Elimination of TFA-Mediated Cleavage in Distributed Drug Discovery

Distributed Drug Discovery (D3) is a multi-disciplinary approach to the discovery of new drugs, which target neglected diseases or conditions common to developing-world countries. As part of a continuing effort to improve D3 methodology, two approaches for eliminating the final step TFA-mediated resin cleavage are proposed for investigation. Cleavage under basic conditions (saponification) and mild acid conditions (dilute HCl/hexafluoroisopropanol or dilute HCl/trifluoroethanol) represent improvements in safety and convenience to the undergraduate student researcher. Previous studies have shown that saponification provides yields comparable to the traditional TFA cleavage but recovery is not as convenient. Further improvements in the saponification workup will be evaluated by analyzing the effectiveness of simple trituration with acetone compared to use of a strong anion-exchange resin or drying reagents to isolate the free acid from the salt. Different trituration procedural modifications have been made and are being tested. Results have shown that in the presence of methanol, esterification will occur when the acid is liberated from the salt using HCl. To counter this problem, the samples are first evaporated to remove methanol and then the pH is adjusted with HCl. It was shown that using acetic acid did not result in pH levels low enough to guarantee complete protonation of the carboxylate. Through the use of a Bill-Board, an apparatus that holds six reaction vessels, several procedural modifications can be carried out simultaneously. Analysis is conducted by liquid chromatography coupled with a mass spectrometer and with nuclear magnetic resonance spectroscopy. Further studies will be carried out to assess the efficiency and practicality of using mild acidic conditions for cleavage using HCl/hexafluoroisopropanol or dilute HCl/trifluoroethanol. Both saponification and mild acid cleavage would represent improvements in safety and convenience to the undergraduate student researcher

Adsorption and Dissociation of a Bicyclic Tertiary Diamine, Triethylenediamine, on a Si(100)-2 x 1 Surface

This study investigates the adsorption and thermal transformations of a bicyclic tertiary amine, triethylenediamine, on the clean Si(100)-2 × 1 surface. Below room temperature, triethylenediamine adsorption leads to the formation of a strong dative bond between one of the nitrogen atoms of this compound and the silicon surface. In contrast to previously studied amines, the datively adsorbed triethylenediamine features a second tertiary amine entity that is not bonded to the surface, with a lone pair orbital that is directed away from the surface and is available for further reactions. The thermal chemistry and electronic properties of triethylenediamine on silicon are studied using thermal desorption spectroscopy, infrared spectroscopy, and X-ray photoelectron spectroscopy. Near-edge X-ray absorption fine structure measurements are utilized to clarify the geometry of the adsorbates at room temperature. Density functional theory calculations are used to describe the binding geometry and electronic properties of the resulting surface species and the likely reaction paths at elevated temperatures

Phospholipid signaling in innate immune cells

Phospholipids comprise a large body of lipids that define cells and organelles by forming membrane structures. Importantly, their complex metabolism represents a highly controlled cellular signaling network that is essential for mounting an effective innate immune response. Phospholipids in innate cells are subject to dynamic regulation by enzymes, whose activities are highly responsive to activation status. Along with their metabolic products, they regulate multiple aspects of innate immune cell biology, including shape change, aggregation, blood clotting, and degranulation. Phospholipid hydrolysis provides substrates for cell-cell communication, enables regulation of hemostasis, immunity, thrombosis, and vascular inflammation, and is centrally important in cardiovascular disease and associated co-morbidities. Phospholipids themselves are also recognized by innate-like T cells, which are considered essential for recognition of infection or cancer, as well as self-antigens. This review will describe the major phospholipid metabolic pathways present in innate immune cells and summarize the formation and metabolism of phospholipids as well as their emerging roles in cell biology and disease

Saponification of N-Acylated L-Phenylalanine Wang and Merrifield Resins. Assessment of Cleavage Efficiency and Epimerization

poster abstractAs part of a continuing effort to modify Distributed Drug Discovery (D3) synthetic procedures to enhance safety and accommodate the limited resources available to students in developing-world countries, we have recently begun to examine alternatives to trifluoroacetic acid (TFA)-cleavage of amino acid derivatives from polystyrene-based resins. Cleavage of a representative example, N-(4-chlorobenzoyl)-L-phenylalanine, from both Wang and Merrifield resins was accomplished in thirty minutes at room temperature using 0.5M sodium hydroxide in methanol/tetrahydrofuran. In a side-by-side comparison with cleavage using TFA, results indicated that saponification from Wang resin was incomplete after thirty minutes. Experiments designed to examine separately the effect of reaction time, temperature, and concentration were performed and results will be presented. Additionally, investigations were performed to assess the degree of epimerization which had occurred during cleavage of Merrifield-bound L-phenylalanine acylated with both (R)- and (S)-mandelic acid. Results revealed a small but significant amount of epimerization (15:1 to 31:1 diastereomeric ratios) after a thirty-minute cleavage time at room temperature

Exchange Field Induced Magnetoresistance in Colossal Magnetoresistance Manganites

The effect of an exchange field on electrical transport in thin films of metallic ferromagnetic manganites has been investigated. The exchange field was induced both by direct exchange coupling in a ferromagnet/antiferromagnet multilayer and by indirect exchange interaction in a ferromagnet/paramagnet superlattice. The electrical resistance of the manganite layers was found to be determined by the absolute value of the vector sum of the effective exchange field and the external magnetic field.Comment: 5 pages, 4 figure

LIPID MAP: Serving the next generation of lipid researchers with tools, resources, data and training

Lipids are increasingly recognized as dynamic, critical metabolites affecting human physiology and pathophysiology. LIPID MAPS is a free resource dedicated to serving the lipid research community

An investigation into minichromosomal maintenance proteins (MCMs) for the diagnosis of prostate cancer, as a possible alternative to prostate specific antigen (PSA)

The current strategy for the diagnosis of prostate cancer includes serum prostate specific antigen (PSA) measurement. There is however debate into its specificity and sensitivity, so new diagnostic markers are under investigation. Minichromosomal maintenance proteins (MCMs) are potential markers for the diagnosis of neoplasia, as they are involved in cellular replication. The aim of this study is to assess MCM2, 5 and 7 as new diagnostic markers for prostate cancer, to compare the clinical usefulness of PSA and to develop a less invasive technique for diagnosis. PSA specificity was investigated in several human cellular lines, and a clinical study was performed to assess expression in prostatic tissue and blood serum. MCM2, 5 and 7 was investigated by translational and transcriptional means in two prostate cell lines PNT1A and PC-3. In addition, a clinical study was performed to assess the expression of MCM2, 5 and 7 in prostate tissue, urine and blood The results suggest that PSA is not prostate specific, as it is synthesised and secreted by several non-prostatic cell lines. In addition PSA testing does not conclusively indicate neoplastic tissue and serum testing only has 63% sensitivity and 60% specificity in accurately identifying prostate cancer. The in vitro results suggest that the PC-3 cells express less MCM2, 5 and 7 on both the protein and mRNA level compared to the PNT1A cells, suggesting that MCM2, 5 and 7 maybe performing a bigger role than just replication of DNA. The tissue results indicate that there is an increase in MCM2, 5 and 7 epithelial nuclei staining for neoplastic condition compared to BPH. While the clinical study on urine sediment indicates increased MCM2, 5 and 7 staining in prostatic neoplasia compared to BPH and the transcriptional study on MCM5 can identify neoplastic tissue from BPH as 11/12 cancerous patients expressed MCM5 compared to only 3/23 BPH patients. Finally the transcriptional study on the blood samples is inconclusive and need to be repeated These results suggest that serum PSA testing is not ideal for the diagnosis of prostate cancer, that MCM2, 5 and 7 appear to have potential as new diagnostic markers and may aid the histopathologist to allocate Gleason score. Also the MCMs may have potential in the development of a less invasive technique through the use of urine sediment.EThOS - Electronic Theses Online ServiceGBUnited Kingdo