McGill University Thèses et mémoires publiés en 1997

The enzyme mechanism, nucleotide interactions and active site residues in the Vibrio harveyi aldehyde dehydrogenase (Vh.ALDH) have been examined. The Vh.ALDH gene encodes a polypeptide of 510 amino acids with molecular mass of 54 kDa. The recombinant Vh.ALDH was purified in a single step using 2', 5' ADP Sepharose affinity chromatography. It was shown that NAD+ and NADP+ bound to the same site and that saturation of Vh.ALDH with NADP+ occurred with a Michaelis constant (Km) of 1.4 m M with dodecanal. The specificity for aldehydes of longer chain length was shown to be reflected in a decrease in (Km). …  Lire la suite

Renin is an aspartyl proteinase implicated in the regulation of blood pressure and fluid balance. As many other secreted enzymes, it is synthesized as a precursor, prorenin, that is cleaved by a processing enzyme during its migration through the cell sorting and secretion pathways. The prosegment plays an important role in the folding, the secretion and the inhibition if renin. A prediction of the three-dimensional structure of this zymogen has been derived from those of other aspartyl proteinases but recent findings have raised some doubts about the validity of this model. The best solution would be to crystallize the human …  Lire la suite

The emergence of multidrug resistant tumours during the course of chemotherapeutic treatment of cancer patients is a major obstacle in cancer chemotherapy. Although several mechanisms may contribute to the appearance of multidrug resistance phenotype (MDR) in tumour cells, reduced drug accumulation and the ability of cells to undergo apoptosis are thought to be very important in expression of MDR. The work in this thesis focuses on the mechanism responsible for the reduced drug accumulation in tumour cells, mainly the multidrug resistance protein (MRP1). The molecular mechanism underlying the binding and efflux of drugs by the MRP1 is currently not well …  Lire la suite

In 1991, a project was initiated at Quinn and Ormstown, two sites with soils representative of Quebec's present-day agriculture. Three field management techniques were studied related to their possible impact on the soils: tillage, rotation, and N fertilization. The three treatments were randomly assigned in two blocks of a split-split-plot design. The main treatment, tillage, had two levels, conventional tillage (CT) and no-till (NT). The sub-treatment was represented by five 4-year rotations, starting from 1991 as follows: CCCC (continuous corn), CSAC (corn-soybean-alfalfa-corn), CSCS (corn-soybean-corn-soybean), SCSC (soybean-corn-soybean-corn) and SSSS (soybean monocrop). The third factor was N fertilization, at three different rates: …  Lire la suite

The semantic organization of Normand Chaurette's Reve d'une nuit d'hopital, Provincetown Playhouse ... and Fragments d'une lettre d'adieu ... plays is quite mysterious. It requires scrupulous deciphering in order to understand the author's sense of direction. This is accomplished by studying the movement of madness, that of writing itself. This movement is heliocoidal, spiral shaped; it is a collection of repeated themes nourished with redundancies, replications, insistence and depth. The spiral symbolizes the cyclonic tendency of the characters' torment, a tendency reaching to embrace the heart of this torment. But this insanity cannot be reasonably revealed. The mystery that sustains …  Lire la suite

A 7.6 cm Laboratory Knelson Concentrator was used to evaluate the performance of one jig circuit (Snip Operation), four Knelson Concentrators circuits (Meston, Est Malartic, Aurbel and Hemlo) and one classification circuit (Agnico-Eagle). To determine the size-by-size unit performance of all units, total and gravity recoverable gold contents were measured in the feed, concentrate, tails, underflow and overflow. Sample dilution with silica was used as a tool to enhance LKC recovery in samples with a high sulphide content. The data generated from the Knelson and the jig was used in a model designed to simulate an actual grinding and gravity …  Lire la suite

This thesis examines the legal aspects of aviation insurance and reinsurance regarding passenger liability, in particular in Europe. The paper identifies and describes four main trends currently affecting the aviation insurance industry: the globalization of aviation insurance and reinsurance undertakings, increased competition in aviation insurance sector, the liberalization of the European insurance market, and the evolution of the international and European air carriers liability regime. The implications of these trends for premium rates, and for insurance and reinsurance activities in general, are then assessed. This analysis indicates that the liberalization of the European insurance and reinsurance markets remains incomplete, given …  Lire la suite

In four pieces selected from the late Baroque repertoire, the "Allemanda" from Corelli's Sonata for Violin and Continuo, Opus 5, No. 8, the "Allemande" from Bach's Clavierubung, Partita, No. 1, the chorus, "Thy Right Hand, Oh Lord" from Handel's Israel in Egypt, and the aria duetto, "Mein Freund ist Mein" from Cantata No. 140, Wachet Auf, by Bach, harmonic, melodic and motivic parameters are analysed and graphed so that their integration in each work is readily observable. Then, in an attempt to establish more general formal models similar to those developed by Arnold Schoenberg, Erwin Ratz, and William E. Caplin …  Lire la suite

In the field of education, the Islamic educational institutions, both formal and non-formal, have played a major role in educating Indonesians from the colonial era 1600-1945, to the present day. One of the Islamic educational institutions famous for its Islamic approach is the pesantren. This institution, however, is facing major challenges at present and is being asked to update, develop and change many of its programs in order to enable its graduates to participate more fully in Indonesian national life, particularly in the field of national development. As a result, some pesantrens began modernizing their educational systems. The modernization process …  Lire la suite

The goal of this thesis is to develop a binocular controller for artificial vision systems, based on principles used in biological binocular control. The controller is a symmetrical, two-sided system utilizing feedback across the midline. In spite of its simple topology, the controller allows for the integration of various aspects of eye movements, which are often modelled as independent systems. In addition, the controller topology naturally lends itself to sensory-fusion. The controller was applied to an artificial vision system and its 3-D tracking performance was evaluated. Eye (camera) movements consist of an appropriate mix of slow (tracking) and rapid (reorienting) …  Lire la suite

The purpose of this study was to examine the effects of a school-based wellness program, Looking Good...Feeling Great! (Zacour & Zacour, 1991), on ninth grade students' wellness levels, and to evaluate student and teacher impressions of the program. Experimental groups (n = 62) from one urban and two suburban secondary schools participated in the four day 175 minute Looking Good...Feeling Great! program, while control groups (n = 37) from the same schools followed their regular academic schedules. All participants completed TestwellTM (National Wellness Institute, Inc., 1994), a wellness inventory for high school students, as a pretest, one week later as …  Lire la suite

The Qur'anic concept of ahl al-kitab ("People of the Book") has a theological significance for Muslims, showing a sympathetic perception of other religions, particularly Jews and Christians, who share the same monotheistic belief as Muslims. There are many references to abl al-kitab in the Qur'an which may be grouped into two categories: the sympathetic verses which give ahl al-kitab a status similar to that of Muslims and the ambivalent verses which condemn the ahl al-kitab. In this study, surat Al 'Imran (3): 64, 113, 114 and 115 are chosen as examples of sympathetic verses. Six major works of selected classical …  Lire la suite

A dinuclear copper(II) complex has been investigated for promoting the transesterification of a phosphate diester, 2-hydroxypropyl-p-nitrophenyl phosphate (HPNP), that is a model for RNA. Rate enhancements of over 10$ sp5$ have been obtained at neutral pH over the background hydroxide rate. For this study the dinucleating ligand 2,6-bis ((bis(benzimidazolymethyl)amino)methyl) -p-cresol was prepared and the reactivity of the copper(II) complex for cleaving 2-hydroxypropyl-4-nitrophenyl phosphate was determined. The two metals were shown to be acting cooperatively by comparing the reactivity of the dinuclear complex to that of a mononuclear complex, copper(II) 2-(bi(benzimidazolymethyl)amino)methyl-4,6-dimethylphenol. A mechanism involving double Lewis acid activation of HPNP is …  Lire la suite

Laboratory scale Cheddar type cheese were made from 411 milk samples originating from Ayrshire, Brown Swiss, Canadienne and Jersey with different phenotypes of kappa-casein (kappa-CN) and beta-lactoglobulin (beta-LG). From the milk input, cheese and whey outputs, the cheese yield, cheese composition and cheesemaking efficiency and other parameters were determined. The overall 37% moisture adjusted cheese yield and cheese yield efficiency were 11.19g, 10.19g, 11.97g, 11.46g and 98.91%, 90.10%, 90.76% and 90.92% for Ayrshire, Brown Swiss, Canadienne and Jersey respectively. The milk of the four respective breeds contained 12.91, 12.69, 13.50, 14.57% total solids; 3.97, 3.58, 4.40, 4.61% fat; 3.61, 3.73, …  Lire la suite

A catalyzed chemimechanical-anthraquinone pulping of black spruce wood was investigated in this study. The effect of liquor pH on anthraquinone performance, AQ and mass transfer limitations on chemimechanical pulp properties and the effects of AQ, liquor pH and sulphite concentration on pulping kinetic were studied. It was observed that AQ was not an effective redox catalyst when added to the sulphite liquor at pH 4, but it was very effective at pH 7 and higher. When chemical treatment of chemimechanical pulping was done with the presence of AQ, the sulphur content of pulp was reduced due to preferential reaction of …  Lire la suite

A technique to measure the evoked vascular response in the human brain has been developed for a Scanditronix PC2048-15B PET scanner. New hardware and software have been designed to enable the scanner to acquire image data in 8 distinct segments of the acquisition memory sequentially and repetitively when gated by an auxiliary signal. For PET activation studies, these modifications facilitate the application of a stimulation pattern consisting of 8 phases. By synchronizing the phases with the acquisition, the time course of the response to the stimulation is measured. Simulation and phantom tests were performed to verify the system performance before …  Lire la suite

Cytogenetic studies to identify chromosomal aberrations in ovarian tumors allow for a better understanding of tumor biology. Fifteen ovarian tumors (1 benign, 7 borderline, and 7 malignant tumors) and one normal control were successfully characterized using conventional cytogenetic methods. Among simple karyotypic changes, trisomy 10, not previously reported in ovarian cancer, was confirmed with fluorescence in situ hybridization (FISH). This latter may be considered as a single causative event or as one among many other chromosomal alterations, being both associated with ovarian tumorigenesis and tumor progression. Among complex karyotypic abnormalities, one cell one (OV90) was further characterized using combined GTG …  Lire la suite

The effect of high external pressures on the vibrational spectra of two different types of compounds have been investigated. The high pressures were achieved with the aid of a diamond-anvil cell. The tetraphenyl group 14 compounds, Ph4M CM = Si, Ge, Sn, Pb), were examined between ambient pressure and 40 kbar (~40,000 atm). The four compounds displayed similar behaviour as the pressure was increased and a structural transition at ~15 kbar most probably associated with rotation of the phenyl ring was identified in each case. The pressure dependences of selected vibrational modes were obtained. The second series examined consisted of …  Lire la suite

The advent of the Virtual Reality Modeling Language (VRML) as a portable file format for describing three-dimensional (3-D) scenes has created the ability for researchers, educators and students to share anatomical models on the WWW. The implication for medical teaching is that students can interactively examine anatomical structures and their 3-D spatial relationships, using current personal computer (PC) technology. The work of this thesis creates, for the first time, a high-resolution middle-ear model that is accessible on the World Wide Web (WWW). The 3-D model is created by automated aligning of the source images (histological sections), interactive segmentation, and 3-D …  Lire la suite

In the "New Economy", state regulation of corporations is in decline and there is little prospect of effective international control. Corporations are increasingly free vis a vis is the state to set their own standards in fields as diverse as working conditions, environmental discharge and relations with aboriginal communities. At the same time, the power of organized labour to control corporate behaviour appears on the wane. The decline of the state and organized labour has left consumer pressure---backed by boycotts---as one of the few checks on corporate power. This thesis examines the boycott phenomenon and the common law reaction to …  Lire la suite

Following the 1837 Rebellion in Lower Canada, British authorities suspended the province's constitution. From April 1838 until February 1841, legislative power was vested in an appointed Special Council. This was a authoritarian institution, designed to facilitate the passage of a single legislative agenda, and not to act as a forum for debate. Even if the creation of the council marked a moment of imperial intervention, the changes imposed by the council were largely those envisioned by a Lower Canadian political movement, the Montreal Constitutional Association. As time went on, the Special Council's membership, powers and legislation increasingly reflected Constitutionalist values. …  Lire la suite

The influence technology has on human subjectivity has been the occupation of philosophy for some time. Recent technological advance has re-motivated the speculation on subjectivity where a bodily dimension of subjectivity becomes necessary to understand the complexities of subjectivity as it is formulated in contemporary society. In this thesis subjectivity has been schematized according to its states relative to the body to demonstrate how technology and its mythologies influences and define individual subjectivity and the larger constructive factors that shape that subjectivity. Various examples are used to show the contemporary postmodern response to technological subjective imposition as subjectivity both negotiates …  Lire la suite

This study examined the efficacy of conjoint behavioural consultation (CBC) with children who are socially withdrawn, the generalization of treatment gains across home, school, and a play session, and whether treatment gains are positively associated with teacher and parent ratings of goal attainment. An A-B design was used and participants included 5 boys (ages 7, 5, 6, 5, and 6) and their parents and teachers. Children evidenced improvements in target behaviour from baseline to treatment at home or at school (effect sizes = $-$6.48 to +1.77). Preliminary evidence was obtained indicating that treatment gains generalize to non treatment settings, however …  Lire la suite

Accumulating evidence suggest the underlying danger of Class IA and Class III antiarrhythmic agents in inducing potentially lethal torsade de pointes arrhythmias (TdP) if associated with hypokalemia and slow heart rates. The primary aim of the following study was to examine the proarrhythmic activity of the Class IA agent quinidine in isolated perfused rabbit hearts in an effort towards developing a reliable model of TdP. Thirty five rabbit hearts were perfused with therapeutic quinidine concentrations (2.5 or 5$ mu$M) in the presence of hypokalemia (K$ sp+$ - 2.7mM) and stimulated at cycle lengths (CLs) ranging from 0.5s-5.5s. Monophasic action potentials …  Lire la suite

Fuks, Abraham (Supervisor)  Lire la suite

Coping behaviour, perceived control, and the self concept of elementary school children with learning disabilities educated in regular and special education classrooms was examined using a comparative design. In addition, the influence of teachers' classroom management orientation on children's self-perceptions and coping behaviour was investigated. Children attending a special school for students with learning disabilities were found to be more adaptive copers than children in special education classes in regular schools, children receiving resource room assistance, and children mainstreamed in regular classes. Children with learning disabilities were found to have positive perceptions of their global self-worth regardless of the type …  Lire la suite

Passively accepting measurements of the world is not enough, as the data obtained is always incomplete, and the inferences made from it uncertain to a degree which is often unacceptable. Machines that operate autonomously will always be faced with this dilemma, and can only be successful if they play a much more active role. This paper presents such a machine. It deliberately seeks out those parts of the world which maximize the fidelity of its internal representations, and keeps searching until those representations are acceptable. This paradigm is called visual autonomous exploration, and the machine an autonomous explorer. There are …  Lire la suite

Les protéines 289R- et 243R-ElA produites par l’adénovirus de sérotype 5 sont des phosphoprotéines nucléaires qui, combinées à ElB ou à une forme activée de c-ras, peuvent transformer des cellules murines primaires. Le mécanisme par lequel ces produits de ElA induisent la transformation implique la liaison de plusieurs protéines cellulaires qui régulent normalement la progression du cycle cellulaire. À la fois 289R- et 243R-ElA sont phosphorylées in vivo au site Ser-132, ce site étant phosphorylé par la caséine kinase II (CKII) in vitro. Cette phosphorylation de ElA augmente légèrement l’affinité pour les protéines cellulaires et semble augmenter son pouvoir transformant, …  Lire la suite

Duder, S. (Supervisor)  Lire la suite

The peripheral and central mechanisms mediating the modulatory effects of glucose and acute stress in rats were investigated using two versions of an appetitive win-stay task. Post-training injections of glucose, but not fructose, enhanced retention on the closed maze task. Acquisition of this task was found to be impaired by lesions of the fimbria-fornix (FF). Further experiments showed that while the celiac ganglion and the FF normally participate in suppressing the memory-enhancing effect of an acute stressor, neither structure is involved in mediating the effect of glucose on memory. Post-training injections of glucose, but not fructose, enhanced retention on the …  Lire la suite

No substantial studies, at least to my knowledge, have yet been dedicated either to Milton's or to Shelley's extensive poetic use of the grotesque. This omission surprises me, especially given the voluminous critical attention both authors receive. Neither Milton nor Shelley's grotesquerie can be viewed as the basis of artistic method or artistic achievement as we might with, say, Rabelais, or Poe, or even Kafka. And neither Milton nor Shelley is self-consciously an artist of "the grotesque." In fact, Milton, from his seventeenth century perspective, would scarcely have regarded the term as being applicable to literary criticism at all. And …  Lire la suite

In this study, we report the experimentally-determined solubility of 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP), and we derive a speciation-based model for estimating the solubilities of other chlorophenols. At 25$ sp circ$C, the log molality of the protonated species of 2,4,6 TCP is $-$2.8 $ pm$ 0.2, whereas for PCP the value is $-$5.1 $ pm$ 0.4. The pK$ rm sb{a}$ values that best fit the solubility data for 2,4,6 TCP and PCP are 6.0 $ pm$ 0.3 and 4.5 $ pm$ 0.5, respectively. At 55$ sp circ$C, the log molality of protonated PCP increases to $-$4.7 $ pm$ 0.2 and …  Lire la suite

Les structures, énergies et réactivités d’hétérocycles azotés ont été étudiées par des méthodes informatique. Nous avons développé une méthode pour calculer les chaleurs de formation d’azoles, d’azines et de benzoazoles via les énergies ab initio ainsi que pour les schémas de réaction isolobale; ce qui donne des chaleurs de formation à l’intérieur de 0-4 kcal/mol des valeurs expérimentales. Les erreurs systématiques des chaleurs de formation obtenues par les méthodes semiempiriques MNDO, AMI et PM3 pour les azotes, azines et benzoazoles sont discutées; des termes correctifs sont aussi suggerés. Les chaleurs de formation du pentazole, du pentazine, de l’hexazine, de la …  Lire la suite

The prevailing metaphysics of modern medicine and bioethics have been largely dualistic and materialistic in nature. The person is conceived of as a duality of mind and body, where the body is treated simply as a material object. In taking such a perspective, the background is set from which people can come to feel distanced from their bodies and believe it acceptable to alienate and sell their body parts. This thesis argues that the dualistic (and to a lesser extent the materialistic) conceptions of the person have contributed significantly to the objectification and commodification of the body. A most disturbing …  Lire la suite

A two-part system for the semi-automatic collection, correction, and analysis of blood data collected during positron emission tomography (PET) studies is presented. The blood data collection system may be used for either manual or automatic sampling of blood, from either arterial or venous source. It performs all corrections required on the blood for confounds external to the body. In addition, this blood collection system allows the integration of an automatic blood sampler with a PET scanner that does not otherwise support one. Finally, it writes a data file in a new, portable, and extensible file format for the storage of …  Lire la suite

Vapour-liquid equilibrium is the driving force behind many separation processes such as distillation. Previous studies have shown that the vapour-liquid equilibria of many mixtures can be altered when the vapour-liquid interface is modified by capillary systems. This thesis studied the effects of capillary actions due to modified vapour-liquid interfaces on the vapour composition of ethanol-water and 1-propanol-water systems. A method was developed to measure and compare the vapour compositions of systems with a planar vapour-liquid interface and systems with capillary plates. Experiments were conducted to investigate the effects of interface materials, pore sizes and liquid compositions. Significant differences in vapour …  Lire la suite

McGilvray, J (Supervisor)  Lire la suite

Studies were designed to investigate the expression and regulation of interstitial collagenase (MMP-1) during endochondral ossification in fetal bovine growth plate chondrocytes in vitro. Fetal bovine growth plate chondrocytes were separated into subpopulations representing different maturational stages by using a Percoll discontinuous gradient. Gene expression and synthesis of MMP-1 in these chondrocyte subpopulations were followed in serum-free cultures as they matured from the prehypertrophic to hypertrophic phenotype. However, MMP-1 mRNA expression and protein were undetectable. This expression was also undetectable in interleukin 1alpha (IL-1alpha) stimulated growth plate chondrocytes. MMP-1 mRNA and protein were however observed in IL-1alpha stimulated bovine fetal …  Lire la suite

The main object of this thesis is to discover some analytical properties of the first passage time of a general diffusion process and related applications in statistical problems. There are three main contributions in this thesis: in the first one, we derive some first passage time laws using two different approaches: one uses the Doob h-transform and the Mehler transform; the other one makes use of a relationship between these laws and the Martin kernel functions. The second contribution is an extension of Brown and Hwang’s work ([10]); we develop a theory of admissibility for general exponential families when the …  Lire la suite

The objective of this research is to map snow cover in the Quebec area using passive microwave and other remote sensing data. The areal snow extent and snow water equivalent are determined and a twelve year snow water equivalent map is produced for the purpose of analyzing interannual snow variability. The presence of vegetation cover will affect the data obtained with passive systems. For heavily vegetated areas such as Quebec, the vegetation effect should be predetermined and classified to reduce the error on snow water equivalence calculation. In dry snow conditions, forest coverage and snow density are the two major …  Lire la suite

Sulfated glycoprotein-2 (SGP-2) has been shown to be secreted by the epididymal principal cells whereupon it binds to sperm where it is possibly involved in transporting lipids to or from their surface or providing them with a protective coat. However, SGP-2 also appear to be endocytosed by principal cells along the epididymis. Recently, it has been demonstrated that glycoprotein 330 (gp330), a low density lipoprotein receptor-related protein, can mediate the endocytosis of SGP-2 in the nonciliated cells of the efferent ducts and cultured cells (Kounnas et al., 1995; Morales et al., 1996). The purpose of the present study were in …  Lire la suite

Lin, Charles (Supervisor)  Lire la suite

In this work, we develop a mathematical model for a rotating Timoshenko beam, and then show its well-posedness. Further, we prove the exact controllability of its linearized model under different sets of controllers. Finally, we work out a computer simulation system for linear as well as nonlinear control problems.  Lire la suite

Acute myocardial ischemia is the main cause of ventricular tachycardia and ventricular fibrillation. Reentrant activity is the most common mechanism of these ventricular arrhythmias, and is often initiated from the border zone between the ischemic and normal tissue. Theoretical studies have suggested that spiral-wave activity may be one form of reentrant arrhythmia. Our study explores the possible relation between spiral-wave activity and ischemia-induced ventricular arrhythmias. We numerically simulate reentrant activity in a two-dimensional sheet of ventricular myocardium which contains an ischemic area. We construct this ischemic area by increasing the extracellular potassium concentration in that area. When pacing the sheet …  Lire la suite

Richardson, John B. (Supervisor)  Lire la suite

Drying is an energy intensive process. The conventional heat-based drying methods often produce changes in the physico-chemical properties of products. A newly developed electrohydrodynamic (EHD) drying technique may be much less destructive to these heat-sensitive materials. This thesis presents comparative analyses of product deterioration in EHD-dried whey proteins, using electrophoresis, differential scanning calorimetry (DSC), and color measurements. Gel electrophoresis showed the disappearance of bands and reduction in band intensities depending upon the temperature of the oven in which the whey protein was dried. The thermograms of the differential scanning calorimeter varied considerably as the temperature of oven-drier increased. EHD, air-drying, …  Lire la suite

In order to model the transport and fate of aniline and chloroaniline in the subsurface, the geochemical reactions between these contaminants and important metals and minerals surfaces must be quantified. The thermodynamic stabilities of the aqueous and surface aluminum-aniline and aluminum-2-chloroaniline complexes were investigated at 55$ sp circ$C and 80$ sp circ$C. Solubility and adsorption experiments place quantitative constraints on the thermodynamic properties of these complexes. No evidence was found for stable Al-aniline or Al-2-chloroaniline aqueous complexes. Conversely, the adsorption data provide unequivocal evidence for the presence of two distinct surface Al-aniline and A-chloroaniline complexes according to the following reactions: …  Lire la suite

The aim of the study was to investigate the mechanisms of bronchoconstriction induced by dry gas hyperpnea challenge in the rat. The interaction of airway hyperresponsiveness to contractile agonists and the atopic constitution of the animals with responsiveness to hyperpnea challenge was also evaluated. A hyperresponsive strain, Fisher 344, two control normoresponsive strains, Lewis and ACI, and an atopic but normoresponsive rat, Brown Norway (BN) to dry gas hyperpnea challenge were studied. The effects of the NK1 (CP-99994), the NK2 (SR-48968) receptor antagonists, and the selective LTD4 receptor antagonist pranlukast on responses to hyperpnea challenge were examined in BN rats. …  Lire la suite

Synthesis of a novel conformationally rigid dimer 106 containing a cyclopropyl-phosphonate linkage is described. A novel 3'-phosphonate building block 105 is synthesized and characterized. During the synthesis of the common precursor 86, unusual base-promoted desilylation of epoxide 80 and vinylselenides 85 and 87 are reported. The instability of the tert-butyldimethylsilyl (TBDMS) and the tert-butyldiphenylsilyl (TBDPS) protecting groups may be attributed to the participation of the uracil C2-oxygen anion. The synthesis of a number of novel bicyclic phosphonate analogs 92b to 95b is described. In search of alternate cyclopropanation methods, dimesylate 113 was synthesized and characterized. Dimethyl methyl phosphonate anion treatment …  Lire la suite