O emprego de solventes no processo de obtenção de óleos de sementes oleaginosas é um processo amplamente empregado, sendo o hexano o solvente tradicionalmente adotado. O objetivo principal desta dissertação de mestrado foi avaliar a viabilidade da substituição do hexano por etanol no processo de extração de óleo de soja. A utilização de etanol apresenta vantagens bastante atrativas como: menor toxicidade, boa seguridade operacional além deste ser obtido de fonte biorenovável. A produção de etanol em larga escala no Brasil torna, ainda, o processo vantajoso do ponto de vista econômico, além de ser um solvente facilmente recuperado para posterior reutilização no processo devido às suas características físico-químicas. Desta forma, neste trabalho foram realizados experimentos de cinética de extração e experimentos de extração sólido-líquido na condição de equilíbrio, nos quais foram avaliadas as variáveis: temperatura (40 a 90 °C) e hidratação do solvente (0 a 12%). Através da execução destes experimentos e a avaliação estatística dos resultados foi possível determinar os rendimentos de óleo e proteína, monitorar o comportamento dos compostos minoritários (ácidos graxos livres) e da água presente na matéria-prima, avaliar a qualidade da fração proteica resultante do processo de extração, além da composição química dos óleos obtidos. Assim, os resultados mostraram que o aumento do teor de água no etanol suprimiu fortemente a extração de óleo enquanto que a elevação da temperatura favoreceu a extração. Já a proteína exibiu um comportamento contrário ao óleo, sendo que o aumento da hidratação do solvente elevou a extração destes compostos e o aumento da temperatura diminuiu o teor de proteínas na fase extrato. Quanto à hidratação da fase extrato, pôde-se notar que esta foi independente da temperatura e que existe um equilíbrio entre a umidade do sólido e o nível de hidratação do etanol. A elevação da temperatura também aumentou a extração de ácidos graxos livres e a avaliação do perfil químico e da composição em AGL dos óleos obtidos via etanol mostrou que estes apresentaram composição típica de óleo de soja, independente da condição adotada. A qualidade da fração proteica resultante da extração do óleo, avaliada na forma de solubilidade de nitrogênio e análise térmica (DSC), mostrou que a proteína também foi fortemente influenciada pela presença da água no solvente e pelo aumento da temperatura, apresentando menores valores de solubilidade conforme o aumento do teor de água no etanol e da temperatura do processo. Diante dos resultados, pode-se inferir que é viável tecnicamente a utilização de etanol no processo de extração de óleo de soja, no entanto as condições de hidratação do solvente e temperatura devem ser consideradas devido à influência destas sobre as características da fração proteica do farelo desengordurado. / The use of solvents in the extraction of oil from oilseeds is a widely employed process and the hexane is the solvent traditionally adopted. The aim of this work was to evaluate the feasibility of replacing hexane by ethanol in the soybean oil extraction process. The use of ethanol has very attractive advantages such as: low toxicity, good operational security, as well as being obtained from a biorenewable source. The large scale production of ethanol in Brazil also makes the process advantageous from the economics point of view, besides being a solvent easily recovered for reuse in the process due to its physicochemical characteristics. Thus, in this work were performed experiments of kinetics of extraction and experiments of solid-liquid extraction in equilibrium condition in which the variables evaluated were: temperature (ranging from 40 to 90 °C) and solvent hydration (0 to 12% of water). The accomplishment of these experiments and the statistical evaluation of the results made possible to determine the yields of oil and protein, monitor the behavior of minor compounds (free fatty acids) and of the water present in raw material, evaluate the quality of the protein fraction resulting from oil extraction process, and the chemical composition of the extracted oils. Then, the results showed that increasing in water content of ethanol suppresses strongly the extraction of oil while the increase of temperature increases the extraction. About protein, it exhibits an opposite behavior to the oil, with the rise in water content of the solvent increasing the extraction of such compounds and the rise of temperature decreases in the protein content of extract phase. Regarding the hydration of the extract phase, it can be seen that this is temperature independent and that there is equilibrium between the solid matrix and the moisture level of the solvent ethanol. The increase in temperature also increases the extraction of free fatty acids and the evaluation of the chemical profile and composition in FFA of oils obtained via ethanol showed that they had typical composition of soybean oil, regardless the condition adopted. The quality of the protein fraction resulting from oil extraction evaluated as nitrogen solubility and thermal analysis (DSC) showed that the protein is also strongly influenced by the presence of water in the solvent and by increasing the temperature, with lower values of solubility with increasing water content in the ethanol and the process temperature. From the results, it can be inferred that it is technically feasible to use ethanol in the soybean oil extraction process, however hydration conditions of the solvent and temperature must be considered due to the influence of these on the protein fraction characteristics of the defatted meal.

A caseína e os ácidos graxos livres (AGL) são importantes componentes do leite relacionados às suas características industriais e sensoriais. Alguns fatores são responsáveis por alterações em suas concentrações, dentre eles, pode-se destacar as condições de armazenamento, além da agitação e, principalmente, a contagem de células somáticas (CCS). Para estudar tais alterações, avaliou-se através do presente estudo o efeito da temperatura de armazenamento (- 20oC e 7oC) e da idade das amostras (3, 6, 9 e 12 dias), assim como da CCS (CCS1: 400 mil, CCS2:400-750 mil e CCS3: 750 mil células somáticas/mL de leite). O efeito das condições de armazenamento sobre a caseína e os AGL foi avaliado no primeiro estudo. O efeito da CCS sobre a caseína e os AGL, por outro lado, foi avaliado no segundo estudo. No primeiro estudo, observou-se aumento nos teores de AGL ao longo do tempo, ou seja, acompanhando o aumento do período de armazenamento, com médias superiores em amostras resfriadas (7oC), em relação às congeladas (-20oC). Desta forma, sugere-se que análises laboratoriais devem ser realizadas em até três dias para este componente, devido ao seu aumento progressivo em amostras resfriadas. Para a caseína, entretanto, não foi identificada interação entre os fatores idade e temperatura. As médias deste componente não diferiram considerando-se as condições de armazenamento avaliadas, indicando que as análises para este componente podem ser realizadas até doze dias após a coleta, independente da temperatura de armazenamento. No segundo estudo, identificou-se interação entre classes de CCS e época de coleta, para caseína. A partir dos resultados de AGL, pode-se concluir que o leite encontra-se com altas concentrações deste componente, quando coletado na propriedade rural, sendo também observada influência da CCS sobre as concentrações de caseína e AGL no leite cru. Os AGL apresentaram incrementos significativos comparando-se amostras coletadas em diferentes locais, no trajeto da fazenda à indústria. Por outro lado, comparando-se os mesmos locais: tanque, rota e silo, as médias de caseína não diferiram. Observou-se correlação entre as variáveis CCS e caseína e CCS e AGL. / The casein and the free fatty acids (FFA) are important milk components related to its industrial and sensory characteristics. Some factors are responsible for changes in their concentration among them can highlight the storage conditions, as well as agitation and, especially, the somatic cell count (SCC). To study such changes, we assessed through the present study the effect of storage temperature (-20oC and 7oC) and the age of samples (3, 6, 9 e 12 days), as well as the CCS (CCS1: 400 mil; CCS2: 400-750 mil; CCS3: 750 mil somatic cells/mL of milk). The effect of CCS storage conditions on casein and FFA was evaluated in the first study. The effect of CCS on casein and FFA moreover, was evaluated in the second study. In the first study, it was observed increased levels the AGL over time, ie, accompanying the increase of the storage period, with means higher in refrigerated samples (7oC), in relation to frozen samples (- 20oC). Thus, it is suggested that laboratory examinations shall be performed up to three days to this component, due to their progressive increase in refrigerated samples. For casein, however, was not identified interaction between the factors age and temperature. The mean of this component did not differ considering the storage conditions, indicating that the analyzes for this component can be made until twelve days after collection, regardless of storage temperature. In the second study, we identified interactions between CCS classes and seasons, for casein. From the FFA results, we can conclude that milk meets with high concentrations of this component, when collected in the rural property, being also observed influence of CCS on concentrations of casein and FFA in raw milk. The FFA showed significant increases compared to samples collected at different locations on the path from farm to industry. On the other hand, comparing the same locations, tank, route and silo, the casein average did not differ. Correlation was observed between the variables casein and CCS and FFA and CCS.

This study focuses on the development of novel two-stage esterification-transesterification synthesis of biodiesel from used cooking oil (UCO) using novel heterogeneous catalysts. The esterification of the UCO was investigated using three types of ion exchange resins catalysts including Purolite D5081, Purolite D5082 and Amberlyst 15. Of all the catalysts investigated, Purolite D5081 resin showed the best catalytic performance and was selected for further optimisation studies. From the optimisation study, it was found that the external and internal mass transfer resistance has negligible effect on the esterification reaction. At the optimum reaction conditions, Purolite D5081 achieved 92% conversion of FFA. During reusability study, the conversion of FFA dropped by 10% after each cycle and it was found that progressive pore blockage and sulphur leaching were dominant factors that decreased the catalytic performance of the Purolite D5081 catalyst. A kinetic modelling for FFA esterification was carried out using Purolite D5081 as a catalyst. Three types of kinetic models were investigated i.e. pseudo homogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Hougen-Watson (LHHW). Experimental data obtained from the batch kinetic studies was successfully represented by the PH model and a good agreement between experimental and calculated values was obtained. The activation energy for esterification and hydrolysis reaction was found to be 53 and 107 kJ/moL. The transesterification of pre-treated cooking oil (P-UCO) was investigated using various types of heterogeneous catalysts including Purolite CT-122, Purolite CT-169, Purolite CT-175, Purolite CT-275, Purolite D5081, Diaion PA306s and Cs-supported heteropolyacids catalysts. Of all the catalysts investigated, Diaion PA306s catalyst showed the highest conversion of triglycerides and was selected for further optimisation studies. At the optimum reaction conditions, Diaion PA306s achieved ca. 75% of triglycerides conversion. During the reusability study, Diaion PA306s catalyst gave a similar conversion of triglycerides after being reused once. Therefore, it was concluded that the resin can be used several times without losing catalytic activity. Several purification methods have been investigated and dry washing method was chosen as the best alternative for biodiesel purification.

Inledning: Uthållighetsträning definieras som den typ av träning där flertalet stora muskelgrupper används och är i behov av hjärt-kärlsystemets kapacitet för att transportera syre till musklerna. Att fasta innebär i de flesta studier att ingen typ av föda intas före träningspassen medan att inte fasta vanligtvis innebär att 90 minuter före ett träningspass intas en kolhydratrik måltid. Insulin är viktig i fett-, protein- och kolhydratmetabolismen samt i uppsamlingen av socker i blodet. Glykogen fungerar som en energireserv i skelettmusklerna. Fria fettsyror är viktiga för att ge energi till den cellulära metabolismen som ska kunna fortgå. Syfte: Syftet med denna studie var att ta reda på om kroppen påverkas på olika sätt av uthållighetsträning på fastande respektive icke-fastande mage vad gäller insulin, muskelglykogen samt fria fettsyror hos människor. Metod: Litteratursökning i OneSearch med sökorden training* AND fasted state där sex artiklar valdes ut. Cohen’s D användes för att ge studiernas resultat en effektstorlek. Konfidensintervall användes för att bestämma om studierna var statistiskt signifikanta. Resultat: Tre studier undersökte insulin där resultaten visade att samtliga grupper som inte fastade före träningspassen hade lägst koncentration av insulin i viloperioden efter eftertestet. Samtliga sex studier undersökte muskelglykogen där resultaten visade att koncentrationen av muskelglykogen var högst efter eftertestet i gruppen som fastade före träningspassen i fem av sex studier. Tre studier undersökte fria fettsyror där resultaten visade att koncentrationen av fria fettsyror var lägst i eftertestet i gruppen som fastade före träningspassen i två av tre studier. Diskussion: Träning i icke-fastat tillstånd leder till att glykogennivåerna sparas vilket i sin tur leder till att oxidationen av insulin ökar vilket resulterar i lägre koncentrationer av insulin efter eftertestet. Träning i fastat tillstånd resulterar i ökad koncentration av muskelglykogen till energiunderhåll samt högre nivåer av β-hydroxyacyl coenzym A dehydrogenas (β-HAD), citratsyntasaktiviteten (CS-aktiviteten) samt succinatdehydrogenasaktiviteten vilket leder till ökad muskulär oxidativ kapacitet. Intag av kolhydrater före ett träningspass leder till ökat glykogenbesparande vilket resulterar i lägre koncentrationer av muskelglykogen jämfört med icke-fastat tillstånd. Högre koncentration av muskelglykogen före förtestet leder till högre koncentrationer av muskelglykogen i eftertestet. Träning i fastat tillstånd resulterar i lägre koncentrationer av fria fettsyror på grund av ökad FATmax (den maximala hastigheten av fettförbränning), ökad maximal oxidativ enzymaktivitet, uppreglering av hormonkänsligt lipas (HSL), ökat proteinuttryck av fettsyra-translokas / CD36 (FAT / CD36) samt ökat membranbundet proteinbindande protein som leder till ökad fettförbränning. Koncentrationen av fria fettsyror höjdes även i en studie på grund av att insulinutsöndringen inte skulle sjunka för lågt i gruppen som fastade före träningspassen. Konklusion: Resultaten visade att i tre av tre studier var insulinkoncentrationen lägst efter eftertestet i gruppen som intog en kolhydratrik måltid före träningspassen. I fem av sex studier var koncentrationen av muskelglykogen högst efter eftertestet i gruppen som fastade före träningspassen. I två av tre studier var koncentrationen av fria fettsyror lägst efter eftertestet i gruppen som fastade före träningspassen. Dessa resultat ökar förståelsen av hur träning på fastande respektive icke-fastande mage påverkar kroppen med avseende på insulin, muskelglykogen samt fria fettsyror. Vidare forskning skulle kunna undersöka dessa tre fysiologiska markörer under sex månader för att se om resultaten blir desamma i dessa två grupper. / Introduction: Endurance training is defined as the type of exercise where most major muscle groups are used in need of the cardiovascular system’s ability to transport oxygen to the muscles. Fasting means in most studies that no type of food is taken before the workout while not fasting usually means that a carbohydrate meal is taken 90 minutes before a workout. Insulin is important in fat, protein and carbohydrate metabolism as well as in the collection of sugar in the blood. Glycogen acts as an energy reserve in the skeletal muscles. Free fatty acids are important to provide energy for the cellular metabolism that can continue. Aim of the study: The aim of the study was to find out if the body is affected in different ways by endurance training exerted in fasted respectively non-fasting state regarding insulin, muscle glycogen and free fatty acids in humans. Methods: Literature search in OneSearch with the words training* AND fasted state where six articles were selected. Cohen’s D was used to give the results of the studies an effect size. Confidence interval was used to determine if the studies were statistically significant. Results: Three studies investigated insulin, where the results showed that all groups that did not fast before the workouts had the lowest concentration of insulin during the rest period after the test. All six studies investigated muscle glycogen, where the results showed that the concentration of muscle glycogen was highest after post-test in the group that fasted before the workouts in five out of six studies. Three studies investigated free fatty acids where the results showed that the concentration of free fatty acids were lowest in the post-test in the group that fasted before the workouts in two of three studies. Discussion: Training in the non-fasting state causes the glycogen levels to be saved, which in turn leads to increased oxidation of insulin resulting in lower concentrations of insulin after the post-test. Training in the fasted state results in increased concentration of muscle glycogen for energy maintenance and higher levels of β-hydroxyacyl coenzyme A dehydrogenase (β-HAD), citrate synthase activity (CS activity) and succinate dehydrogenase activity, leading to increased muscular oxidative capacity. Intake of carbohydrates prior to a workout leads to increased glycogen saving, resulting in lower concentrations of muscle glycogen compared to non-fasted state. Higher concentration of muscle glycogen before the pretest leads to higher concentrations of muscle glycogen in the post-test. Training in fasted state results in lower concentrations of free fatty acids due to increased FATmax (maximum rate of fat burning), increased maximal oxidative enzyme activity, hormone sensitive lipase (HSL) upset, increased fatty acid translocase / CD36 protein expression (FAT / CD36) as well as increased membrane bound protein binding protein which leads to increased fat burning. The concentration of free fatty acids was also increased in a study due to the fact that insulin secretion should not fall too low in the group that fasted before the workouts. Conclusion: The results showed that in three out of three studies, the insulin concentration was lowest after the post-test in the group who took a carbohydrate meal before the workouts. In five out of six studies, the concentration of muscle glycogen was highest after the post-test in the group that fasted before the workouts. In two out of three studies, the concentration of free fatty acids was lowest after the post-test in the group that fasted before the workouts. These results increase the understanding of how exercise in the fasted state and non-fasted state affects the body with regard to insulin, muscle glycogen and free fatty acids. Further research could investigate these three physiological markers for six months to see if the results are the same in these two groups.

Whole grains are an increasingly popular health food in America. However, shelf life of whole grains is compromised due to the presence of lipoxygenases in the bran and germ, which lead to rancidity and generation of oxidative byproducts. These byproducts reduce sensory quality and may have a degradative effect on vitamins in whole grain products. The purpose of this study was to determine the degree of lipid and vitamin degradation during long-term storage of three whole grains: whole wheat flour, brown rice, and rolled oats. We also examined vitamin loss after cooking to determine if oxidative byproducts had an effect on vitamins during typical household cooking. Whole wheat flour, brown rice, and rolled oats were stored for 12 months and periodically analyzed for conjugated dienes, free fatty acids, tocopherols, thiamin, and riboflavin. Whole wheat bread, steamed brown rice, and oat porridge were made from samples stored for 0 months and 12 months and were analyzed for thiamin and riboflavin. Conjugated dienes increased significantly only in rolled oats, while tocopherols decreased significantly in whole wheat flour and rolled oats and insignificantly in brown rice. Free fatty acids increased significantly in whole wheat flour and brown rice. Thiamin and riboflavin were stable in raw stored grains and cooked products made from stored grains with the exception of brown rice, in which we observed a significant decrease in thiamin after 12-month storage and cooking. These results suggest whole wheat flour, brown rice, and rolled oats experience significant lipid and tocopherol degradation, but it does not appear to affect thiamin and riboflavin in raw stored products. Cooking appears to cause degradation of thiamin after storage of brown rice, but thiamin and riboflavin were otherwise stable in these whole grains.

Cheddar Cheese samples (good cheese, weak cheese, cheese made with pasteurized milk, cheese made with heat-shocked milk, cheese from production plant A, cheese from production plant B, cheese made with adjunct culture, and cheese made without adjunct culture), were evaluated during the ripening stage. Proteolysis was studied by a fractionation scheme, resulting in an insoluble fraction analyzed by urea polyacrylamide gel electrophoresis (Urea-PAGE), and a soluble fraction which was further investigated through water soluble nitrogen (WSN), trichloroacetic acid soluble nitrogen (TCA-SN) and phosphotungstic acid soluble nitrogen (PTA-SN) analyzed by total Kjeldahl nitrogen content (TKN). Reversed phase high performance liquid chromatography (RP-HPLC) was used to study the peptide profile of the water soluble fraction. Lipolyisis was studied by levels of individual free fatty acids determined through gas chromatography-flame ionization detection (GC-FID) after isolation employing solid phase extraction (SPE). Volatile sulfur compounds were studied using head space solid phase micro-extraction (SPME) coupled with gas chromatography-pulsed flame photometric detection (PFPD). It was found that Urea-PAGE is capable to differentiate samples according their age, but cannot discriminate samples regarding the treatment assessed, quality or origin of the samples. However, measurements of total Kjeldahl Nitrogen (TKN) of the WSN, TCA-SN, and PTA-SN fractions, and the principal component analysis of the RP-HPLC peptide profile of the WSN fraction, revealed differences in the rate and pattern of proteolysis for each one of the manufacturing cases. Good cheese, cheese produce in plant TCCA, cheese made in plant CRP with adjunct culture isolated from plant TCCA cheese, and cheese made with heat-shocked milk developed higher level of total nitrogen for the WSN, TCA-SN and PTA-SN fractions, indicating that primary and secondary proteolysis were faster for these samples. This is supported by a PCA model with three principal components that account for the 80-83% of the variability of the data from the RP-HPLC peptide profile analysis, which discriminates the samples according to age and manufacturing practice. In addition, FFA profiles demonstrated higher levels of low and medium chain free fatty acids for good cheese, cheese produce in plant TCCA, cheese made in plant CRP with adjunct culture, and cheese made with heat-shocked milk samples, which suggest faster lipolysis during ripening. The Volatile Sulfur Compounds (VSC) analysis showed higher levels of DMS and MeSH and lower levels of H2S, suggesting faster catabolism of sulfur containing amino acids in good cheese, cheese produce in plant TCCA, cheese made in plant CRP with adjunct culture, and cheese made with heat-shocked milk. / Graduation date: 2013

Type 2 diabetes mellitus (T2DM) ensues from diminished insulin sensitivity and abated compensatory insulin secretion. While diminished insulin secretion has a strong genetic origin, environmental factors are central in the development of insulin resistance; these include hyperinsulinemia and lipotoxicity. Insulin resistance results in the dysregulation of hypothalamic neurons that mediate its central actions: a key intermediary neuron is the neuropeptide Y/agouti-related peptide (NPY/AgRP) neuron. The hypothesis therefore was generated that insulin directly regulates NPY/AgRP neurons, and that prolonged insulin or palmitate, a prevalent free fatty acid (FFA), exposure inhibits neuronal insulin signaling. Using well characterized hypothalamic cell lines, mHypoE-46 or mHypoE-44, which express NPY, AgRP and insulin receptor signaling machinery, this hypothesis was examined in three studies. Correspondingly, insulin decreased NPY and AgRP mRNA expression in the mHypoE-46 cells, through an extracellular signal-regulated kinase (ERK) dependent mechanism; whereas prolonged exposure of NPY/AgRP cells to insulin or palmitate attenuated insulin signaling, determined by analysis of phosphorylated Akt. Insulin induced insulin receptor substrate-1 (IRS-1) serine 1101 phosphorylation in mHypoE-46 cells, utilizing the mTOR-S6K1 pathway, as the mTOR inhibitor rapamycin prevented IRS-1 serine phosphorylation. Insulin also decreased insulin receptor and IRS-1 protein levels; this was prevented by lysosomal and proteasomal pathway inhibitors, 3-methyladenine and epoxomicin, respectively. Importantly, rapamycin, epoxomicin or 3-methyladenine pre-treatment decreased the attenuation of insulin signaling during long-term insulin exposure. On the other hand, palmitate activated c-Jun N-terminal kinase (JNK), the apoptosis effector caspase 3, and induced endoplasmic reticulum (ER) stress in mHypoE-44 cells: JNK inhibition prevented ER stress. In an attempt to avert the deleterious effects of palmitate, the neuronal cells were treated with the 5`AMP-activated protein kinase (AMPK) activator AICAR, a possible insulin sensitizer. Interestingly, AICAR attenuated JNK and caspase 3 activation, and restored insulin signaling. These findings demonstrate that insulin directly regulates NPY/AgRP neuronal cells, and that insulin and palmitate provoke neuronal insulin resistance through different mechanisms. These findings substantiate the idea that environmental factors known to trigger peripheral insulin resistance may have consequences at the level of the individual hypothalamic neuron, which may ultimately contribute to the resulting pathophysiological states of obesity and T2DM.

Type 2 diabetes mellitus (T2DM) ensues from diminished insulin sensitivity and abated compensatory insulin secretion. While diminished insulin secretion has a strong genetic origin, environmental factors are central in the development of insulin resistance; these include hyperinsulinemia and lipotoxicity. Insulin resistance results in the dysregulation of hypothalamic neurons that mediate its central actions: a key intermediary neuron is the neuropeptide Y/agouti-related peptide (NPY/AgRP) neuron. The hypothesis therefore was generated that insulin directly regulates NPY/AgRP neurons, and that prolonged insulin or palmitate, a prevalent free fatty acid (FFA), exposure inhibits neuronal insulin signaling. Using well characterized hypothalamic cell lines, mHypoE-46 or mHypoE-44, which express NPY, AgRP and insulin receptor signaling machinery, this hypothesis was examined in three studies. Correspondingly, insulin decreased NPY and AgRP mRNA expression in the mHypoE-46 cells, through an extracellular signal-regulated kinase (ERK) dependent mechanism; whereas prolonged exposure of NPY/AgRP cells to insulin or palmitate attenuated insulin signaling, determined by analysis of phosphorylated Akt. Insulin induced insulin receptor substrate-1 (IRS-1) serine 1101 phosphorylation in mHypoE-46 cells, utilizing the mTOR-S6K1 pathway, as the mTOR inhibitor rapamycin prevented IRS-1 serine phosphorylation. Insulin also decreased insulin receptor and IRS-1 protein levels; this was prevented by lysosomal and proteasomal pathway inhibitors, 3-methyladenine and epoxomicin, respectively. Importantly, rapamycin, epoxomicin or 3-methyladenine pre-treatment decreased the attenuation of insulin signaling during long-term insulin exposure. On the other hand, palmitate activated c-Jun N-terminal kinase (JNK), the apoptosis effector caspase 3, and induced endoplasmic reticulum (ER) stress in mHypoE-44 cells: JNK inhibition prevented ER stress. In an attempt to avert the deleterious effects of palmitate, the neuronal cells were treated with the 5`AMP-activated protein kinase (AMPK) activator AICAR, a possible insulin sensitizer. Interestingly, AICAR attenuated JNK and caspase 3 activation, and restored insulin signaling. These findings demonstrate that insulin directly regulates NPY/AgRP neuronal cells, and that insulin and palmitate provoke neuronal insulin resistance through different mechanisms. These findings substantiate the idea that environmental factors known to trigger peripheral insulin resistance may have consequences at the level of the individual hypothalamic neuron, which may ultimately contribute to the resulting pathophysiological states of obesity and T2DM.

Diss. (sammanfattning). Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

The objective of the study was to analyze the relationship of psychrotrophic lipolytic bacteria in bulk samples of cow?s raw milk and their metabolic activity based on the content of free fatty acids and identifying the factors that may influence their levels. The contents of free fatty acids (FFA) and counts of total bacteria, psychrotrophic lipolytic bacteria (PLiBC) and somatic cells were determined in 150 samples of cow?s bulk raw milk on 20 farms with three different milking technologies in South Bohemia during 2008?10. FFA were determined using an extraction-titration method. Within the compared technologies, the highest mean values of FFA (38,8 mmol?kg-1; P<0,001) and PLiBC (696 CFU?ml?1) were observed on farms with pipeline milking in stalls. The lowest mean FFA level (15,4 mmol?kg-1) was determined on farms with an automatic milking system. Medium values were determined on farms with parlour milking. From the aspect of the inhibition of an increase in psychrotrophic bacteria, and mainly in psychrotrophic lipolytic bacteria in conditions of cold storage of raw milk the temperature of 4°C seems optimum as it markedly inhibits the growth of mesophilic and psychrotrophic bacteria and at the same time the increase in the values of free fatty acids is slower at this temperature compared to the temperatures of 6,5 and 10°C.