS Workshop on Methods and Joint Impact Targets in Western and Central Africa 3-5 May 1995

Regional workshops were held at Sadore, Niger and Samanko, Mali, to evaluate the joint impact of ICRISAT and National Agricultural Research Systems (NARS) in Western and Central Africa. Twentyone scientists from ICRISAT and the national program in Cameroon, Chad, and Niger participated in the workshop at Sadore. The Samako workshop was at tended by 18 scientists from ICRISAT, NARS collaborators in Burkina Faso and Mali, INSAH and the West and Central African Sorghum Research Network (WCASRN) . National program representatives identified specific jointly-developed technologies that should be targeted for impact assessment. Methodological approaches for measuring welfare benefits to consumers and producers were discussed and illustrated wi th case studies. Minimum dataset requirements were outlined and protocols for case studies on technologies targeted by NARS partners were develope

Agrobiodiversity and climate change: what do students need to know?

Key note paper presented at 2nd ANAFE International Symposium: ‘Mainstreaming climate change into agricultural education: tools, experiences and challenges’, Malawi, 2008. The paper informs that adaptation of production systems to climate change requires human capacity in agricultural biodiversity but a 2007 survey in African universities showed that education in this area is weak or absent. The authors argue that role of agricultural biodiversity in adaptation to climate change should be better understood, and that universities should seek to develop such competencies in their students. Universities should review curricula to include agricultural biodiversity dimensions through innovative, experiential teaching methods and active student participation

A Universal Nanogel-Based Coating Approach for Medical Implant Materials

Coatings are essential for biomedical applications antifouling and antimicrobialproperties, supporting cell adhesion and tissue integration and particularlyinteresting in this field are nanogel (nGel)-based coatings. Since biomaterialsdiffer in physiochemical properties, specific nGel-coating strategies need to bedeveloped for every distinct material, leading to complex coating strategies.Hence, the solution lies in adopting a universal strategy to apply the same nGelcoating with the same function on a wide range of implant surfaces. To this end, auniversal nGel-based coating approach provides the same coating using a singlemethod on implant materials including stiff polymer materials, metals, ceramics,glass, and elastomers. The coating formation is achieved by electrostatic interactionsbetween oxygen plasma–activated surfaces and positively charged nGelsusing a spray-deposition method. Fluorescent labels are introduced into thenGels as a model for post-modification capabilities to increase the functionality ofthe coating. The coating is highly stable under in vitro physiological conditionswith the retention of its function on different clinically relevant materials.Meanwhile, the in vivo study indicates that the nGel coating on a polyvinylidenefluoride hernia mesh is stable and biocompatible, therefore, making the coatingand the coating strategy, a highly impactful approach for future clinicaldevelopments

Genomic epidemiological analysis identifies high relapse among individuals with recurring tuberculosis and provides evidence of household recent TB transmission in Ghana

OBJECTIVE: We investigated the cause of recurring tuberculosis (rcTB) among pulmonary TB participants recruited from a prospective population-based study conducted between July 2012 and December 2015. METHODS: Mycobacterium tuberculosis complex isolates obtained from rcTB cases were characterized by standard mycobacterial genotyping tools in addition to whole genome sequencing, followed by phylogenetic analysis to assess strain relatedness. RESULTS: A greater proportion (58.3%, 21/36) of individuals with rcTB episodes had TB recurrence within 12 months post treatment. Only 19.4% (7/36) of participants with rcTB harbored a strain with isoniazid (INH) resistance at baseline of which 29% (2/7) were additionally resistant to rifampicin. However, 27.8% (10/36) harbored an INH resistant strain upon recurring of which 40% (4/10) were MDR-TB strains. Recurrent TB was attributed to relapse (same strain) in 75.0% (27/36) of participants with 25.0% (9/36) attributed to re-infection. CONCLUSION: Our findings indicate that unresolved previous infection due to inadequate treatment may be the major cause of rcTB

Combined Inflammatory and Metabolic Defects Reflected by Reduced Serum Protein Levels in Patients with Buruli Ulcer Disease

Buruli ulcer is a skin disease caused by Mycobacterium ulcerans that is spreading in tropical countries, with major public health and economic implications in West Africa. Multi-analyte profiling of serum proteins in patients and endemic controls revealed that Buruli ulcer disease down-regulates the circulating levels of a large array of inflammatory mediators, without impacting on the leukocyte composition of peripheral blood. Notably, several proteins contributing to acute phase reaction, lipid metabolism, coagulation and tissue remodelling were also impacted. Their down-regulation was selective and persisted after the elimination of bacteria with antibiotic therapy. It involved proteins with various functions and origins, suggesting that M. ulcerans infection causes global and chronic defects in the host’s protein metabolism. Accordingly, patients had reduced levels of total serum proteins and blood urea, in the absence of signs of malnutrition, or functional failure of liver or kidney. Interestingly, slow healers had deeper metabolic and coagulation defects at the start of antibiotic therapy. In addition to providing novel insight into Buruli ulcer pathogenesis, our study therefore identifies a unique proteomic signature for this disease