In this thesis, ultrasound pulse transit time measurement techniques are applied to aquaculture, specifically to measure the intramuscular fat in salmon muscle tissue. The main advantages of this technique are that it is noninvasive and that it uses low-cost components. Fat in salmon muscle exists as oil dispersed throughout the tissue. Therefore, a phantom was built to empirically model a dispersed fat system. The phantom was a mixture of low-fat milk and high-fat double cream. By varying the quantities of each component, the fat level of the phantom could be controlled. A trend of increasing speed of sound and attenuation with fat content was observed. Prom velocity measurements at a single temperature, it was possible to predict the fat content of the mixture to within ±1.5% fat. A measurement system was created to measure the sample thickness and the speed of sound through a sample at the same time. Velocity and attenuation measurements were made on fifty samples of salmon muscle tissue containing two distinct fat ranges. A trend of decreasing speed of sound with fat content was observed. Further measurements were taken on twelve more samples and compared to the results of chemical fat analysis to determine the strength of the correlation between fat content and speed of sound through the samples. Again, a trend of decreasing speed of sound with increasing fat content was observed (r=0.73, 71=12). This trend was not as strong as that observed for the phantom due to natural variation in the structure of the tissue. A conclusion drawn from this part of the research is that it may be possible to group the data into "high fat", "medium fat" and "low fat" categories. Attenuation measurements proved too dependent on muscle structure to yield a correlation between attenuation and fat content. Ray-tracing techniques were used to model the propagation velocity of a wavefront travelling through a single salmon sample. The model provided an insight into how variations in temperature, fat content, myoseptum thickness and myosepta configuration affect measured velocity. This thesis provides an insight into how ultrasound velocity measurement may be used to assess the fat content of salmon white muscle tissue. It also provides a starting point for future work in which these techniques may be combined with a vision system to enable similar measurements on live fish.

This Thesis investigates the effect of membrane-active agents, such as synthetic ether lipids (SEL), local anaesthetics and polyunsaturated fatty acids (PUFAs) on human leukaemia cells. The two cell lines used were human acute myeloblastic leukaemia (HL60) cells and human myelogenous leukaemia (K562) cells. SEL, local anaesthetics and PUFAs were found to be cytotoxic to both cell lines at certain concentrations. The SEL ET-18-OCH(_3) was found to be cytotoxic to both cell lines but the HL60 cells were found to be the more sensitive cell line. HL60 cells were found to be so sensitive to the action of the local anaesthetic dibucaine that a subtoxic concentration that killed ≤10% was not determined. However, in K562 cells the combination of a subtoxic dibucaine concentration together with a range of ET-I8-OCH(_3) concentrations increased the cytotoxicity over that of ether lipid alone. PUFAs were shown to incorporate into plasma membrane phospholipids at concentrations as low as 1 μM after an incubation of 48 hours. PUFAs were shown to be cytotoxic, but the addition of vitamin E reduced the cytotoxicity of arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid in HL60 cells, and of docosahexaenoic acid in K562 cells. This implied that lipid peroxidation was involved in PUFA cytotoxicity. This was, however, not confirmed. PUFA in combination with ET-I8-OCH3 resulted in a slight decrease in cytotoxicity. PUFA combined with dibucaine did not alter cytotoxicity. Cells were also treated with a combination of PUFA and 1-β-D- arabinofliranosylcytosine (ara-C), which is an agent known to induce cell differentiation. Onset of differentiation was determined by following haemoglobin accumulation in K562 cells. PUFA on their own were found to promote accumulation of haemoglobin. The greatest accumulation of haemoglobin was observed with K562 cells treated with PUFA and ara-C.

Purpose To study the impact of lactoferrin and lipids on the kinetic deposition and denaturation of lysozyme on contact lens materials. Methods The contact lenses investigated in this thesis included two silicone hydrogel lenses [AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A] and two conventional hydrogel lenses [ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A]. All lenses were incubated in four solutions: a complex artificial tear solution (ATS); an ATS without lactoferrin; an ATS without lipids; and an ATS without lactoferrin and lipids. Following various time points, all lenses were prepared for lysozyme analysis using the methods below: • To quantify the kinetic uptake of lysozyme to different contact lens materials, I125-radiolabelled lysozyme was added to each incubation solution. Total lysozyme deposition was quantified using a gamma counter. • To study the activity of lysozyme deposited to contact lenses, a fluorescence-based lysozyme activity assay was compared to a turbidity assay. Potential interactions with lens materials and extraction solvents were evaluated. • To investigate the kinetic denaturation of lysozyme deposited to different contact lens materials, the fluorescence-based activity assay and the enzyme-linked immunosorbent assay were used. Results The presence of lactoferrin and lipids decreased lysozyme uptake to lotrafilcon B. Lysozyme deposition on senofilcon A was greater in the absence of lipids after day 21, however the opposite was seen with etafilcon A, where lysozyme uptake was lower without lipids in the ATS. Lactoferrin and/or lipids had no effect on lysozyme adsorption to omafilcon A. The fluorescence-based lysozyme activity assay demonstrated high sensitivity and a wide linear range of detection, which covers the amount of lysozyme typically extracted from contact lenses. Using this assay, lysozyme activity on both silicone hydrogel materials was lower in the presence of lipids in the ATS. In addition, lactoferrin had a protective effect on lysozyme activity for lysozyme sorbed to senofilcon A. Moreover, the presence of lactoferrin and/or lipids did not exhibit any effect on lysozyme denaturation with conventional hydrogel lenses. Conclusions The presence of lactoferrin and lipids in an artificial tear solution impacted lysozyme deposition and denaturation of lysozyme on various contact lenses. It is important for in vitro studies, when developing tear film models, to consider the effects of tear film components when investigating protein deposition and denaturation on contact lenses.

Mutations in the clk-1 gene of Caenorhabditis elegans result in an average slowing down and deregulation of a variety of developmental and physiological processes. In addition, clk-1 mutants are defective in responding to temperature changes. For example, wild-type worms adjust their defecation cycle length after a temperature shift whereas the defecation cycle length of clk-1 mutants is unaffected by such a shift. To understand the basis of the clk-1 phenotype, a number of genetic screens have been carried out to isolate feature-specific suppressor mutations. dsc-3(qm179) and dsc-4(qm182) were isolated in this manner. It has previously been found that dsc-3(qm179) and dsc-4(qm182) strongly suppress the slow defecation phenotype of clk-1 mutants at 20°C, as well as after a temperature shift to 25°C. Molecular analysis of dsc-4, which encodes the microsomal triglyceride transfer protein, suggests that dsc genes affect lipid metabolism. We carried out a genetic screen for additional mutations that can suppress the slow defecation of clk-1 mutants after a temperature shift to 25°C and isolated two new suppressor mutations. Complementation tests as well as linkage analysis and mapping indicates that dsc-6(qm192) and dsc-7(qm193) define new dsc genes. We analyzed the phenotype of the new suppressor strains and have found that, like dsc-4(qm182), dsc-6(qm192) and dsc-7(qm193) can suppress a variety of clk-1 phenotypes. Based on additional phenotypic analyses of the new suppressor strains, including the determination of their sensitivity to exogenous cholesterol, we believe that, like dsc-4, dsc-6 and dsc-7 encode activities that affect lipid metabolism in worms.

Mechanically separated turkey meat (MSTM) is one of the cheapest sources of protein; however its use for production of further-processed poultry products is limited due to undesirable composition. pH-shifting extraction was applied to overcome the problems associated with MSTM. In the first study the effect of acid pH-shifting extraction with the aid of citric acid and calcium ions on lipids and heme pigments removal from MSTM was investigated. The maximum removal of total, neutral and polar lipids was achieved with addition of 4, 6 and 2 mmol/L of citric acid, respectively. Addition of 6 or 8 mmol/L of citric acid was the most efficient for total heme pigments removal. In the second and third studies chemical, functional and rheological properties of proteins isolated from MSTM were investigated as influenced by different (2.5, 3.5, 10.5 and 11.5) extraction pH. Gel-forming ability was found the highest for pH 3.5 extracted protein. / Food Science and Technology

Graduation date: 1963

Thesis (Ph. D.)--University of Washington, 1988. / Vita. Bibliography: leaves [141]-155.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2002. / Härtill 5 uppsatser.

Thesis (Ph.D. 1979) from the Department of Biochemistry, University of Adelaide.