Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

published_or_final_version / Zoology / Master / Master of Philosophy

Thesis (M. Phil.)--University of Hong Kong, 1998. / Cover title. Includes bibliographical references (leaves 169-192).

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Microbiology and Molecular Genetics." Includes bibliographical references (p. 56-60).

The synthesis of analogs of toxoflavin: 1,3,4,6-tetramethyl-1,5,6, 7-tetrahydropyrimido[4,5-c]-5,7-pyridazinedione; 1,6-dimethyl-3,4-diphenyl-1,5,6,7-tetrahydropyrimido[4,5-c]-5,7-pyridazinedione; 3,5,7-trimethyl-8-phenyl-2,3,4,8-tetrahydropyrido[2,3-d]-2,4-pyrimidinedione are discussed. The synthesis of analogs of fervenulin: 3,4,6-trimethyl-5,6,7,8-tetrahydropyrimido[4,5-c]-5,7-pyridazinedione; 6-methyl-3,4-diphenyl-5,6,7,8-tetrahydropyrimido[4,5-c]-5,7-pyridazinedione; 2-hydroxy-3,5,7-trimethyl-4(3H)pyrido[2,3-d]-2,4-pyrimidinone are discussed. Several intermediates have been prepared: 6 -methylamino-3-methyluracil by a new method; 6-n-propylamino-3-methyluracil: 6-n-butylamino-3-methyluracil and 3-ethyl-2-ethylthio-2-hydroxy-4(3H)pyrimidinone.

M.Sc. (Nanoscience) / Ochratoxin A and Aflatoxin B1 are important food contaminates as they are known to be mutagenic, genotoxic, nephrotoxic, hepatotoxic, immunosuppressive and teratogenic to both animals and humans. These mycotoxins are associated with the contamination of food stuff such as grapes, maize, red pepper, meat, milk, beans and processed products from contaminated raw material. Current physical, biological and chemical methods employed to improve the safety of food often compromise the nutritional value and result in huge losses. The alternative to these treatments are addition of supplements with protective properties to reduce the toxicity of mycotoxins or prevent their formation. The work presented in this dissertation reports an attempt to develop such materials to prevent damage caused by ochratoxin A and aflatoxin B1. This was done through the synthesis; characterisation and cytotoxicity study of chitosan nanoparticles with methanolic plant extracts (L. leonurus, M. longifolia and A. montanus). Inhibition of cellular damage due to mycotoxins for possible application in prevention of cellular damage by mycotoxins also presented. Chitosan nanoparticles were synthesised using an ionic gelation method with sodium triphosphate as the cross linker. The methanolic medicinal plants extracts were incorporated into the chitosan solution before synthesising nanoparticles, and nanoparticle synthesis initiated by the addition of sodium triphosphate solution. The synthesised products were characterised using zetasizer, transmission electron microscopy, x-ray diffraction and Fourier-transform infrared spectroscopy. The extracts’ antioxidant ability was evaluated before incorporation into chitosan using 2, 2-diphenyl- 1-picrylhydrazy (DPPH) radical scavenging assay. This assay was performed using UVvis spectroscopy. The cytotoxicity of the synthesised nanoparticles was assessed using a Vero cell line and by evaluating the cell viability with an MTS assay. The nanoparticles were successfully synthesised and showed the presence of different functional groups as expected. Plain chitosan nanoparticles were roughly spherical shaped and had smooth surfaces, nanoparticles containing extracts similarly were spherical in shape as well but had rougher surfaces when visualised under TEM. All nanoparticles had positive zeta potentials between 26 – 28 mV. The average particle sizes ranged between 31 – 65 nm as measured using TEM and average particle sizes obtained using zetasiser was 78 – 190 nm. The cytotoxicity studies of plain nanoparticles and nanoparticles with extract showed that the synthesised nanomaterials were not toxic even at concentration of 500 μg/ml and less than 20% of the Vero cells were affected under these conditions.

Biological weapons have the ability to inflict mass casualties while keeping existing infrastructure intact. They are inexpensive to manufacture, difficult to detect, and have a low signature for attribution. In the 1970s, the Soviet Union began amassing the largest stockpile of biological weapons worldwide. The U.S. Intelligence community repeatedly failed to detect the scope and character of this large-scale Soviet development effort despite implausible explanations for outbreaks of unexplained disease, credible ground reports from informants, and strange behavior patterns viewed through reconnaissance efforts. Toward the end of the Cold War, the U.S. Intelligence realized its grave error. Unfortunately, the majority of these weapons are unaccounted for today. By examining the reasons the Soviet Unionâ s biological weapons program went undetected, the United States may gain a better advantage for future assessments and prevent the large-scale stockpiling and development of biological weapons.

Thesis--Copenhagen. / At head of title: Johs. Ipsen. "The translation from Danish is by Mr. Einar Christensen."--Pref. "Dansk resume": p. [151]-157. "Literature": p. [246]-248.

Thesis--Copenhagen. / At head of title: Johs. Ipsen. "The translation from Danish is by Mr. Einar Christensen."--Pref. "Dansk resume": p. [151]-157. "Literature": p. [246]-248.

Les systèmes toxine-antitoxine (TA) sont composés d’une toxine intracellulaire qui cible un processus cellulaire essentiel et qui est neutralisée par une antitoxine. Ces systèmes sont très abondant chez les bactéries et sont impliqués dans la réponse aux stress, la formation de biofilm, le phénomène de persistance, etc.<p>Mon projet de thèse a porté sur l’étude de la diversité des systèmes TA à deux niveaux. Dans un premier temps, plusieurs toxines de la famille RelE provenant de différentes espèces bactériennes et associées à des antitoxines non-canoniques ont été étudiées. Dans la seconde partie de ma thèse, nous avons caractérisé l’activation spécifique de deux systèmes TA d’Escherichia coli au niveau de la régulation transcriptionnelle du système et de l’activation de la toxine. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished