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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Purification and Characterization of a Protease From a Lamb Gastric Extract Used for Cheese Flavor Improvement

Chaudhari, Ramjibhai V. 01 May 1972 (has links)
An assay for catheptic activity of lamb gastric tissue extract has been proposed which involves the use of a pH 3.5 hemoglobin substrate following activation of zymogens at pH 2.0, 25C for 30 min.; and inactivation at pH 8.0, 40C for 30 min thereby eliminating the effects of pepsin and rennin. Cathepsin was isolated and purified by ammonium sulfate fractionation, acetone precipitation and gel viii filtration. The purified cathepsin represented approximately 50 fold increase in specific activity over the original extract and a recovery of 15% of the original activity. Degree of purity was monitored by isoelectric focusing in polyacrylamide gels. Some characteristics of the cathepsin were determined. The purified cathepsin hydrolyzed urea-denatured hemoglobin readily at pH 3.5, but it had no activity on substrates specific for cathepsins A, B or c. a-N-benzoyloxycarbonyl- L-gutamyl-L-tyrosine, a-N-benzoyl-L-argininamide hydrochloride and a-N-acetyl-L-tyrosinamide. Approximate isoelectric point was pH 5.6. The purified enzyme was similar to cathepsin D. Parmesan, Romano, and Cheddar cheese manufactured with lamb pregastric esterase and gastric extracts added to the curd or milk were superior in flavor when both were employed, and either extract alone made better cheese than the uninoculated control.
32

Application of Traditional Medicines on Textiles

Swarup, Ashish, ash198@gmail.com January 2007 (has links)
As science and technology has developed, the manner by which drugs can be delivered has grown. This research explores an alternative method for the delivery of therapeutic compounds to the body. The basis of the study involves the application of traditional medicines on textiles. Boswellia Serrata Extract (B.S.E.) is a common traditional medicine used for curing body pains. The most common form of B.S.E. based products are creams that are applied directly to the skin. Experiments show that these creams were not suitable as a basis for applying to textile materials because the creams contain highly volatile compounds, which on drying the treated textile, post application, cause almost total loss of the B.S.E. The approach used was the application on textiles of a 'commercial' topical medicine applied as a cream for, where B.S.E. is a major constituent. Cotton woven fabric was padded with this cream and tested for washing and rubbing fastness. The presence of highly volatile substances in the topical cream resulted in a negligible amount of the medicine on the dried treated fabric. Another approach was used for the application of B.S.E. onto the textile substrate. A commercially available B.S.E. powder was applied to woven fabric using a pad mangle. Tests were carried out to validate the
33

Inhibition and success of prymnesium parvum invasion on plankton communities in Texas, USA and prymnesium parvum pigment dynamics

Errera, Reagan Michelle 17 September 2007 (has links)
Prymnesium parvum Carter, a haptophyte species capable of forming harmful algal blooms (HABs), has been identified in fresh and brackish water habitats worldwide. In Texas, P. parvum blooms have diminished local community revenues from losses to tourism, fishing, and hatchery production. In this thesis, P. parvum dynamics were studied using in-situ microcosm experiments at Lake Possum Kingdom, Texas during three seasons (fall, winter, spring) in 2004-2005. Specifically, nutrient additions were used to test the hypothesis that increased nutrient levels would not enhance P. parvum's ability to invade phytoplankton communities. In addition to full nutrient additions to levels of f/2 media, other treatments included nutrient additions deficient in either nitrogen (N) or phosphorus (P). Additionally, barley straw extract was tested as a growth inhibitor to prevent P. parvum blooms. Furthermore, P. parvum initial population density was examined to test the hypothesis that increased initial populations could promote an increase in P. parvum population densities. Findings indicated that P. parvum populations in Lake Possum Kingdom would not likely gain a selective advantage over other species when inorganic nutrients (nitrogen and phosphorus) were not limiting. P. parvum did, however, gain an advantage during both N- and P-limited conditions as indicated by toxicity, cell concentrations, and bulk phytoplankton community shifts. Furthermore, P. parvum blooms in Lake Possum Kingdom would likely not be inhibited by barley straw extract application. Initial population densities affected the final population density, but only when initial populations were low. A method to quickly and accurately detect the presence of P. parvum is needed due to P. parvum's potential to cause toxic and lethal blooms. This thesis tested whether P. parvum photopigments are conservative regardless of growth conditions and could be used to quantify the relative abundance of P. parvum in mixed community samples. If biomarker pigments are conservative, then an optimized version of CHEMTAX could be employed as an alternative diagnostic tool to microscopy for enumeration of P. parvum. However, P. parvum pigments in the Texas strain were not conservative throughout the growth cycle and therefore may not be a reliable indicator of cell abundance.
34

The Effect of Green Tea Extract on Endurance Performance in Young Adults

Green, Eric D. 14 May 2010 (has links)
Background: Green tea is rich in catechin, a polyphenolic antioxidant. Consumption of green tea or extract from green tea has been shown to result in weight loss, increased fat oxidation, and elevated energy expenditure in mice and humans. Green tea consumption has also been shown to result in increased exercise endurance in mice and improved maximal oxygen uptake (VO2max) in humans. It is not clearly known whether green tea consumption would increase exercise endurance in humans. Objective: The aim of this study was to determine if the daily consumption of decaffeinated green tea extract for 4-5 weeks, would improve exercise endurance in humans, as measured by running 2.5 miles on an indoor track. Subjects, Design, and Methods: This study was based on a randomized, double-blind design. Fourteen, normal, healthy individuals volunteered for participation and completed the study. They were divided into two groups (n= 7 for each group). All participants completed 2 endurance trials, 1 at the baseline and 1 at the conclusion of the study. Each trial consisted of a 2.5 mile run around the GSU Recreation Center indoor track. One group consumed green tea extract pill containing 900 mg catechins and the other group consumed a placebo for 4-5 weeks between run trials. Results: Green tea and placebo groups improved their running times, however, there was no significant difference between these two groups in mean end time (P = 0.74). Under one statistical analysis, the green tea group significantly improved their running time compared to baseline (P = 0.019), while the placebo group did not. However, under another statistical analysis (removing one participant due to possible skewing effect), both groups significantly improved their running time over baseline (P< 0.05). Conclusions: This study was not able conclusively ascertain whether or not the daily consumption of green tea improved endurance performance as measured by 2.5 mile run times. Results of this study should be used with caution due to small sample size. Future studies are warranted on the impact of green tea consumption on exercise endurance, using a longer duration and a larger sample size than has been studied.
35

Inhibition and success of prymnesium parvum invasion on plankton communities in Texas, USA and prymnesium parvum pigment dynamics

Errera, Reagan Michelle 17 September 2007 (has links)
Prymnesium parvum Carter, a haptophyte species capable of forming harmful algal blooms (HABs), has been identified in fresh and brackish water habitats worldwide. In Texas, P. parvum blooms have diminished local community revenues from losses to tourism, fishing, and hatchery production. In this thesis, P. parvum dynamics were studied using in-situ microcosm experiments at Lake Possum Kingdom, Texas during three seasons (fall, winter, spring) in 2004-2005. Specifically, nutrient additions were used to test the hypothesis that increased nutrient levels would not enhance P. parvum's ability to invade phytoplankton communities. In addition to full nutrient additions to levels of f/2 media, other treatments included nutrient additions deficient in either nitrogen (N) or phosphorus (P). Additionally, barley straw extract was tested as a growth inhibitor to prevent P. parvum blooms. Furthermore, P. parvum initial population density was examined to test the hypothesis that increased initial populations could promote an increase in P. parvum population densities. Findings indicated that P. parvum populations in Lake Possum Kingdom would not likely gain a selective advantage over other species when inorganic nutrients (nitrogen and phosphorus) were not limiting. P. parvum did, however, gain an advantage during both N- and P-limited conditions as indicated by toxicity, cell concentrations, and bulk phytoplankton community shifts. Furthermore, P. parvum blooms in Lake Possum Kingdom would likely not be inhibited by barley straw extract application. Initial population densities affected the final population density, but only when initial populations were low. A method to quickly and accurately detect the presence of P. parvum is needed due to P. parvum's potential to cause toxic and lethal blooms. This thesis tested whether P. parvum photopigments are conservative regardless of growth conditions and could be used to quantify the relative abundance of P. parvum in mixed community samples. If biomarker pigments are conservative, then an optimized version of CHEMTAX could be employed as an alternative diagnostic tool to microscopy for enumeration of P. parvum. However, P. parvum pigments in the Texas strain were not conservative throughout the growth cycle and therefore may not be a reliable indicator of cell abundance.
36

Regulation of the thioredoxin system in Saccharomyces cerevisiae.

Padayachee, Letrisha. January 2013 (has links)
The thioredoxin system consisting of thioredoxin (Trx), thioredoxin reductase and NADPH plays a significant role in a large number of redox-dependent processes such as DNA synthesis and anti-oxidant defense. Elevated levels of this system have been associated with a number of diseases including cancer and HIV. Understanding the regulation of this network from a systems perspective is therefore essential. However, contradictory descriptions of thioredoxin as both an enzyme and redox couple have stifled the adoption of systems biology approaches within the field. Using kinetic modeling, this discrepancy was resolved by proposing that saturation of Trx activity could be due to the saturation of the Trx redox cycle which consequently allowed development of the first computational models of the thioredoxin system in Jurkat T-cells and Escherichia coli. While these models successfully described the network properties of the thioredoxin system in these organisms, further confirmatory studies were required before this modeling approach could be generally accepted. The aim of this study was to utilize computational and molecular methods to confirm or reject this proposed mechanism for thioredoxin activity. To determine if there is any difference in the kinetic models obtained when thioredoxin was modeled as an enzyme or as a redox couple, representative core models were developed. The data showed that when modeling Trx as a redox couple, the system was able to achieve steady state, there was a re-distribution of Trx into its oxidized form and, thioredoxin reductase affected the rates within the system. On the other hand, when Trx was modeled as an enzyme, the system could not reach a steady state, Trx remained in the reduced form and thioredoxin reductase concentration had no effect on the rates within the system. As these properties could be directly tested invitro, we sought to directly confirm which model was correct. The thioredoxin system from Saccharomyces cerevisiae was cloned, expressed and purified and substrate saturation curves were generated using insulin as a model substrate. The data showed that the system reached steady state and with increasing concentrations of insulin, the system saturated with a progressive re-distribution of the thioredoxin moiety into its oxidized form. Further, increasing the thioredoxin reductase concentration increased the flux through the system. Collectively, the results obtained through invitro analyses provided unambiguous support for the thioredoxin redox couple model. These results will enable the construction of a complete computational model of the yeast thioredoxin system and provide a basis for the analysis of this network in a number of pathologies. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.
37

Fortification of Potassium Silicate with Compost Tea and Seaweed Extract for the Management of Dollar Spot (S. homoeocarpa) of Turfgrass

Manoharan, Mullaivannan 23 October 2013 (has links)
The effect of potassium silicate fortified with cow manure compost tea and seaweed extract on dollar spot (Sclerotinia homoeocarpa) was studied in creeping bentgrass (Agrostis stolonifera L.) and perennial ryegrass (Lolium perene L.). Application of potassium silicate fortified compost tea increased the silicon content in bentgrass and ryegrass at 5 days after treatment, but there was only a minimal effect on silicon content in the grass at 15 days after treatment. However, the fortified treatments did not affect the susceptibility of grass to dollar spot disease in the greenhouse experiments. Fortified treatments did not have a significant effect on the chlorophyll content, total phenol content and phenylalanine ammonia lyase activity in creeping bentgrass. Similarly, the treatment did not affect area of the lesion and mycelial growth of the fungus. Although the synergistic effect of silica fortification was not investigated in detail, preliminary results of the study indicate potassium silicate fortified with compost tea or seaweed extract was not different from that of non-fortified treatments in reducing dollar spot disease in the greenhouse trial.
38

The effect of bone matrix extract on bone cell activity

Powell, Diane Elizabeth January 2006 (has links)
Bone remodelling is a complex process, which involves the coupling of bone formation to completed foci of bone resorption, the balance between these 2 processes determines if bone is lost or gained at a particular site. During bone resorption osteoclasts release growth factors sequestered in bone matrix, which are thought to initiate new bone formation. On the other hand, osteoblasts can regulate osteoclast activity through the expression of the counter-acting cytokines, RANKL and OPG. The aim of this project was to determine if factors released during bone resorption impact on the RANKL/OPG system or on osteoclasts directly to regulate bone remodelling. OPG secretion was characterized in a number of osteoblast-like cells and the osteosarcoma cell line MG-63 was chosen as a model for osteoblastic cell behaviour in vitro. EDTA bone extracts prepared from normal human cortical bone powder were used to treat MG-63 cells in vitro. The response to the extract was dependent on the purification procedure used. OPG production was inhibited by partially purified extracts prepared using hydrophobic interaction chromatography, C18 SPE. In comparison extracts prepared using size exclusion centrifugal filters stimulated OPG secretion in confluent MG-63 cells. Therefore bone matrix constituents were able to influence osteoclast activity directly and indirectly through the osteoblastic cells to produce the same response. The simplest mechanism for this co-ordinated response would be the presence of one factor in the extract that is able to influence both osteoblasts and osteoclasts. The identity of the factor responsible for the opposing effects seen in the bone matrix extracts is at the moment unknown. The work presented in this thesis clearly demonstrated that unknown growth factors present in bone matrix influence bone remodelling.
39

Microbial response to different carbon source amendments in agricultural soils as monitored by culture-independent techniques

Adhikari, Deepak. January 2008 (has links)
Thesis (M.S.)--University of Delaware, 2008. / Principal faculty advisor: Jeffry J. Fuhrmann, Dept. of Plant & Soil Science. Includes bibliographical references.
40

Björkbarksextrakt, BBE : en lönsam lösning på betningsproblematiken? = Birch bark extract, BBE : a profitable solution to the moose browsing problem? /

Torkelstam, Anna. January 2007 (has links) (PDF)
Thesis (master's)--Sveriges lantbruksuniversitet, 2007. / Includes bibliographical references (p. 34). Also issued electronically via World Wide Web in PDF format.

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