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  • Engström-Öst, Jonna (Helsingin yliopisto, 2002)
  • Pilvi, Taru (Helsingin yliopisto, 2008)
    Diet high in dairy products is inversely associated with body mass index, risk of metabolic syndrome and prevalence of type 2 diabetes in several populations. Also a number of intervention studies support the role of increased dairy intake in the prevention and treatment of obesity. Dairy calcium has been suggested to account for the effect of dairy on body weight, but it has been repeatedly shown that the effect of dairy is superior to the effect of supplemental calcium. Dairy proteins are postulated to either enhance the effect of calcium or have an independent effect on body weight, but studies in the area are scarce. The aim of this study was to evaluate the potential of dairy proteins and calcium in the prevention and treatment of diet-induced obesity in C57Bl/6J mice. The effect of dairy proteins and calcium on the liver and adipose tissue was also investigated in order to characterise the potential mechanisms explaining the reduction of risk for metabolic syndrome and type 2 diabetes. A high-calcium diet (1.8%) in combination with dietary whey protein inhibited body weight and fat gain and accelerated body weight and fat loss in high-fat-fed C57Bl/6J mice during long-term studies of 14 to 21 weeks. α-lactalbumin, one of the major whey proteins, was the most effective whey protein fraction showing significantly accelerated weight and fat loss during energy restriction and reduced the amount of visceral fat gain during ad libitum feeding after weight loss. The microarray data suggest sensitisation of insulin signalling in the adipose tissue as a result of a calcium-rich whey protein diet. Lipidomic analysis revealed that weight loss on whey protein-based high-calcium diet was characterised by significant decreases in diabetogenic diacylglycerols and lipotoxic ceramide species. The calcium supplementation led to a small, but statistically significant decrease in fat absorption independent of the protein source of the diet. This augments, but does not fully explain the effects of the studied diets on body weight. A whey protein-containing high-calcium diet had a protective effect against a high-fat diet-induced decline of β3 adrenergic receptor expression in adipose tissue. In addition, a high-calcium diet with whey protein increased the adipose tissue leptin expression which is decreased in this obesity-prone mouse strain. These changes are likely to contribute to the inhibition of weight gain. The potential sensitisation of insulin signalling in adipose tissue together with the less lipotoxic and diabetogenic hepatic lipid profile suggest a novel mechanistic link to explain why increased dairy intake is associated with a lower prevalence of metabolic syndrome and type 2 diabetes in epidemiological studies. Taken together, the intake of a high-calcium diet with dairy proteins has a body weight lowering effect in high-fat-fed C57Bl/6J mice. High-calcium diets containing whey protein prevent weight gain and enhance weight loss, α-lactalbumin being the most effective whey protein fraction. Whey proteins and calcium have also beneficial effects on hepatic lipid profile and adipose tissue gene expression, which suggest a novel mechanistic link to explain the epidemiological findings on dairy intake and metabolic syndrome. The clinical relevance of these findings and the precise mechanisms of action remain an intriguing field of future research.
  • Kemi, Virpi (Helsingin yliopisto, 2010)
    Dietary habits have changed during the past decades towards an increasing consumption of processed foods, which has notably increased not only total dietary phosphorus (P) intake, but also intake of P from phosphate additives. While the intake of calcium (Ca) in many Western countries remains below recommended levels (800 mg/d), the usual daily P intake in a typical Western diet exceeds by 2- to 3-fold the dietary guidelines (600 mg/d). The effects of high P intake in healthy humans have been investigated seldom. In this thesis healthy 20- to 43-year-old women were studied. In the first controlled study (n = 14), we examined the effects of P doses, and in a cross-sectional study (n = 147) the associations of habitual P intakes with Ca and bone metabolism. In this same cross-sectional study, we also investigated whether differences exist between dietary P originating from natural P sources and phosphate additives. The second controlled study (n = 12) investigated whether by increasing the Ca intake, the effects of a high P intake could be reduced. The associations of habitual dietary calcium-to-phosphorus ratios (Ca:P ratio) with Ca and bone metabolism were determined in a cross-sectional study design (n = 147). In the controlled study, the oral intake of P doses (495, 745, 1245 and 1995 mg/d) with a low Ca intake (250 mg/d) increased serum parathyroid hormone (S-PTH) concentration in a dose-dependent manner. In addition, the highest P dose decreased serum ionized calcium (S-iCa) concentration and bone formation and increased bone resorption. In the second controlled study with a dietary P intake of 1850 mg/d, by increasing the Ca intake from 480 mg/d to 1080 mg/d and then to 1680 mg/d, the S-PTH concentration decreased, the S-iCa concentration increased and bone resorption decreased dose-dependently. However, not even the highest Ca intake could counteract the effect of high dietary P on bone formation, as indicated by unchanged bone formation activity. In the cross-sectional studies, a higher habitual dietary P intake (>1650 mg/d) was associated with lower S-iCa and higher S-PTH concentrations. The consumption of phosphate additive-containing foods was associated with a higher S-PTH concentration. Moreover, habitual low dietary Ca:P ratios (≤0.50, molar ratio) were associated with higher S-PTH concentrations and 24-h urinary Ca excretions, suggesting that low dietary Ca:P ratios may interfere with homeostasis of Ca metabolism and increase bone resorption. In summary, excessive dietary P intake in healthy Finnish women seems to be detrimental to Ca and bone metabolism, especially when dietary Ca intake is low. The results indicate that by increasing dietary Ca intake to the recommended level, the negative effects of high P intake could be diminished, but not totally prevented. These findings imply that phosphate additives may be more harmful than natural P. Thus, reduction of an excessively high dietary P intake is also beneficial for healthy individuals.
  • Hang, Ingrid (Helsingin yliopisto, 2015)
    Considerable evidence suggests that dietary macronutrients impact upon activities and conditions in the gastrointestinal tract (GIT) including: functions and processes, digestive enzymes secretion, microbial ecology and bacteria-derived metabolism. Knowledge about the modulation of canine intestinal microbiota, bacteria-derived metabolic products,intestinal inflammatory status and adaptive exocrine pancreatic secretion in response to macronutrients is limited. However, such information is necessary to investigate further the complex interplay between host and intestinal microbiota in response to changes of diet. The reasearch for this PhD thesis focused upon the changes of the intestinal microbiota,bacteria-ferivedmetabolicproducts,anintestinalinflammatorymarker and pancreatic enzyme profiles of five healthy Beagle dogs in response to being fed three different diets: high-carbohydrate starch (HCS), high-protein greaves-meal (HPGM), or a balanced dry commercial (DC) diet. Every diet was crossed-over and fed to each dog for three 21-day periods. The microbial deoxyribonucleic acid (DNA) was profiled according to its percentageoftheguanine-cytosinecontent(%G+C)inordertodetectthefluctuations in intestinal microbiota. Thereafter, 16S ribosomal ribonucleic acid (16S rRNA) gene amplicons were obtained from the most abundant %G+C peaks and analysed by sequence analysis. The DC diet sample was associated with high abundances of representatives of the orders Clostridiales, Lactobacillales, Coriobacteriales and Bacteroidales. Sequence diversity was highest for the DC diet samples and included representatives of the orders Lactobacillales and Bacteroidales, which were not detected in samples obtained for the HPGM and HCS diets. The HPGM and HCS diets also had reduced numbers of representatives of the family Lachnospiraceae; specifically Clostridium cluster XIVa. The HCS diet favoured the proliferation of representatives of the order Erysipelotrichales, specifically the Clostridium cluster XVIII, whereas the HPGM diet favoured representatives of the order Fusobacteriales. Bacterial metabolism and intestinal inflammatory status were assessed by determining dry matter, pH, ammonia, short-chained fatty acids (SCFAs), and faecal canine calprotectin concentrations. Faecal ammonia concentrations decreased with the HCS diet. All dogs fed the HPGM diet developed diarrhoea, which led to differences in faecal consistency scores and increased faecal pH. Moreover, decreases in propionic and acetic acids coupled with increases in branched-chain fatty acids and valeric acid caused changes in faecal total SCFAs. Faecal canine calprotectin concentration was also higher for the HPGM diet than with the other diets and correlated positively with valeric acid concentrations.8 Dietary effects on digestive enzyme composition in the serum, in jejunal fluid, and in the faeces were studied by determining the following factors: amylase activity, the concentrations of canine trypsin-like immunoreactivity (cTLI), canine pancreatic lipase immunoreactivity (cPLI), and canine pancreatic elastase (cE1) concentrations with the two radioimmunoassays (RIAs) for determining cTLI and cPLI concentrationswere specifically validated for jejunalfluid and faecal specimen analysis. Both RIAs were linear, accurate, precise, and reproducible. Dog specific serum enzyme concentrations did not differ between diets. Feeding the HCS diet was associated with decreased amylase activities and cPLI concentrations in the lower jejunum, when compared to the corresponding cPLI activities of the HPGM and the DC diet. The HPGM diet decreased the concentrations of cPLI and cE1 in faecal samples, but not in the jejunal fluid. In conclusion, all bacterial clusters discovered in this research represent the normal GIT microbiota of canines. The HPGM diet favoured Fusobacterium and this Gram-negative bacterial genus may be associated with the observed elevated inflammation status. The latter was deduced from the observed diarrhoea and elevated levels of canine faecal calprotectin in all dogs fed the HPGM diet. It seems likely that these research results could be associated with the quality and increased or decreased amounts of dietary protein or carbohydrate being available for fermentation by the intestinal microbiota. The limited capacity of pancreatic enzymes to adapt adequately by a change inprofile inresponse to changes indietary components seems to be an essential factor, which influences the nutrient levels available for the intestinal microbiota.
  • Lübbers, Henning (2012)
    General-purpose lossless data compression continues to be an important aspect of the daily use of computers, and a multitude of methods and corresponding compression programs has emerged since information theory was established as a distinct area of research by C.E. Shannon shortly after World War II. Shannon and others discovered several theoretical bounds of data compression and it is, for instance, nowadays known that there can be neither a compressor that can compress all possible inputs, nor any mechanism that compresses at least some inputs while preserving the lengths of the incompressible ones. Although it is therefore indisputable that any compressor must necessarily expand some inputs, it is nonetheless possible to limit the expansion of any input to a constant number of bits in worst case. In order to determine how the established theoretical bounds relate to existing compression pro- grams, I examined two popular compressors, GZip and BZip2, and concluded that their behaviour is not optimal in all respects as they may expand inputs in worst case more than theoretically necessary. On the other hand, the examined programs provide very good compression for most realistic inputs rather swiftly, a characteristic that is most likely appreciated by most computer users. Motivated by a review of the most fundamental bounds of data compression, i.e. Kolmogorov Complexity, Entropy and the Minimum Description Length Principle, and further encouraged by our analysis of GZip and BZip2, I propose a generic, pipelined architecture in this thesis that can - at least in theory - be employed to achieve optimal compression in two passes over the input to be compressed. I subsequently put the proposed architecture directly to the test, and use it to substantiate my claim that the performance of compression (boosting) methods can be improved if they are configured for each input anew with a dynamically discovered set of optimal parameters. In a simple empirical study I use Huffman Coding, a classic entropy-based compression method, as well as Move-To-Front Coding (MTF), a compression boosting method designed to exploit locality among source symbols, to demonstrate that the choice of implied source alphabet influences the achieved compression ratio and that different test inputs require different source alphabets to achieve optimal compression.
  • North, Ace (Helsingin yliopisto, 2010)
    Environmental variation is a fact of life for all the species on earth: for any population of any particular species, the local environmental conditions are liable to vary in both time and space. In today's world, anthropogenic activity is causing habitat loss and fragmentation for many species, which may profoundly alter the characteristics of environmental variation in remaining habitat. Previous research indicates that, as habitat is lost, the spatial configuration of remaining habitat will increasingly affect the dynamics by which populations are governed. Through the use of mathematical models, this thesis asks how environmental variation interacts with species properties to influence population dynamics, local adaptation, and dispersal evolution. More specifically, we couple continuous-time continuous-space stochastic population dynamic models to landscape models. We manipulate environmental variation via parameters such as mean patch size, patch density, and patch longevity. Among other findings, we show that a mixture of high and low quality habitat is commonly better for a population than uniformly mediocre habitat. This conclusion is justified by purely ecological arguments, yet the positive effects of landscape heterogeneity may be enhanced further by local adaptation, and by the evolution of short-ranged dispersal. The predicted evolutionary responses to environmental variation are complex, however, since they involve numerous conflicting factors. We discuss why the species that have high levels of local adaptation within their ranges may not be the same species that benefit from local adaptation during range expansion. We show how habitat loss can lead to either increased or decreased selection for dispersal depending on the type of habitat and the manner in which it is lost. To study the models, we develop a recent analytical method, Perturbation expansion, to enable the incorporation of environmental variation. Within this context, we use two methods to address evolutionary dynamics: Adaptive dynamics, which assumes mutations occur infrequently so that the ecological and evolutionary timescales can be separated, and via Genotype distributions, which assume mutations are more frequent. The two approaches generally lead to similar predictions yet, exceptionally, we show how the evolutionary response of dispersal behaviour to habitat turnover may qualitatively depend on the mutation rate.
  • Dadzie, Samuel K (2007)
    The thesis is about a one year follow-up ergonomic intervention study on the improvement of low back disorders, perceived health status and overall working ability, among various kitchen institutions in Finland, with the ultimate aim of meeting the requirements of workers’ capabilities by addressing their issues and the working environment; the match between personnel and equipments usage, work processes and environment. LBP is a typical MSD which may be characterised by periodic and protracted pains, stresses and strains around the low back often as a result of fitting workers in working environments whose design falls short of targeted ergonomic standards. Effective ergonomic changes can be attained by means of technical, administrative and socioeconomic procedures. Workers involvement in the planning and implementation of possible changes effects ergonomic efficiency. Individual physical attributes and habits ought to be taken into consideration to better understand and assess the effect of ergonomic intervention programs. Effective ergonomic approach is realised through a reduction in MSD (eg. LBP) cases and associated pain reduction, minimal absenteeism, perceived health improvement and hence, improved work ability. Linear mixed models was the main statistical analyses employed in modelling the mean changes in low back pain, as well as accounting for the covariances in the repeated measures. The statistical results revealed that, generally, there was an improvement in low back pain, reduced LBP sick leaves, among the intervention group compared to that of the control group. These differences, however, were often not, statistically, significant. Further, the intervention group excelled in their respective perception of health (in terms of aspects of quality of life). It is recommended that work organization be improved in the direction of elevated levels of WPFs, which are keys to job satisfaction and LBP recovery. Larger sample size is required in guaranteeing further and detailed analyses to deepen our understanding and appreciation of the interrelationships among many underlying constructs associated with MSDs, and their progression, for the effective evaluation of intervention program
  • Sutton, David (2003)
    Peacekeeping operations have grown in scope and frequency over the decades since the establishment of the Unite Nations (UN). In particular, the optimism attending the UN’s prospects of greater leadership in conflict resolution in a new season of openness following the end of the Cold War saw increasing UN involvement in varied and complex conflicts – many involving ethnic rivalries that have surfaced amid the turbulence of the formation of new states and the spread of democracy in the last decade. Unfortunately, few of these operations have been widely regarded as successful, and some have ended in absolute disaster. There is a continuing need to search for the factors which hinder success and to evaluate the compatibility of current peacekeeping methods and assumptions with conflicts in which those factors play a significant role. Thus, this paper begins by examining the design, function and doctrine of traditional peacekeeping missions, from which a definition of success is also established. The nature and particular difficulties of ethnicity and ethnic conflict are delineated and a key interaction between these and the current broad UN approach to conflict is explored. From this understanding, two UN missions – the United Nations Operation in Mozambique (ONUMOZ) and the United Nations Assistance Mission for Rwanda (UNAMIR) – are compared to determine whether a substantial ethnic component to a conflict may in fact emerge as a significant hindrance to successful peacekeeping operations given current methods and assumptions. The conclusion drawn is that the success of UN peacekeeping missions, which are designed to facilitate negotiated settlements with the consent of the parties involved, is seriously challenged when the conflict in question is characterized by significant ethnic animosity. It is suggested that UN planners should therefore intervene in ethnic conflict more circumspectly, and that more serious consideration should be given to more robust measures if a peacekeeping mission is undertaken.
  • Mujunen, Virpi (2004)
    In the social psychological research, language and identity may be seen as reciprocally related. As the abundance of sociolinguistic research has focused on how identity explains behaviour, the focus of this study was reversed, that is, how one´s identity is shaped by language. The goal of this study was two-fold, to find out about the relationship among objective ethnolinguistic vitality (EV), individual network of language contacts (INLC), and ethnolinguistic identity, as well as to find out about the importance of childhood language background to ethnolinguistic identity. Ethnolinguistic vitality construct developed by Giles, Bourhis and Taylor (1977), as well as the model by Allard and Landry (1986, 1992, 1994) were used as the theoretical framework for this study. According to the latter model, INLC acts as a link between the sociological level (EV) and the psychological level (identity). The sample consisted of 563 Swedish-speaking Finns, out of which 51% came from South Finland province and 49% from West Finland province. About 44% of the participants were males and 56% were females. The study was conducted using data collected in the fall 2000 for a research project “Swedish and Finnish as minority and as majority: Stereotypes, group identification and self-images” led by professors Karmela Liebkind and Anders Lange. The data was analyzed using mainly hierarchical regressional analysis. The results of this study supported earlier research according to which ethnolinguistic vitality has an effect on ethnolinguistic identity via individual network of language contacts. The objective vitality, in this case the language of community, allows these networks to expand, but it is these networks that have the effect on identity.
  • Mujunen, Virpi (2004)
    Sosiaalipsykologisessa tutkimuksessa kieli ja identiteetti nähdään usein olevan molemminpuolisessa vuorovaikutussuhteessa keskenään. Koska suuri osa aikaisemmasta tutkimuksesta on käsitellyt identiteetin vaikutusta käyttäytymiseen, tämän tutkimuksen tarkoitus oli päinvastainen eli selvittää, miten kieli vaikuttaa identiteettiin. Tutkimuksessa keskityttiin lähinnä kahteen kysymykseen: Ensinnäkin selvitettiin objektiivisen etnolingvistisen vitaliteetin, henkilökohtaisten kielikontaktiverkostoiden ja etnisen identiteetin välisiä suhteita. Toisaalta haluttiin saada selville mikä merkitys lapsuuden kielitaustalla on etniselle identiteetille. Viitekehyksenä näiden tekijöiden välisiä suhteita tarkasteltaessa oli Gilesin, Bourhisin ja Taylorin (1977) sekä Allardin ja Landryn (1986, 1992, 1994) esittämät etnolingvistisen vitaliteetin mallit. Jälkimmäisen mallin mukaan kielikontaktiverkostot toimivat välittäjinä sosiologisen ja psykologisen tason välillä. Tutkimuksen otos koostui 563 ruotsinsuomalaisesta, joista 51% oli Etelä-Suomen läänistä ja 49% Länsi-Suomen läänistä. Naisia tutkimukseen osallistuneista oli 56% ja vastaavasti miehiä 44%. Tutkimusaineistona käytettiin syksyllä 2000 professori Karmela Liebkindin ja professori Anders Langen johtamaa tutkimusta varten kerättyä aineistoa (”Suomalaiset ja ruotsalaiset vähemmistönä ja enemmistönä: Stereotypiat, ryhmäsamastuminen ja minä-käsitys”). Aineisto analysoitiin pääasiassa hierarkkisten regressioanalyysien avulla. Tutkimuksen tulokset tukivat aikaisempia tutkimuksia, joiden mukaan kielikontaktiverkostot toimivat välittäjinä etnolingvistisen vitaliteetin sekä identiteetin välillä. Objektiivinen vitaliteetti eli tässä tapauksessa kunnan kielisyysaste luo puitteet, joissa kielikontaktiverkostot voivat kehittyä. Nämä verkostot ovat kuitenkin niitä, jotka vaikuttavat etniseen identiteettiin. Samoin toisesta kysymyksestä saadut tulokset tukivat aiempaa tutkimusta eli lapsuuden kielitausta oli merkittävä etniselle identiteetille.
  • Penttinen, Heidi (2013)
    The main goal of the thesis was to investigate the effects of a 12-month supervised exercise intervention on breast cancer patients' QoL shortly after adjuvant treatment. The secondary aims were to assess the physical and psychological well-being of patients immediately after adjuvant treatment of the largest breast cancer survivor population intervention study (BREX) to date and the patients' willingness to participate in such a long intervention. In addition, the work aimed to further clarify the results of the intervention by analyzing the QoL changes of participants of the exercise study compared to those of normal follow-up patients. Patients: Of the 573 randomized patients (aged 35 to 68 years), 500 were included in the final analyses of the effects of exercise intervention: 263 in the exercise group and 237 in the control group. A total of 73 patients were excluded from the final analyses for various reasons: not meeting the inclusion criteria (36), declined for personal reasons (20), breast cancer recurrence (14), and new malignancy during the intervention (3). All 537 patients who met the inclusion criteria after the baseline visit and investigations were included in the baseline analysis. Patients of the additional study consisted of two separate patient groups: 237 control patients of the BREX study and 108 similar breast cancer patients (who met the same inclusion criteria and were treated according to the same guidelines as the patients in exercise study) participating in a follow-up study which did not contain any intervention. Methods: The EORTC QLQ-C30 and BR-23 questionnaires were used to evaluate QoL, FACIT-F for fatigue, and the Finnish modified version of Beck s 13-item depression scale (BDI). Physical fitness was assessed by a 2-km walking test and figure-8 running test, and physical activity (PA) by metabolic equivalent (MET) hours per week (MET-h/wk) based on data collected by a prospective two-week physical activity diary. Results: Of the eligible patients 78.3% participated in the study. At baseline, the global QoL of the study patients was lower than in the general population; 26% of them were rated as depressed, 20% as fatigued, and 82% suffered from menopausal symptoms, which seemed to impair QoL. Most scores from the EORTC QLQ-C30 improved significantly within both the exercise and control groups during 12 months, with no significant differences between groups. Participation in the exercise intervention study per se seemed not to improve the QoL of breast cancer survivors. At baseline, 62% of the walking test results were below the population average. Physical performance in walking tests correlated significantly to MET hours and to previous leisure-time physical activity. The amount of physical activity increased from baseline over a 12-month period in both groups; there were no significant differences between the groups. Neuromuscular performance improved significantly in the training group during 12 months. No significant effect of intervention was observed on cardiorespiratory fitness. However, the walk time improved significantly in both groups during the intervention. Already at baseline, PA improved QoL. After the 12-month follow-up there was a linear relationship between increased PA and improved QoL, irrespective of the intervention. There was a significant linear trend between higher physical activity and improved QoL and recovery from fatigue. No significant relationship was detected between physical activity and depression or between physical performance (figure-8 running or 2-km walking test) and QoL, fatigue or depression. Conclusions: Recruiting patients to the study succeeded excellently. With the exception of age limit and musculoskeletal disorders, the study population represents the general Finnish breast cancer population. At baseline, the QoL of the patients was impaired and the physical performance poor compared with the general population; in particular, depression and fatigue were related to impaired QoL. The study did not find evidence to support the superiority of the 12-month supervised vigorous aerobic exercise and home training over the control arm in improving physical activity and QoL of the patients. In contrast, both groups improved equally during the follow-up duration. Spontaneous recovery of QoL seems to be the most likely explanation for the observed results, at least when the intervention is timed to the rehabilitation period. Future exercise intervention studies targeting improvement of QoL should identify groups of patients that could benefit the most from an intervention and tailor the interventions to their specific needs.
  • Alam, Syed Ariful (Helsingin yliopisto, 2012)
    Oats are a good source of protein and dietary fibre, especially β-glucan. Due to the health benefits of β-glucan, oats have gained popularity in snack food formulations. The literature review deals with oats and its components, removal of lipids and fractionation of oat products. The particular emphasis of the literature review was given to studies on the effects of different oat fractions and extrusion process variables on the properties of oat-containing extrudates. The aim of this study was to find out how different oat fractions and extrusion process variables (screw speed, water content and feed rate) affect the physical and chemical properties of the extrudates. The measured physical properties were expansion, hardness and water content. Extrusion trials were carried out by using defatted oat endosperm flour (EF) as the main ingredient. Whole grain oat flour (WF) was used as a reference. To improve the nutritional quality, defatted oat protein concentrate (PC) and defatted oat bran concentrate (OBC) were added to EF. The oat fractions were defatted by supercritical carbon dioxide (SC-CO2). Pregelatinised corn starch (CS) and waxy corn starch (WS) were added in some trials to increase the expansion of the extrudates. A co-rotating twin-screw extruder was used for the extrusion. Different process variables were: water content of the mass (16, 18 and 20%), screw speed (240, 370 and 500 rpm) and feed rate (68, 76 and 84 g/min). The temperature profile of the extruder barrel was held constant in all of the trials: 40, 70, 70, 100, 110, 130 and 130 °C (sections 1 6 and die). Screw speed had significant effect on the expansion and hardness. Expansion increased and hardness decreased with increasing screw speed. Water content of the mass affected all the response variables in WF extrudates and all but not hardness and torque in EF extrudates. Increased water content of mass decreased the expansion and hardness in WF extrudates. Feed rate did not have significant effect on the physical properties. When using EF, more expanded and less hard extrudates compared to the WF were obtained. Addition of PC or OBC (10%) decreased the expansion and increased the hardness. Mixing of EF with corn starch (CS or WS; 30%) gave less hard and more expanded extrudates compared to pure EF. The highest expansion was achieved by the addition of WS. Even addition of OBC (20%) in a presence of WS (30%) gave highly expanded and less hard extrudates with high β-glucan content 7.4% (dry weight). Decreasing the particle size of OBC (by ultra-fine milling) or the molecular weight of β-glucan (by enzymatic hydrolysis) did not affect the physical properties of the extrudates even though small decrease in hardness was observed in the trial with enzyme-hydrolysed OBC. The results showed that defatted oat fractions can successfully be used in extrusion when mixed with corn starch. Screw speed had the most profound effect on the physical properties of the oat-containing extrudates followed by the water content of mass.
  • Xiang, Xiaoqiang (Helsingin yliopisto, 2011)
    Bile acids are important steroid-derived molecules essential for fat absorption in the small intestine. They are produced in the liver and secreted into the bile. Bile acids are transported by bile flow to the small intestine, where they aid the digestion of lipids. Most bile acids are reabsorbed in the small intestine and return to the liver through the portal vein. The whole recycling process is referred to as the enterohepatic circulation, during which only a small amount of bile acids are removed from the body via faeces. The enterohepatic circulation of bile acids involves the delicate coordination of a number of bile acid transporters expressed in the liver and the small intestine. Organic anion transporting polypeptide 1B1 (OATP1B1), encoded by the solute carrier organic anion transporter family, member 1B1 (SLCO1B1) gene, mediates the sodium independent hepatocellular uptake of bile acids. Two common SNPs in the SLCO1B1 gene are well known to affect the transport activity of OATP1B1. Moreover, bile acid synthesis is an important elimination route for cholesterol. Cholesterol 7α-hydroxylase (CYP7A1) is the rate-limiting enzyme of bile acid production. The aim of this thesis was to investigate the effects of SLCO1B1 polymorphism on the fasting plasma levels of individual endogenous bile acids and a bile acid synthesis marker, and the pharmacokinetics of exogenously administered ursodeoxycholic acid (UDCA). Furthermore, the effects of CYP7A1 genetic polymorphism and gender on the fasting plasma concentrations of individual endogenous bile acids and the bile acid synthesis marker were evaluated. Firstly, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for the determination of bile acids was developed (Study I). A retrospective study examined the effects of SLCO1B1 genetic polymorphism on the fasting plasma concentrations of individual bile acids and a bile acid synthesis marker in 65 healthy subjects (Study II). In another retrospective study with 143 healthy individuals, the effects of CYP7A1 genetic polymorphism and gender as well as SLCO1B1 polymorphism on the fasting plasma levels of individual bile acids and the bile acid synthesis marker were investigated (Study III). The effects of SLCO1B1 polymorphism on the pharmacokinetics of exogenously administered UDCA were evaluated in a prospective genotype panel study including 27 healthy volunteers (Study IV). A robust, sensitive and simple HPLC-MS/MS method was developed for the simultaneous determination of 16 individual bile acids in human plasma. The method validation parameters for all the analytes met the requirements of the FDA (Food and Drug Administration) bioanalytical guidelines. This HPLC-MS/MS method was applied in Studies II-IV. In Study II, the fasting plasma concentrations of several bile acids and the bile acid synthesis marker seemed to be affected by SLCO1B1 genetic polymorphism, but these findings were not replicated in Study III with a larger sample size. Moreover, SLCO1B1 polymorphism had no effect on the pharmacokinetic parameters of exogenously administered UDCA. Furthermore, no consistent association was observed between CYP7A1 genetic polymorphism and the fasting plasma concentrations of individual bile acids or the bile acid synthesis marker. In contrast, gender had a major effect on the fasting plasma concentrations of several bile acids and also total bile acids. In conclusion, gender, but not SLCO1B1 or CYP7A1 polymorphisms, has a major effect on the fasting plasma concentrations of individual bile acids. Moreover, the common genetic polymorphism of CYP7A1 is unlikely to influence the activity of CYP7A1 under normal physiological conditions. OATP1B1 does not play an important role in the in vivo disposition of exogenously administered UDCA.
  • Zou, Ling (2009)
    Andean lupin (Lupinus mutabilis Sweet) is a potential oilseed crop, with a very high protein content (40–45%) and 15–20% oil content. It is valued as an alternative protein source for both human and animal consumption, and like several other lupin species, has a potential role in phytoremediation. Previous experience in central and southern Europe has shown the crop to have low and unstable yields with high sensitivity to heat and drought during the grain–filling stage. The species may therefore be more suitable for cool–temperate climates, as it comes from similar altitudes and latitudes as potato. Therefore, an experiment was set out to quantify the responses of Andean lupin to heat stress, using both gradually and suddenly rising temperatures during grain filling. In preliminary tests 60 accessions from 4 germplasm banks were screened for time to flowering and daylength sensitivity. For this experiment, 3 accessions were chosen, 478435, 457972, 457977, with vegetative phase durations of 44, 53, 64 days from sowing to first flower, respectively. Forty two plants of each accession were sown and reduced to 30 on the basis of uniformity. Plants were grown in a glasshouse with 22 °C, 18 h days and 18 °C, 6 h nights until about 25 days after flowering. Ten plants of each accession were subjected to one of the following treatments: control (continuing in the same glasshouse conditions), sudden heat stress (transferred to a growth chamber and subjected to 38 °C from 11:00 to 15:00) or gradual heat stress (transferred to a growth chamber and subjected to temperature increases of 4 °C day temperature and 2 °C night temperature, with the final two days at 38 °C from 11:00 to 15:00). The plants were returned to the glasshouse and when mature, the seeds were harvested and pooled into 3 replicates per accession and treatment for quality analysis. Seed protein, oil, soluble sugar, ash and moisture content were determined. Data were calculated on the basis of percentage of overall seed mass and also on a milligrams per seed basis in order to reflect the seed physiology at grain–filling stage. Sudden heat stress had greater effects on seed composition than gradual heat stress. When compared with control, sudden heat stress resulted in more loss of every component than gradual heat stress, on a per–seed basis, in all 3 accessions and the responses of the accessions to the sudden stress were not statistically different. Under sudden heat stress, mean seed weight declined by 70%, protein content by 70%, oil content by 85%, ash content by 50%, and soluble sugar content by 75%. The accessions responded differently, however, to the gradual heat stress. Accession 478435 experienced significantly greater reduction in seed weight, protein and ash content than accessions 457972 and 457977. Oil content per seed and soluble sugar content per seed were also lower in 478435 than in the other two cultivars, but the difference was not significant. On the flour basis, sudden heat stress increased ash content and decreased oil content and soluble sugar content significantly in all accessions. Accession 478435 had highest value in ash content at significant level. Under gradual stress, protein and ash content were increased while oil mass and soluble sugar mass were decreased. 478435 had significantly higher protein mass and ash mass in flour with respectively 57% and 5.1%, 457977 had significantly higher soluble sugar content with 112 mg/g. The results showed that heat stress can have a significant effect on the quantity and quality of seed yield in Andean lupin. While all tested accessions were severely susceptible to sudden heat stress, gradual stress identified differences between accessions, with one being much more susceptible than the other two. The most susceptible accession was the earliest to flower. Gradual heat stress allows better resolution than sudden heat stress when screening germplasm for heat tolerance.