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Supplementary Material Available: Table I11 listing values of kinetic and thermodynamic parameters for chosen values of K , and K2 (1 page). Ordering information is given on any current masthead page. calculated using r = r+, only a rough (order of magnitude) correspondence was to be expected from the above calculation, whose virtue is only to reassure that a AVof the order 1-100 cm3/mol can be predicted by a model based only on electrostatic premises.Single-determinant, SCF 6-3 IG**/6-3 IC calculations are reported for meta-and para-protonated substituted benzenes, [Ph-X]H+, with X = OH, F, H, and CN. Assuming that the protonation energies relative to X = H provide a relative measure of the energy of activation for electrophilic substitution, these calculations, together with those for the parent species, predict OH to be para directing and activating, F to be para directing but not activating, and CN to be meta directing and deactivating. The results are interpreted in terms of the changes in the energies, charges, first moments, and quadrupolar polarizations of the atoms that accompany the formation of the arenium ion intermediates. The perturbation of the charge distribution of benzene caused by a replacement of H by a +M or -M substituent is as anticipated in terms of the corresponding classical resonance structures. However, the actual response of these same groups to the charge requirements of forming the protonated intermediates is overriding and just the opposite, the +M substituents not donating charge to the ring but polarizing toward it and the -M substituents donating charge to the ring and polarizing away from it. The pattern of charge alternation and changes in other properties of the ring carbon atoms is a function not of the substituent but of the position of the carbon atom relative to the site of protonation, a position that determines its identity in the pentadienyl fragment of the intermediate, the dominant factor in determining its properties. The para-directing substituent OH lowers the energy of activation by increasing the transfer of electronic charge from the pentadienyl fragment to the newly formed C-H bond, the substituent itself being stabilized.

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Recent epidemiological studies have revealed that Porphyromonas gingivalis, a major pathogen in periodontal disease, is associated with the development of oral squamous cell carcinoma (OSCC). However, the underlying mechanisms induced by P. gingivalis have not been well-defined. We aimed to determine the role of P. gingivalis in OSCC proliferation and the relevant molecular mechanisms. A cellular proliferation model of OSCC Tca8113 cells infected by P. gingivalis at a multiplicity of infection (MOI) of 50 was established. Cell proliferation was drastically increased in the infected cells compared with the control cells, while the proportion of cells in S phase was increased and the proportion of cells in G1 phase was decreased in the infected cells compared with the control cells. Additionally, the levels of activator protein 1 (AP-1; c-Jun and c-Fos) and its target gene cyclin D1 were increased in P. gingivalis-infected Tca8113 cells compared with control cells. miR-21 expression was elevated when programmed cell death 4 (PDCD4) expression was downregulated. Cyclin D1 expression was regulated by miR-21, PDCD4, and AP-1. The disruption of the pathway by silencing c-Jun, blocking miR-21 expression, or overexpressing PDCD4 led to decreased cyclin D1 expression and inhibited cell proliferation. P. gingivalis DNA levels were positively correlated with miR-21 and c-Jun expression and negatively correlated with PDCD4 expression in clinical OSCC samples. Our findings indicated that P. gingivalis might promote OSCC proliferation by regulating cyclin D1 expression via the miR-21/PDCD4/AP-1 negative feedback signaling pathway.

Purpose Mounting fiscal constraints and increasing complexity of public services have led governments to search for alternative service delivery mechanisms. The public–private partnership (PPP) is one type of service arrangement in which the public and private sectors enter into a long-term cooperative relationship for the purpose of delivering a public good or service. Despite increasing private sector participation in developing nations, there is a need for more systematic assessment of PPPs in such countries. The purpose of this paper is to explore the factors that affect the adoption and implementation of projects in the context of developing countries. Design/methodology/approach A multiple case holistic design is employed to analyze 19 select projects across several developing countries to identify and pool clusters of variables that facilitate or impede PPPs. Findings The results indicate five broad categories of political, economic, legislative, financial and management requisites. Research limitations/implications A limitation of this research is that the cases were not selected at random. However, the projects are spread across several areas such as public health, public utilities, public works, transportation and water/wastewater infrastructure in different countries. This allows the authors to examine how the common factors apply across different contextual settings. Originality/value This paper seeks to contribute to the literature by examining several developing countries to identify and pool clusters of variables that facilitate or impede the effective implementation of PPP projects in the context of such regions.