published_or_final_version / Dentistry / Master / Master of Dental Surgery

Four methods of analysis for the determination of total and individual glucosinolates in Brassica napus cultivars (ie Gas Chromatography (GC), High Pressure Liquid Chromatography (HPLQ, Glucose Release, and X-ray Fluorescence Spectrometry (XRF)) were developed, refined, validated and applied. These were used to investigate both high and low glucosinolate cultivars of rapeseed (oilseed rape, Brassica napus), and reproducibility (between replicates) and repeatability (between analysis days) of these methods was assessed. From these studies, an indirect method of glucosinolate determination, involving X-Ray Fluorescence analysis, proved to give the least variable results. Furthermore, this was markedly more rapid than the other methods of analysis. Of the methods assessed for the determination of individual glucosinolates, High Pressure Liquid Chromatography (HPLC) gave less variable results than Gas Chromatography (the European Community (EC) recommended method for glucosinolate determination in oilseed rape at the time of study). Thus, BPLC and XRF analysis were selected as methods for subsequent glucosinolate analysis in the remainder of the study. Effects of geographicallo cation in relation to atmospherics ulphur depositiona nd plant sulphur uptake in Brassica napus cv Ariana grown throughout the UK were determinedin two consecutivey ears. An initial study comparedg lucosinolatele vels in rapeseed samples from 211 sites. A second more detailed study involved determinationo f foliar sulphurl evels (by XRF analysis)a t three stagesd uring plant developmenftr om selecteds itest hroughoutt he UK, and comparisono f thesew ith glucosinolate levels in the harvested seed from these sites. The results of these investigations proved comparable between years, with final glucosinolate levels generally corresponding to atmospheric sulphur deposition levels. Furthermore, high glucosinolatele vels in harvesteds eedg enerallyc orrespondewd ith high sulphur levelsi n foliage ast he plantse ntereds eed-podd evelopment.A series of controlled environment and glasshouse experiments were developed to investigate the effects of sulphur nutrition on glucosinolate development in rape plants during growth. These highlighted that glucosinolate levels in plant material could be manipulated with variation in supplied nutrients. Furthermore, plants initially propagated with sulphur-complete nutrient in hydroponic media, then transferred to sulphur-free nutrient mid-development, were found to give good seed yields with substantially lower glucosinolate levels. In conclusion, attention must be given to choosing the appropriate method for analysis of glucosinolates. Secondly, sulphur availability and sulphur status are critical factors in the determination of glucosinolatelevels, and the relationship between these factors merits further study

When any method of surface wave testing that involves Rayleigh waves is performed, one important assumption is that plane Rayleigh waves are being measured. In the forward modeling or inversion procedure that is used to analyze the field dispersion curve to determine the field V[subscript s] profile, the analysis is based on the wave field consisting of plane Rayleigh waves. Therefore, field dispersion curves that contain near-field data could adversely distort the field V[subscript s] profile. To minimize the influence of near-field effects, several criteria have been recommended in the past. However, most of the criteria were based on empirical equations that implicitly assumed zones of influence, or numerical simulations. There is a lack of experimental investigation, particularly full-scale field investigations. Even, the numerical solutions have been based on simple soil profiles without significant velocity contrasts between soil layers and/or varying thicknesses of soil layers which can significantly influence near-field effects. Data from full-scale field test using the Spectral-Analysis-of-Surface-Waves (SASW) method was used in this thesis research. SASW tests performed at two stages in the construction of a deep, 90-ft thick backfill were studied. The V[subscript s] profiles were normally dispersive, with a substantial increase in the velocity of the layer beneath the backfill. The study shows the adverse distortions that can occur in the field dispersion curve from near-field effects when the spacing of the receiver pair is: (1) above the zone of rapidly increasing V[subscript s] near the surface and (2) less than the depth to the stiffer layer in deeper measurements. Other factors that affect the results are discussed and recommendations are presented to minimize the introduction of near-field effects, at least in these relatively simple V[subscript s] profiles. / text

The effect of oral contraceptives on the urinary excretion of several methionine metabolites was determined in women before and after they had received a 3-g dose of L-methionine. Nine women between the ages of 20-29 years served as subjects: five had been using a combination-type oral contraceptive for six months or more (experimental group), and four had not been using these drugs (control group). Cystathionine excretion by both groups before and after the methionine loading was in the range reported for normal female subjects who were not deficient in vitamin B₆ (Krishnaswamy, 1972; Shin and Linkswiler, 1974). Changes in urinary methionine metabolites that were apparently produced by oral contraceptive drugs are: (1) homocysteine was detected in the basal urine of three of the oral contraceptive users. After methionine loading, it was found in the urine of four of these subjects, two of whom excreted measurable quantities. In contrast, three of the control subjects excreted traces of homocysteine only after methionine loading. (2) The mean excretion of taurine by oral contraceptive users was only one-tenth of that excreted by the control subjects. The activity of erythrocyte glutamic oxaloacetic transaminase (EGOT) before and after in vitro stimulation with added pyridoxal phosphate was similar in both groups. Basal activity of erythrocyte glutamic pyruvic transaminase (EGPT) was lower in oral contraceptive users, although the mean values for both groups were within the normal range reported by Miller et al. (1975) and Woodring and Storvick (1970). The percent in vitro stimulation after addition of pyridoxal phosphate was somewhat higher in oral contraceptive users, but the difference was not statistically significant. Thirteen free acidic and neutral amino acids (including metabolites of the methionine pathway) were measured in the urine specimens. The sum of the urinary excretion of these 13 amino acids was significantly lower (p < 0.01) for oral contraceptive users than for control subjects. However, total α-amino nitrogen excretion, measured in the same urine specimens, was similar for both groups. / Graduation date: 1976

The effect of oral contraceptives on urinary and plasma vitamin B₆ as well as erythrocyte transaminase activities was investigated in women. Five women who were taking oral contraceptives and four who were not using these drugs served as subjects. They were apparently healthy and free from any known metabolic disorder. The subjects, who consumed normal diets, recorded their dietary intake for three days. Twenty-four hour urine specimens were collected on two consecutive days by the subjects. On the morning of the second day blood for the various biochemical measurements was drawn from fasting subjects. Following the blood drawing the women were given an oral dose of 3 g of L-methionine. Results of the methionine load test are reported elsewhere. The subjects consumed diets that supplied at least two-thirds or more of their National Academy of Science-National Research Council (1974) Recommended Dietary Allowances (RDA) for most nutrients except iron and vitamin B₆. The mean dietary intake of vitamin B₆ was 1.57 mg per day for the untreated women and 1.52 for the oral contraceptive users. On both days the mean levels of free and total vitamin B₆ in urine were less in the oral contraceptive users than that in the untreated controls, but the differences were not statistically significant. There appeared to be some relationship between dietary intake of vitamin B₆ and urinary excretion of the vitamin. The methionine loading dose did not affect the excretion of vitamin B₆ The mean plasma level of vitamin B₆ was lower for the oral contraceptive users than for the untreated controls although the difference is not statistically significant. There was, however, a large variation in values among the subjects taking oral contraceptives. Two of them had extremely low plasma vitamin B₆ levels. Vitamin B₆ in the plasma did not appear to be related to dietary intake or urinary excretion of the vitamin. Erythrocyte glutamic oxaloacetic transaminase (EGOT) and erythrocyte glutamic pyruvic transaminase (EGPT) activities with and without in vitro stimulation with pyridoxal phosphate (PALPO) were also measured. There were no significant differences between the two groups in EGOT and EGPT activities with and without in vitro stimulation. According to the activity indexes (PALPO stimulated activity/activity without added PALPO) for EGOT and EGPT (Sauberlich et al., 1972), all subjects had adequate vitamin B₆ nutritional status. Activity indexes for EGOT and EGPT did not appear to be related to urinary or plasma levels of vitamin B₆ Urinary and plasma vitamin B₆ levels and erythrocyte trans- aminase activities were not related to the length of time the women had been taking oral contraceptives or the estrogen content of their oral contraceptive agent. / Graduation date: 1976

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