Showing papers by "University of Saskatchewan published in 1973"

Toothbrushing Frequency as It Relates to Plaque Development and Gingival Health

Abstract: EPIDEMIOLOGICAL and experimental studies have dem­ onstrated that gingival inflammation, as well as dental caries, is dependent upon the presence of bacterial plaque on the teeth. 1 9 On a clean tooth surface, plaque begins to develop with the formation of a salivaryand glycoprotein containing pellicle 1 0 1 3 into which bacteria may subsequently colonize . 1 4 1 8 Alterations in the bac­ terial flora, and changes in the chemical composition of plaque as it grows have been demonstrated. 2 0 2 3 However, information on the rate of plaque growth and its pattern of development on the dentition is lacking.

Cow's milk allergy: prevalence and manifestations in an unselected series of newborns.

Abstract: Summary 1. A consecutive series of 787 babies born at the University Hospital were followed for 12–36 months in order to determine the prevalence of cow's milk allergy (CMA). 2. Fifty-nine babies (7.5%) were shown by repeated challenge to have evidence of CMA. 3. The main manifestations of CMA were eczema in 27, recurrent diarrhea in 24, recurrent rhinorrhea in 18, repeated vomiting in 12, recurrent bronchitis in 10, and asthma in 7. 4. Thirty-four babies had two or more allergic problems, e.g., had recurrent rhinorrhea and eczema, or recurrent bronchitis and recur-rent diarrhea, 25 babies had only one. 5. Babies allergic to cow's milk were often allergic to other foods, 20% for example were allergic to soya. 6. Twenty-five babies developed their first symptoms within 7 days of being given their cow's milk formula. 7. Seventeen of the babies lost their sensitivity to cow's milk, 10 of these babies were less than 12 months old. Thirty-eight babies over 12 months of age when last reviewed were still allergic to cow's milk. 8. Babies with CMA, as well as those with other allergic problems, attended their doctors on account of illness more frequently than did the non-allergic babies. 9. Allergic disorders were commonest in the parents and siblings of babies with CMA, and least common in the parents and siblings of the non-allergic children.

Turnover of microbial tissue in soil under field conditions

Abstract: The microbial population of a Brown Chernozemic soil was labelled in situ by adding 14C-glucose and 15NH415NO3 to the plow layer. The loss of 14C, nitrogen immobilization-mineralization reactions, bacterial numbers (plate count, direct count) and fungal hyphal lengths were determined periodically throughout the growing period in amended and unamended microplots and in the surrounding field soil. After 5 days, 90 per cent of the labelled N occurred in the organic form with little subsequent mineralization. Of the labelled C added, 63, 56 and 39 per cent, remained in the soil after 3, 14 and 104 days, respectively. The ratio of fungal C to bacterial C increased as soil moisture decreased. Viable (plate count) and total numbers of bacteria in samples from unamended plots and field soil were significantly correlated with each other and with soil moisture. Fungal hyphal lengths from amended soil were also significantly related to moisture but the rate of loss of 14C and mineralization of 15N were not. The synthesized microbial material (tissue and metabolites) exhibited a high degree of stability throughout the study. The half-life of labelled C remaining in the soil after 30 days was calculated to be 6 months compared to only 4 days for the added glucose C. The amount of energy used for maintenance by the soil population under field conditions was calculated from measurements of biomass C, respired labelled C and respired soil C.

The role of gaba metabolism in the convulsant and anticonvulsant actions of aminooxyacetic acid

Abstract: — At high dosage levels AOAA acted as a convulsant agent in mice and rats but in lower amounts it was an effective anticonvulsant agent against INH-induced seizures, by tripling the time to the onset of the convulsions. AOAA elevated brain GABA levels as a result of a preferential inhibition of the GABA-T enzyme system but, contrary to previous reports, the activity of the GAD enzyme system was also inhibited, even by relatively low dosage levels of AOAA. The state of excitability of the brain following the administration of AOAA was related, within the limits of the present study, to changes in GAD activity and GABA levels, but additional data are required before the relationship can be properly evaluated.

Changes in enzymic activity and distribution of acid-soluble, amino acid-nitrogen in soil during nitrogen immobilization and mineralization

Abstract: During a period of immobilization of nitrate- 15 N and mineralization of organic N in a sandy-loam, changes were recorded in: (a) the concentration of an added carbon source, glucose- 14 C: (b) evolution of 14 CO 2 : (c) bacterial populations; (d) distribution and concentration of newly-synthesized, acid-soluble, amino acid- 15 N; and (e) distribution and activities of several oxidative and hydrolytic enzyme systems. Added glucose- 14 C was rapidly metabolized by the soil microflora. After 1.5 day's incubation, when only 3.6 per cent of the added glucose was present, 68 per cent of the 14 C remained in the soil-microbial system. During this period there was a marked increase in viable bacterial numbers and an almost complete immobilization of nitrate- 15 N. On continued incubation, microbial metabolites were oxidized at decreasing rates, the more rapid phase corresponding to a period of net decline in the viable bacterial population. Soil was fractionated by a relatively mild procedure into components containing: (a) extractable proteins; (b) extractable amino acids and peptides; (c) particulate material containing microbial cells, cell debris and material bound to larger soil particles; and (d) microbial metabolites mainly bound to soil colloids. Although the total, acid-soluble, amino acid- 15 N remained relatively constant for about 50 days, there were marked changes in their concentration in different fractions, especially in the extracts and in the fraction containing fine colloidal material. However, the relatively large decline in labelled, acid-soluble, amino acid- 15 N occurred during the active phase of oxidation of microbial metabolites when little net mineralization of labelled compounds occurred. Increases in enzymic activities generally coincided with increased viable bacterial populations although there were some exceptions, notably casein and benzoyl arginine amide-hydrolysing enzymes. The stabilities of the newly-formed enzymes varied markedly. The greatest relative changes in activity occurred with the casein-hydrolysing enzymes. Their activity reached a maximal value after the main flush of bacterial growth, was short-lived and was to a large extent extractable. The formation and disappearance of this extracellular proteolytic activity coincided approximately with that of a secondary peak of extractable, newly-synthesized, protein- 15 N. In general however, changes in enzymic activity could not be identified with changes of protein- 15 N concentrations of the different fractions.

Optimum Network Var Planning by Nonlinear Programming

Abstract: Controllable network VAr compensators are required in high voltage transmission networks for system loss reduction and voltage maintenance during normal and emergency operation. Long term planning of network compensators is generally based on contingencies which cause the system voltage to move out of the desired operational range. A non-linear analysis based on multi-contingency states is presented for optimum network VAr planning. The proposed approach is critically evaluated and compared with the existing techniques and is illustrated by an application to a high voltage model system.

Assessment of biological nitrogen fixation in grassland and associated sites

Abstract: The extent of nitrogen fixation in native grassland on clay soil was measured using the C2H2 reduction assay Undisturbed soil cores incubated in microcanopies in the field indicated fixation rates of 2 kg N/ha per season Less nitrogen fixation activity was found in associated cultivated soils Other sites on different soil associations were found capable of fixing 1 kg·N/ha or less per growing season The fixation by several legumes and nodulated nonlegumes ranged up to 18 μg/cm2 h

Amino Acid Composition of Oilseed Meals and Protein Isolates

Abstract: Amino acid analyses of oilseed meals indicated that varietal differences in amino acid composition were much greater in soybean, turnip rapeseed, rapeseed and sunflower than in safflower and flax. In general, soybean and rapeseed proteins contained high proportions of essential amino acids required for human nutrition such as leucine, lysine and threonine while flax, sunflower and safflower proteins contained more of the nonessential arginine, aspartic acid and glutamic acid. Rapeseed proteins were also rich in methionine + cystine and proline while soybean had a higher level of phenylalanine. Because of serious deficiencies in lysine, the oilseed meals and protein isolates of flax, sunflower and safflower rated poorly in essential amino acid indices and protein scores. Higher ratings were obtained for soybean and rapeseed meals and isolates but soybean was deficient in sulfur-containing amino acids while the rapeseed species were low in isoleucine. Since the latter amino acid is rarely deficient in mixed diets, the rapeseed products appeared to have the best protein for the supplementation of human diets. The nitrogen-to-protein conversion factors were calculated from the amino acid compositions of the oilseed meals and protein isolates. The values for the present oilseed proteins varied between 5.33 and 5.74, indicating that the standard factor of 6.25 caused a substantial overestimation in crude protein content. A common factor of 5.50 is proposed for oilseed meals and, based on literature values, for all seed proteins.

Green revolution in india

Abstract: The introduction of hybrid seeds in India has doubled the yield of foodgrains. The High Yielding Variety Seed Program (H.V.P.) has contributed to serious interregional disparities in agriculture. Surplus production of foodgrains is not the true measure of success of the Green Revolution; many areas in India remain unaffected by this program, and are still vulnerable to famines.

The use of C14O2 canopy techniques for measuring carbon transfer through the plant-soil system

Abstract: Methods for labelling growing plants by exposing them to C14O2 under a cellulose acetate-butyrate canopy have been developed for laboratory and field use. The length of labelling ranged from 2 to 33 days and the C14O2 content of the atmosphere was automatically controlled. This made it possible to measure carbon assimilation by the plants, transfer of photosynthates beneath ground and respiration of the roots.

Single nuclear gene inherited cross resistance and collateral sensitivity to 17 inhibitors of mitochondrial function in S. cerevisiae.

Abstract: Previous tetrad analyses defined a yeast strain (332-7c) as containing a single nuclear gene (11.8 map units from the centromere) conferring resistance to oligomycin. Resistance to 18 additional inhibitors of mitochondrial function (Table 1) was determined on (i) ascospore isolates from tetrads segregating 2 resistant: 2 sensitive for oligomycin (Table 2) and (ii), spontaneously derived sensitive isolates of the oligomycin resistant strain (Tables 3 and 4). The observed pattern of resistance suggests that the gene for resistance to oligomycin also results in (i) cross resistance to rutamycin, venturicidin, triethyltin bromide, antimycin A, carbonylcyanide m-chlorophenylhydrazone, tetra-N-butylammonium bromide, dibenzyl-dimethylammonium chlorop and tetracycline and (ii), collateral sensitivity to paromomycin, neomycin, dequalinium chloride, ethidium bromide and acriflavin.

Mass of the Graviton

Abstract: The graviton is assumed to have a mass and it is allowed to decay into two photons. From the transition probability for this decay an illustrative restriction is placed upon the graviton mass. Restrictions are also made on the mass with regards to the speed of propagation of gravitational radiation and to the range of gravitational forces.

Absorption of dietary cholesterol in man

Abstract: Cholesterol absorption was studied by balance methods in 10 hyperlipemic subjects. The cholesterol (401–1214 mg/day) and β-sitosterol (171–454 mg/day) were integral parts of the diets. The absorption was 37% ± 5% and the amounts of cholesterol absorbed were 149–508 mg/day. The amounts absorbed had an excellent correlation with the dietary intake of cholesterol (r = 0.98), and there was no leveling off of the amounts absorbed even at an intake of 1214 mg/day. Assuming that the percentage absorption of dietary and endogenous cholesterol in the gastrointestinal tract is identical, the amounts of endogenous cholesterol secreted into the gastrointestinal tract were calculated from the amounts of fecal neutral steroids of endogenous origin. The relationship of total (dietary plus endogenous) cholesterol in the gastrointestinal tract and its absorption was also excellent (r = 0.97) and also without any evidence of leveling off of the slope up to 2300 mg. These data indicate that within the normal range for North America, the amounts of dietary cholesterol absorbed are proportional to its intake.

Laboratory incubation studies of chlorophenoxyacetic acids in chernozemic soils

Abstract: The relative persistence of 2,4-D, MCPA and 2,4,5-T in some Saskatchewan soils was assessed under laboratory conditions. Under moist conditions, 2,4-D and MCPA showed half-life times of between 14 and 41 days but the MCPA half-life was usually 1 or 2 days longer. 2,4,5-T exhibited a half-life period over twice the length of the other chemicals. The half-life times were directly correlated to microbial plate counts, the larger numbers of soil microorganisms being associated with shorter residence times. Half-lives depended on soil moisture content and the best moisture levels for chemical loss appeared to be just less than field capacity. The use of 14 C in 2,4-D incubation studies showed that the initial cleavage of the 2,4-D molecule was associated with the ether linkage and was not a decarboxylation.

ISIS–II Atomic Oxygen Red Line Photometer

Abstract: One of the new features of the ISIS-II spacecraft, fourth in the Alouette/ISIS series, is the inclusion of two optical instruments. The scanning auroral photometer is described by Anger et al. in a companion paper [ Appl. Opt.12, 1753 ( 1973)]. The red line photometer described here is similar in concept; it is designed to map the global distribution of the OI 6300-A emission with a spatial resolution of about 100 km, a measurement accuracy of 10%, and a detection threshold of 10 R. The objective is to delineate the various processes leading to the excitation of O(1D) in the airglow and aurora by observing the global variation and by comparison with data from other instruments on board the same spacecraft. The device is now operating successfully in orbit, and detailed orbital performance characteristics will appear in a later publication.

A soil test for sulphur and interpretative criteria for Saskatchewan

Abstract: An automated soil test for sulphur and interpretative criteria for Saskatchewan conditions are presented. Sulphate‐sulphur (SO4‐S) in 0.01 M CaCl2 extracts of soil is determined by turbidimetric and nephelometric procedures operating simultaneously in an AutoAnalyzer system. A procedure for the segregation and elimination of samples containing excessive amounts of SO4‐S is described. The total amounts of soluble SO4‐S in the 0–60 cm soil layer is considered for interpretative purposes. Tentative critical values for two broad groups of field crops and a preliminary summary of the sulphur status of Saskatchewan soils based on analysis of farm samples are discussed.

Properties of an inducible C 4 -dicarboxylic acid transport system in Bacillus subtilis.

Abstract: The transport of the tricarboxylic acid cycle C 4 -dicarboxylic acids was studied in both the wild-type strain and tricarboxylic acid cycle mutants of Bacillus subtilis . Active transport of malate, fumarate, and succinate was found to be inducible by these dicarboxylic acids or by precursors to them, whereas glucose or closely related metabolites catabolite-repressed their uptake. l-Malate was found to be the best dicarboxylic acid transport inducer in succinic dehydrogenase, fumarase, and malic dehydrogenase mutants. Succinate and fumarate are accumulated over 100-fold in succinic dehydrogenase and fumarase mutants, respectively, whereas mutants lacking malate dehydrogenase were unable to accumulate significant quantities of the C 4 -dicarboxylic acids. The stereospecificity of this transport system was studied from a comparison of the rates of competitive inhibition of both succinate uptake and efflux in a succinate dehydrogenase mutant by utilizing thirty dicarboxylic acid analogues. The system was specific for the C 4 -dicarboxylic acids of the tricarboxylic acid cycle, neither citrate nor α-ketoglutarate were effective competitive inhibitors. Of a wide variety of metabolic inhibitors tested, inhibiors of oxidative phosphorylation and of the formation of proton gradients were the most potent inhibitors of transport. From the kinetics of dicarboxylic acid transport ( K m approximately 10 −4 M for succinate or fumarate in succinic acid dehydrogenase and fumarase mutants) and from the competitive inhibition studies, it was concluded that an inducible dicarboxylic acid transport system mediates the entry of malate, fumarate, or succinate into B. subtilis . Mutants devoid of α-ketoglutarate dehydrogenase were shown to accumulate both α-ketoglutarate and glutamate, and these metabolites subsequently inhibited the transport of all the C 4 -dicarboxylic acids, suggesting a regulatory role. Images

Synthesis of cholesterol in hypercholesterolemia and its relationship to plasma triglycerides

Abstract: Cholesterol synthesis was estimated by three independent methods in a number of subjects with hypercholesterolemia with or without hypertriglyceridemia Cholesterol balance studies indicated that the synthesis of cholesterol in those who had hypertriglyceridemia was almost three times greater than in those who did not Similar differences in synthetic rates were also suggested by data on kinetics of plasma cholesterol and by relative rates of incorporation of radioactive acetate and mevalonate into plasma cholesterol This difference in endogenous synthesis of cholesterol between the two groups appeared mainly to be related to the hepatic cholesterogenesis Although the subjects with hypertriglycerdemia had greater body weights than those who did not, the relative body weights did not show significant correlation with cholesterol synthesis Neither did the latter correlate well with plasma cholesterol levels The correlation of cholesterol synthesis was best with concentrations of plasma triglycerides It is therefore suggested that increased synthesis of cholesterol is primarily related to the increased concentrations of plasma triglycerides, which in turn may be dependent on increased hepatic synthesis of very low density lipoproteins in those subjects

On subsequences of the Haar system inL p [0, 1], (1<p<∞)

Abstract: We show that ifX is the closed linear span inL p [0,1] of a subsequence of the Haar system, thenX is isomorphic either tol p or toL p [0,1], [1

Real and Reactive Power Optimization by Suboptimum Techniques

Abstract: The short-term real and reactive power optimization of a large system is a non-linear programming problem and its solution requires a considerable amount of computational effort. In actual practice separate real and reactive power suboptimization techniques may be more suitable than a complete optimization(1). The results obtained by the suboptimal techniques under ideal conditions coincide with those from a real and reactive power optimization. In this paper, complete real and reactive optimization has been solved by suboptimization techniques. The proposed approach decomposes the complete problem into two halves, i. e. the optimum voltage evaluation and the real power optimization with optimally determined voltages. A theoretical treatment of the technique along with a qualitative and analytical discussion is provided. The method is applied to a small system and the results obtained are compared with a real and reactive power optimization.