No description available.

No description available.

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 6 uppsatser.

No description available.

No description available.

Thesis (M.Sc.)--Memorial University of Newfoundland, 1999. / Bibliography: leaves 118-130.

The green alga, Selenastrum capricornutum, was cultured in artificial nutrient medium utilizing five-gallon carboys, each of which contained 16 1. of culture. The algal cells were separated from the nutrient medium by continuous-flow centrifugation at 7500 RPM, and were then lyophilized. The lyophilized cells were extracted by refluxing with ether, acetone, and chloroform:methanol (2:1). Free sterols and sterol esters were separated from the crude extract using preparative thin-layer chromatography. Sterol esters were saponified and both the sterols and the fatty acids were recovered. Individual sterols were separated from the free sterol fraction using argentation thin-layer chromatography. Gas chromatograms, mass spectra, and ultraviolet spectra were obtained for these sterols. The free sterol fraction was found to contain approximately 40% 24-methylcholesta-5,7-dien-3B-ol and 60% 24-ethylcholesta-5,7-dien-3B-ol. The sterol ester fraction also contained these two sterols; however, the composition and amount of esterified sterols varied as a function of culture age. Sterol ester content was higher for older cultures, and in older cultures the composition of the esterified sterols more closely resembled that of the free sterols. The fatty acids obtained from the saponification of the sterol esters were methylated and were analyzed using gas chromatography. Tentative identifications, based upon comparative retention times, were made for several of these acids. Sterols were extracted from the nutrient medium after harvest of the algal cells. Extraction was accomplished by mixing large quantities of nutrient medium with ether for several days, or by shaking small aliquots with ether. 24-methylcholesta-5,7-dien-3B-ol and 24 ethylcholesta-5,7-dien-3B-ol were isolated from the nutrient medium in approximately the same relative amounts as from the algal cells. The concentration of sterols in the nutrient medium was approximately equal to the water-solubility of cholesterol (25-29)t g./l.). Extraction procedures which release sterols from water soluble complexes were carried out on extracted cells and on extracted nutrient medium. These procedures failed to yield measurable quantities of sterols. Treatment of extracted cells with strong base and subsequent extraction showed that all sterols had been extracted without prior cell lysis or pretreatment. An extraction of algal cells was carried out using DMSO:ether as the extraction solvent. This extraction resulted in complete removal of sterols from the cells, and the sterols were accompanied by only small amounts of other lipidsoluble material.

Lowering plasma LDL-cholesterol (LDL-C) and increasing HDL-cholesterol (HDL-C) concentrations remain the primary targets in cardiovascular disease (CVD) risk reduction. Dietary cholesterol and plant sterols differentially modulate cholesterol kinetics and lipoprotein distribution. Inter-individual variations in the rates of cholesterol absorption and synthesis, and the reciprocal interaction between them affect the responses to dietary sterols. Genetic heterogeneity profoundly influences such responsiveness. However, limited research exists on the genetic determinants of dietary cholesterol versus plant sterols responsiveness in healthy individuals, especially in a founder population, such as the Hutterites in Manitoba of European descent who practice a communal living system. Our study examined the differential effects of dietary cholesterol versus plant sterol consumption on plasma lipoprotein levels, subclasses, and cholesterol kinetics and assessed how genetic variants influenced these responses. A double-blind, randomized, crossover study with three interventional periods of 4 wk duration each was conducted. Healthy Hutterite individuals (n=49) from Manitoba consumed daily either 2 g of plant sterols or 600 mg of cholesterol incorporated into milkshakes, or a placebo during each period. Plasma lipid profile and lipoprotein subclass distribution were determined. Cholesterol absorption and synthesis were assessed by stable isotopic tracer techniques. Participants were genotyped for 38 candidate single nucleotide polymorphisms across 25 genes involved in cholesterol and lipoprotein metabolism. Dietary cholesterol consumption increased plasma TC, HDL-C concentrations and large HDL subclasses with no changes in cholesterol absorption or synthesis. In contrast, plant sterol intake failed to reduce LDL-C concentrations, with a modest reduction in cholesterol absorption, and did not affect lipoprotein subclasses. However, a large non-compensatory increase in cholesterol synthesis was observed due to plant sterol consumption. Gender and common genetic variants affected plasma HDL-C and HDL subclass distribution to dietary cholesterol and plant sterol consumption. ACAT2 and NPC1L1 gene variants affected plasma campesterol and β-sitosterol concentrations respectively, to plant sterol intake by modifying cholesterol absorption. In summary, our results demonstrate that dietary cholesterol and plant sterol intake differentially modulate cholesterol trafficking in a manner dependent on common genetic variants and gender in healthy individuals. Such knowledge facilitates the development of effective cholesterol lowering strategies for the alleviation of CVD burden. / October 2016

Pollution from human and animal faecal waste is a major cause of deteriorating water quality and increased nutrient loads in coastal and inland waterways. Management of this problem depends on knowing which sources of faecal matter are the cause and what is the degree and extent of the pollution. Bacterial indicator organisms have long been the principal method used to test water samples for faecal contamination. However, none of the currently used bacterial indicators on their own are source specific enough to distinguish different sources of faecal matter. The use of faecal sterol biomarkers in conjunction with existing bacterial indicators offers a new way to distinguish sources of faecal contamination. This study investigates the sources of faecal sterols, the relationship of coprostanol to existing bacterial indicators of faecal pollution, the degradation of faecal sterols and the problem of determining the sources of faecal contamination and the distribution of faecal contamination using faecal sterol biomarkers. 5p-Stanols (i.e. faecal sterols) were found to be significant constituents of human, herbivore (i.e. cows, sheep etc.) and pig and cat faeces. Human faeces contained 73 ± 4% coprostanol in relation to the sum of coprostanol and 24-ethylcoprostanol and primary treated effluent contained 86 ± 0.4% coprostanol. Herbivore faeces contained 38 ± 4% coprostanol and 62 ± 4% 24-ethylcoprostanol whereas pig faeces contained 50 � 5% of each compound. Both birds and dogs faeces contained either trace amounts of 5B-stanols or they could not be detected. Notable differences were observed in the abundance of Closthdium perfringens spores between the faeces of birds and domestic pets such as cats and dogs. The above differences were subsequently exploited to distinguish faecal contamination in Lake Tuggerah. An examination of the relationships between coprostanol and bacterial indicator concentrations from several environments revealed that 60 and 400 ng L of coprostanol corresponded to currently defined primary and secondary contact limits for bacteria measured as either thermotolerant coliforms or enterococci in the environment. Four degradation experiments showed faecal sterols and related sterols such as cholesterol decay at similar rates. An induction period was observed in all experiments which meant that simple exponential equations to describe the rate of decay of coprostanol were inadequate; a complimentary log - log transformation of the data was used and the equation: Y = l-Exp(-Exp(time x -0.01 + temp x -0.158 + 3.33)) x 100 was derived where Y equals the predicted percentage of coprostanol remaining over time at a given temperature. In terms of persistence in the environment, Clostridium perfringens spores > coprostanol > enterococci > thermotolerant coliforms. Two field studies were undertaken to highlight the use of faecal sterols. In the Lake Tuggerah study, the results indicated that faecal contamination of receiving waters in the Tuggerah Lakes during rain events was significant, but was not derived from human faecal matter; rather it appears to be principally derived from native birds and, to a lesser extent, domestic pets. In the Derwent Estuary study, based on the distribution of the faecal biomarker coprostanol, the mid estuary and parts of the upper estuary (from Newtown Bay to Taroona), were found to be severely contaminated by sewage. In summary, the use of faecal sterols to trace faecal contamination were found to be an invaluable addition to the tools water managers use to investigate faecal pollution.

Many of Hawaii’s recreational streams and beaches contain high fecal indicator bacteria levels that are not indicative of sewage pollution. Instead, this pollution is due to environmental sources of fecal bacteria which reside and multiply in tropical soils. Current EPA fecal indicator bacteria are no longer representative of human fecal contamination in tropical waters. Fecal sterols have been used as chemical indicators of fecal pollution in many parts of the world. The primary sterol found in human feces is coprostanol. Detection and quantification of coprostanol and related sterols using GCMS analysis provides a fingerprint that can be used to characterize fecal contamination. The objective of this study was to assay for fecal sterols as an independent method to determine whether streams in Hawaii are contaminated with sewage. This method was applied to ambient streams, a stream recently contaminated by a sewage spill, and a stream suspected to be affected by a sewage line leak. The results of this study showed that some ambient streams in Hawaii contain high levels of fecal indicator bacteria, but low concentrations of coprostanol (<10 ng/L). A stream contaminated with sewage during a sewage spill event contained high concentrations of coprostanol (18,000 ng/L) in the first 24 hours after contamination, but this level dropped to ≤ 60 mg/L after 72 hours. A stream suspected to be contaminated with sewage contained significant levels of coprostanol (>1000 ng/L) when fecal indicators were also high, confirming a possible sewage line leak. This study demonstrated that coprostanol is a useful and independent measurement of sewage pollution. It is best used in conjunction with other fecal indicators and human fecal markers if confirmation of human fecal pollution is sought.