<p>Ryanodine, a neutral alkaloid, is a widely used pharmacological tool in the studies<br />of muscle excitation-contraction coupling. The specific binding sites for ryanodine have<br />been identified to exist on sarcoplasmic reticulum (SR) in both skeletal muscle and<br />cardiac muscle. The ryanodine receptor has been purified from different tissue types. The purified ryanodine receptor from skeletal muscle was found to be identical with foot<br />structure, a protein spanning the gap between t-tubule and SR membrane. The ryanodine<br />receptor was also found to have Ca²⁺ channel activity, a Ca²⁺-induced Ca²⁺ release channel.<br />In functional studies with isolated SR vesicle or single channel, ryanodine was found to<br />have dual effects on Ca²⁺ channel. At lower concentrations, ryanodine locked Ca²⁺ channel<br />in the open state, but fully closed the channel at higher concentrations. In smooth muscle,<br />ryanodine was also found to affect intracellular Ca²⁺ movement in the functional studies<br />using intact tissue. However, direct evidence was not available for the presence of<br />ryanodine receptor in smooth muscle before this research was carried out.</p> <p>In the present study, a high affinity binding site was found located on SR<br />membranes of rat vas deferens (RVD) smooth muscle (Kd=5.6 nM, Bmax=435 fmol/mg).<br />The ryanodine receptor in smooth muscle shared many similarities with that of skeletal<br />muscle, but was not identical. The time required for [³H]ryanodine binding to microsomal<br />fraction was about two hours to reach a steady state, and [³HJryanodine could be dissociated from its binding site by 20 fold dilution. However, the dissociation was very<br />slow and incomplete when initiated by excess ryanodine. The [³H]ryanodine binding in<br />smooth muscle was Ca²⁺ dependant. The affinity was increased with increased Ca²⁺<br />concentrations, but the Bmax was unchanged. The [³H]ryanodine binding also increased<br />with higher ionic strength and higher osmolarity, but later has less effect. Many factors<br />that affect Ca²⁺-induced Ca²⁺ release (CICR) channel activity were also found to affect [³H]ryanodine binding in my study; e.g., both Mg²⁺ and ruthenium red inhibited binding<br />and caffeine potentiated it, especially in the presence of a low Ca²⁺ concentration. In the<br />present study, I also showed that varied levels of [³H]ryanodine binding site existed among different smooth muscles. This variation was not correlated with the density of innervation or the SR content of different smooth muscles.</p> <p>In dog mesentery artery smooth muscle, a low affinity binding site (Kd=269 nM) was also identified, in addition to the high affinity binding site.</p> <p>In the present study, I also tried to show functional effect of ryanodine on the<br />CICR channel using subcellular membrane vesicles from vas deferens. Ryanodine, at<br />higher concentrations, inhibited oxalate-stimulated Ca²⁺ uptake, an effect which was observed as early as 5 minutes after uptake was initiated. This inhibitory effect was partially additive to that of cyclopiazonic acid (CPA), a potent SR Ca²⁺ pump inhibitor,<br />when this agents were used at submaximal concentrations. However, when CPA was used at a maximal concentration, ryanodine had no additional effect. Ryanodine at concentrations of 10⁻⁹ to 5x10⁻⁴ M, did not significantly change the Ca²⁺ release rate. In Ca²⁺ release experiments, no functional Ca²⁺ channel was observed, but the data are consistent with an inhibition of the SR Ca²⁺ pump at high ryanodine concentrations.</p> <p>My study provided the first direct evidence ofthe existence ofryanodine receptors located on smooth muscle SR which may represent a CICR channels. Since another type of Ca²⁺ channel, IP₃-induced Ca²⁺ release channel (IICR), has also been identified in different smooth muscles, the varied levels of ryanodine binding site observed in the present study may be correlated to the ratio of occurrences of the two types of Ca²⁺ channel. This suggests that different excitation-contraction coupling mechanisms may exist in different tjpes of smooth muscle depending on different expression of these two channels. The present study also suggests that ryanodine, at higher concentrations, may inhibit the Ca²⁺ pumps located on SR. Suitable conditions for membrane isolation and Ca²⁺ transport experiment must be defmed to restore a functional Ca²⁺ release channel in smooth muscle, in order to study the functional effect of ryanodine on this channel.</p> / Doctor of Philosophy (PhD)

<p>A strategy to investigate the effect of two exercise modes upon patients with chronic airflow obstruction (CAD) is developed. The difficulties in defining and diagnosing the various pathological entities covered by the umbrella term CAO are discussed. Following a review of the published studies of endurance exercise in the before mentioned patient population a clinical problem is identified. Cycle ergometer exercise and voluntary hyperventilation were the two modalities chosen to be investigated. A 2² factorial design is selected in order that both modalities may be efficiently studied, singly and in combination, with the inclusion of a placebo exercise group.</p> <p>A statistical method is depcribed for measuring agreement between two technicians conducting a test identifying the diagnostic inclusion criteria. An additional criterion for entry into the study will be inclusion of only those patients who are particularly likely to maintain the randomly assigned maneuver. This will be determined by the response to carried out a pre-experimental sequence of three weekly test events carried out current to a CAO stabilization period. The intensity of the exercise will be established using a standardized progressive exercise test and a maximum sustainea ventilatory capacity procedure. The choice of the three dutcomes was based upon a more total definition of rehabilitation. The three primary outcomes are endurance as measured by both a twelve minute walking test and a progressive multistage treadmill test. The patients' perception of their social, emotional and physical function in response to the exercise regimen is additionally measured using a health index questionnaire.</p> / Doctor of Philosophy (PhD)

<p>The acid-base and structural chemistry of freshwater dissolved organic matter (DOM) is known to vary with time and location. The purpose of this dissertation is to show how the chemical quality of DOM in temperate streams, wetlands and lakes of the Kejimkujik National Park area in central Nova Scotia varies over an annual cycle and how the changes in quality are related to DOM formation and diagenesis. New techniques were developed and used to better define the chemical quality DOM. A titration method described by Brassard et al. (1990) allowed the description of the acid-base characteristics of DOM. A reverse osmosis method is also described for the concentration of DOM without its fractionation to allow structural determination by ¹³C NMR of whole material. The results indicate that the chemical quality of DOM found in freshwaters is not similar to that found in soils. This difference suggests that interactions between soils, biology and hydrology modify the DOM in streams. A laboratory experiment suggests that the most likely pathway of DOM formation is the breakdown of plant structural material into aliphatic material with subsequent aromatic formation via semi-quinone and quinone. Comparison of incubation experiments with field results also shows that DOM acidity in natural water decreases with time caused by biological and chemical oxidative processes. Theoretical considerations indicate that the acidity of DOM does not follow the simple relationship suggested by Oliver et al. (1983) because of differences in source material and diagenetic processes, as well as the influence of inorganic cations and anions which until now have been assumed to be uncomplexed with organic matter.</p> / Doctor of Philosophy (PhD)

<p>Herpes simplex virus (HSV) is unusual in its ability to cause recurrent infection in a host with an ostensibly competent immune system. This thesis describes two mechanisms by which HSV evades the cellular immune response, which contribute to its ability to persist.</p> <p>Human cells infected with HSV inhibit lysis by natural killer (NK) and lymphokine-activated killer (LAK) cells. Contrary to the conclusions of previous workers, this effect is due to infection of the lytic effector cells, as shown by experiments with mutant HSV and by immunofluorescence staining of effector cells in contact with HSV-infected targets. The inhibition of lytic effector cells by HSV by cell-to-cell spread may play an important role late in the infectious cycle.</p> <p>Early in the infectious cycle, infectious virus is not present and the above mechanism cannot take effect. Instead, HSV imposes a block on the cellular pathway which presents antigen to CD8⁺ cytotoxic T lymphocytes. The result is that HSV-infected human fibroblasts show abnormalities of their class I major histocompatibility complex (MHC class I) similar to those seen in antigenpresenting mutant cell lines: the MHC class I is retained within the ER and is misfolded and unstable, implying that peptide is not associated with the heavy chain/β₂-microglobulin complex. Experiments with mutant and recombinant viruses established that this effect is due to an HSV irnmediate-early protein, ICP47, and showed that cells expressing ICP47 are not efficiently recognized and lysed by CD8+ CTL. Since ICP47 is not detectably membrane-associated, it presumably affects some cytoplasmic component of the antigen-processing pathway. One candidate for this cellular target is a small (8.5 - 9 kDa) protein, which, like ICP47, is located within the cytoplasm and nucleus of certain cell types. This protein was detected by its ability to bind to a protein consisting of ICP47 fused to the carboxy terminus of glutathione S-transferase (GST).</p> / Doctor of Philosophy (PhD)

<p>A study evaluating the response of canopy transpiration (Ec) and growth rates to reduced water input, was conducted in a managed 70-year old planted temperate white pine (Pinus strobus L.) forest, in Southern Ontario, Canada from January to December 2009. In order to induce the drought, a 20m x 20m throughfall exclusion setup was established using interlocking aluminum troughs at a 3-inch slope. Throughfall was excluded from April 1st until July 3rd. During this period, 270mm of rainfall occurred (27% of annual precipitation) of which 90% was excluded. Sap flow velocity, soil moisture and soil temperature (at multiple depths) were measured continuously in both reference and drought plots. Dendrometer bands were also installed on all instrumented trees. Prior to enforced drought, adjacent plots showed slight variability in soil moisture while tree diameter and soil temperature did not show significant variability. Daily values of Ec from each plot ranged from 0 to 1.6 mm d-1 over the growing season (March-November) for the drought and reference plot respectively. The impact of the rainfall exclusion did not affect Ec until early June, 60 days after the drought was in place. Normalized values of Ec showed a 20% decrease from the drought trees compared to the reference. Cumulative growth rates between the two plots showed a net decrease in the drought trees of 42% from the reference and earlier termination of growth. However, the growing season Ec values were 174 mm y-l and 171 mm y-l for the drought and reference plot respectively. Currently, the effects of extreme drought<br />events on carbon and water balances in conifer forests are poorly understood, due<br />to their sporadic occurrence in natural ecosystems. The findings of this study help<br />to establish the impacts drought may have on these ecosystems and evaluate their<br />potential responses under predicted future climate regimes.</p> / Master of Science (MS)

In many parts of the world soils have been found that have apparently been formed under climatic conditions that no longer exist. In many places in northern Utah in areas associated with ancient Lake Bonneville, deep soils, fine-textured and non-calcareous, have been observed immediately above the highest shore line of the ancient lake. These soils have essentially no free carbonates to depths ranging from 4 to 15 feet, even though they exist on relatively steep slopes. In Davis and Utah Counties, soils having these characteristics have been given the tentative series name, Manila.

Tall wheatgrass Agropyron elongatum (Host) Beauv. has gained in importance since its introduction into the United States in 1909 from its native habitat on saline meadows and seashores of Southern Europe and Asia Minor. This very 1late-maturing, coarse, nonlodging 2 1/2 to 6-foot-tall bunchgrass was discarded in Utah in 1919 for being too aggressive. It is now under production in the intermountain and other regions because of its cold and drought tolerance as well as for its salt tolerance and its ability to make excellent fall and spring recovery. According to Weintraub (1953) this salt-tolerant plant gives high yields of forage on sub-irrigated alkaline soils.

Plant breeding and the development of new or better varieties of plants are essential parts of modern agronomy, horitculture and forestry. The basis for such improvement is a knowledge of the factors and principles of genetics. A number of genetic studies have been made with barley in recent years. This is partly because of the commercial importance of the crop, and partly because of the many distinct heritable characters of barley plants. The cultivated species of barley offers the plant breeder and geneticist a wealth of material for genetic studies. Varieties differ in a great many readily distinguishable characters, species hybridize readily, and their small number of chromosomes make it good material for inheritance studies. The barly genetic work has been divided among the principal workers in the U.S., each being responsible for one linkage group. This station has been assigned group IV of which this study is a part. A study of the inheritance of other genes not located in linkage group IV, but appearing in the crosses used, has also been made. This investigation is a by-product of the cereal breeding and improvement program being carried on at the Utah Agricultural Experiment Station.

Several wheat characters have been shown to exhibit rather complicated inheritance. Examples are such characters as cola length, spike density, and awn classes. This paper reports a study of the inheritance and of the correlated inheritance of these and some other plant characters in a cross between a hybrid of Dicklow X Sevier (III C 18) with Federation.

Throughout much of western United States the soils contain considerable calcium carbonate. This lime is either distributed throughout the soils profile or it occurs in a zone of accumulation at varying depths. On many of these soils certain plants exhibit a chlorosis in varying intensity. This chlorotic condition is not stable as it varies from year to year and even day to day with changing conditions of climate and soil. this chlorosis has been reported from the wine and fruit regions of Europe, from the pineapple and sugar cane areas of Puerto Rico and Florida, from the sorghum and bean areas of the Great Plains and Southwest. The variety of plants subject to lime-induced chlorosis is great and varied. It includes such diverse species as citrus fruits, deciduous fruits, conifers, grapes, strawberries, raspberries, pineapple, sugar cane, sorghum, peas and beans. Also many flowers, shrubs and ornamental tress are affected. The economic importance of the disease is evident. Because addition of iron salts to the diseased foliage is known to correct the chlorosis, and because analysis of diseased tissue has failed to prove iron to be deficient, it will be the purpose of this study to investigate the iron content of plants in relation to the disease. An explanation for the observed relationships of iron to the disease will be sought.