Comparison of the Molecular Structures of Monovalent Cation Salets of N,N-Dimethyldithiocarbamate. Novel Synthesis and Crystal Structure of (Phi4)(S2CN(CH3)2)2H2O

Crystals of the tetraphenylphosphonium N,N-dimethyldithiocarbamate dihydrate (C₂₇H₃₀NO₂PS₂; F.W. = 495.6) are monoclinic; P2₁/n; a = 13.349(6), b = 20,968(6), c = 9.800(4) Å, β = 109.01(3)°; Z = 4; V = 2593.4(16) Å^3; Dₓ = 1.269 gcm- 3 . Data were collected at ambient temperature using MoKα radiation (λ = 0.71069 Å).F(000) = 1048, linear absorption coefficient, n = 2.80 cm- 1. The structure was solved by direct methods and subsequently refined by full matrix least squares techniques. Final R value = 0.064 for 1 61 0 reflections and 298 varied parameters. Due to the nature of the cation, interactions between the tetraphenylphosphonium group and the sulfur atoms of the anion are absent, unlike previous dimethyldithiocarbamate structures (Na+, Cs+, TI+). Intermolecular interactions between the waters of hydration and the anion are present

Recovery of Prostacyclin Production by De-endothelialized Rabbit Aorta CRITICAL ROLE OF NEOINTIMAL SMOOTH MUSCLE CELLS

A B S T R A C T Prostacyclin (PGI2) synthetic capacity was assayed at the surface of aortas at various intervals after removal of endothelium with a balloon catheter. Results were correlated with morphologic changes in the vessel wall seen by light microscopy, scanning and transmission electron microscopy. To assay PGI2 synthetic capacity, we applied an incubation chamber to the luminal surface of the aortas; after arachidonic acid stimulation we assayed the PGI2 synthesized with a bioassay and radioimmunoassay. PGI2 synthesis in deendothelialized aortas was determined immediately after balloon-catheter injury and at intervals of 1 h and 2, 4, 15, 35, and 70 d. PGI2 synthesis was low at 1 h and increased over time with levels at 35 and 70 d reaching that of normal artery. Scanning and transmission electron microscopy of de-endothelialized areas showed persistent absence of endothelium with formation of a neointima composed of smooth muscle cells. De-endothelialized aorta was covered with adherent platelets shortly after injury, however several days later only a few platelets adhered to the denuded surface. Results indicated that (a) endothelium is responsible for nearly all PGI2 production at the luminal surface of the normal aorta, (b) de-endothelialized muscular neointima synthesized increasing quantities of PGI2 with time after injury, and (c) increase of PGI

Tetrahydropyrazolo[1,5-a]Pyrimidine-3-Carboxamide and N-Benzyl-6′,7′-Dihydrospiro[Piperidine-4,4′-Thieno[3,2-c]Pyran] analogues with bactericidal efficacy against Mycobacterium tuberculosis targeting MmpL3

Mycobacterium tuberculosis is a major human pathogen and the causative agent for the pulmonary disease, tuberculosis (TB). Current treatment programs to combat TB are under threat due to the emergence of multi-drug and extensively-drug resistant TB. As part of our efforts towards the discovery of new anti-tubercular leads, a number of potent tetrahydropyrazolo[1,5-a]pyrimidine-3-ca​rboxamide(THPP) and N-benzyl-6′,7′-dihydrospiro[piperidine-4,​4′-thieno[3,2-c]pyran](Spiro) analogues were recently identified against Mycobacterium tuberculosis and Mycobacterium bovis BCG through a high-throughput whole-cell screening campaign. Herein, we describe the attractive in vitro and in vivo anti-tubercular profiles of both lead series. The generation of M. tuberculosis spontaneous mutants and subsequent whole genome sequencing of several resistant mutants identified single mutations in the essential mmpL3 gene. This ‘genetic phenotype’ was further confirmed by a ‘chemical phenotype’, whereby M. bovis BCG treated with both the THPP and Spiro series resulted in the accumulation of trehalose monomycolate. In vivo efficacy evaluation of two optimized THPP and Spiro leads showed how the compounds were able to reduce >2 logs bacterial cfu counts in the lungs of infected mice

Advancement of Passive Sampling Applications for Assessing Contaminant Transport, Bioaccumulation, and Toxicity

In the environment, it is the unbound fraction of chemical (Cfree) which is able to diffuse across environmental interfaces and biological membranes. It is therefore Cfree which drives many important biological-environmental processes including contaminant transport, bioaccumulation and toxicity. Passive sampling devices (PSDs) offer a simplified and more accurate approach for measuring Cfree compared to traditional methods. The chapters of this dissertation extend the applications of passive sampling for answering questions related to the transport, bioaccumulation, and toxicity of contaminants, specifically polycyclic aromatic hydrocarbons (PAHs). In Chapter 1, using PSDs, we measured the diffusive flux of PAHs between sediment, water, and air at the Portland Harbor Superfund site (PHSS). Data indicated that modern (atmospheric) sources of 2- and 3-ring PAHs were more significant than legacy (sediment) sources. Additionally, the data pointed toward PHSS sediments as potential atmospheric sources of 4-ring and larger PAHs through diffusion. This result may have significant health risk implications for those living near the PHSS and other contaminated sites. Ultimately, data generated by this study was used to make a regulatory decision at the McCormick and Baxter Superfund site, highlighting the growing acceptance and applicability of passive sampling devices. Transport of contaminants may lead to exposure and bioaccumulation in humans and organisms. When organisms are consumed by humans, measuring bioaccumulation of contaminants in those organisms is essential for assessing human health risk. This is especially true for subsistence consumers who have elevated ingestion rates including Native American tribes. Traditional predictive methods for bioaccumulation in benthic organisms are often inaccurate because of reliance on poorly characterized and understood site specific sediment characteristics. Passive sampling devices directly measure Cfree and therefore inherently account for these site specific differences. In Chapter 2, sediment PSDs were used to build a model for predicting PAH concentrations in traditionally harvested clams on Native American tribal land in the Puget Sound region of the Salish Sea. The model was able to predict PAH concentrations in butter clams (Saxidomus giganteus) within a factor of 1.9 ± 0.2. This model will provide a more accurate and simplified method to monitor PAH concentrations in clams without having to remove clams from the environment. Additionally, data from this study highlighted spatial differences in carcinogenic risk associated with the consumption of clams and was used to inform local communities. Bioaccumulation of PAHs may result in health effects if the PAHs are toxic. In the environment PAHs exist as mixtures and it is therefore essential to consider the toxicity of relevant environmental PAH mixtures. There is growing evidence for developmental effects (morphological and neurological) from PAH exposure. In Chapter 4, data from passive sampling devices deployed in surface water at the PHSS was used to construct a surrogate mixture of the 10 most abundant PAHs (Supermix10). Using the zebrafish model, we assessed the developmental toxicity of Supermix10 (SM10), its toxic (Supermix3) and non-toxic (Supermix7) sub-fractions, and the 10 individual PAHs. Data indicated that the general additivity model may be sufficient for explaining the overall developmental effects caused by these PAH mixtures. However, we showed that individual PAH toxic endpoints may not be predictive of the toxic endpoints in PAH mixtures. Finally, SM10 caused behavioral effects in adult fish following exposure during development at concentrations below those which caused overt morphological effects. Ultimately the work in this dissertation advances the application of passive sampling technologies toward a better understanding of PAH transport, bioaccumulation, and toxicity

Environmental and Plant-Derived Controls on the Seasonality and Partitioning of Soil Respiration in an American Sycamore (<i>Platanus occidentalis)</i> Bioenergy Plantation Grown at Different Planting Densities

Bioenergy is one of the most considered alternatives to fossil fuels. Short-rotation woody crops (SRWCs) as bioenergy sources are capable of alleviating energy constraints and sequestering atmospheric CO2. However, studies investigating soil carbon (C) dynamics at SWRC plantations are scarce. We studied American sycamore (Platanus occidentalis) as a model tree species for SRWC at different planting densities ((1) 0.5 × 2.0 m (10,000 trees·ha−1 or tph), (2) 1.0 × 2.0 m (5000 tph), and (3) 2.0 × 2.0 m (2500 tph)) to examine seasonal variation in total soil respiration (Rtotal), partitioned into heterotrophic (Rh) and autotrophic (Ra) respiration, and we evaluated climatic and biological controls on soil respiration. Rtotal and Rh exhibited larger seasonal variation than Ra (p total was 0.60 ± 0.21 g·C·m−2·day−1 in winter and 1.41 ± 0.73 g·C·m−2·day−1 in fall. During the growing season, Rtotal was 2–7 times higher in spring (3.49 ± 1.44 g·C·m−2·day−1) and summer (4.01 ± 1.17 g·C·m−2·day−1) than winter. Average Rtotal was 2.30 ± 0.63 g·C·m−2·day−1 in 2500 tph, 2.43 ± 0.64 g·C·m−2·day−1 in 5000 tph, and 2.41 ± 0.75 g·C·m−2·day−1 in 10,000 tph treatments. Average Rh was 1.72 ± 0.40 g·C·m−2·day−1 in 2500 tph, 1.57 ± 0.39 g·C·m−2·day−1 in 5000 tph, and 1.93 ± 0.64 g·C·m−2·day−1 in 10,000 tph, whereas Ra had the lowest rates, with 0.59 ± 0.53 g·C·m−2·day−1 in 2500 tph, 0.86 ± 0.51 g·C·m−2·d−1 in 5000 tph, and 0.48 ± 0.34 g·C·m−2·day−1 in 10,000 tph treatments. Rh had a greater contribution to Rtotal (63%–80%) compared to Ra (20%–37%). Soil temperature was highly correlated to Rtotal (R2 = 0.92) and Rh (R2 = 0.77), while the correlation to Ra was weak (R2 = 0.21). Rtotal, Rh, and Ra significantly declined with soil water content extremes (e.g., 50%). Total root biomass in winter (469 ± 127 g·C·m−2) was smaller than in summer (616 ± 161 g·C·m−2), and the relationship of total root biomass to Rtotal, Rh, and Ra was only significant during the growing seasons (R2 = 0.12 to 0.50). The litterfall in 5000 tph (121 ± 16 g DW·m−2) did not differ (p > 0.05) from the 2500 tph (108 ± 16 g DW·m−2) or 10,000 tph (132 ± 16 g DW·m−2) treatments. In no circumstances were Rtotal, Rh, and Ra significantly correlated with litterfall amount across planting densities and seasons (p > 0.05). Overall, our results show that Rtotal in American sycamore SRWC is dominated by the heterotrophic component (Rh), is strongly correlated to soil environmental conditions, and can be minimized by planting at a certain tree density (5000 tph)