The Truth About Fat Burning Foods
Directed differentiation of adult stem cells has confirmed previous in vivo studies, which concluded that adult stem cells have less plasticity than ES cells. When stem cells from an adult mouse brain are placed in culture, they differentiate into different kinds of neural tissue but not the variety of cell types that are produced by ES cells. Likewise, adult stem cells from the bone marrow differentiate, in vitro, into blood cells, neurons, and fat cells, but not glandular tissue (see table on page 13). Moreover, scientists have less control over the differentiation process of adult stem cells than that of ES cells. Adult bone marrow stem cells differentiate spontaneously when placed in culture, and there is no way to stop them. Consequently, it is very difficult to maintain a continuous culture of these cells. So far, only mouse ES cells are able to proliferate in vitro for an indefinite period of time while retaining an embryonic phenotype.
The peak level of leptin, which is produced by fat cells, is normally seen at around 9.00 pm. In sleep deprivation less leptin is secreted. There is a smaller diurnal amplitude in its secretion, particularly in those who are obese and have a high initial leptin level. The findings are similar to those seen in the elderly. Ghrelin, released by the stomach, has opposite effects to leptin, and its secretion increases by around 25 in sleep deprivation.
Insulin is secreted in response to increased levels of blood glucose. This may occur after a meal or if glucagon is released and circulating glucose increases. Increased insulin levels cause glucose to enter cells more quickly where it is either used for fuel or, in the case of fat cells, is converted to triglycerides and stored. Blood glucose levels then drop. Data support the contention that hunger and eating are initiated when nutrient levels, especially glucose levels, decrease in the blood. Thus a high insulin level could lead to hunger because it decreases blood glucose. Furthermore, insulin levels can be influenced by the hypothalamus, and disruption of this control by hypothalamic lesions may explain some of the effects of such lesions on eating behavior and body weight.
The most promising antiobesity treatment once involved the anti-fat hormone, leptin its discovery led to a surge of obesity drug research. Leptin, discovered in 1994, seemed promising because it is produced by fat cells and was the first antiobesity hormone that surfaced.
Omega-3 Fatty Acid Supplementation Based upon a few studies linking consumption of omega-3 polyunsaturated fatty acids, commonly found in fish, to lower blood pressure, several studies have examined whether diets supplemented with fish oil would lead to reductions in blood pressure. In a meta-analytic review of these studies, Appel et al. (1993) reported that use of fish oil supplements resulted in approximately a 4 mm Hg reduction in blood pressure. In combination with weight loss, fish oil supplements have been shown to result in reductions as high as 13 mm Hg (Bao et al., 1998). Although not commonly recommended for lowering blood pressure, omega-3 fatty acid supplementation appears to hold promise for reducing blood pressure, at least in combination with other antihyper-tensive therapies.
In the outer segments of photoreceptors, rhodopsin is immersed in phospholipids endowed with the highest content of DHA of any cell type (Bazan, 1990 Choe and Anderson, 1990 Anderson et al., 2002). The RPE cells, which are in close contact with the photoreceptor tips, are the most active phagocytes of the body, and phagocytize the distal tips of photoreceptor outer segments in a daily process of rod outer segment renewal (Hu and Bok, 2001) that is completed by addition of new membrane to the base of the outer segments. DHA is conserved in photoreceptors by its retrieval through the interphotore-ceptor matrix, which supplies the fatty acid for outer segment biogenesis (Bazan et al., 1985 Stinson et al., 1991 Gordon et al., 1992). This renewal is tightly regulated to maintain photoreceptor length and chemical composition, including that of their phospholipids. Most of the DHA in photoreceptor phospholipids is esterified in carbon-2 of the glycerol backbone, but DHA-containing molecular...
The principal fluid medium of the cell is water, which is present in most cells, except for fat cells, in a concentration of 70 to 85 per cent. Many cellular chemicals are dissolved in the water. Others are suspended in the water as solid particulates. Chemical reactions take place among the dissolved chemicals or at the surfaces of the suspended particles or membranes.
Feedback mechanisms for control of food intake. Stretch receptors in the stomach activate sensory afferent pathways in the vagus nerve and inhibit food intake. Peptide YY (PYY), cholecys-tokinin (CCK), and insulin are gastrointestinal hormones that are released by the ingestion of food and suppress further feeding. Ghrelin is released by the stomach, especially during fasting, and stimulates appetite. Leptin is a hormone produced in increasing amounts by fat cells as they increase in size it inhibits food intake. In mice or humans with mutations that render their fat cells unable to produce leptin or mutations that cause defective leptin receptors in the hypothalamus, marked hyperphagia and morbid obesity occur. In most obese humans, however, there does not appear to be a deficiency of leptin production, because plasma leptin levels increase in proportion with increasing adiposity. Therefore, some physiologists believe that obesity may be associated with leptin resistance that is,...
Sympathetic nerve activity, especially in the kidneys, is increased in overweight patients. The causes of increased sympathetic activity in obesity are not fully understood, but recent studies suggest that hormones, such as leptin, released from fat cells may directly stimulate multiple regions of the hypothalamus, which, in turn, have an excitatory influence on the vasomotor centers of the brain medulla.
The mechanism by which cortisol promotes fatty acid mobilization is not completely understood. However, part of the effect probably results from diminished transport of glucose into the fat cells. Recall that a-glycerophosphate, which is derived from glucose, is required for both deposition and maintenance of triglycerides in these cells, and in its absence the fat cells begin to release fatty acids.
In almost all the body's muscles, essentially all the carbohydrates utilized for energy are degraded to pyruvic acid by glycolysis and then oxidized. However, this gly-colytic scheme is not the only means by which glucose can be degraded and used to provide energy. A second important mechanism for the breakdown and oxidation of glucose is called the pentose phosphate pathway (or phosphogluconate pathway), which is responsible for as much as 30 per cent of the glucose breakdown in the liver and even more than this in fat cells.
Phycocyanin, a photoharvesting pigment, belongs to the class of phycobillipro-teins that are found in blue-green algae. All phycobiliproteins are water-soluble and therefore, unlike carotenoids, cannot exist within a membrane. Rather, phycobili-proteins cluster and adhere to the membrane, forming phycobilisomes. Phycocyanin normally represents up to 20 of the dry weight of a blue-green algae harvest. Bhat and Madyastha11,13 examined C-phycocyanin, which is responsible for the deep bluish color of Spirulina, and found that it was able to not only scavenge free radicals, but also exhibited significant hepatoprotective effects.44 As stated above,25,26 phycocyanin can inhibit inflammation in mouse ears.26 An in vivo study has verified that the blue-green algae can reduce the level of arachidonic acid in plasma because it contains considerable amounts of omega-3-a-linolenic acid.45
Antipsychotic agents and anxiolytic compounds are often added to patients' lithium or anticonvulsant regimes, depending upon the patients' clinical presentation. Elec-troconvulsive therapy (shock treatment) is recommended for treatment-refractory patients, particularly when they are in severe depressive states. Other treatment approaches that require more investigation include bright light treatment and omega-3 fatty acids (fish oil).
Most of these investigations have not evaluated training levels and have not adequately matched groups for gender and other physical characteristics that may have a substantial impact on mitochondrial metabolism. A recent study on individuals characterized by similar VO2max and body fat percentage has shown that insulin-resistant obese subjects had significantly reduced expression of PGC-1a and COX1, indicating reduced mitochondr-
The remaining endocrine glands are the pancreas, thyroid, and parathyroid. The endocrine pancreas secretes insulin necessary for glucose and fats to enter cells so that the cells can use them for energy or, in the case of fat cells, store them. The thyroid gland secretes thyroxin, which regulates metabolic rate and protein synthesis by cells throughout the body. The parathyroid secretes a hormone involved in the regulation of calcium concentration in blood. This gland has little direct influence on behavior.
The amino acids glutamine and arginine may be useful dietary additives for patients at risk of or with established ARDS.37 Enterocytes metabolise glutamine in a manner that enhances intestinal mucosal integrity and reduces translocation of bacteria and toxins into the portal circulation that may fuel a systemic inflammatory response. Glutamine and arginine also augment lymphocyte function, and arginine improves monocyte function in critically injured patients. L-arginine supplementation may also increase NO production, alter vascular tone, and augment free radical mediated antibacterial defences. Similarly, omega-3 fatty acids such as eicosapentaenoic acid and the unsaturated oil gamma-linolenic acid reduce proinflammatory cytokine and eicosa-noid production.38 Less biologically active eicosanoids such as prostaglandin PGE1, thromboxane TXA,, and leukotriene LTB5 are produced from these unsaturated fats by cyclo-oxygenase (COX) and 5-lipoxygenase during inflammation. Animal...
Decreased oxidative capacity and mitochondrial dysfunction have been proposed to be a major contributor to the development of insulin resistance and type 2 diabetes 55 . Under normal conditions blood glucose levels are tightly controlled by insulin secretion from pancreatic b-cells and insulin action on liver, muscle, and fat cells. Mitochondrial oxidative metabolism provides a direct link between glucose stimulation and insulin secretion by increasing the ATP ADP ratio in the cytosol 56 as a result of increased glucose concentration within the cell. This will trigger a cascade of events that leads to exocytosis of insulin-containing vesicles. Diabetes is usually accompanied with an increased production of free radicals or impaired antioxidant defenses 57 . Diabetes caused by mitochondrial dysfunction is estimated to account for 1 of all cases. It can be caused by different mutations in mtDNA, but the most common is the A3243G mutation in the gene encoding tRNALeu(UUR) 58 . This...
Blood monocytes have been shown to de-differentiate under certain cultural conditions, into cells which can be persuaded with growth factors and certain cultural conditions to proliferate some 5- to 6-fold and then differentiate into liver-like cells producing albumen islet-like cells producing insulin and glucogen and fat cells or return back to monocytes.23-25
The fat cells (adipocytes) of adipose tissue are modified fibroblasts that store almost pure triglycerides in quantities as great as 80 to 95 per cent of the entire cell volume. Triglycerides inside the fat cells are generally in a liquid form. When the tissues are exposed to prolonged cold, the fatty acid chains of the cell triglycerides, over a period of weeks, become either shorter or more unsaturated to decrease their melting point, thereby always allowing the fat to remain in a liquid state. This is particularly important, because only liquid fat can be hydrolyzed and transported from the cells. Fat cells can synthesize very small amounts of fatty acids and triglycerides from carbohydrates this function supplements the synthesis of fat in the liver, as discussed later in the chapter. Exchange of Fat Between the Adipose Tissue and the Blood Tissue Lipases. As discussed earlier, large quantities of lipases are present in adipose tissue. Some of these enzymes...
The rate of formation of new fat cells is especially rapid in the first few years of life, and the greater the rate of fat storage, the greater the number of fat cells. The number of fat cells in obese children is often as much as three times that in normal children. Therefore, it has been suggested that overnutrition of children especially in infancy and, to a lesser extent, during the later years of childhood can lead to a lifetime of obesity.
Clinical experience with bone marrow transplantation relies on the mul-tipotency of stem cells in the marrow and umbilical cord blood. Stem cells can be mobilized into the peripheral blood of normal adults treated with growth factors. It has been suggested that the normal differentiation of these marrow stem cells into cells of red and white cell lineage might be deviated by cultural techniques similar to those discussed for ESCs. The strict hierarchy of the three primary stem cell lines, mesoderm, endoderm and ectoderm seems to be more malleable than was believed. Ruhnke etal.25 have reported apparent de-differentiation of normal peripheral blood buffy coat monocytes, which can proliferate up to six divisions and then be programmed to differentiate into liver-like cells producing albumin, and fat cells and islet-like cells producing insulin and gluco-gen that temporarily reversed the diabetic state when grafted into strep-tocytocin treated mice. Stem -like cells have been found in...
In men about 20 of estradiol is formed in the Leydig cells, and the rest in peripheral tissues, especially fat cells, from aromatization of androgens mainly T but also adrenal androstenedione 1 . As a result, the estradiol level is higher in men with increased BMI, as well as in diabetic patients, while aromatization seems decreased by physical exercise 257 . According to the studies there is no or only a slight decrease of serum estradiol with age, resulting in an increase in the estradiol T ratio. However serum levels of free estradiol decrease because concentrations of SHBG, which binds estradiol, increase with age.
Omega-3 Polyunsaturated Fatty Acids Consumption of eicosapentanoic (EPA) and docosahexanoic (DHA) acids, two omega-3 polyunsaturated fatty acids commonly found in fish, has been shown to be associated with reduced risk for coronary heart disease as well as essential hypertension (Mori et al., 2000). Additionally, significant reductions in blood pressure have been observed among hypertensives who increased consumption of omega-3 polyunsaturated acids (Bao et al., 1998). However, no studies to date have examined the relation between consumption of omega-3 polyunsatu-rated fats and cardiovascular reactivity to stress.
The fats naturally present in fish that swim in cold waters, known as omega-3 fatty acids or fish oils, are all polyunsaturated. These fats are crucial for brain tissue. They lower your cholesterol levels and protect against heart disease. Mackerel, albacore tuna, salmon, sardines, and lake trout, which have a layer of fat to keep them warm in cold water, are all rich in omega-3 fatty acids. In fact, whale meat and seal meat are enormous sources of omega-3 fatty acids. These foods were once the staples of the Inuit diet, and once protected that population from heart disease.