Nanotherapies for Treating Prostate Cancer

Current prostate cancer treatment remains ineffective primarily due to ineffectual therapeutic strategies and numerous tumor-associated physiological barriers which hinder efficacy of anticancer agents. Therefore, the focus of this study was to investigate a new combination therapy approach for treating prostate cancer and develop polymeric nanocarriers to facilitate anticancer drug and nucleic acid delivery. It was hypothesized that simultaneously targeting androgen-androgen receptor (AR) and X-linked inhibitor of apoptosis protein (XIAP) signaling pathways would be effective in treating prostate cancer. The effect of bicalutamide (antiandrogen) and embelin (XIAP inhibitor) on the growth of prostate cancer cells in vitro and in vivo was first examined. Embelin induced caspase 3 and 9 activation in LNCaP and C4-2 cells by decreasing XIAP expression and was more potent than bicalutamide in killing prostate tumor cells irrespective of their androgen status. Using a combination of MTT assay and isobologram analyses, combination of bicalutamide and embelin was observed to be cell line and schedule dependent. Since bicalutamide and embelin are extremely hydrophobic, polymeric micelles were fabricated using polyethylene glycol-bpolylactic acid (PEG-b-PLA) copolymer to improve drug solubility. Micellar formulations were found to result in at least 60-fold increase in the aqueous solubility of bicalutamide and embelin. Tumor growth was also effectively regressed upon treatment with bicalutamide, but the extent of tumor regression was significantly higher when bicalutamide was formulated in micelles. To further improve bicalutamide aqueous solubility, a series of novel biodegradable copolymers for the systematic micellar delivery of bicalutamide was designed and synthesized. Flory-Huggins interaction parameter (χFH) was used to assess compatibility between bicalutamide and poly (L-lactide) or poly (carbonate-co-lactide) polymer pairs. Polyethylene glycol-b-poly (carbonate-co-lactide) [PEG-b-P(CB-co-LA)] copolymers were synthesized and characterized by NMR and gel permeation chromatography. Micelles formulated using these copolymers had average diameter of 100 nm and distinct spherical shape. Drug loading studies revealed that adding the carbonate monomer could increase bicalutamide loading. Among the series, drug loading of micelles formulated with PEG-b-P(CB-co-LA) copolymer containing 20 mol% carbonate was about four-fold higher than PEG-b-PLLA and aqueous solubility of bicalutamide increased from 5 to 4000 µg/mL. CMC values for PEG-b-P(CB-co-LA) copolymers was up to 10-fold lower than those of PEG-b-PLLA. Bicalutamide-loaded PEG-bP(CB-co-LA) micelles showed significant inhibition of LNCaP cell growth in a dose dependent manner which was similar to the methanol solution of free drug. Bicalutamide tends to act as an agonist rather than an antagonist after prolonged treatment. Hence, a second generation antiandrogen ((S)-N-(4-cyano-3-(trifluoromethyl) phenyl)-3-((4-cyanophenyl)(methyl)amino)-2-hydroxy-2-methylpropanamide) (CBDIV17)) was synthesized and its effect in combination with XIAP inhibitors for treating advanced prostate cancer was determined. CBDIV17 was more potent than bicalutamide and inhibited proliferation of C4-2 and LNCaP cells. CBDIV17-induced apoptosis more effectively compared to bicalutamide and significantly inhibited DNA replication. Combination of CBDIV17 and embelin resulted in supra-additive antiproliferative and apoptotic effects. Embelin downregulated AR expression and decreased androgen-mediated AR phosphorylation at Ser81. These hydrophobic drugs were solubilized using micelles prepared using polyethylene glycol-b-poly (carbonate-co-lactide) (PEG-b-p(CB-co-PLA)) copolymer. Combination therapy inhibited prostate tumor growth more effectively compared to control or monotherapy in vivo. Polymeric micelles tend to be unstable in vivo. To address this, lactic acid- and carbonate-based biodegradable core- and core-corona crosslinkable copolymers for anticancer drug delivery were synthesized and evaluated. Methoxy poly (ethylene glycol)-b-poly (carbonate-co-lactide-co-5-methyl-5-allyloxycarbonyl-1,3-dioxane-2-one) [mPEG-b-P(CB-coLA-co-MAC)] and methoxy poly (ethylene glycol)-b-poly(acryloyl carbonate)-b-poly (carbonate-co-lactide) [mPEG-b-PMAC-b-P(CB-co-LA)] copolymers were synthesized by ring opening polymerization of LA, CB and MAC using mPEG as an macroinitiator and 1,8- diazabicycloundec-7-ene (DBU) as a catalyst. These amphiphilic copolymers which exhibited low polydispersity (1.08) and CMC values (0.8-1 mg/L) were used to prepare micelles with or without drug and stabilized by crosslinking via radical polymerization of double bonds introduced in the core and interface to improve stability. 1 H NMR and IR spectroscopy confirmed successful crosslinking (crosslinking efficiency of ~70%) while light scattering and transmission electron microscopy were used to determine micelle size and morphology. Crosslinked micelles demonstrated enhanced stability against extensive dilution with aqueous solvents and in the presence of physiological simulating serum concentration. Since nucleic acids are not susceptible to chemoresistance, it was determined whether simultaneous AR and XIAP gene silencing via RNA interference (RNAi) has the potential to treat hormone refractory prostate cancer. Small interfering RNAs (siRNAs) targeting three different regions of AR and XIAP were screened by transfecting LNCaP and C4-2 prostate cancer cells and their silencing effects determined at mRNA and protein levels by real time RTPCR, Western blot and ELISA. The most potent siRNAs against AR and XIAP were selected and their combination was more effective in inducing apoptosis and inhibiting C4-2 cell proliferation. N-(2-hydroxypropyl) methacylamide (HPMA) based copolymer containing polycationic, lipid and pka modulator moieties was developed for delivering the most potent siRNA and bipartite plasmid encoding two different shRNAs targeting AR and XIAP. HPMA based copolymer showed efficient cellular uptake in prostate cancer cells. The findings reported in this work demonstrate the potential benefit of combination therapy targeting AR and XIAP pathways for treating prostate cancer using polymeric nanocarriers. Systematic chemical tailoring of polymers for improving drug loading as well as efforts made to improve micelle stability through crosslinking also generated insights which can be applied to other drugs and cancer types. Results reported in this study therefore offer a new way of addressing the time old problem of treating cancer

Productivity growth, human capital and distance to frontier in Sub-Saharan Africa

Using the Malmquist productivity index and panel data methods, we study the role of total human capital and its composition in the technological "catch-up" process and productivity growth via the channels of innovation and adoption of technology in a panel of 19 sub -Saharan African countries between 1960 and 2003. Our findings indicate different roles played by the composition of human capital and a follow-on consistent and significant contribution of total human capital to productivity growth. Primary and secondary school attainment (unskilled labour) contribute significantly to the adoption of technology(the main source of productivity growth in sub-Saharan Africa) whilst tertiary school attainment (skilled labour) plays a significant role in local innovation. Total human capital on the other hand, contribute more significantly to the adoption of technology and innovation. Technological "catch-up" remains a significant element in productivity growth in sub-Saharan Africa and economies with higher tertiary school attainment(skilled labour) and higher total human capital tend to contribute significantly to productivity growth through the channel of technological "catch-up". Our results rather point towards a circuitous depiction of the symbiotic characteristics of the composition of human capital in enhancing productivity growth in sub-Saharan Africa and hence efforts in scaling- up investments in human capital by governments, development partners etc should not be too concentrated on one composition of human capital. --Productivity growth,Human capital,Sub-Saharan Africa

Sorption of phenolics by framework materials containing β-cyclodextrin

This MSc thesis research is divided into two projects; (1) synthesis and characterization of non-porous Templated (T-) and Non-Templated (NT-) β-Cyclodextrin-Epichlorohydrin polymers to yield globular and linear sorbents for the sorption of para-nitrophenol (PNP) and trinitrophenol (TNP) and phenolphthalein (Phth); and (2) synthesis and characterization of porous framework polymer and fluorescent-based porous framework polymers for sorption of PNP, TNP and Phth and the detection of TNP (a nitroaromatic explosive compound) in aqueous solution. T- and NT- cross-linked materials containing β-cyclodextrin (β-CD) and epichlorohydrin (EPH) were prepared at variable β-CD: EPH ratios (1:15, 1:20, and 1:25) in the presence and absence of a molecular template (toluene). The structural characterization of the materials was carried out using spectroscopy (FT-IR, solids 13C NMR, and SEM) and thermogravimetric analysis (TGA). The adsorption properties were studied using phenolic dyes (TNP; 2,4,6-trinitrophenol and PNP; p-nitrophenol) as probes at equilibrium and kinetic conditions. The Sips model provided estimates of the monolayer adsorption capacity (Qm) for the T- and NT-polymers. The Qm value for T-polymer/TNP complex ranged from 0.0953 to 0.952 mmol/g, while the NT- materials had Qm values that ranged from 0.231 to 0.827 mmol/g. The Qm values for the T-polymer/ PNP systems ranged from 0.263 to 0.616 mmol/g, while the Qm values for the NT-polymer/ PNP systems were 0.234 to 0.399 mmol/g. T-polymers with greater EPH content had higher dye uptake over NT-polymers. The pseudo-second order (PSO) and pseudo-first order (PFO) kinetic models were used to evaluate the uptake properties of the polymer/phenolphthalein (phth) systems. The PSO model provided a satisfactory fit to the experimental results with a sorption capacity ranging from 40 to 60 mmol/g, whereas; estimates of the β-CD inclusion site accessibility of the polymer materials was variable (15-20 %). Porous framework polymers (PFP) containing binary components (β-CD-diisocyanate) and fluorescent-based polymer (FL-PFP) with a ternary composition polymer system (βCD- diisocyanate-tetrakis(4-hydroxyphenyl) ethene were synthesized. FT-IR spectroscopy, thermal gravimetric analysis (TGA) and solid-state 13 C NMR spectral measurements were used to confirm polymer structure. The determination of β-CD inclusion site accessibility using phenolphthalein showed that the PFP and FL-PFP had β-CD inclusion site accessibility values of 24% and 19% respectively. By comparison, nitrogen gas adsorption revealed that the surface area of the materials was estimated at 100 to 250 m2/g while carbon dioxide gas adsorption ranged from 5.5 to 20 m2/g. The uptake of TNP in aqueous solution (pH 4.5) was investigated with PFP and FL-PFP. PFP showed a greater uptake of TNP than FL-PFP with equilibrium TNP sorption capacities of 0.831 mmol/g and 0.341 mmol/g respectively. The dual-function of FL-PFP, the TNP detection and removal was exploited using quantum yield and lifetime measurements. FL-PFP showed a lifetime decay response to variable concentrations of TNP. The quantum yield of FL-PFP was estimated to be 0.399 and a detection limit of TNP at 50 nM signifying the sensitivity of FL-PFP. With the advantage of synthesis, high surface area, and high sensitivity, the β-CD-EPH and β-CD-PU polymers provide a promising candidate for the detection and removal of PNP and TNP from aqueous media

Genotype × Environment Interaction: A Prerequisite for Tomato Variety Development

Tomato (Solanum lycopersicum L.) is the second most important vegetable crop in the world due to its high level of nutrition particularly in vitamins and antioxidants. It is grown in several ecologies of the world due to its adaptability and ease of cultivation. Besides field conditions, tomatoes are grown in controlled environments which range from hydroponics and simple high tunnel structures to highly automated screen houses in advanced countries. However, the yield and quality of the fruits are highly influenced by the environment. This results in unpredictable performances in different growing environments in terms of quality, a phenomenon known as genotype by environment (G × E) interaction which confounds selection efficiency. Various approaches are employed by plant breeders to evaluate and address the challenges posed by genotype by environment interaction. This chapter discusses various field and controlled environments for growing tomatoes and the effect of these environments on the performance of the crop. The various types of genotype × environment interactions and their effect of the tomato plant are discussed. Finally, efforts are made to suggest ways and methods of mitigating the confounding effects of genotype × environment interaction including statistical approaches

Review on Tomato (Solanum lycopersicum, L.) Improvement Programmes in Ghana

Tomato is an important component of every Ghanaian meal, and its cultivation contributes significantly to livelihood improvement. The demand for tomato in Ghana outstrips supply, and therefore local production is augmented by imports from neighbouring countries. Despite the importance of tomato in Ghana, past tomato-breeding programmes have been unsystematic and had not led to the development of new varieties that meet the needs of consumers as well as environmental stresses. This review outlined tomato production trends, constraints and past tomato improvement programmes in Ghana, which mainly focused on germplasm collection, morphological and agronomic characterization, molecular evaluation, diversity study, as well as screening germplasm against biotic and abiotic stresses. The established variability and the outcomes of the evaluations against the various biotic and abiotic stresses have not been utilized in the development of new varieties. This work will serve as a reference for developing future tomato-breeding programmes

Marker-Assisted Selection (MAS): A Fast-Track Tool in Tomato Breeding

Marker-assisted selection (MAS) is a complementary tool for conventional breeding where a molecular marker linked to a trait is indirectly selected. Many studies conducted have been able to identify and develop markers for traits such as disease and pest resistance and other abiotic stresses. Despite the availability of these markers, the technology has been extensively used in tomato breeding for the identification of some economic traits in particular disease resistance. In developed countries, MAS is utilized routinely in breeding programs, but this cannot be said for developing countries such as Africa. It is high time Africa as a continent looks at the importance of the technology and invests in it. In addition to MAS, other strategies such as marker-assisted backcrossing and recurrent selection have also been employed for breeding in tomato. The use of MAS in crop improvement will not only reduce the cost of developing new tomato varieties but will also increase the precision and efficiency of selection in the breeding program as well as lessen the number of years required to come up with a new crop variety

Subnational governance in Ghana: a comparative assessment of data and performance

In this chapter, we conceptualise an ideal framework that captures three reinforcing levers for measuring local government performance in sub-Saharan Africa, specifically Ghana, namely policy pronouncement, political processes and internal operations, and policy implementation. Given data limitations we employ a ‘next best’ approach to apply this framework and measure local government performance by combining a weighted ‘quality of reporting’ measure with selected available measures on political processes and internal operations, and policy implementation, so as to construct a composite index for local government performance (LGI). We also look at the relationship between our performance indices and other indices of local government performance in Ghana, as well as poverty headcounts. We find that, on average, urban districts perform better than their rural counterparts and also districts located in the southern half of Ghana perform better. Our constructed composite index is positively correlated with indices from Ghana’s district league tables. It has a negative relationship with poverty headcount in districts, indicating that districts with lower poverty incidence are more effective and responsive to their citizens. The findings provide a snapshot of institutional performance across Ghana’s districts, and offer a more comprehensive basis for considering variations in subnational institutional performance, including the effects of decentralisation than previous studies of Ghana – or indeed African countries more broadly