title: MECHANISM OF ENHANCED INTESTINAL TRANSEPITHELIAL ANTIGEN TRANSPORT IN FOOD ALLERGY: ROLE OF IgE, IL-4, AND CD23/FcεII

contributor:
Perdue, Mary H.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Enhanced transepithelial antigen transport in intestine of sensitized rats was previously demonstrated using horseradish peroxidase (HRP) as a model antigen. In senitized rats, transepithelial antigen transport was rapid (< 2 min) and of greater magnitude (three-fold) compared to controls. In my project, the essential components involved in the enhanced antigen transcytosis were investigated using mice with genetic deletions for IL-4 and CD23/FcεII. Increased transepithelial antigen transport was demonstrated in actively sensitized IL-4⁺/⁺ mice, but not IL-4⁻/⁻ mice, in which the phenomenon paralleled the expression of CD23 protein on enterocytes. Passively sensitized mice (both IL-4⁺/⁺ and IL-4⁻/⁻ mice) displayed greater antigen transport after transfer of immune serum unless the serum was first depleted of IgE or IL-4. IL-4 added to cultures of epithelial cells upregulated expression of CD23 mRNA. Finally, this augmented antigen uptake system was inhibited by luminal anti-CD23 and was absent in sensitized CD23⁻/⁻ mice. RT-PCR showed that cultured cells expressed only the b isoform of CD23. Sequencing revealed classical and alternative CD23b transcripts lacking exon 5 (b∆5) or 6 (b∆6), in which all forms were translated into functional IgE receptors. Endocytosis of the b∆5 and b∆6, but not the classical CD23b protein, was observed after binding with saturating anti-CD23, suggesting continuous endocytosis of the alternative forms that agrees with their intracellular localization at steady state. Classical CD23b proteins were expressed on the cell surface and only endocytosed upon antigen-induced IgE cross-linking of the receptor. Taken together, the results demonstrated that IgE/CD23 mediates enhanced transepithelial transport of antigen in sensitized mouse intestine, and that IL-4 plays a major regulatory role. We identified the expression of classical and alternative CD23b transcripts in intestinal epithelial cells, and demonstrated taht the translated proteins display distinct endocytic functions. We concluded that antigen binding to epithelial CD23/IgE facilitates its entry into the body resulting in intestinal anaphylaxis.

abstract: Doctor of Philosophy (PhD)


title: NEUROPROTECTIVE PROPERTIES OF CILIARY NEUROTROPHIC FACTOR ON THE SURVIVAL OF AXOTOMIZED RETINAL GANGLION CELLS IN VIVO

contributor:
Ball, Alexander K.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Over 90% of retinal ganglion cells (RGCs) die after intraorbital optic nerve transection close to the eye. Several factor contribute to RGC death including: loss of neurotrophic support, overproduction of free radicals, glutamate-mediated excitotoxicty, activation of pro-apoptotic caspases (3 and 9), and reactive glia. In the present study, the model of optic nerve transection was used to study the neuroprotective mechanisms and effects of ciliary neurotrophic factor on the survival of axotomized retinal ganglion cells. It was demonstrated that axotomized RGCs die by apoptosis since overexpression of Neuronal Inhibitory Apoptosis Protein (NAIP), a potent and selective inhibitor of caspase 3, protected axotomized RGCs that would have otherwise died if untreated. Protection of axotomized RGCs was further enhanced by overexpression of Ciliary Neurotrophic Factor (CNTF) using adenoviral and lentiviral vectors. It was demonstrated that intraocular administration of adenoviral vectors selectively transduced retinal Muller cells, and injection of this vector into the optic nerve stump at the time of optic nerve transection selectively transduced a small percentage of RGCs. Regardless of the route of administration, adenoviral-mediated overexpression of CNTF protected axtomized RGCs. In comparison to adenoviral-mediated delivery, the delivery of CNTF using lentiviral vectors protected greater numbers of axotomized RGCs and for an extended period of time not typically seen using the optic nerve transection model. It was assumed that viral-mediated transfer of CNTF rescued axotmized RGCs by directly activating the high affinity CNTF receptor alpha (CNTFRα) expressed on RGCs. However, CNTF can also protect axotomized RGCs indirectly, by activating the low affinity leukemia inhibitory receptor beta (LIFAβ) expressed on retinal astrocytes and Muller cells. It was demonstrated that viral-mediated overexpression of CNTF resulted in phenotypic changes in retinal glial cells (astrocytes and Muller cells) that may have increased their neuroprotective function. Overexpression of CNTF increased retinal levels of the gap junction protein, connexin 43 (Cx43), the intermediate filament glial fibrillary acidic protein (GFAP), the astrocyte-specific glutamate/aspartate trasporter-1, GLAST-1, and the astrocyte specific enzyme, glutamine synthetase (GS). Taken together, these results suggest that CNTF is capable of protecting axotomized RGCs by directly binding to injured neurons or by modulating surrounding glia. Together, these results suggest that pharmacological interventions that maintain or upregulate CNTF expression may confer a clinically beneficial neuroprotection.

abstract: Doctor of Philosophy (PhD)


title: Factors Affecting the Selective Localization of Mucoal Lymphoblasts in Mucosae

contributor:
Bienenstock, John
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The selective localization in mucosal tissues of lymphoblasts derived from the mesenteric lymph node (MLN) compared to those from peripheral lymch nodes (PLN axial, brachial and inguinal) was studied using an adoptive transfer model in syngeneic CBA/J mice. The localization of lymphoblasts which had been labelled in vitro with ³H-thymidine or ¹²⁵I-deoxyuridine was assessed using autoradiography or radiocounting.

I found that the number of MLN lymphoblasts which localized in the small intestine, lung, Peyer's patches, MLN, PLN, spleen, and liver was directly proportional to the number transferred. This relationship was also present in intestinal epithelium and basal and villus lamina propria and in pulmonary parenchyma, BALT and bronchial epithelium. Even at doses of MLN lymphoblasts which approximated four times the daily output of blasts in thoracic duct lymph, I could not saturate the capacity of these tissues to accommodate MLN blasts, nor was their intra-intestinal distribution altered. Because of this dose relationship it is necessary to control the number of blasts transfered when comparing the localization of lymphoblasts from different organ sources using autoradiography. Thus my dose studies show that, contrary to earlier studies which were not controlled in this manner, MLN blasts do not selectively localize compared to PLN blasts in pulmonary parenchyma. In addition the result suggest that any method of increasing the number of lymphoblasts released from MALT (e.g. by mucosal immunization) or increasing the delivery of these cells to a particular organ (by altering the proportion of the carciac output which it receives) will increase the number of immublasts in a tissue.

Although the enumeration of radiolabelled or fluorescent cells in tissue sections has been used extensively in the literature to assess localization, the variation in these results has rarely been stated. I found that this variation can be quite high and is largely due to the probability of detecting a low number of cells in a small volume of tissue.

I found that the sex of the recipiegt had no effect on the number of MLN lymphoblasts which localized in the small intestine 24 h after transfer. In contrast, initial experiments showed that lymphoblasts from male donors localized two to three times more frequently than those from female donors in the small intestines of recipients of either sex. However this phenomenon disappeared between September 1980 and August 1981 and neither its initial existence nor its subsequent lops have been explained. I found that the gonadal hormone environment in which the MLN lymphoblasts developed did not influence their capability to localize in the small intestine 24 h after transfer. However, I do not know whether this observation relates to the phenomenon of greater localization of male lymphoblasts because this phenomenon had likely already disappeared when the experiments involving hormonally altered donors were performed.

Using autoradiography in a series of experiments analyzing the kinetics of lymphoblast localization, I demonstrated that MLN lymphoblasts selectively localize compared to MLN blasts in the small intestine by 0.5 h after transfer. This suggests that one factor in selective localization is the selective entry of MLN blasts from the vasculature, perhaps mediated by specific receptors on blasts and tissue of localization.

The concentration of MLN lymphoblasts was the same in the lamina propria adjacent to the Peyer's patch and distant from the Patch at both 0.5 and 24 h after transfer. This suggests that lymphoblasts extravasate in the lamina propria rather than extravasating in the Peyer's patch and subsequently migrating into the lamina propria. In addition, the distribution of blasts in the basal and villus lamina propria was the same at 0.5 and 24 h after transfer but labelled cells appeared in the intestinal epithelium after 0.5 h.

The evidence presented in this thesis suggests that the selective localization of MLN lymphoblasts is mediated the vascular endothelium in the lamina propria, perhaps by specific receptors.

abstract: Doctor of Philosophy (PhD)


title: Studies on Some Early Polypeptides Encoded by Adenovirus Type 5

contributor:
Bayley, S.T.
Biology

subject: Biology Biology

abstract:
In recent years a substantial amount of research work has concentrated on defining the polypeptides encoded by the early regions of adenovirus. However, large gaps remain in the knowledge of the identities, relationships and viral DNA sequences encoding the various early polypeptides. This study adds to the information on the early antigens of Ad5 and provides a basis upon which further studies can build.

A series of polypeptides present in cells early after infection by Ad5 have been studied. They have been immunoprecipatated with five different antisera from extracts of infected cells and from cell-free extracts following the translation of viral mRNA. The antigens have been divided into families of related products by peptide mapping techniques. Partial amino terminal amino acid sequences have been obtained for five early polypeptides which has allowed these products to be associated with specific open reading frames in the Ad5 genome.

The results show that: Region E1A encodes two families of antigens which are closely related but are not identical [52K(12) and 48K(12) from the 135 mRNA; 50K(12) and 44K(12) from the 125 mRNA] and all but the 44K(12) (which was not examined) are synthesized from one translation initiation site, located at 1.43 mu in the Ad5 genome. Early region IB encodes a 19K polypeptide which is not related to a second family of antigens from the same region (58K, 53K, 29K and 18K). The 19K polypeptide is produced from an initiation codon located at 4.68 mu in the Ad5 genome, while the 58K family is (are) synthesized from a different initiation site(s). An antigen of 14K has been identified as a product of subregion 3 in region E4. This polypeptide is initiated by an AUG codon located in the Ad5 genome at 96.55 mu. Region E2A encodes three related products, the 72K and 47K DBPs described previously and a novel 64K polypeptide. Finally, two related products of 21K and 20K have been identified and these may be encoded by regions E3 or E4.

The observations made on the antigens defined in this study are related to those described in other publications.

abstract: Doctor of Philosophy (PhD)


title: Model Reduction Methods Applied to Power Systems

contributor:
Alden, R.T.H.
Sinha, N.K.
Electrical and Computer Engineering

subject:
Electrical and Computer Engineering
Electrical and Computer Engineering

abstract:
This thesis presents a continuation in the process of rationalizing, unifying and improving existing model reduction techniques. Thus a method of reduction is developed which combines the method of aggregation and partial Pade approximation in such a way as to maintain their separate advantages while simultaneously removing their disadvantages. The important aspects associated with the reduced-order models obtained are: guaranteeing the stability of the reduced-order models saving computation time, retaining the invariance property under state variable feedback conditions and matching some of the original system time moments.

Also, a criterion is proposed for selecting the state variables of the original system to be retained in the reduced-order model. This criterion leads to developing a reduction technique which can be regarded as a combination of the methods of aggregation and singular perturbation. Therefore, the reduced-order model obtained retains the physical significance of the state variables and the dominant eigenvalues of the original system.

Furthermore, a procedure is developed for obtaining dynamic equivalents of multimachine systems. This procedure utilizes the concept of component cost analysis for identifying the coherent groups of generators.

Verification of the methods developed in the thesis is established using a variety of realistic power system models including a single synchronous machine connected to an infinite bus, a three-machine system and a 10-machine system. These applications include simulation, analysis and simple controller design.

abstract: Doctor of Philosophy (PhD)


title: The Hydrology of a Glacierised Alpine Karst Castlegaurd Mountain, Alberta

contributor:
Ford, D. C.
Geography

subject: Geography Geography

abstract:
Alpine karst throughout the world has been affected by past glaciation, and yet little is known of the interactions between glacier ice and karst. This dissertation attempts to gain some understanding of the problem through the study of the Castleguard Area, Alberta, where a karst aquifer is presently overlain by temperate glacier ice.

Quantitative fluorometric tracing and hydrometric measurements generated a broad data base on aquifer behaviour. Tracer breakthrough curves were interpreted using a new systematic approach which considers an explicit set of processes likely to affect the particular tracer under the given experimental conditions. Non-linearity in aquifer behaviour and rapid groundwater velocities demonstrated the aquifer to be an extreme conduit type Conduit springs are elements in a vertical hierarchy in which the topmost springs are "overflows" and exhibit greater flow variability than their associated "underflows". A numerical model was developed to simulate a conduit aquifer. It demonstrated that pulse train and recession analysis widely accepted methods of karst aquifer investigation, could be rather misleading when applied to conduit aquifers.

Interactions between ice and groundwater were observed at two scales: regulation water appeared to feed a diffuse percolation system and supraglacial melt passed into subglacial conduits which entered open vadose shafts. Karst is unlikely to be entirely subglacial in origin because of the limited aggressiveness of subglacial waters.

The Castlegaurd karst appeared to have originated preglacially in response to the breaching of impermeable caprock. Glaciation re-ordered the landscape and produced abundant clastic debris which subsequently blocked or obstructed karst conduits. Much of the resulting karst is paragenetic and comparatively immature due to glacial disruption and slow growth rates. Geomorphic and hydrologic interactions between ice and karst depend intimately upon the relationship between the geographic zones of the glacier and the aquifer.

abstract: Doctor of Philosophy (PhD)


title: Hemoglobin Switching During Murine Embryonic Development

contributor:
Chui, David H.K.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Around day 8 of mouse embryonic development, yolk sac produces circulating nucleated erythroblasts synthesizing primarily embryonic hemoglobins (Hb E). By day 12 of gestation, fetal liver releases nonnucleated erythrocytes containing adult hemoglobins (Hb A). The objective herein was to examine the cellular mechanism of hemoglobin ontogeny during mouse embryonic development.

Embryonic peripheral blood cells from 9-12 day embryos were cultured in either plasma clot or methylcellulose for 6-8 days. Pokeweed mitogen stimulated adult spleen cell conditioned medium (SCM) either with or without erythropoietin (Epo) was added to these cultures. Large erythroid colonies were observed by the sixth day of culture. In another type of experiment embryonic fluid was obtained from exocelomic cavity of day 10 embryos and was added to these cultures with Epo, but without SCM. Erythroid colonies were also observed. In some other experiments, cultures of yolk sac cells from 9 - 10 day embryos with SCM, with or without Epo also gave rise to large erythroid colonies after 6 - 8 days in vitro. Furthermore, such colonies were also detected when fetal hepatic cells of 11 - 13 day embryos were cultured with SCM with or without Epo. Hemoglobin synthesis was analysed by various techniques, i.e., electrophoresis, isoelectric focusing and ion-exchange chromatography. In all cultures, only Hb A synthesis could be detected, although the experiments do not rule out the possibility that minute amount of embryonic hemoglobins were present.

In another series of experiments, fragments of embryonic tissues from day 8 embryos were cultured for 6-8 days in methylcellulose with Epo and/or SCM. Hemoglobin present in cultures was examined by the sensitive isoelectric focusing microassay. Cultures of early day 8 tissues produce only Hb E. Cultures of late day 8 embryonic tissues with Epo alone produce primarily Hb E with some Hb A as well. Similar cultures with both Epo and SCM produce both Hb E and Hb A, and the proportion of Hb A synthesized is considerably higher. Cultures of day 10 tissues in the presence of both Epo and SCM produce only adult hemoglobins.

These results suggest the following model for the development of murine embryonic erythropoiesis: Hemopoietic progenitor cells capable of giving rise to erythroblasts synthesizing Hb E occur early in embryonic development. This is followed shortly by the appearance of erythroid progenitor cells committed to produce erythroblast progeny synthesizing Hb A. The latter progenitor cells are present in circulation. They seed fetal liver and initiate fetal hepatic erythropoiesis.

abstract: Doctor of Philosophy (PhD)


title: Finite Element Modelling and Elasto-Plastic Analysis of RHS Double and Single Chord T-Joints

contributor:
Korol, Robert M.
Mirza, Farooque A.
Civil Engineering

subject:
Civil Engineering
Civil Engineering

abstract:
A research program is presented to investigate the behaviour of rectangular hollow section (RHS) T-joints in the elasto-plastic range of loading. The study includes the determination of both rotational and punching shear stiffnesses and strengths of the RHS T-joints due to branch moment or punching shear or a combination of both. The determined joint characteristics are then incorporated into an elasto-plastic analysis of Vierendeel trusses composed of RHS members.

Two different joint types have been analyzed, the double chord T-joint and the single chord type. In both cases, the joint is modelled by the chord top flange treated as a thin plate loaded on the perimeter of a rigid inclusion and restrained by coupled translational and rotational springs along its longitudinal edges. These springs simulate the restraining effect of the side walls and connecting bottom flange. Transverse edges, some distance from the joint, are taken as simply supported.

The proposed finite element formulation incorporates rectangular plate, beam and boundary spring elements. The formulation considers both bending and in-plane actions. Material nonlinearities of the joint are assumed to be adequately represented by the Von-Mises yield criterion and the associated flow rule. While geometric nonlinearities have been neglected, this assumption is reasonable for the range of deformations deemed important in this study.

A parametric analysis has been undertaken for each of the double chord and single chord joints under either branch moment or punching shear. Each analysis considers the effect of each of five non-dimensiononal geometric parameters. One of the parameters, considered, is used to study the stiffening effect of a reinforcing flange plate. Results of the analysis are presented in the form of non-dimensionalized load-deformation (M-Φ and P-δ) curves.

A standardization procedure has been used to develop generalized (M-Φ and P-δ) formulae, based on the parametric analyses. In addition, formulae for the joint stiffness and strength, in terms of its geometry, are presented for each case.

When the joints are analyzed under combined loading, the branch moment and punching shear are applied in different ratios. The results are presented in the form of interaction equations.

Next, the joint characteristics have been incorporated in an elasto-plastic finite element analysis of Vierendeel trusses. The effect of the joint flexibility on the truss behaviour is investigated. Also considered is a comparison between trusses possessing single chords and those possessing double chords.

Another aspect of this investigation is to predict upper bound capacities for the double chord joints due to branch moment or punching shear. The yield line theory has been utilized for this purpose.

The experimental part of the study involves the testing of ten double chord joints. Results of these tests along vith other available experimental data are used in examining the validity of the analytical models that have been developed.

abstract: Doctor of Philosophy (PhD)


title: Fault Analysis and Parameter Tuning in Analog Circuits

contributor:
Bandler, John W.
Electrical Engineering

subject:
Electrical and Electronics
Electrical and Electronics

abstract:
This thesis addresses itself to the two principal problems of computer-aided-testing in analog circuits, namely, fault analysis and postproduction tuning.

A unified approach to fault location in large analog circuits is introduced. The approach closely meets the goals of practical criteria for fault analysis. Network decomposition and logical analysis are incorporated to identify faulty subnetworks. Necessary and almost sufficient testing conditions for locating fault-free subnetworks are derived. These conditions are based on invoking KCL and topological relations between subnetworks. The application of the approach to practical linear and nonlinear networks is presented. Further fault analysis is carried out to identify faulty elements or regions inside the faulty subnetwork. Deterministic and approximate methods are introduced for that respect. The approximate method utilizes an estimation criterion, namely, the least-one objective function to predict the most likely faulty elements. The deterministic methods verify the existence of faults by examining the consistency of algebraic equations or by matching the subnetwork response using faulty models of the subnetwork elements. A number of network examples are considered to illustrate the application of the introduced methods.

The deviation in the response of a manufactured circuit can often be compensated by adjusting specified tunable elements. A number of aspects of the postproduction tuning problem are studied. In particular, the relevant fundamental concepts and definitions are given, the tuning algorithms either functional or deterministic are reviewed and new techniques for choosing tunable parameters and critical response points are introduced. Two new functional tuning techniques are presented. The application of the new techniques in tuning a microwave network example is illustrated. A comparison and evaluation of four different tuning techniques are given by testing them in tuning an active filter example.

abstract: Doctor of Philosophy (PhD)


title: THE ROLE OF THE PEA3 SUBFAMILY ETS GENES IN MAMMARY TUMORIGENESIS: USE OF TRANSGENIC MOUSE MODELS OF BREAST CANCER

contributor:
Hassell, John A.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: The ets genes encode DNA-binding proteins capable of regulating the expression of target genes that contain ETS sites within their promoter sequences. The ets gene PEA3 is overexpressed in a majority of human breast tumour samples, as well as in the mammary tumours and lung metastases of several transgenic mouse models of this disease. The Pea3 subfamily genes, which include Pea3, Erm, and Er81, are expressed during mouse mammary gland development. However, in mammary tumours induced by the HER2/Neu receptor tyrosine kinase, the Pea3 subfamily genes were upregulated by five-two twenty-fold as compared to normal mammary tissue of wild-type control mice. To understand the role of the PEA3 subfamily proteins in mammary tumorigenesis, transgenic mice were generated which overexpress either PEA3 or a dominant-negative mutant of PEA3 (∆NPEA3En) under the transcritional control of the mouse mammary tumour virus (MMTV) promoter/enhancer. ∆NPEA3En was able to inhibit the function of all three PEA3 subfamily proteins and reduce oncogenic Neu-induced transformation of mouse fibroblasts in cell culture-based assays. ∆NPEA3En was able to delay tumour formation as well as reduce the number and the size of tumours that developed in MMTV-neu/∆NPEA3En bi-transgenic mice as compared to MMTV-neu transgenic female mice. The tumours that did form in bi-transgenic mice generally lacked ∆NPEA3En expression indicating that PEA3 subfamily function is required for tumour progression. The mammary gland of MMTV-PEA3 transgenic female mice exhibited increased ductal branching and side bud formation in virgin mice, and decreased lobuloalveolar differentiation during pregnancy. Surprisingly, MMTV-neu/PEA3 bi-transgenic mice had a longer latency in mammary tumour formation than did MMTV-neu female mice, similar to what was observed in MMTV-neu/∆PEA3 bi-transgenic mice had a longer latency in mammary tumour formation than did MMTV-neu/∆NPEA3En bi-transgenic mice. These results implicate PEA3 subfamily protein function during mammary gland development and in Neu-induced mammary tumorigenesis. Thus, inhibiting PEA3 subfamily protein function, or that of one or more specific target gene products, may complement other current therapies in the treatment of human breast cancer

abstract: Doctor of Philosophy (PhD)


title: THE ADMINISTRATIVE ETHOS IN NURSING: A STUDY OF THE CAREERS OF CANADIAN AND AUSTRALIAN NURSE ADMINISTRATORS

contributor:
Shaffir, William B.
Sociology

subject: Sociology Sociology

abstract: This thesis presents a sociological portrait of the "typical" administrative career and a typology of the characteristics and beliefs of those who achieve the high status designation "nurse administrator." The thesis contributes to a sociological understanding of the prepatation, recruitment, selection and appointment of senior administrators in nursing. This information is important to hospitals and health agencies requiring nursing leaders to shape and advance the objectives of the organization; and the prospective administrators who need to understand career routes to administrative positions, and to recognize attributes rewarded by promotion. The theoretical framework for the study derives from social psychology as reflected in the symbolic interactionist perspective. Life and organizational contingencies influencing career pathways have been identified through semi-structured biographic interviews. These are used to demonstrate the dominant modes of entryy to an administrative career in nursing. This approach has enabled the isolation and description of a set of beliefs influencing the career decisions of nurses who become administrators. This collective belief system is referred to as the administrative ethos in nursing. Through an exploration of this ethos from the perspective of the nurse administrators interviewed, three variants - the clinical ethos, the management-organizational ethos, and the corporate-executive ethos - are proposed. The thesis concludes that recognition of these variants is important in understanding how the career and professional practice of an administrator are shaped. Sixty-two Executive Directors, Directors and Assistant Directors of Nursing, or their equivalents, were interviewed in detail. They were drawn from twenty-five large hospitals across seven major cities in three Canadian provinces and two Australian states. The cross-national comparative element of the study reveals that nurse administrators in both Canada and Australia have comparable beliefs about nursing administration. While their career paths to an administrative position do not differ greatly, the administrative position is more likely to be a final career position for Australians, while Canadians are more likely to move between senior appointments in clinical service, administration and education, or to have join appointments.

abstract: Doctor of Philosophy (PhD)


title: STRUCTURE AND FUNCTION STUDIES OF MAMMALIAN ADENOSINE KINASE

contributor:
Gupta, R.S.
Biochemistry

subject: Biochemistry Biochemistry

abstract: Adenosine kinase (AK) is a purine salvage enzyme which catalyzes the phosphorylation of the 5'-hydroxyl of adenosine via ATP. AK is a key enzyme which controls the intra and extracellular concentration of adenosine (Ado). Agents which inhibit the activity of AK have been found to attentuate cellular damage, demonstrating therapeutic utility in a variety of disease processes. In order to design inhibitors of AK with increased efficacy, a better understanding of enzyme activity is required. Previously a number of novel characteristics of mammalian AK had been discovered. It was shown that the activity of AK is influenced by the presence of pentavelent ions (PVI) such as inorganic phosphate (Pi), arsenate and vanadate. A detailed study of the influence of Pi on the kinetic parameters of Chinese hamster (CH) and beef liver AK was performed. These studies suggested that the Km (Ado) decreases and the Ki (Ado) increases asymptotically in the presence of increasing concentrations of Pi. Under the same conditions, the Vmax for activity increases hyperbolically. The effect of phosphate is not limited to the mammalian form of AK. Pi, arsenate and vandate were all found to have similar effects on AK from yeast, spinach and Leishmania donovani AK. PVI as well as the metabolite phoshoenol pyruvate were also found to stimulate the activity of the enzyme ribokinase (RK) from E. coli, which similar to AK, is a member of the PfkB family of carbohydrate kinases. Although AK and RK show little sequence similarity, the residues at the active site and the 3D structures of these two proteins are very similar. Based on sequence alignment of PfkB family members, we have identified a conserved sequence motif, NXXE, which based upon the available structural information appears to be involved in the binding of phosphate. To confirm and understand the role of this motif in Pi binding, the residues at the NXXE site were altered by site-directed mutagenesis and their effect on activity of the recombinant CH AK was examined. Though the residues at the NXXE site do not directly interact with substrate, nor the putative catalutic base, the resulting proteins were found to have greatly altered phosphate requirement, substrate inhibition characteristics and different magnesium requirements. In the AK structure, aspartic acid at position 316 presumed to act as the catalytic base. This residue was changed to aspargine and glumatic acid by mutagenesis. The resulting proteins were found to be nearly completely devoid of activity, confirming its critical role in AK activity. The amino acid sequence at the extreme N-terminus of AK has been found to exhibit the greatest variability within and among species, though the rest of the protein remains greatly conserved. To delineate the residues that are involved in the structural stability and activity of AK, systematic deletions of the residues from both the N- and C- terminus were performed, and the structure-activity relationships were examined. It was determined that the first 16 residues of CH AK can be removed without affecting activity. Removal of the next 11 residues in sequential decreases in enzyme stability and activity. These 11 residues are involved in the first βstructure of the protein and are required for the stability of the tertiary structure. All residues at the C terminus were required for activity, and involved in a hydrogen-bonding network necessary for the stability of the ATP binding site. Thesestudies provide novel insight to the structure-activity relationship of mammalian AK as well as the PfkB family of enzymes. Our work has identified a site distal to the catalytic site, that is implicated in the PVI binding and catalytic effect. Further studies should be aimed at understanding how binding of PVI at this site influences the catalytic activity of AK. Development of inhibitors which bind to this site and modulate the activity of AK should prove very useful in this regard.

abstract: Doctor of Philosophy (PhD)


title: EFFECTS OF NEUROTROPHIC AND ANTI-INFLAMMATORY CYTOKINES ONF THE SURVIVAL OF AXOTOMIZED RETINAL GANGLION CELLS

subject:
Medical Sciences
Medical Sciences

abstract: Transection of the optic nerve (axotomy) is a model of central nervous system (CNS) injury. Eighty to ninety percent of retinal ganglion cells (RGCs) die within two weeks after transection of the optic nerve. We demonstrated that the recently discovered neurotrophic factors glial cell-line derived neurotrophic factor (GDNF) and neurturin (NTN) enhance the survival of axotimized RGCs. We also showed that these factors produce additive neurotrophic effects with brain derived neurotrophic factor, suggesting that they act by independent mechamisms. We also demonstrated that the high affinity receptor for GDNF (GFRα-1) is localized to RGCs, Muller glia, and the astrocytes in the retina. GDNF was localized to RGCs, photoreceptors, and pigment epithelial cells, suggesting possible autocrine or paracrine roles for GDNF in the retina. Our results also demonstrate that an indirect neurprotective mechanism of GDNF is the upregulation of the glutamate transporter, GLAST-1, in the retinal glia. This mechanism may protect RGCs from glutamate mediated excitotoxicity. Our findings suggest that multiple neurotrophic factors may be required for the rescue of injured CNS neurons, as suggested by the findings that these factors act independently. We demonstrated that there are increases inducible nitric oxide synthase (iNOS) expression in retinal glial cells, and increases in constitutive (cNOS) expression in RGCs after axotomy, and that increases in NOS expression parallel the timecourse of RGC degeneration. Our results indicate that NO plays a toxic role in promoting RGC death after axotomy, as demonstrated by the findings that NOS inhibition enhances the survival of axotomized RGCs. Furthermore, we examined the neuroprotective effects of the anti-inflammatory cytokines-10 (IL-10), IL-4, and transforming growth factor-β (TGF-β on RGC survival. These cytokines have been shown to inhibit iNOS expression and NO synthesis by glial cells in vitro. Our in vivo studies showed that IL-10 and IL-4 enhanced the survival of axotomized RGCs, and suggest that one of the neuroprotective mechanisms of these cytokines is inhibiting peroxynitrite formation in the retina. These findings suggest that IL-10 and IL-4 inhibit NO synthesis in the retina may inhibit reactivity after optic nerve transection. Our findings point to the possible benefit of IL-10 or IL-4 treating CNS trauma and diseases of the CNS that demonstrate the presence of activated NO synthesizing glial cells.

abstract: Doctor of Philosophy (PhD)


title: CELLULAR AND MOLECULAR HOST-PATHOGEN INTERACTIONS DURING CHLAMYDIA PNEUMONIAE INFECTION

contributor:
Mahony, James B.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Chlamydia pneumoniae is a Gram-negative bacterial pathogen that has evolved to survive completely within the intracellular environment of a host cell. The obligate intracellular lifestyle of this bacterium necessitates an efficient invasion strategy, exemplified by a broad host cell tropism with little propensity for any single cell type and the ability to replicate within both professional phagocytic cells and cells with low phagocytic capacity. After cellular invasion, C. pneumoniae actively evades host immune defenses, establishes a parasitic relationship with the host cell and forms a microcolony by dividing within a non-fusogenic cytoplasmic vacuole called an inclusion. The varied spectrum of host cell pathways modified by C. pneumoniae suggests a complex interaction between the bacteria and the host cell. Identifying the requisite host-pathogen interactions contributing to C.pneumoniae virulence is a major research goal. While the morphological features of the chlamydial development cycle have been described in detail, our understanding of the cellular and molecular events underlying C.pneumoniae invasion and potential mechanisms of disease pathogenesis are preliminary. The work presented in this thesis examines cellular and molecular interactions between C.pneumoniae and various types of host cells during invasion and intracellular growth of chlamydiae. Some of the research questions addressed herein are framed within the context of atherosclerosis and coronary artery disease, with the a posteriori reasoning that a potential microbiologic contribution to human atherosclerosis, specifically due to C.pneumoniae infection, is suggested by several converging lines of investigation. We found that c.pneumoniae invasion of human epithelial cells requires bacterial-induced remodeling of the host acting cytoskeleton and the activation of at least two host cell signal transduction pathways. These host modifications are required for C.pneumoniae uptake but not cellular attachment, suggesting that the C.pneumoniae invasion sequence is biphastic, whereby initial attachment is rapidly followed by activation of host cell signaling and actin polymerization to facilitate uptake. Secondly, we used cDNA array technology to study the endothelial cell transcriptional response to C.pneumoniae infection and found a prominent transactivation of several cytokines, chemokines and smooth muscle cell growth factor genes during early times after infection. Furthermore, using cell culture-based experiments and an established rabbit model of C. pneumoniae-induced artherosclerosis, we showed that C. pneomoniae infection is associated with paracrine activation of smooth muscle cell proliferation and aortic intimal thickening, potentially mediated through platelet-derived growth factor.

abstract: Doctor of Philosophy (PhD)


title: The Neuroprotective Properties of Mood Stabilizers: from Gene Regulation to Ultrastructural Characterization

contributor:
Young, L.T.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract: Bipolar disorder, or manic-depressive illness, is a common psychiatric illness affecting 1.5% of the population. It is a chronic illness that requires long-term (often lifetime) pharmacotherapy. The need for lifetime treatment with mood stabilizers (i.e. lithium, valproate and carbmazepine) and high relapse rates suggests that changes in gene expression may be involved in the mechanism of action of these drugs. Using differential display, we identified the 78-kilodalton glucose-regulated protein, GRP78, as being at valporate-regulated gene in both rat brain and cultured cells. GRP78 belongs to a family of resident endoplasmic reticulum proteins, referred to as teh ER stress proteins, which includes GRP94 and calreticulin. These proteins act as both calcium binding proteins and molecular chapterones within the endoplasmic reticulum and when overexpressed protect the cell against cytotoxic insults. In addition to GRP78, we were able to show that GRP94 and calreticulun are also upregulated in a concentration-and-time-dependent manner in response to valporate. This effect was shown to be either drug-or drug class-specific, as treatment with other psychotropic drugs did not elicit a similar response. In patient samples, all three ER stress proteins were increased in postportem temporal cortex from depressed subjects to who died by suicide. These results suggest a possible cytoprotective role for mood stabilizers, since studies have shown that valporate as well as lithium can regulate the expression of proteins with known cytoprotective properties. Indeed, when rat hippocampal neurons were treated for 7 days with the mood stabilizers, lithium, valporate and carbamzepine, a significant reduction in NMDA-mediated cytoplasmic vacuolization could be quantified using transmission electron microscopy. In conclusion, the results of this thesis contribute to a growing number of studies that propose neuroprotective for mood stabilizing drugs, and suggest that valporate might act in part by regulating ER stress proteins.

abstract: Doctor of Philosophy (PhD)


title: A Michael Addition Approach Towards a Thienamycin Synthesis

contributor:
Bell, Russell Arthur
Chemistry

subject: Chemistry Chemistry

abstract:
A number of 2-aryl, 2-alkyl-4-[(E and Z]-1-alkoxyethyl-idene]-5-oxazolones, 2-alkylthio-4-[(E and Z)-1-alkoxyethyl-idene]-5-thiazolones and 2-ethoxy-4-[(E and Z)-1-ethoxyethyl-idene]-5-thiazolone were prepared. The configurations of the E and Z isomers of these compounds were assigned on the basis of the X-ray crystal structure of 4-[(Z)-1-ethoxyethylidene)-2-phenyl-5-oxazolone and by ¹H and ¹³C chemical shift data. These compounds were studied for reactivity to nucleophiles and electrophiles. Substitution reactions on the alkoxyethylidene portion of these compounds were effected with nitrogen, oxygen and suIfur nucleophiles and reaction with ring positions of 4-[(Z)-1-ethoxyethylidene]-2-phenyl-5-oxazolone and 2-ethoxy-4-[(Z)-1-ethoxyethylidene]-5-thiazolone gave ethyl 2-benzamido-3-ethoxy-2-butenoate and 4-[(Z)-1-ethoxyethylidene]-2,5-thiazolidinedione. The later product was ring opened to give ethyl 3-ethoxy-2-[N-methyl(methylthioamido)]-2-butenoate.

Dienolate anions of many of the 4-(1-alkoxyethylidene)-5-oxazolones and corresponding thiazolones were prepared by removal of an allylic proton. These anions reacted with methyl 2-(chloromethylene)-3-oxobutanoate in a Michael reaction. The resulting 4-(1-alkoxy-4-carbomethoxy-5-hydroxy-2,4-hexadienylidene)-5-oxazolones and thiazolones were found to be susceptible to cyclization to the corresponding 4-(5-carbomethoxy-6-methyl-2-pyranylidene)-5-oxazolones and thiazolones.

The dienolate anion of 4-[(Z)-1-ethoxyethylidene]-2-phenyl-5-oxazolone, was found to undergo Michael addition reactions with methyl 2- (chloromethylene)-3-oxobutanoate, methyl 2-(methoxymethylene)-3-oxobutanoate and ethyl 2-(phenylthio)-propenoate but not with ethyl 2-(phenylsulfinyl)propenoate, methyl (Z)-3-bromopropenoate and methyl (E)-3-chloropropoenoate.

abstract: Doctor of Philosophy (PhD)


title: Hydrogenolysis of Hydrocarbons on Iron Catalysts

contributor:
Anderson, R.B.
Chemical Engineering

subject:
Chemical Engineering
Chemical Engineering

abstract: In the hydrogenolysis of hydrocarbons, iron is unique among the transition metals since it breaks molecules extensively and produces large quantities of methane even at low conversion. Hydrogenolysis of propane, isopentane and n-hexadecane were studied at 325 and 355ºC over reduced Fe and carbided Fe catalysts prepared from a commercial NH₃ synthesis catalyst. Reaction network analysis applied to the selectivity data yielded a quantitative estimate of the relative importance, for an adsorbed species, of desorbing or undergoing C-C bond splitting; this method indicated that product desorption is the slow step in the reaction mechanism. Power rate expressions were obtained for hydrogenolysis of propane and isopentane at 325ºC. Used catalysts, characterized by Mössbauer spectroscopy, contained α-Fe at high feed ratios of H₂ to hydrocarbon, and Fe₃C, at low ratios. The formation of bulk iron carbides led to changes in selectivity, yielding less methane and more intermediate hydrocarbons. In hydrogenolysis of n-hexadecane, the analysis of the C₇-C₁₅ products by gas chromatography-mass spectrometry showed the presence of alkylbenzenes, alkenes and branched alkanes, which account altogether for as much as 20 mole % of the heavier hydrocarbons. The data also suggest that the breaking of paraffins on iron possibly occurs by rapid demethylation. Hydrogenolysis of hydrocarbons is completely inhibited when carbon monoxide is added to the feed, even at concentration as low as 4 mole %; CO is presumably more strongly adsorbed on the catalyst than hydrocarbons. The products obtained were similar to those found in the Fischer-Tropsch synthesis. Traces of water in the feed reduce the rate of hydrogenolysis. An increase in the K₂O content of Fe catalyst decreases its activity but does not affect its selectivity. A new method of deriving selectivity equations from reaction networks is presented. Network analysis is shown to apply to irreversible reactions for hydrogenolysis and isomerization.

abstract: Doctor of Philosophy (PhD)


title: Glutamine and asparagine metabolism in developing corn endosperm (Zea Mays L.)

contributor:
Oaks, Ann B.
Biology

subject: Biology Biology

abstract:
Metabolism of glutamine and asparagine was examined in developing endosperm of maize with emphasis on:

1. Characterization of the enzymes of amide metabolism.

2. A comparison of the levels of activity of enzymes of nitrogen assimilation in the endosperm of a normal variety of maize (W64A) and its isogenic high lysine mutants opaque-2 and_floury-2.

3. Investigations of the metabolism of (UL-¹⁴C) glutamine in the endosperm of cultured corn caryopsis.

Results showed that glutamate synthase (GOGAT), glutamine synthetase (GS), glutamate dehydrogenase (GDH), asparagine synthetase (AS), asparaginase (ASnase) and asparagine transaminase activities were present in the developing endosperm. The enzymes increased in activity just prior to the onset of zein biosynthesis, reached a maximum between 15 and 35 days after pollination and then declined. Two forms of GOGAT with molecular weights, estimated to be 171,000 and 270,000 for ferredoxin- and NADH-GOGAT, respectively, were identified. Almost equal levels of each enzyme were present at every stage of development. Either of these enzymes could mediate the transfer of the amide nitrogen of glutamine to α-amino nitrogen of glutamate. Glutaminase activity was not detected in the endosperm tissue.

The pattern of developmental changes in activity, and the actual levels of activity of GDH, GS, AS, and ASnase were similar in the control and the mutant varieties. In the mutants, the level of GOGAT activity was higher at all developmental stages examined. Twenty days after pollination the activity was 13 ± 0.6, 29 ± 0.5 and 18 ± 0.07 nmol NADH oxidized·minˉ¹·endospermˉ¹ in normal, opaque-2 and floury-2, respectively.

To estimate the capacity of the endosperm tissue to metabolize glutamine, (UL-¹⁴C) glutamine was injected into the endosperm of cultured caryopses. After 168 hr of incubation, 21% of the total label incorporated was recovered in starch, 38% in zein, 8% in glutelin and 13% in the free amino acid fraction. In the zein hydrolysate, glutamine accounted for 14% of the total label in this fraction. The results from tracer studies as well as the observations on the presence of enzymes lead to the conclusion that corn endosperm tissue is fully capable of metabolizing glutamine. The presence of label in the amino acid fraction as well as in carbohydrates suggests the presence of an enzyme system for the extensive metabolism of glutamine in the endosperm tissue.

abstract: Doctor of Philosophy (PhD)


title: Metallogeny of the "East South C" ore zone in the Dickenson Mine, Red Lake, Ontario; evidence for syngenetic gold deposition

contributor:
Crocket, James H.
Geology

subject: Geology Geology

abstract:
The Dickenson Mine, a gold producer in the Uchi volcanic-plutonic subprovince of the Canadian Shield, lies along the eastern flank of a volcanic complex consisting mainly of massive to pillowed basaltic komatiites and magnesium tholeiites with some ultrabasic and felsic flows, chemical and clastic sediments and proximal volcaniclastites. Studies of the 17, 22, 24, 25 and 30 Levels in the "East South C" and "East South C Footwall" ore zones show that the gold-bearing horizons lie within stratigraphically conformable fragmental rocks, which have been derived from a source dominated by basaltic komatiites and felsic volcanics with minor cherts and Fe-rich tholeiites.

At least two different types of mineralization are recognized. In the "East South C Footwall" zone (25 Level), the mineralization occurs in the metamorphosed argillaceous sediments. Increasing gold content correlates with a strong enrichment in total Fe, MnO, S, As, Zn and Ce, and with moderate increases in MgO, CO2, Ni, Co, Cu, Cr and V. There is also a strong depletion in SiO2, CaO and Ba in the auriferous rocks. The dominant opaques are pyrrhotite and magnetite with accessory pyrite, arsenopyrite and ilmenite. The "East South C" ore zone on the 30 Level is a felsic volcaniclastic horizon enclosed by pillowed mafic volcanics. With increasing gold content samples from this ore zone show a strong enrichment in total Fe, As, S, Zn and Ce and moderate increases in Cr, Ni, V and Ba. There is also a strong depletion in MgO and Zr. Profiles of Au, As and S about this ore zone indicate a strong asymmetry, in that background gold content is greater by a factor of 5 to 20 in the footwall rocks. The dominant opaques are pyrite, pyrrhotite and arsenopyrite with accessory magnetite.

These ore zones are pre-tectonic and post dated by at least two periods of lower amphibolite grade metamorphism. The dominant structural element is a northwesterly foliation. In areas of high strain, stratigraphy and mineralization parallel this trend. In areas of low strain, stratigraphy and mineralization trend in a northeasterly fashion and exhibit numerous northwest trending axial planes. The dominant metamorphic minerals are almandine, andalusite, cordierite and amphibole.

The metal-rich mineralized zone on the 25 Level is an auriferous sediment in which both chemical (exhalative) and clastic components are recognizable. Low temperature solutions carried and precipitated Au, As, S, Fe, Ti, Mn, Cu, Co, Zn and perhaps Si. MgO, Ni and Cr may have been enriched through leaching or erosion of nearby komatiites. The aluminum and silica content of these rocks indicates a significant detrital component. In the mineralized felsic volcaniclastites on the 30 Level, the precipitation of metals (Au, As, S, Fe, Zn) was synchronous with felsic volcanism or erosion of a felsic source.

In conclusion, the "East South C" and "East South C Footwall" ore zones are syngenetic deposits.

abstract: Master of Science (MS)


title: "Intrinsic Organization of a Motoneuron Pool in the Adult Rat"

contributor:
Diamond, Jack
Neuroscience

subject:
Neuroscience and Neurobiology
Neuroscience and Neurobiology

abstract: It is becoming increasingly clear from physiological and histochemical observations that many skeletal muscles are not used in an all-or-none fashion, but rather that some parts of the muscle are more active in one movement than another. Such a functional compartmentalization" could have an appropriate anatomical correlate; for example, within the pool of motoneurons supplying an individual muscle, subsets of motoneurons could be spatially grouped according to the location of their peripheral muscle fields. For a number of technical reasons, this possibility is difficult to investigate in the typical skeletal muscle. The cutaneous trunci muscle (CTM) of the rat, however, is ideally suited for such an investigation. This vast thin sheet of muscle is inserted into the deep surface of back and flank skin and is reflexly activated by nociceptive information from the overlying skin. A punctate stimulus evokes a localized contraction of the CTM in the immediate vicinity of the stimulus: the reflex activation of this muscle is therefore organized behaviorally into functional compartments. The simplest expectation would be that the peripheral nerves that drive the CTM reflex are segmentally organized. While this is true for the sensory nerves, I find that it is not the case for the motor ones. I have used electrophysiological and histochemical techniques to examine the pattern of motor innervation of the CTM and retrograde tracers to study its motoneuron pool. Interestingly, all the CTM motoneurons are located in the cervical spinal cord, several segments rostral to even the most rostral sensory input that activates the CTM. My findings indicate that there is a spatial organization within the CTM motoneuron pool; this organization corresponds to the pattern of motor nerve innervation of the muscle, and moreover, seems appropriate for the compartmentalized nature of the reflex activation of the muscle by cutaneous sensory nerves.

abstract: Doctor of Philosophy (PhD)


title: Alterations in the renal vasculature during the development of hypertension

contributor:
Forrest, J.B.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The alterations in renal vascular structure and function, and their role in the development and maintenance of hypertension were examined in Kyoto Wistar spontaneously hypertensive rats (SHR) and Wistar Kyoto normotensive controls (WKY). A study of the renal vascular bed in SHR with established hypertension and age matched normotensive WKY indicated that when the isolated kidney was perfused at a variety of flow rates, under maximally relaxed conditions, the renal vascular resistance (RVR) was similar between SHR and WKY. Consistent with the above finding, morphometric measurements of light and electron micrographs indicated that the lumen diameter of relaxed main renal, interlobar, arcuate and interlobular arteries, as well as the preglomerular arterioles was similar in SHR and WKY. The cross-sectional areas of total intima, endothelium, subendothelial space, internal elastic lamina and total adventitia, as well as the volume fraction of axons, nerve sheath cells, fibroblasts, collagen and fluid filled space within the adventitia were only modestly altered in SHR. However, with the exception of the preglomerular arterioles, the media of all the renal arterial classes of SHR exhibited an increase in smooth muscle cell (SMC) cross-sectional area and volume that was produced by SMC hypertrophy and/or hyperplasia, while the extracellular space surrounding the SHCs was increased in both arteriolar and pre-arteriolar vessels.

Based on these structural alterations, it was hypothesized that, if the mass of the arterial media is increased, contraction from the adventitial side would tend to push the media of the thicker hypertensive vessel into the lumen to a greater degree than the thinner walled WKY vessel. Under relaxed conditions, the RVR would be expected to be similar between SHR and WKY; however, during contraction RVR should be elevated to a greater degree in SHR than WKY. To test the above hypothesis, pharmacological studies were undertaken. Consistent with the model, at maximal relaxation the RVR was similar in SHR and WKY, while contraction of the renal vascular bed with infused norepinephrine (HE), BaCl₂ angiotensin II, or by stimulating the periarterial nerves produced a larger elevation of RVR in SHR. Aside from a modest increase in HE sensitivity within the renal vasculature of WKY, the contractile sensitivity to the various agents was not altered when SHR and WKY were compared. These studies indicated that the nerve mediated contractile responses within the renal vasculature were mediated by alpha₁ and dopamine receptors, and the proportion of the maximal response attributed to each receptor was similar in SHR and WKY.

Similar alterations, but of lesser magnitude, as those present in SHR with established hypertension were found to occur in prehypertensive SHR. The RVR at maximal relaxation was similar to that present in WKY, while the lumen diameter of the main renal, interlobar and cortical arteries was not modified between the two groups. All renal arteries of prehypertensive SHR that were studied exhibited an increase in the cross-sectional area ratio of arterial wall (intima + media) in relation to the lumen, and an increased number of SMC layers within the media. Consistent with the proposed model, when the renal vasculature of prehypertensive SHR was maximally contracted by infusing NE or by stimulating the periarterial nerves (under conditions where the presynaptic uptake of NE was blocked) the amplitude of RVR change was higher in prehypertensive SHR than WKY. As in SHR with established hypertension, the contractile sensitivity of the renal vasculature to NE was modestly increased in WKY.

To further test if such alterations occur independently of high blood pressure, hydralazine (an antihypertensive drug that crosses the placental barrier) was fed to female SHR prior to, and during, pregnancy, and subsequently to newborn rats from birth to 21 weeks of age. These animals were compared to similarly treated WKY and nontreated SHR and WKY controls. Treated SHR maintained normal blood pressure throughout the treatment period. The in utero and post-natal normalization of blood pressure in SHR had virtually no effect in altering the renal vascular wall thickness. Within most of the arteries studied, SHR with normalized blood pressure had similar cross-sectional quantities of media and SMC layers as were present in untreated SHR, and greater quantities than that present in either control or treated WKY. The withdrawal of hydralazine from 26 week old in utero and post-natally treated SHR resulted in the re-establishment of hypertension within two days of withdrawal to the levels that were present in control SHR.

These results suggest that the thickening of the renal vascular wall in SHR could be of etiological importance in the initiation and maintenance of high blood pressure in SHR, and that such changes are not a secondary modification produced by the elevation of blood pressure.

abstract: Doctor of Philosophy (PhD)


title: Skeletal Muscle Metabolism and Performance During Heavy Muscular Contraction in the Isolated Perfused Rat Hindquarter

contributor:
Jones, N.L.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
Direct assessments of the relative contributions of the major energy releasing pathways in human skeletal muscle during heavy exercise are difficult to obtain due to the invasive measurements required. With an isolated muscle preparation the muscles' environment is carefully controlled and all metabolic measurements are directly obtained. For this reason the isolated perfused rat hindquarter model, previously used to study resting muscle metabolism, was developed to examine the metabolism and performance heavily contracting skeletal muscle.

Energy calculations based upon measurements of O₂ uptake (aerobic metabolism), lactate production (anaerobic glycolysis) and CP hydrolysis (alactic anaerobiosis) were made during 20 minutes of repetitive tetanic stimulation. During the initial 5 minutes of stimulation isometric tension production was high but fatigued rapidly and anaerobic involvement in energy production was large (30%), especially in the fast-twitch glycolytic muscle fibers. Muscle glycogenolysis provided the majority of substrate for both anaerobic glycolysis and aerobic metabolism. During the final 15 minutes of stimulation aerobic metabolism dominated (90%) while 60% of peak tension was held, mainly by the fast-twitch oxidative, glycolytic muscle fibers. Glycogen utilization was minimal and intramuscular triacylglycerol became the dominant fuel for oxidative metabolism, contributing 62% of the energy produced.

Perfusions with acidotic mediums (metabolic and respiratory) reduced muscle glycogenolysis and lactate accumulation by 35% during the initial 5 minutes of stimulation. The decreased glycolytic flux reduced the availability of carbohydrate substrate for aerobic metabolism and O₂ uptake decreased. The associated reduction in energy release produced an increased rate of tension decay. Total energy release and tension production were also reduced during acidosis in the final 15 minutes of stimulation. The decreased glycolytic flux appeared to be due to an earlier fall in muscle pH during acidosis and subsequent inhibition of key regulatory enzymes such as phosphorylase and phosphofructokinase. However an alternate hypothesis is that acidosis exerted a direct negative effect on the excitation-contraction coupling mechanism, thereby reducing the need for energy production.

abstract: Doctor of Philosophy (PhD)


title: Physical and Molecular Characterization of Human Malignant Melanoma Antigens Defined by a Monkey Antiserum and a Mouse Monoclonal Antibody

contributor:
Liao, S. K.
Medical Sciences

subject:
Medical Sciences
Medical Sciences

abstract:
The studies contained in this thesis describe physical, biochemical and immunochemical characterization of human malignant melanoma cell surface antigens defined by a monkey antiserum and a mouse monoclonal antibody (MoAb).

The monkey anti-CaCL 73-36 antiserum identified, melanoma-associated surface antigens (MAAs) that were shed from cultured melanoma cells. The shed MAAs appeared to be similar to shed HLA-A,B,C antigens in terms of flotation on KBr, sedimentation in sucrose gradient, and association with B2-microglobulin.

The MoAb 140.240, which reacted with a melanoma-specific oncofetal antigen identified an epitope on an 87kd molecule that was integrally associated with melanoma cell plasma membrane. This molecule was a monomeric sialoglycoprotein that originated from a 77kd precursor polypeptide (p77). The precursor was converted to an intermediate 83kd giycopolypeptide (gp83) which in turn was further glycosylated to yield the mature 87kd glycopolypeptide (gp87).

Both gp87 and p77 were detectable in the chase medium of melanoma cells metabolically labelled in the presence of tunicamycin (TM), but had molecular weights slightly larger than their cellular counterparts. Comparison of tryptic peptide maps of cellular and shed gp87 showed complete overlapping, except that the shed form contained two additional methionine-containing peptides. Surface radioiodination of TM-treated cells showed that p77 was also expressed on the cell surface.

The purification of gp87 from membrane lysate and spent medium of cultured melanoma cells was achieved by a procedure involving ion-exchange, gel filtration, and antibody affinity column chromatography. Compared with the starting materials, the procedure yielded a purification factor of >3,300 and 28.6% recovery for cellular gp87, and a purification factor of >1,200 and 41.5% recovery for shed gp87. On SDS-PAGE, the purified preparations gave a single band of 87kd.

Immunochemical analysis of MoAb 96.5 to a 97kd MAA (p97) developed in another laboratory showed that gp87 and p97 were identical molecules, although the epitope recognized by MoAb 140.240 was distinct from that recognized by MoAb 96.5.

The biological and clinical significance of these findings in relation to the reports of other investigators on human melanoma-associated antigens are discussed.

abstract: Doctor of Philosophy (PhD)


title: Neutron Transport in Radiography

contributor:
Harms, A.A.
Nuclear Engineering

subject:
Nuclear Engineering
Nuclear Engineering

abstract:
A frequently important source of image degradation in diagnostic radiography series from the scattering of radiation within the object itself. The research presented in this dissertation is directed towards the elucidation of this source of radiographic image degradation.

The physical context selected is the passage of collimated thermal neutrons through an object of radiographic interest while the mathematical context is that of neutron transport. The analytical and computational methods are selected to emphasize the macroscopic image degradation effects of object scattering. Accordingly, isotropic neutron scattering and thermal one-group neutron-nucleus macroscopic cross-sections are employed as characterizations of the relevant interaction physics. Calculations and experiments undertaken pertain primarily to homogeneous objects of plunar geometry.

The conceptual basis of this dissertation is divided into two domains.

First, the transport of a collimated neutron beam through an object is modelled in isolation to the image formation domain with the goal of estimating the extent of object scattering that occurs. This is accomplished initially for a one dimensional homogeneous infinite slab object using a one-group integral transport formulation based on the point source diffusion kernel. An original solution to this particular form of the integral neutron transport equation is developed featuring the exact specification of a build-up factor function based on the forward partial neutron current and admitting an arbitrary degree of multiple scattering.

Additionally, an original extension to the double Pℯ method for solving the one-group integro-differential neutron transport equation is developed for calculating the two-dimensional transport of collimated neutrons through a rectangular object.

The second approach involves calculating the distribution of object scattered neutrons on the image formation plane thereby quantifying the incurred image degradation. This is accomplished by incorporating both problem domains into a system transfer function framework, involving the calculation of scattering based spatially variant point and line spread functions which are applied in the response determination for a homogeneous knife-edged slab object. Applications to the location of edges and corners on blurred neutron radiographs are established. These should ultimately be useful in the accurate radiographic dimensioning of nuclear fuel pins.

One significant result of these calculations is the quantitative evaluation of scattering based distortions that have previously been noted in neutron radiographic edge responses. The existence and relative magnitude of this phenomenon has been confirmed here using an analog Monte Carlo simulation. Experimental tests using the neutron radiography facility at the McMaster Nuclear Reactor have also been undertaken. Each of these confirmation techniques suggests that this scattering based edge distortion may possess merit as a neutron beam diagnostic indicator.

In summary, image degradation attributable to object scattering has been quantitatively examined and clarified for thermal neutron radiography. Applications in the interpretation of radiographic responses are thereby enhanced.

abstract: Doctor of Philosophy (PhD)


title: Psychological and Situational Factors in International Migration

contributor:
Carment, D.W.
Psychology

subject: Psychology Psychology

abstract:
Although Canada is populated by immigrants and their descendants, little beyond demographic characteristics is known about those who settle here. Migration has most often been viewed as solely economically motivated, a conclusion that is based to a large extent on analyses of aggregate data. Few researchers have obtained information from individuals and psychological factors which may be implicated in migration have been almost completely ignored.

The research reported in this thesis focused on applicants for immigrant visas at the Canadian High Commission in India and a matched sample of Indian nonemigrants. A multivariate analysis allowed for the simultaneous examination of a number of psychological and situational factors. Several differences between these groups were identified, the most important of which were that the potential emigrants were less satisfied with their occupation, were relatively high sensation seekers, were more interested in world events and had a more internal locus of control. The reasons potential emigrants gave for wanting to leave India, for choosing Canada as their destination and the gains they expected through migration were all related to these differences.

An additional component of the study was an investigation of Indians who had previously immigrated to Canada. It was found that the demographic characteristics of these migrants and their perceptions of migration have generally remained stable over three decades. There was some suggestion that personality traits had changed among these immigrants but the etiology of these changes requires confirmation.

abstract: Doctor of Philosophy (PhD)


title: Catabolite Resistant Mutants of Bacillus subtilis

contributor:
Takahashi, I.
Biology

subject: Biology Biology

abstract:
Mutations that confer resistance to catabolites in sporulation (crs) are located in six distinct loci on the chromosome of Bacillus subtilis. One of the crs mutations, crsEl, is found in the rpoBC operon which codes for β and β' subunits of RNA polymerase. Some stv and std mutations in the same operon also confer partial resistance to glucose. Another mutation, crsA47, is located in the gene for the σ-factor of RNA polymerase. These findings indicate that certain mutations in RNA polymerase can alter the response of cells to the inhibitory effect of catabolites on sporulation.

The crs mutants differ from each other in the growth characteristic and glucose utilization. Specific activities of IMP dehydrogenase and alkaline phosphatase vary widely among the crs mutants. These results suggest that the growth characteristic and the enzymes examined are not closely related to catabolite resistance in sporulation.

The crs mutants are resistant to at least one of the membrane-affecting agents, cerulenin, ethanol and NaCl in sporulation. This suggests that the membrane and its associated functions are important in initiation of sporulation. It is also suggested that functions affected in the crs mutants are related to the membrane.

Mutations scal9, rfmll, eryl and relA can offset the catabolite resistance in some of the crs mutants. Possibly, these suppressors suppress the catabolite resistance by affecting the membrane or by causing a metabolic imbalance which affect membrane functions.

abstract: Doctor of Philosophy (PhD)


title: Pressure Wave Propagation in a Horizontal Air-Water System

contributor:
Banerjee, S.
Nuclear Engineering

subject:
Nuclear Engineering
Nuclear Engineering

abstract:
Finite amplitude pressure waves were investigated in a horizontal air-water system to determine the multidimensional propagation characteristics. Five classes of waves were analysed in this system of which four occurred in the water phase. The duct used to investigate these waves was square, 9 cm on a side, and 5 m in length.

Weak shock waves of finite length were used in the gas phase. Theory by Whitham accurately predicted the attenuation.

Pressure wave propagation in the water was dominated in all cases by characteristics associated with a Klein-Gordon equation. This equation is derived assuming a free surface but is found to play a role even when the surface of the water has an applied pressure.

Pressure waves in the water under a free surface were studied in the system. Amplitudes of this class of waves were found to be small and they travel quickly throughout the system.

An impulsive applied pressure to the water at a vertical wall can generate two types of waves depending on the period of the pressure pulse. If it is longer than a cutoff period defined by the Klein-Gordon dispersion relation, amplitudes decay as tˉ½, where t is the time, and exponentially with distance. If the period is less than cutoff, pressure waves in the water can propagate down the duct under a free surface. Pressure amplitudes in the water at the vertical wall can be large due to additive effects from the applied surface pressure.

The water region beneath the shock can act as a three dimensional waveguide. This phenomenon depends on the depth of the water. High pressure amplitudes can occur in the water relative to the shock. The frequency source needed to drive the waveguide is conjectured to be a Klein-Gordon wave packet which remains steady with the shock.

If bubbles are present in the water so that the effective sound speed in the water is less than the speed of the shock, high amplitudes will exist in the water accompanying the shock since energy cannot quickly disperse away from the shock region.

abstract: Doctor of Philosophy (PhD)


title: Pipeline Pulsing Flow of Slurries

contributor:
Round, G. F.
Mechanical Engineering

subject:
Mechanical Engineering
Mechanical Engineering

abstract:
This thesis presents the results of pulsing flow experiments on solid-liquid suspensions. Specifically, the hydraulic energy requirement in pulsing flows for a given slurry flowrate is compared with the steady state energy consumption for the same flowrate. It is also shown theoretically that, for the same time-averaged flowrate as in the steady state case, it is feasible to reduce the time-averaged pressure gradient and hence power requirement by pulsing.

The following five different types of flow systems were the subject of study: water, bentonite clay water, fine sand water, fine sand bentonite clay water and coarse sand water.

For the above five types of flow systems the following pertinent flow variables were studied: pulsation frequency, pulsation amplitude, average slurry velocity, solids volume concentration, mean particle size and the presence of a small amount of ultra fine particles in coarse solid liquid mixtures.

The experimental results of pulsing flow of water alone indicated that the pulsing to steady state power ratio (Jᴘ/Js) was always greater than unity indicating that for a Newtonian fluid the hydraulic energy in pulsing flow is greater than the steady flow, the increase of energy being used to maintain pulsation.

Results of pulsing flow experiments with bentonite slurry have indicated that the power ratio (Jᴘ/Js) was observed to be less than unity for certain combinations of frequency, amplitude and slurry velocity. The minimum value of (Jᴘ/Js) found was about 0.75 at a frequency of about 0.80 Hz, amplitude of 51 mm and velocity of 1.9 m/s.

In the ranges investigated, results with sand-water slurries have indicated that the power ratio (Jᴘ/Js) was a function of the variables listed above. The minimum value of the power ratio (Jᴘ/Js) for sand water slurries was found to be about 0.50 at the following values of the variables: pulsation frequency 0.45 Hz, amplitude 32 mm, slurry average velocity 1.8 m/s, solids volumetric concentration 12.5% and particle size 0.47 mm.

The reduction in the power ratio in the case of pulsing flow of sand water slurries is attributed to the formation of a particle free layer near the pipe wall while the bulk of the particles flow as a plug in the middle of the annulus of the lubricating particle free layer.

In the case of bentonite clay water slurry the reduction in the power ratio is attributed to the formation of a low viscosity layer near the pipe wall. The bulk of the slurry flows as a plug in the middle of the annulus of the low viscosity layer.

Results of this thesis indicate that power consumption for transport of slurries using pulsing flow is considerably less than power required to transport the same amount of slurry by a steady flow method.

abstract: Doctor of Philosophy (PhD)


title: The Analysis of Nitro Polycyclic Aromatic Hydrocarbons in Diesel Exhaust and Urban Airborne Particulate Samples

contributor:
Quilliam, M.A.
Chemistry

subject: Chemistry Chemistry

abstract:
Analytical methodology has been developed for the determination of nitro polycyclic aromatic hydrocarbons (nitro-PAHs), polycyclic aromatic hydrocarbons (PAHs) and other PAH derivatives in diesel exhaust and urban airborne particulate samples. Samples were Soxhlet extracted with methylene chloride for twenty-four hours and the organic extract filtered to remove particulate matter. This extract was taken through a three stage clean-up procedure. Very polar materials were initially removed using a silica Sep-Pak. The aromatic compounds were than separated from the aliphatic substances by Sephadex LH-20 chromatography. Normal phase semi-preparative high performance liquid chromatography was used for the final fractionation of the aromatic compounds. Three fractions, containing PAHs (Fraction A), nitro-PAHs (Fraction B) and dinitro-PAHs (Fraction C), were collected for further analysis. Two diesel exhaust (Oldsmobile and Peugeot) and four airborne particulate (Toronto and Hamilton, Ontario) samples were taken through this procedure.

Capillary column gas chromatography (GC) with flame ionization and nitrogen-selective detection was used for the detection and quantitation of nitro-PAHs. Confirmation of the identity of nitro-PAHs was done by capillary column GC-MS in the selected-ion-monitoring mode and other compounds were identified by capillary column GC-MS in the full scanning mode of operation.

Nitro-PAHs including 1-nitropyrene, nitro(phenanthrenes/anthracenes), methylnitro(phenanthrenes/anthracenes), nitrobenzo[a]fluorene and 6-nitrobenzo[a]pyrene were confirmed and quantitated in the samples using 1-nitronaphthalene as an internal standard. PAHs, found in Fraction A, and oxygenated-PAHs (e.g., ketone- and quinonederivatives of PAHs) found in Fractions B and C were tentatively identified and their levels estimated.

abstract: Doctor of Philosophy (PhD)


title: Test of the Charge Density Wave Model of Potassium Using the Induced Torque Method

contributor:
Datars, W.R.
Physics

subject: Physics Physics

abstract:
The conductivity tensor of potassium was studied using the induced torque technique in two magnetometers. The response of the two magnetometers was calculated and tested with standard materials. The phase of the induced torque was calculated.

The induced torque in potassium showed different behaviour in magnetic fields, below 0.2 T, between 0.2 and 4 T and above 4 T. A two-fold torque anisotropy with peaks separated by 180º was observed at low fields and a four-fold pattern with peaks separated by 90º is dominant up to fields of 4 T. At high fields there are peaks in the induced torque rotation pattern which are characteristic of open orbits in a metal. The amplitude and magnetic field direction of some of the peaks changes non-monotonically with temperature over the temperature range 1.1 to 2.1 K. The high field peaks are independent of the presence of the four-fold torque which depends on sample preparation.

The amplitude and phase of the induced torque were calculated for two models, an ellipsoidal sample with free electron conductivity and a sample with a charge density wave ground state. The four-fold induced torque was quantitatively explained by an ellipsoidal sample. Reasons why a model of an ellipsoidal sample is valid were presented.

Qualitative agreement between the high field peaks and the charge density wave model which predicts open orbits was obtained. A quantitative explanation of the temperature dependence could not be obtained. Other possible explanations of the high field peaks were considered and found to be unsuitable.

abstract: Doctor of Philosophy (PhD)


title: Combinatorial Designs With Prescribed Automorphism Types

contributor:
Rosa, Alexander
Mathematics

subject: Mathematics Mathematics

abstract:
In this thesis we deal with the following question: given a permutation α on a set V, does there exist a certain block design on V admitting α as an automorphism?

We are able to give a (complete or partial) answer to this question for the following: 1) 3- and 4-rotational Steiner triple systems,

2) 3-regular Steiner triple systems,

3) Steiner triple systems with an involution fixing precisely three elements,

4) 1-rotational triple systems,

5) cyclic extended triple systems,

6) 1-, 2- and 3-rotational extended triple systems,

7) 2-, 3- and 4-regular extended triple systems,

8) 1- and 3-rotational directed triple systems,

9) 1-rotational Mendelsohn triple systems,

10) cyclic extended Mendelsohn triple systems,

11) 1-rotational extended Mendelsohn triple systems.

We also present a recursive doubling construction for cyclic Steiner quadruple systems, and construct the latter for several orders.

abstract: Doctor of Philosophy (PhD)


title: Studies on the Assembly of Membrane Proteins: Topological Organization and Interactions of the Membrane Proteins of Vesicular Stomatitis Virus

contributor:
Ghosh, Hara P.
Biochemistry

subject: Biochemistry Biochemistry

abstract:
The purpose of this study was to investigate the assembly of membrane proteins by examining the topological organization and interactions of the membrane proteins G and M of vesicular stomatitis virus (VSV).

Exhaustive proteolytic digestion of VSV resulted in the complete degradation of G protein, however, a small peptide fragment having an apparent molecular weight of approximately 9,000 D remained associated with the viral membrane. Characterization of this membrane embedded frargment by tryptic peptide analysis and amino acid sequence determination demonstrated that it was derived from the COOH-terminal end of G protein. Furthermore, comparison of the partial amino acid sequence of this peptide fragment with the predicted amino acid sequence of G protein indicated that this peptide contains an uninterrupted hydrophobic domain of sufficient length to span the viral envelope. Thus, the G protein of VSV is anchored in the viral membrane by a hydrophobic domain located near the COOH-terminus.

In addition to the COOH-terminus, the NHZ-terminus of G protein was also shown to be protected from proteolytic attack by the integrity of the viral envelope. This may be related to the tertiary structure of G protein that is imposed by the viral membrane or the fact that the NHz-terminus may be in close proximity to the surface of the membrane and thus protected from proteolytic attack.

It has recently been reported that the VSV G protein contains tightly bound fatty acid residues. Proteolytic digestion of VSV labeled with [³H]-palmitic acid demonstrated that all the fatty acid residues present in G protein are localized exclusively in the membrane interacting domain. Thus, the lipophilic fatty acids in conjunction with the hydrophobic domain may play an important role in the interaction of G protein with the viral envelope.

VSV grown in the presence of w-[9-³H] diazirinophenoxy nonanoate resulted in the biosynthetic incorporation of this photoreactive fatty acid into the viral phospholipids as well as into the membrane anchoring domain of G protein. Photolysis of the virus resulted in extensive phospholipid crosslinking to the G protein but not to the M protein. This confirms that the COOH-terminal region of G protein is in intimate contact with the hydrophobic core of the lipid bilayer and directly demonstrates that M protein does not penetrate the viral membrane to a significant extent. In addition, a new product was obtained following photolysis and identified as a G-G dimer on the basis of its molecular weight and immunoreactivity. This product arose presumably from protein crosslinking mediated by the photoreactive fatty acid attached to G protein. Thus, the biosynthetic incorporation of this photoreactive fatty acid makes it possible to not only identify integral membrane membrane proteins but also to make photoaffinity probes of membrane proteins which are normally fatty acid acylated.

The nature of the association of M protein with membranes was examined by reconstituting the purified protein into artificial phospholipid vesicles. The M protein was shown to have a strong affinity for such vesicles and the association, once made, could not be disrupted by salt treatment. This suggests that the interaction was at least partly hydrophobic in nature. The nucleocapsid protein N was shown to have no affinity for artificial lipid vesicles, however, it could associate with vesicles in the presence of M protein. The same results were obtained when in vitro synthesized proteins were used for reconstitution. These results support the concept that the M protein is involved in virus maturation through its ability to interact with both the plasma membrane and the ribonucleoprotein core containing N protein.

The maturation of membrane proteins is thought to be directed by discrete polypeptide domains present in the protein which are recognized and decoded by specialized mechanisms of the cell. As an approach to study the function of these various polypeptide domains, a hybrid gene was constructed from plasmids containing cDNA copies of the complete coding sequences of the G and M mRNAs. A chimeric gene, which contained the signal sequence coding region of G protein fused to the bulk of the coding sequence specific for M, was constructed and placed into an expression vector. Introduction of this hybrid gene into mammalian cells by DNA mediated gene transfer resulted in the synthesis of a 36,000 D polypeptide immunoreactive with anti-M antibody. This plasmid should thus be useful for the functional examination of the signal sequence of G protein. As well, it should be useful for examining polypeptide domains which are involved in glycosylation since M protein contains a cryptic glycosylation target site.

The studies reponed in this thesis have been presented, in part, in the following publications.

1. Ghosh, H.P., Capone, J., Irving, R., Kotwal, C., Hofmann, T., Levine, G., Rachubinski, R., Shore, G., and Bergeron, J. (1981) Viral Membrane Proteins: Assembly and Structure. In Replication of Negative Strand Viruses. D.H. Sishop and R.W. Campans ed. p. 655 Elsivier North Holland.

2. Capone, J., Toneguzzo, F., and Ghosh, H.P. (1982) Synthesis and Assembly of Membrane Glycoproteins: Membrane Anchoring COOH-Terminal Domain of Vesicular Stomatitis Virus Envelope Glycoprotein G contains Fatty Acids. J. Biol. Chem. 257, 16

3. Leblanc, P., Capone, J., and Gerber, G.E. (1982) Synthesis and Biosynthetic Utilization of Radioactive Photoreactive Fatty Acids. J. BioI. Chem. 257. 14586

4. Capone, J., Leblanc, P., Gerber, G.E., and Ghosh, H.P. (1983) Localization of Membrane Proteins by the use of a Photoreactive Fatty Acid Incorporated in vivo into Vesicular Stomatitis Virus. J. Biol. Chem. 258, 1395.

5. Kotwal, G., Capone, J., Irving, R., Toneguzzo, F., Bilan, P., Rhee, S., Hofmann, T., and Ghosh, H.P. (1983) Viral Membrane Glycoproteins: Comparison of the Amino Terminal Amino Acid Sequences of the Precursor and Mature Glycoproteins from different Serotypes of Vesicular Stomatitis Virus. Virology (in press).

abstract: Doctor of Philosophy (PhD)


title: The Businessmen of Brantford, Ontario: Self-employment in a Mid-nineteenth Century Town

contributor:
Gagan, David P.
History

subject: History History

abstract:
Industrial capitalism altered the class structure of mid-nineteenth century Brantford, Ontario; by more clearly distinguishing the business and working cIasses. This dissertation addresses that process through the means of a collective biography of the town's businessmen. To this end, as many businessmen as possible have been identified at roughly decadal intervals from 1830 to 1881 and personal and economic data on them assembled from a number of quantifiable sources, principally manuscript census schedules and assessment rolls.

As a social activity, business was in Brantford in the 1870s no longer what it had been twenty or thirty years previously, a stage of life for a large proportion of the adult male population and a state of independence to which ambitious young men could realistically aspire. The desire for this independence attracted British and American immigrants to Brantford from the 1830s to the 1850s in hopes of achieving a life style which had become difficult to sustain in more developed economies. The favourable conjuncture of staple based prospensity within a relatively isolated consumer market made it possible for men with limited assets to establish viable and successful enterprises. Moreover, in a culture which wholeheartedly encouraged independence, a man could command credit on the strength of his own character and sense of responsibility.

The basis for pervasive self-employment was undermined in Brantford by the contraction of credit during and following the depression of the late 1850s and early 1860s and by the integration of the urban economy into a larger and more competitive regional trading system. Nevertheless, those who survived this critical period were in a position to expand their businesses. Unlike the 1850s when increases in demand were met by roughly proportionate increases in the number of businesses, in the 1870s growing demand encouraged the expansion of existing businesses. The result of this was a shrinkage in the size of the business community by about forty per cent.

The presence of entrenched and established business interests made it far more difficult to become self-employed in the 1870s and it took longer to acquire the experience, assets and connections needed to embark on a business career. For this reason, newcomers were at a disadvantage in comparison with natives and businessmen were increasingly drawn from the Canadian-born population or from those who possessed that familiarity with the community derived from a lengthy residence. Moreover, once in business, advancement was much less likely for the novice and small businessman than it had been in the 1850s. The high rates of business discontinuation suffered in the 1870s by men in business less than ten years and by the least wealthy contrasted with the solid security of the business elite.

These more limited opportunities for self-employment and for advancement through self-employment provided a sharper definition of the business class in mid-nineteenth century Brantford. No longer was a business career a mark of social maturity and independence. Instead, the businessman was the exceptional survivor of demanding economic and social circumstances.

abstract: Doctor of Philosophy (PhD)


title: Simultaneous Temporal Interval Production and Duration Discrimination in Practised Subjects

contributor:
Kristofferson, A.B.
Psychology

subject: Psychology Psychology

abstract:
Theories of the perception of short time intervals have generally postulated a single timing mechanism which serves in all experimental situations, including both duration discrimination and interval production. Despite this hypothesis, the characteristics of timing behaviour are not always the same for different timing tasks.

A dual timing task was devised, in which subjects concurrently perform both response-stimulus synchronization and duration discrimination. They were required to discriminate the time of occurrence of a brief auditory stimulus presented during a 460-msec, synchronization interval, also marked by brief auditory stimuli. The internal interval produced to perform response-stimulus synchronization can be deterministic and, if this interval could be used as a criterion for duration discrimination in the dual task, "perfection" discrimination might result. This end was not attained but both synchronization and duration discrimination were performed as well concurrently as they are when they are performed separately. The independence of the variability found in the two tasks suggests that they may not be accomplished by the same timing mechanism.

Although performances on the concurrent tasks were largely independent, the stimuli marking the duration discrimination interval had systematic effects on synchronization performance. A qualitative model was proposed to account for these effects. When stimuli are expected during the synchronization interval, the produced interval is occasionally interrupted, until the stimulus is observed. The momentary discontinuities, each of which adds a small amount of time to the final response, occur within a temporal "observation window" which is established after experience with a particular stimulus set.

The variances of the two concurrent tasks were independent, indicating that a single timing mechanism will not easily account for behaviour in all situations involving the timing of brief intervals. However, the systematic effects of the duration discrimination stimuli on synchronization behaviour suggest that the two tasks do share some processing resources.

abstract: Doctor of Philosophy (PhD)


title: Watershed Acidification Model And The Soil Acid Neutralization Capacity Concept

contributor:
Kramer, J. R.
Geology

subject: Geology Geology

abstract:
A computer simulation model is developed and tested which is capable of simulating the movement of water and chemical constituents, specifically H⁺, through a watershed.

Emphasis is placed on the interaction of H⁺ with the soil system. An acid titration method has been developed to determine the acid neutralization capacity (ANC) of bulk soil or soil minerals. ANC functions have been developed which consider the effect of H⁺ - cation exchange, H⁺ - Al⁺³ exchange and solution reactions at low pH levels (< pH 4.5). The ANC and ANC function concepts developed in this research are more relevant to acidic loadings on soils than cation exchange capacity or base saturation.

The model operates on a daily time step and the input data required to drive the model are: 1) precipitation depth 2) mean air temperature 3) mean relative humidity and 4) precipitation pH and alkalinity/acidity.

The model has been applied to a calibrated watershed, Batchawana Lake Basin, the headwater basin of the Turkey Lakes Watershed, located approximately 50 km north of Sault Ste. Marie, Ontario. The model has been found to be capable of accurately predicting all of the hydrologic flows for the Batchawana Lake Basin and should be applicable for most small (< 5 km²) non-urban watersheds. The model also accurately predicts the daily lakewater pH values, snowpack and snowmelt chemistry and average stream-water pH values. The ANC functions used in the model are not designed to predict short-term fluctuations in soilwater pH values which are normally due to biological processes but rather long-term changes in soilwater pH levels due to long-term inputs of acidic precipitation.

Sensitivity analyses were carried out on the model in order to determine the key parameters controlling the rate of acidification of a watershed. In addition to the actual acidic loading rate, the more sensitive parameters in decreasing significance are:

i) -infiltration rates ]

ii) -soil depth ]

both control the "degree of interaction" of the incident acidity with the soil materials

iii) -soil horizon ANC's

abstract: Doctor of Philosophy (PhD)


title: Regulation of Nuclear Division and Ascosporogenesis in Apomictic Strains of Saccharomyces cerevisiae

contributor:
Miller, J.J.
Biology

subject: Biology Biology

abstract:
Effects of nutritional alterations (carbon source, zinc) on nuclear division and protein synthesis during apomictic and meiotic differentiation in Saccharomyces cerevisiae strain 19el were investigated. The approach taken has led to identification of: physiological prerequisites for both developmental routes, landmark cytological and molecular events controlling the manner of nuclear division and spore production, other environmental modifications suppressing apomixis, and the period of sporulation during which a decision is made concerning the manner of differentiation.

Unlike cells cultured under meiosis-promoting conditions, cells cultured under apomixis-promoting conditions exhibited extensive protein synthesis during the first 3 h of sporulation. Cycloheximide treatment of the latter cells induced meiosis and maximum yields of meiotic asci resulted when the treatment was given for the first 3 h in sporulation medium. Temperature shock treatments administered during early hours under sporulation-inducing conditions also increased the frequency of meiosis. Thus the data indicate that the decision concerning which developmental route, apomictic or meiotic, a given cell will follow is made shortly after transfer of cells to sporulation medium. Electrophoretic analysis of labeled proteins synthesized during sporulation revealed bands unique to both developmental routes.

A novel microcytochemical staining procedure was developed to determine sites of zinc accumulation in vegetative and sporulating yeast. The procedure was used to monitor intracellular distribution of zinc during sporulation in an effort to integrate cytological with molecular data. The micronutrilite translocated from vacuolar to nuclear compartments during the early critical period of sporulation. Possible roles of zinc were considered and several hypotheses were offered to explain the restoration of meiosis in apomictic mutants by environmental manipulation.

abstract: Doctor of Philosophy (PhD)