Synthesis, Characterization and Antimicrobial Activity of Garcinol Coated Titanium Dioxide Nanoparticles

Background: Garcinol is a secondary metabolite derived from the plants of Clusiaceae Family. It has shown a broad range of bioactivities such as antimicrobial, antioxidant, anticancer and anti-inflammatory. Titanium dioxide nanoparticles (TiO2NPs) are known to have a significant photocatalytic activity and are widely used in medicine. In this study, garcinol was used to modify the surface of TiO2NPs to enhance the antibacterial activity.Objectives: To synthesize, characterize and determine antimicrobial activity of garcinol coated titanium dioxide nanoparticles G-TiO2NPs.Methods: Garcinol was isolated from the dried fruit rinds of Garcinia quaesita. TiO2NPs were coated by garcinol and characterized by using Scanning Electron Microscopy (SEM), Powder X-Ray Diffraction (XRD), and Diffused Reflectance Spectroscopy. Minimum Inhibition Concentration (MIC) was tested against five microbial species including Staphylococcus aureus (ATCC 25623), Pseudomonas aeruginosa (ATCC 27853),Escherichia coli (ATCC 25922), Candida albicans (ATCC 10231) and clinical isolates of Methicillin Resistant Staphylococcus aureus (MRSA), using broth micro-dilution assay. Time-kill kinetic study was performed to determine the inhibition percentage of Staphylococcus aureus over time.Results: SEM images confirmed the spherical shape of G-TiO2NPs, diameter ranging from 20 - 200 nm. XRD data revealed the anatase phase and rutile phase of TiO2NPs. Formation of G-TiO2NPs caused a red shift of the absorption wavelength. G-TiO2NPs and TiO2NPs showed a MIC range of 250-500 μg/ml and 500-1000 μg/ml against the tested microbial species, respectively. In the time-kill kinetic studies, inhibition percentage (IP) of microbial growth was determined at 60 minute time intervals. TiO2NPs and G-TiO2NPs demonstrated inhibition over 50% at 3 hours.Conclusions: G-TiO2NPs presented a significant enhancement in antimicrobial activity against S. aureus compared to TiO2NPs. Surface modification of TiO2NPs with garcinol has created a synergistic antimicrobial effect against S. aureus.Acknowledgement: University Grant ASP/01/RE/SCI/2017/1

Chitosan-Alginate Nanoparticle System Efficiently Delivers Doxorubicin to MCF-7 Cells

A chitosan-alginate nanoparticle system encapsulating doxorubicin (DOX) was prepared by a novel ionic gelation method using alginate as the crosslinker. These nanoparticles were around 100 nm in size and more stable with higher positive zeta potential and had higher % encapsulation efficiency (95%) than DOX loaded chitosan nanoparticles (DOX Csn NP) crosslinked with sodium tripolyphosphate (STPP). FTIR spectroscopy and thermogravimetric analysis revealed successful loading of DOX. In vitro drug release showed an initial release phase followed by slow release phase with higher cumulative release obtained with DOX loaded chitosan-alginate nanoparticles (DOX Csn-Alg NP). The in vitro cytotoxicity of DOX released from the two nanoparticle systems showed a notable difference on comparison with that of free DOX on the MCF-7 cell line. The SRB assay, AO/EB staining, and fluorescence uptake study indicated that free DOX only showed dose dependent cytotoxicity, whereas both dose and time dependency were exhibited by the two sets of NPs. While both systems show sustained release of DOX, from the cell viability plots, DOX Csn-Alg NPs showed their superiority over DOX Csn NPs. The results obtained are useful for developing DOX Csn-Alg NPs as a sustained release carrier system for DOX.This research was financially supported by the HETC QIG Window 3 Grant, University of Peradeniya, Peradeniya, Sri Lanka.Peer Reviewe

The environmental security debate and its significance for climate change

Policymakers, military strategists and academics all increasingly hail climate change as a security issue. This article revisits the (comparatively) long-standing “environmental security debate” and asks what lessons that earlier debate holds for the push towards making climate change a security issue. Two important claims are made. First, the emerging climate security debate is in many ways a re-run of the earlier dispute. It features many of the same proponents and many of the same disagreements. These disagreements concern, amongst other things, the nature of the threat, the referent object of security and the appropriate policy responses. Second, given its many different interpretations, from an environmentalist perspective, securitisation of the climate is not necessarily a positive development

State Capacity and the Environmental Investment Gap in Authoritarian States

We construct an n-period, constrained optimization model where the authoritarian ruler maximizes expected rents subject to budget constraint of available surplus. We show that the larger state capacity is in the previous period, the worse environmental quality will be in the next period: while infrastructural investment and environmental protection increase with state capacity, the former increases at a faster rate which enlarges the gap between the two?the environmental investment gap. Given infrastructural public goods typically damage the environment, the larger this gap is the worse the environmental quality would be. This follows from rulers? optimizing logic of equating marginal returns once we assume the declining marginal productivity of factors of production of surplus. We model three types of air and water pollutants in autocracies as a function of state capacity and other relevant variables. State capacity is associated with higher levels of all three types of pollutants

Comment on Benjamin Smith (2004): 'Oil Wealth and Regime Survival in the Developing World, 1960-1999'

In “Oil Wealth and Regime Survival in the Developing World, 1960-1999“ Benjamin Smith examines the effects of oil wealth, as well as of sudden changes in oil prices, on regime failure, political protest and civil war. He finds that oil wealth is robustly associated with more durable regimes, and significantly related to lower levels of anti-state protest and civil war. In this comment, I discuss Smith's empirical approach - especially his treatment of possible reverse causality between conflict and economic performance, his use of the Polity democracy index, and his choice of the resource dependence variable - and provide suggestions for improvement

Worker remittances and the global preconditions of ‘smart development’

With the growing environmental crisis affecting our globe, ideas to weigh economic or social progress by the ‘energy input’ necessary to achieve it are increasingly gaining acceptance. This question is intriguing and is being dealt with by a growing number of studies, focusing on the environmental price of human progress. Even more intriguing, however, is the question of which factors of social organization contribute to a responsible use of the resources of our planet to achieve a given social result (‘smart development’). In this essay, we present the first systematic study on how migration – or rather, more concretely, received worker remittances per GDP – helps the nations of our globe to enjoy social and economic progress at a relatively small environmental price. We look at the effects of migration on the balance sheets of societal accounting, based on the ‘ecological price’ of the combined performance of democracy, economic growth, gender equality, human development, research and development, and social cohesion. Feminism in power, economic freedom, population density, the UNDP education index as well as the receipt of worker remittances all significantly contribute towards a ‘smart overall development’, while high military expenditures and a high world economic openness are a bottleneck for ‘smart overall development’

Enhancing implementation of tobacco use prevention and cessation counselling guideline among dental providers: a cluster randomised controlled trial

Background: Tobacco use adversely affects oral health. Tobacco use prevention and cessation (TUPAC) counselling guidelines recommend that healthcare providers ask about each patient's tobacco use, assess the patient's readiness and willingness to stop, document tobacco use habits, advise the patient to stop, assist and help in quitting, and arrange monitoring of progress at follow-up appointments. Adherence to such guidelines, especially among dental providers, is poor. To improve guideline implementation, it is essential to understand factors influencing it and find effective ways to influence those factors. The aim of the present study protocol is to introduce a theory-based approach to diagnose implementation difficulties of TUPAC counselling guidelines among dental providers.Methods: Theories of behaviour change have been used to identify key theoretical domains relevant to the behaviours of healthcare providers involved in implementing clinical guidelines. These theoretical domains will inform the development of a questionnaire aimed at assessing the implementation of the TUPAC counselling guidelines among Finnish municipal dental providers. Specific items will be drawn from the guidelines and the literature on TUPAC studies. After identifying potential implementation difficulties, we will design two interventions using theories of behaviour change to link them with relevant behaviour change techniques aiming to improve guideline adherence. For assessing the implementation of TUPAC guidelines, the electronic dental record audit and self-reported questionnaires will be used.Discussion: To improve guideline adherence, the theoretical-domains approach could provide a comprehensive basis for assessing implementation difficulties, as well as designing and evaluating interventions. After having identified implementation difficulties, we will design and test two interventions to enhance TUPAC guideline adherence. Using the cluster randomised controlled design, we aim to provide further evidence on intervention effects, as well as on the validity and feasibility of the theoretical-domain approach. The empirical data collected within this trial will be useful in testing whether this theoretical-domain approach can improve our understanding of the implementation of TUPAC guidelines among dental providers

Mouse Genome-Wide Association and Systems Genetics Identify Asxl2 As a Regulator of Bone Mineral Density and Osteoclastogenesis

Significant advances have been made in the discovery of genes affecting bone mineral density (BMD); however, our understanding of its genetic basis remains incomplete. In the current study, genome-wide association (GWA) and co-expression network analysis were used in the recently described Hybrid Mouse Diversity Panel (HMDP) to identify and functionally characterize novel BMD genes. In the HMDP, a GWA of total body, spinal, and femoral BMD revealed four significant associations (−log10P>5.39) affecting at least one BMD trait on chromosomes (Chrs.) 7, 11, 12, and 17. The associations implicated a total of 163 genes with each association harboring between 14 and 112 genes. This list was reduced to 26 functional candidates by identifying those genes that were regulated by local eQTL in bone or harbored potentially functional non-synonymous (NS) SNPs. This analysis revealed that the most significant BMD SNP on Chr. 12 was a NS SNP in the additional sex combs like-2 (Asxl2) gene that was predicted to be functional. The involvement of Asxl2 in the regulation of bone mass was confirmed by the observation that Asxl2 knockout mice had reduced BMD. To begin to unravel the mechanism through which Asxl2 influenced BMD, a gene co-expression network was created using cortical bone gene expression microarray data from the HMDP strains. Asxl2 was identified as a member of a co-expression module enriched for genes involved in the differentiation of myeloid cells. In bone, osteoclasts are bone-resorbing cells of myeloid origin, suggesting that Asxl2 may play a role in osteoclast differentiation. In agreement, the knockdown of Asxl2 in bone marrow macrophages impaired their ability to form osteoclasts. This study identifies a new regulator of BMD and osteoclastogenesis and highlights the power of GWA and systems genetics in the mouse for dissecting complex genetic traits