NMR Studies of Inclusion Compounds

This thesis presents the application of some of the NMR methods in studying host-guest complexes, mainly in solution. The general focus of the work is on investigating the reorientational dynamics of some small molecules that are bound inside cavities of larger moieties. In the current work, these moieties belong to two groups: cryptophanes and cyclodextrins. Depending on the structure of the cavities, properties of the guest molecules and the formed complexes vary. Chloroform and dichloromethane are in slow exchange between the cage-like cavity of the cryptophanes and the solvent, on the chemical shift time scale, whereas adamantanecarboxylic acid, quinuclidine and 1,7-heptanediol in complex with cyclodextrins are examples of fast exchange. Kinetics and thermodynamics of complexation are studied by measuring exchange rates and translational self-diffusion coefficients by means of 1-dimenssional exchange spectroscopy and pulsed-field gradient (PFG) NMR methods, respectively. The association constants, calculated using the above information give estimates of the thermodynamic stability of the complexes. Carbon-13 spin relaxation data were obtained using conventional relaxation experiments, such as inversion recovery and dynamic NOE, and in some cases HSQC-type (Hetereonuclear Single Quantum Correlation Spectroscopy) experiments. Motional parameters for the free and bound guest, and the host molecules were extracted using different motional models, such as Lipari-Szabo, axially symmetric rigid body, and Clore models. Comparing the overall correlation times and the order parameters of the free and bound guest with the overall correlation time of the host molecule one can estimate the degree of the motional restriction, brought by the complexation, and the coupling between the motion of the bound guest and the reorientation of the host molecule. In one case, the guest motions were also investigated inside the cavities of a solid host material

Middle Ear Administration of a Particulate Chitosan Gel in an in vivo Model of Cisplatin Ototoxicity

Background: Middle ear (intratympanic, IT) administration is a promising therapeutic method as it offers the possibility of achieving high inner ear drug concentrations with low systemic levels, thus minimizing the risk of systemic side effects and drug-drug interactions. Premature elimination through the Eustachian tube may be reduced by stabilizing drug solutions with a hydrogel, but this raises the secondary issue of conductive hearing loss. Aim: This study aimed to investigate the properties of a chitosan-based particulate hydrogel formulation when used as a drug carrier for IT administration in an in vivo model of ototoxicity. Materials and Methods: Two particulate chitosan-based IT delivery systems, Thio-25 and Thio-40, were investigated in albino guinea pigs (n = 94). Both contained the hearing protecting drug candidate sodium thiosulfate with different concentrations of chitosan gel particles (25% vs. 40%). The safety of the two systems was explored in vivo. The most promising system was then tested in guinea pigs subjected to a single intravenous injection with the anticancer drug cisplatin (8 mg/kg b.w.), which has ototoxic side effects. Hearing status was evaluated with acoustically evoked frequency-specific auditory brainstem response (ABR) and hair cell counting. Finally, in vivo magnetic resonance imaging was used to study the distribution and elimination of the chitosan-based system from the middle ear cavity in comparison to a hyaluronan-based system. Results: Both chitosan-based IT delivery systems caused ABR threshold elevations (p < 0.05) that remained after 10 days (p < 0.05) without evidence of hair cell loss, although the elevation induced by Thio-25 was significantly lower than for Thio-40 (p < 0.05). Thio-25 significantly reduced cisplatin-induced ABR threshold elevations (p < 0.05) and outer hair cell loss (p < 0.05). IT injection of the chitosan- and hyaluronan-based systems filled up most of the middle ear space. There were no significant differences between the systems in terms of distribution and elimination. Conclusion: Particulate chitosan is a promising drug carrier for IT administration. Future studies should assess whether the physical properties of this technique allow for a smaller injection volume that would reduce conductive hearing loss

Human Dorsal Basal Ganglia Network.

<p>A dorsal basal ganglia network in the human brain was defined by placing a bilateral seed in Talairach coordinates in mm: +/-21; 0; 7. Top left image displays an axial, top right a sagittal and bottom image a coronal view of the human brain. Note the possitive FC-values of the bilateral putamen, as well as the supplementary motor area in the axial view, the unilateral sagittal view of putamen, and the coronal bilateral view of putamen. FC-values are displayed with a pseudo-colored scale bar; with increments of 0.2 each designated a color (see the color-bar in the image).</p

Human Ventral Basal Ganglia Network.

<p>A bilateral seed placed in Talairach coordinates in mm: +/-14; 5; -8 revealed the ventral basal ganglia network. Top left image displays an axial, top right a sagital and bottom image a coronal view of the human brain. Note the possitive FC-values of the bilateral nucleus accumbens in the axial view, the unilateral sagittal view of nucleus accumbens and the possitive FC-values in the caudate as well as putamen, and the coronal bilateral view of nucleus accumbens as well as lower possitive FC-values indicating a part of the ventromedial prefrontal cortical region. FC-values are displayed with a pseudo-colored scale bar; with increments of 0.2 each designated a color (see the color-bar in the image).</p

Education Nonprofit Organization: A Hierarchical Decision Modeling Tool for State Engagement Choice

Decision models can be useful in various industries. In this project, a hierarchical decision model (HDM) is employed to assist a nonprofit organization called “eKnow” that is concerned with improving high-speed internet access to American schools. When initially launched, eKnow’s engagement decisions were based on immediate opportunities and educational or political connections in particular states. Now, after having already worked a number of states, decision criteria have matured. Over the winter of 2017/2018, eKnow is working to identify which which states to enter next. The purpose of this study was to assist eKnow in their effort by helping to identify and define the most relevant decision criteria and then to use those criteria in an HDM-based prioritization of five states by subject matter experts at eKnow. This result is then available to assist decision makers move forward

Rat Seed Correlation Matrix.

<p>Note the high correlations between the somatosensory and motor regions as well as the high correlations between the seeds in the DMN. CPu = Caudatus Putamen, Acb = n. Accumbens, M1 = primary motor cortex, S1 = primary somatosensory cortex, RACC = Rostral Anterior Cingulate Cortex, DMN-Rost = PrL: Prelimbic Cortex DMN-Caud = Cg1: Cingulate Cortex, area 1. The values displayed are Fisher z-transformed correlation values.</p

Rat Dorsal Basal Ganglia Network.

<p>To define this network, a bilateral seed was placed at approximately Bregma in mm: +/-3.5; 4; -0.3. Axial rat brain images are sorted from left to right in rostral to caudal order. The images from the far left to the right all show bilateral positive FC-values bilateral caudate putamen and week positive FC-values in the rostral somatosensory cortex in the three images to the left. Note that all images also includes an anticorrelated caudal cingulate gyrus region. FC-values are displayed with a pseudo-colored scale bar; with increments of 0.2 each designated a color (see the color-bar in the image).</p

Rat Default Mode Network.

<p>When the bilateral seed was placed in the Rostral Anterior Cingulate Cortex approximately Bregma in mm: +/-0.5; 2.5; 1.7 the DMN was distinguished. Axial rat brain images are sorted from left to right in rostral to caudal order. The image to the far left shows positive color-coded FC-values in pre limbic cortex, infra limbic cortex, orbital cortex and cingulate cortex. The two middle images show positive FC-values in cingulate cortex, septal nuclei. Also, note the bilateral anticorrelated color-coded regions in the motor-sensory cortical region throughout the images. Note the lack of signal in hippocampus. FC-values are displayed with a pseudo-colored scale bar; with increments of 0.2 each designated a color (see the color-bar in the image).</p

Seed placement in rat for; DMN, motor network, dorsal basal ganglia network, and ventral basal ganglia network.

<p>Seed placement in rat for; DMN, motor network, dorsal basal ganglia network, and ventral basal ganglia network.</p

Human Seed Correlation Matrix.

<p>Note the high correlations between the somatosensory and motor regions as well as the high correlations between the prefrontal regions of the brain. Put = Putamen, NAcc = Nucleus Accumbens, PriMot = Primary Motor Cortex, PriSen = Primary Sensory Cortex, DMN = Posterior Cingulate Cortex, Put-BA6 = Brodmann Area 6 within the Putamen network DMN-PFC = Prefrontal Cortex within the DMN, NAcc-BA10 = Brodmann Area 10 within the ventral basal ganglia network. The values displayed are Fisher z-transformed correlation values.</p