Search

In recent years, there have been many reports of the beneficial effects derived from the taking of large, i.e. gram, doses of ascorbic acid. These reports have stressed the harmless nature of the vitamin, due largely to its water-solubility. However, these reports have been countered by a smaller number describing adverse effects of large doses of ascorbic acid. Such reports have been given considerable publicity in spite of the fact that few of the effects have been systematically investigated. When gram doses of ascorbic acid are consumed, it is probably no longer possible to consider the substance as a vitamin for the doses are pharmacological and the substance itself becomes a drug and like other drugs becomes involved in the detoxification system of the liver. The activity of the drug metabolising enzymes is known to be reduced by ascorbic acid deficiency. The bulk of the work described in this thesis involves a series of experiments designed to investigate the effects and mechanisms of action of large doses of ascorbic acid over periods of 4 and 28 days on the hepatic drug metabolising enzymes, using the guinea pig as an animal model, since this species, like man, is unable to synthesise the vitamin. The relative importance of the effects found is discussed together with possible mechanisms of action. In the doses given, which correspond approximately to 4.5g/day in man, ascorbic acid had an inhibitory effect on the mixed function oxidase system, which was not. extended to a generalised effect on the endoplasmic reticulum or the liver cell, but was characterised by altered haem synthesis. The activities of cytochromes P450 and b[5] and the concentrations of microsomal haem were decreased as was hydroxy-lation of type I substrates. However, type II substrates were unaffected, suggesting that specific species of cytochrome P450 may have been involved. The concentrations of the phospholipid, phosphatidylcholine and its precursor, phosphatidylethanolamine, were also decreased. A dose dependent relationship was apparent, with decrease in the concentrations of the cytochromes first occurring with dose levels of 200mg/day, with exacerbation of the effect with 300mg/day. Phase II metabolism of drugs was also affected, with the activity of 1-naphthol glucuronyl transferase showing a decrease. Another membrane-bound enzyme, glucose-6-phosphate, was unaffected, as was the cytosolic enzyme, glucose-6-phosphate dehydrogenase. The extent of lipid peroxidation also remained unchanged. Activity of the rate-limiting enzyme in haem synthesis, delta-amino laevulinic acid synthetase, was significantly increased, whereas the activity of the degradatory enzyme, haem oxygenase, was decreased, suggesting an attempt to conserve haem. The possible involvement of transition metals, such as copper, zinc and iron, was investigated but no significant trends were seen in the concentrations of these metals in either the serum or liver of control and treated animals. Ascorbic acid also appears to be capable of augmenting the action of the natural superoxide anion scavenger, superoxide dismutase. This finding is perhaps significant since such ions may be involved in the hydroxylation of xenobiotics, perhaps as precursors of the active oxygen species associated with cytochrome P450. Both deficiency and large quantities of ascorbic acid appear capable, therefore, of exerting a similar inhibitory effect on the hepatic mixed function oxidase system of the guinea pig. Hence results of these studies suggest that large doses of ascorbic acid can no longer be considered to be totally innocuous and. care should be taken when prescribing large doses of the vitamin to at least some groups of the population. Finally, it should not be forgotten that other adverse effects, besides those affecting the drug metabolising system, have been reported in the literature, including increased excretion of uric acid and oxalate. Although reports of these effects have been used to counter the claim that the use of large doses of ascorbic acid is without risk, this argument is no longer valid since these effects have recently been shown to be negligible. However, the results presented in this thesis provide strong new evidence of a possible adverse effect of large doses of the vitamin.

The director of career education and coordinator of the department of human growth and development at a private college implemented a practicum designed to expand the knowledge level of early childhood students in teacher training by requiring that they participate in the college's day care center. The primary purpose of the practicum was to improve students' competencies by means of hands-on experiences. A second aim was to expand the use of the center as a teaching tool. Activities included: (1) the coordination of the efforts of the teaching faculty, child care center director, and participating students; (2) establishment of a control group; (3) collection and analysis of data on students collected while students interacted with children; (4) development of a questionnaire and analysis of survey data; and (5) development of an interview format and analysis of interview data. Data indicated that many of the participating students characterized their experiences in the child care setting as rewarding or extremely rewarding. The use of the child care center as a teaching site was expanded. Student grades suggested that a satisfactory level of competence was reached by participating students. Related materials are appended, including questionnaires and study results. (RH)

Geography plays an important role in the study of evolutionary ecology. It has implications for the coevolution of species interactions, our ability to accurately and confidently delimit species boundaries, and can influence species’ adaptations that may provide resilience, or make them vulnerable, to climatic change. A geographic consideration of these issues can help to improve our understanding of the processes generating biodiversity and its fate under predicted climate change. In this thesis, I investigated the genetic structure of a pollinator-parasitoid interaction over a wide geographic range, assessed the reliability of DNA barcoding under different geographic scenarios, and examined the resilience of a temperate fig-pollinating wasp species to climate change. Figs are keystone species in many regions and the fig – pollinator system is a classic example of an obligate mutualism. In this thesis, I explored the evolutionary ecology of pollinator and non-pollinator fig wasps associated with the Port Jackson fig (Ficus rubiginosa) in eastern Australia. This system is particularly interesting due to the sheer number of species that interact within F. rubiginosa fruits. There are five recognised pollinating wasps of F. rubiginosa: Pleistodontes imperialis sp. 1, 2, 3, 4 and 5 (sensu Haine et al. 2006). All of these are parasitised by Sycoscapter non-pollinating fig wasps, of which there are three species: Sycoscapter sp. A, B and C. The results presented in this thesis highlight the importance of population genetic approaches to coevolutionary studies and biodiversity assessments. Importantly, in estimating biodiversity, we must consider contemporary processes that are likely to be shaping the future of biodiversity, rather than focussing purely on past processes that have shaped biodiversity as we see it today. Only then can realistic predictions be made about the future of species under predicted climate change.

As a response to agronomic constraints present in a particular irrigation scheme of Tanzania, an experiment was funded by USAID as part of the Feed the Future Initiative to evaluate two sustainable agriculture systems and the suitability of Moshi, Tanzania for Conservation Agriculture (CA) and the System of Rice Intensification (SRI). The CA system involves reduced tillage, residue retention, and crop rotation on a field growing rice (Oryza sativa L.) and maize (Zea mays L.). The System of Rice Intensification requires fewer seeds, planting of younger seedlings, reducing plant density of transplants, while reducing the amount of water used throughout the season. The objectives of this specific study are to: 1) Classify the soil of the region based on profile evaluation and soil analysis, 2) Use the Universal Soil Loss Equation to calculate the average annual soil loss of the Lower Moshi Irrigation Scheme, 3) Evaluate the impact of different management techniques on key soil properties for continuous rice and maize-rice rotation, and 4) Assess the impacts of CA and SRI on agronomic productivity. The two fields used in this study are located in the Lower Moshi Irrigation Scheme and are smallholder farms, 0.3 ha in size. The soil was classified as a Eutric Cambisol and a Eutrustept. The average soil loss from sheet and rill erosion was calculated using ArcGIS, and Universal Soil Loss Equation to be 4.91 Mg ha-1.The soils of the study sites had never been tested in a quantitative manner. The soil was recently tested as part of this project for many properties critical to determining soil structure, fertility, and classification. Carbon and nitrogen concentrations were highest in the top 20 cm of the soil, and the pH and electrical conductivity were within ideal ranges for crop production. Nitrogen and carbon concentrations did not vary significantly between an N, P, K fertilization and urea application at either field site. The field that cultivated rice continuously had higher carbon stocks, at an average of 20.15 Mg C ha-1, than the maize-rice rotation field which averaged 13.51 Mg C ha-1. Total nitrogen concentrations were higher in the continuous rice field, averaging 1.4 g N kg-1 and the maize-rice rotation averaging 0.75 g N kg-1. The results of this study found improved crop yields compared to national averages and demonstrated that any chemical inputs or residue can improve crop yields. The average crop yields of this study were significantly higher in the continuous rice field that produced IR64 variety of rice, averaging 9.53 Mg ha-1. The maize-rice rotation more than doubled the national average rice yield when a local variety of SARO 5 was planted and averaged 5.26 Mg ha-1. The level of water had a much smaller impact on crop yields than rice variety or nutrients applied. The water level used in the SRI treatments was 4 cm and not continuously flooded which saved nearly twice the amount of water compared with the conventional management of a continuously flooded water level of 7 cm.

Child sexual abuse (CSA) is a prevalent public health concern (APA, 2011; Finkelhor, Turner, Ormrod, & Hamby, 2010). Research shows that some individuals appear to report potentially manageable symptoms or will not develop psychopathology following CSA (Kendall-Tackett et al., 1993; Paloucci et al., 1993; Yancey et al., 2011). The purpose of the current research was to investigate characteristics available and amenable to change that may assist clinicians in treatment following CSA. Specifically, the present research examined how resiliency affects emotional distress indices, such as depression and anxiety, in adults with a history of CSA. It was hypothesized that resiliency would moderate the relationship between history of CSA and emotional distress indices. Participants include 253 undergraduate adults (70.5% women) enrolled at a medium-sized southeastern university. Participants completed a Trauma Questionnaire, CES-D, Burns Anxiety Inventory, and a Connor-Davidson Resilience Scale. As expected, results from hierarchical regressions indicate that resilience significantly moderates the relationship between history of CSA and depression and the relationship between history of CSA and anxiety. Results suggest that resilience might be another factor associated with outcomes following CSA and clinical interventions should focus on resilient factors. Future research should examine resilience across the lifespan.

Vitamin D is essential for calcium and phosphate homeostasis and for protecting skeletal mineralization. The primary targets of 1,25(OH)2D3, the most bioactive derivative of vitamin, are the intestine and the kidney where this hormone stimulates mineral absorption or reabsorption to maintain appropriate serum concentrations of calcium and phosphate. By tightly regulating systemic mineral ion levels, 1,25(OH)2D3 prevents mobilization of calcium and phosphate stores from the bone, and, thus indirectly protects bone mineral density. However, 1,25(OH)2D3 also directly influences bone tissue by modulating the activities of osteoblasts, bone-forming cells, and osteoclasts, bone-resorbing cells. 1,25(OH)2D3 can either inhibit or promote bone mineralization depending on the physiological or pathophysiological state of the organism. The goal of this dissertation was to more fully understand the pleiotropic effects of 1,25(OH)2D3 in the bone by analyzing individual 1,25(OH)2D3-induced target genes. To this end, we have identified a multitude of 1,25(OH)2D3-regulated genes in osteoblastic cells through global gene expression profiling. We have chosen four induced genes, MN1, C/EBPâ, SEMA3B, and thrombomodulin, to further characterize by exploring the regulation and function of these targets in both isolated osteoblastic cells and in the more complex bone environment. First, this dissertation uncovers both a molecular and a cellular function for MN1, a transcription factor first identified as a gene disrupted in meningiomas, in augmenting 1,25(OH)2D3-stimulated transcription and in restricting cell growth. Second, our findings suggest that a cooperative interplay exists between VDR and the transcription factor C/EBPâ in regulating gene expression and in modulating bone density. Third, analysis of mice overexpressing SEMA3B, a secreted cell adhesion molecule, indicates that high levels of this protein causes severe osteopenia due to enhanced osteoclastogenesis and bone resorption. Finally, overexpression of thrombomodulin, a transmembrane anticoagulant protein, accelerates osteoblast proliferation. Osteoblast-selective disruption of thrombomodulin does not result in overt skeletal abnormalities, but further analyses are required to fully understand the function of thrombomodulin in bone. Future studies exploiting the in vitro and in vivo tools developed in this work will provide a more complete picture of the multiple functions of 1,25(OH)2D3 and its target genes in the bone.

The purpose of this study was to examine the correlation between the timing of assessment instrument usage and the perceived value of assessment instruments for adult clients in career transition counseling settings. Comparisons of career counselor and adult client perspectives on assessment instrument usefulness were also studied. A mailed self-administered questionnaire was developed to collect data. Fifteen counselors and 47 clients, associated with the downsizing of an electric utility company's regional office in southern New Jersey, responded and formed the basis of all data analysis. An independent t Test for unequal groups was used to compare counselor and cheat ratings of assessment instrument usefulness. Results showed significantly higher ratings by the counselors as compared to the client ratings. A dependent t Test was used to compare client ratings of assessment instruments used during the initial stage of counseling to client ratings of instruments used later in the counseling process. Results showed significantly higher client ratings for assessment instruments used in the later stages of counseling. These results lend support to career transition theories and research on "job loss trauma" and other factors that may inhibit adults during the initial stage of career transition.

U.M.

A natural population of Pleuroptya ruralis has been studied for three years with the following aims: (1) to elucidate its life history; (2) to study the variations in the larval and adult densities; (3) to identify the mortality factors acting upon them; (4) to investigate possible relationships between the intensity of the mortality factors and the spatial distribution (horizontal and vertical) of P. ruralis ; (5) to describe the role of the major mortality factors in determining the size of the population studied; (6) to assess the potential of the system for further studies about the mechanism of population regulation. P. ruralis caterpillars were individually labelled and followed throughout their development on a natural growth of their food plant, Urtica dioica (the nettle), near Leeds, Yorkshire, United Kingdom. Parasitism and predation as well as the distribution and movements of the larvae on the host plant were assessed. Caterpillars were also collected and reared in the laboratory for identification of the parasitoid species and to provide support for the field results. Adults were studied in the field by the mark- release- recapture method. Potential female fertility was investigated in the laboratory. The population suffered a dramatic decline in numbers during the period of this study. The main factors determining the observed population levels were the interactions between the weather, time spent in development, deviations in the sex ratio, bird predation towards the completion of pre-adult development and parasitization by a braconid (Macrocentrus grandii). Other parasitoids also had some effect, notably Diadegma sp. Predation also had a strong impact on the population of M. grandii. Birds appear to concentrate their attack in the part of the plant in which they are more likely to find the prey. Weather also influenced adult activity and availability of nectar sources in the field, and starvation of females reduced fecundity in the laboratory. Thus, egg shortfall may also have been important in the decrease of population size. The field method used with the caterpillars provided detailed and valuable information about individual and spatial variation and it is suggested that the system 'nettles / P. ruralis / natural enemies' can be a powerfull tool for studies on the mechanisms of population regulation.

Distribution, population dynamics, biomass and population production of macrodecomposers have been studied in order to clarify the role of four species in the processes of energy transfer in a dune grassland ecosystem. The-species worked on were Armadillidiun vulgare, Porcellio scaber, Philoscia muscorum (Isopoda) and Cylindroiulus latestriatus (Diplopoda). Population data were available for the species from 1968 to 1975. Preliminary investigations indicated little difference in the diet of each species and in their interactions with predators; however there were significant differences in vertical and horizontal distribution. The vertical distribution of each species changed with season, mainly in response to variations in temperature in winter and relative humidity-in summer. Despite these movements there was a consistent-difference in the mean depth of each species. The millipede showed a particularly marked difference from the woodlice because it was mainly a root layer inhabitant whereas they were most abundant in the litter layer. Horizontal distribution studies indicated that P. muscorum stable predominated in the stable dune while A. vulgare. and P. scaber were more abundant towards the dune crest. The last two species showed evidence of migration between different areas of the dune system in early summer 1975. Changes in abundance and aggregation were, also. observed. P. muscorum declined from a maximum density of 103.7 0.1m-2 in August 1970 to zero in October 1974 whereas A. vulgare increased from a minimum of 1.7 0.1m 2 in January 1969 to a maximum of 73.9 in September 1973. P. scaber and C. latestriatus exhibited smaller changes; maximum and minimum estimates were 27.1 and 0.9 0.1 m 2, and 16.0 and 1.9 0.1m 2 respectively, All species showed changes in aggregation during the course of the study. Aggregation increased in the woodlice in 1974 and 1975 and decreased in the millipede. It is suggested that the changes in density and aggregation were related to changing conditions on the study site, particularly those caused by rabbit disturbance and sand accumulation. There were seasonal density fluctuations also. Changes in size structure, the breeding biology and cohort dynamics of the A. vulgare and P. scaber populations were examined to obtain insight into the importance of natality, mortality and migration in determining these fluctuations. The density of each species peaked in late summer when brood release occurred and declined at other times due to continuous losses. Immigration caused spring and summer density increases and appeared to be the main determinant of breeding population size. Population size structure, breeding biology and biomass of C. latestriatus was studied. The rate of development of C. latestriatus at Spurn is intermediate between that of populations to the North and South. It is suggested that the more northerly populations take longer to mature due to lower mean annual temperatures. Comparison of biomass and population production for the three isopod species indicated large fluctuations in individual species but the total values were fairly steady with a maximum mean annual standing crop of 744 mg live weight 0.1m 2 during 1973/74 and a minimum of 295 during 1968/69. Maximum and minimum mean annual population production figures for the three isopods -combined were 366.6 mg dry weight 0.1n 2 during 1971/72 and 147.4 during 1968/69. Finally the results are discussed in relation to niche separation, iv life history strategies and the role of macrodecomposers in the dune grassland ecosystem.

The dynamics and life history of an isolated population of Ligia oceanica (L. ) inhabiting a sea-wall exposed to moderate wave action have been studied over a period of three years. Sex ratio, size at maturity, growth, breeding phenology, size and age structure, population density and size, female breeding size, fecundity regression and broodpouch mortality have been determined. From these data population natality, and schedules of survivorship, fecundity and reproductive value are calculated. Although the supralittoral zone of rocky shores is generally regarded as a severe and stressful habitat, the dynamics of the population exhibit only minor differences between years, and no direct influence of wave exposure can be determined. This population is compared with another nearby but isolated population occupying an harbour wall completely protected from wave action. These populations are presumed to suffer different levels of density-independent mortality due to the wave exposure characteristics of the sites. The sheltered site population shows no significant differences between the two years of study. Interpopulation differences in age and size structure, growth rate, population breeding phenology and breeding sizes are slight. However the sheltered population shows increased adult survival and longevity, decreased weight specific fecundity and reproductive allocation, and increased brood-pouch mortality. Because winter survival is high, when mortality due to wave action is expected to be severe, this factor is rejected as an important determinant of the life history. The reduced survival at the exposed site can be interpreted as a consequence of the increased reproductive allocation by individuals at this site. The majority of females are semelparous, but within both populations two distinct waves of breeding activity occurred each year. Larger, faster growing individuals breed at the end of their first ýear, LATE in the season, and have high weight specific fecundities and low absolute and weight specific egg sizes. Smaller, slower growing individuals delay reproduction and breed in their second year, EARLY in the season. Although gaining greatly in size through growth the effect on fecundity is offset by a decrease in weight specific fecundity and parallel increases in absolute and weight specific egg size. The following trade-offs are recognised for individual female Ligia : between growth and reproduction (within breeding groups), growth and reproduction (between breeding groups), reproduction and survival (between breeding groups), weight specific egg size and weight specific fecundity (between breeding groups), and between absolute egg size and fecundity (within breeding groups). Two possible life history strategies are recognised. (i) An ability of a female parent to alter egg size seasonally may optimise total offspring fitness in the different environments they experience.(ii) An ability of small, mature females to delay reproduction until the following year may also increase their fitness. By assuming that offspring survival is related to egg size it is possible to model this tactic. The population breeding phenology is seen as a direct consequence of the life history and has the indirect effect of stabilizing the population. The ability of individual females to vary their life history traits depending on individual circumstances (size and season) may represent a flexible approach to the environment which is not envisioned in the more formal models of life history evolution.