Cyclical Ketogenic Diets Review
Only three major sources of carbohydrates exist in the normal human diet. They are sucrose, which is the disaccharide known popularly as cane sugar lactose, which is a disaccharide found in milk and starches, which are large polysaccharides present in almost all nonanimal foods, particularly in potatoes and the different types of grains. Other carbohydrates ingested to a slight extent are amylose, glycogen, alcohol, lactic acid, pyruvic acid, pectins, dextrins, and minor quantities of carbohydrate derivatives in meats.
Abstract Hypocholesterolemic effects of taurine in rats fed a high-fat and high-cholesterol diet are well established. However, there are few studies on long-term effects of taurine on cholesterol metabolism. In the present study, taurine was dissolved in drinking water and given to C57BL 6J mice during 6 months-feeding of a high fat diet. Taurine treatment significantly decreased serum LDL and VLDL cholesterol, while it significantlyincreased serum HDL cholesterol. In the liver, taurine decreased cholesteryl ester contents, accompanied by decrease in acyl Co-A cholesterol acyltransferase (ACAT) activity. Hepatic activity of cholesterol 7a-hydroxylase, a rate-limiting enzyme for bile acid synthesis, was doubled with taurine. Taurine reduced by 20 the high-fat diet-induced arterial lipid accumulation. Thus, taurine prevented elevation of serum and liver cholesterol levels, as possibly related to accelerated cholesterol elimination from the body through the stimulation of bile acid...
When the body's stores of carbohydrates decrease below normal, moderate quantities of glucose can be formed from amino acids and the glycerol portion of fat. This process is called gluconeogenesis. About 60 per cent of the amino acids in the body proteins can be converted easily into carbohydrates the remaining 40 per cent have chemical configurations that make this difficult or impossible. Each amino acid is converted into glucose by a slightly different chemical process. For instance, alanine can be converted directly into pyruvic acid simply by deamination the pyruvic acid is then converted into glucose or stored glycogen. Several of the more complicated amino acids can be converted into different sugars that contain three-, four-, five-, or seven-carbon atoms they can then enter the phosphogluconate pathway and eventually form glucose. Thus, by means of deamination plus several simple interconversions, many of the amino acids can become glucose. Similar interconversions can change...
Pancreatic secretion, like saliva, contains a large quantity of a-amylase that is almost identical in its function with the a-amylase of saliva but is several times as powerful. Therefore, within 15 to 30 minutes after the chyme empties from the stomach into the duodenum and mixes with pancreatic juice, virtually all the carbohydrates will have become digested. In general, the carbohydrates are almost totally converted into maltose and or other very small glucose polymers before passing beyond the duodenum or upper jejunum.
Three other major types of substances make up the body. Carbohydrates, another name for sugars, can be dissolved in the blood and used as fuel for the body's cells, or they can be attached to some proteins to become part of their structure. Fats, also known as lipids, can be found in the blood as free fatty acids, attached to proteins (sometimes known as lipoproteins), or in solid lumps as body fat. Lastly, minerals can be found in the bones of the body, forming the fourth type of body substance.
The way the cellular machine works is by having catalysts that favor only certain chemical reactions. This ability to catalyze certain specific reactions and not others is the major virtue of the living machine. Stated more strongly, the specificity of an enzyme is such that it does not catalyze other reactions than the one it was designed for. Add to this a little bit of structure and life could work. That structure was initially abiotic (in the first living generation, for example, life was a vesicle probably created by environmental wave action). In addition, there has been extensive evolution of cell structures after the First Cell. These include chromosomes instead of unlinked genes, cell walls instead of no walls, protein aggregates like muscle fibrils to do mechanical work and cytoskeletons to support the cellular structure. Add the existence of binding proteins and bound carbohydrates on the outsides of cells allowing them to interact and add other cells, and with little bit...
Numerous excellent review articles deal with potential applications and characteristics of multivalent ligand-receptor interactions. The principles and biomedical applications of polyvalent interactions are discussed systematically by Mammen et al. 1 . The thermodynamic basis of multivalent binding is evaluated with respect to lectin-carbohydrate interaction by Brewer 54 and with respect to drug-DNA interaction by Chaires 55 . Classical examples of multivalent interactions, known as the cluster effect, are described by Lee and Lee 26 in the context of carbohydrate-protein (C-type lectin and animal lec-tin) interaction, and multivalent selectin inhibitors are reviewed by Simanek et al. 72 . The mechanism of action by dimers of the FK506 class and its biomedical uses are reviewed by Crabtree and Schreiber 68 . Accounts by Roy 29 and Kiessling and Pohl 60 deal with chemical and biological aspects of multivalent neoglycoconjugates, and those by Yarema and Bertozzi 73 and Bertozzi and...
All living things are composed of the compounds proteins, fats, carbohydrates, and nucleic acids. Proteins, the compounds that make up muscles, consist of long chains of amino acids. Every amino acid has the group -NH2 at one end, and the group -COOH at the other. Between those groups are elements that vary according to which amino acid is involved. For instance, the amino acid glycine has the formula NH2CH2COOH, and alanine has the formula NH2CHCH3COOH. Carbohydrates are the sugars and starches made by plants. As their name implies, carbohydrates are made of carbon, hydrogen, and oxygen atoms. When animals eat plants, they take in carbohydrates and break them down for energy by the process of respiration.
Many proteins exist as glycoproteins or lipoproteins. The former has carbohydrates covalently attached to the protein molecule, whereas the latter has lipid molecules attached. The addition of carbohydrate or lipid components to a protein occurs after the translation process. Other modifications include phosphorylation (adding phosphate groups to amino acid side chains), and acetylation (adding acetyl groups).
Aversion studies typically use flavors that produce positive ingestive responses, such as a dilute solution of saccharin. After administration of an emetic agent such as lithium chloride (LiCl), a decrease in ingestion rapidly emerges in animals that received the CS and US paired closely in time. Any distinctive taste or flavor can be the target of a conditioned aversion, but some types of flavors seem to be particularly prone to the development of aversions. For example, proteins such as eggs, cheese, and meat are more likely to become targets of conditioned food aversions than carbohydrates, and novel foods are more likely to become targets than familiar foods (Bernstein, 1999).
Any appreciable amount, only a few hundred grams as glycogen in the liver and muscles. Most consumed carbohydrates (sugars) are converted under the influence of insulin into fat and are stored throughout the body, often in aesthetically undesirable places. In fact, sugar is directly responsible for most cholesterol. Only 40 percent of ingested cholesterol is absorbed from the gastrointestinal tract. Most cholesterol is actually manufactured by the liver under the influence of insulin. The higher the insulin level, the more cholesterol is manufactured. What makes insulin levels rise Sugar A healthy diet must address everything fats (triglycerides) carbohydrates (sugars) protein (amino acids) and fiber. Many people are aware of the harmful effects of too much fat and have taken appropriate steps. Now, people must look carefully at carbohydrate consumption. Attention to correct carbohydrates will involve not only sugar, but also fiber, which has been shown to have a beneficial effect on...
Until recently, carbohydrates were ignored as a health issue. They are at least as important, and probably more so, than fats in determining weight and cardiovascular fitness. The key to carbohydrates' influence is insulin. Insulin is a hormone secreted by the pancreas in response to
Because insulin secretion is a direct result of eating carbohydrates, should everyone stop or slash their carbohydrate intake Of course not The body is primarily fueled by carbohydrates diets too restrictive in all carbohydrates are unhealthy. However, people should learn to make better carbohydrate choices. This involves avoiding carbohydrates that are highly insulin producing or high-glycemic. Certain carbohydrates, such as white potatoes, white rice, white bread, corn, and beets, should be avoided or used sparingly. Foods containing more than five grams of added sugar are generally unhealthy. Check the labels of foods for unnecessarily added refined sugar these foods even though they may be low in fat will result In a high insulin response, causing the body to convert and store this sugar as fat.
One explanation of the high frequency of type II DM among these populations is that they developed a highly efficient carbohydrate metabolism under traditional lifestyles of a feast and famine cycle. The thrifty mechanisms of carbohydrate metabolism, however, became detrimental with rapidly changing lifestyles associated with a decrease in physical activity, an increase in energy in the diet, a reduction of dietary fiber, an increase of refined carbohydrates, and an increase in psychosocial stress.
New studies are beginning to show that moderate to light alcohol consumption (one drink a day, six days a week) may have a protective effect on the heart. This explains why some wine-consuming European countries experience relatively lower rates of coronary artery disease despite high-fat diets.
Radiation-induced changes in salivary pH and quantity produce an environment conducive to the development of caries. Xerostomia and a high carbohydrate diet can predispose the pediatric cancer patient to radiation-induced caries. Frequent dental visits to identify early caries, periodontal disease, infection, gingival recession and soft tissue ulcers are im portant. Salivary flow studies are helpful in assessing xerostomia, and salivary substitutes may be offered to symptomatic patients. Nutritional counseling on the importance of avoiding fermentable carbohydrates and maintaining excellent oral hygiene is critical. Mouth rinsing is essential and daily topical fluoride applications (either as a solution for mouth rinsing, a gel delivered on a tray or brushed on as a paste or gel) are all effective in reducing the risk of radiation caries 17 .
Ingestion of the high-fat diet led to a marked elevation of serum LDL and VLDL cholesterol from 10.9 to 93.8 mg dl (Table 1). Taurine treatment decreased serum LDL and VLDL cholesterol levels by 49 . Although serum HDL cholesterol tended to decrease by ingestion of the high-fat diet, taurine significantly increased serum HDL cholesterol.
Activities of enzymes in the liver responsible for cholesterol synthesis and metabolism were determined (Fig. 2). HMG-CoA reductase activity was markedly suppressed in mice fed a high-fat diet, and taurine tended to increase the enzymatic activity. Acyl-CoA cholesterol acyltransferase (ACAT) activity was measured to determine conversion of free cholesterol to cholesteryl ester. Feeding of high-fat diet markedly increased the ACAT activity, while taurine significantly decreased it. In agreement with reported data21, cholesterol 7a-hydroxylase activity decreased in case of high-fat diet supplemented with cholesterol and cholic acid. Taurine doubled the enzymatic activity up to the control level in mice fed a high-fat diet. The stimulatory effect of taurine on cholesterol 7a-hydroxylase activity was also seen in mice fed regular chow. Figure 1. Effect oftaurine on liver cholesterol content. C57BL 6J mice consumed a high-fat diet for 6 months (HF) and the control group (C) consumed...
The lack of leptin and increase in ghrelin reduce the sensation of satiety and increase hunger and appetite, with an increase particularly for carbohydrate and fatty foods. Sleep deprivation in effect leads to an internal misperception of body fat and other energy stores, leading to increased energy intake coupled with an impaired ability to utilize the absorbed carbohydrates and fats. The insulin resistance due to sleep deprivation further increases the risk of diabetes and is associated with an increased triglyceride level and reduced high-density lipoproteins (HDL). These features, together with hypertension, constitute the 'metabolic syndrome'.
To maintain homeostasis, the body requires a variety of substances such as vitamins, minerals, trace elements, fats, carbohydrates, and proteins. If excess amounts of any of these substances are present in the circulation, they may be either excreted or stored. If too small an amount is present, it is necessary, in most cases, to ingest the missing substance. However, inadequate levels of vitamins, minerals, and trace elements (with the possible exception of salt) do not induce hunger. Hunger and consequent behaviors related to finding food and eating are induced by low levels of carbohydrates, fats, and possibly proteins.
This membrane also contains molecular assemblies, called porins, to permit small molecules from the medium to enter and leave the periplasm. This membrane is composed of two leaflets with quite different properties. The inner leaflet is formed of hydrophobic phospholipids, while the outer leaflet contains special hydrophilic carbohydrates. Together these layers prevent the entry of a variety of kinds of molecules. In addition there are molecular system aiding in pumping out a variety of kinds of molecules from the cell. The class of molecules excreted by these multiple drug excretion mechanisms contains antibiotics and other fairly non-polar molecules.
From 10 to 25 of DOM consists of identifiable molecules of known structure carbohydrates and fatty, amino, and hydroxy acids. The remainder (50-75 , up to 90 in colored waters) can be placed in general categories such as humic and fulvic acids, and hydrophilic acids. Humic acids separate from fulvic acids by precipitating at a pH 2 while fulvic acids remain in solution. Fulvic acids are also smaller than humic acids, which often form colloidal aggregates of high molecular weight (HMW) and may be associated with clays or oxides of iron and aluminum. Fulvic acids generally are the majority of humic substances (Thurman 1985). In the Amazon, for example, fulvic acids were approximately 50 and humic acids 10 of riverine DOC (Ertel et al. 1986). average value of 19 labile DOC may not be representative of less disturbed rivers. Amon and Benner (1996) estimated that 1.4-7.5 of DOC in the Amazon was labile. Based on DOC disappearance in batch incubations, del Giorgio and David (2003) estimated...
These include gypsum sheetrock, wood, wallpaper, carpet, cardboard, spoiled foods, and clothing. Some fungi can use only simple carbohydrates such as starch and hemicellulose as food, while others are capable of breaking down more complicated compound such as cellulose and lignin, which can cause structural damage to the substrate the fungi are growing on.
The value for R changes under different metabolic conditions. When a person is using exclusively carbohydrates for body metabolism, R rises to 1.00. Conversely, when a person is using exclusively fats for metabolic energy, the R level falls to as low as 0.7. The reason for this difference is that when oxygen is metabolized with carbohydrates, one molecule of carbon dioxide is formed for each molecule of oxygen consumed when oxygen reacts with fats, a large share of the oxygen combines with hydrogen atoms from the fats to form water instead of carbon dioxide. In other words, when fats are metabolized, the respiratory quotient of the chemical reactions in the tissues is about 0.70 instead of 1.00. (The tissue respiratory quotient is discussed in Chapter 71.) For a person on a normal diet consuming average amounts of carbohydrates, fats, and proteins, the average value for R is considered to be 0.825.
The human colon serves to absorb water and electrolytes, store intraluminal contents until elimination is socially convenient, and salvage nutrients after bacterial metabolism of carbohydrates that have not been absorbed in the small intestine. These functions are dependent on the ability of the colon to control the distal progression of contents in healthy adults, colonic transit normally requires several hours to almost 3
Examination of the relation between hostility and lifestyle factors, Musante et al. (1992) found some support for this alternative hypothesis. Increased hostility was related to poorer health habits, including consumption of a less healthy diet (increased fat and sugar consumption accompanied by decreased fiber intake) and a greater tendency to smoke cigarettes. Data from the cardia Study support these conclusions as well, with hostility being associated with higher frequency of smoking cigarettes and marijuana as well as consumption of a higher number of calories (Scherwitz et al., 1992). Finally, prospective links between measures of hostility taken during the undergraduate years and health behaviors in adulthood have provided additional evidence for this hypothesis. Data from the UNC Alumni Heart Study showed that high hostility during young adulthood was associated with increased smoking and consumption of alcohol and a high-fat diet, obesity, and low social support at midlife...
Tumour markers are biological or molecular substances (protein, carbohydrates, hormones, etc.) that can be produced and attributed to the events in tumorigenesis. They may be produced by the tumour cells themselves, or by the body in response to the presence of cancer, or in certain benign conditions, e.g. dermatofibroma, benign prostatic hyperplasia and benign prostatic hypertrophy. Those produced intra-cellularly, or on the cell membrane (oestrogen receptor - ER) are detected by immunohistochemistry (IHC) on the tumour tissue. Those secreted into body fluids can be quantified by immunoassay methods. The production of tumour markers can result from 2. Tumour-associated markers oncofetal antigens, oncogenes, oncoproteins, carbohydrates, hormones, enzymes, cytokines, soluble receptors, growth factors, cellular markers - not tumour specific, but expressed in higher levels than in normal tissue (CEA, AFP, p2M, p21 ras protein, vascular endothelial growth factor - VEGF).
Feelings of tiredness and low energy, which are symptoms of hypothyroidism, may cause you to crave carbohydrates and quick-energy foods, which are higher in fat and calories. When you are hypothyroid, your activity level will decrease as a result of your fatigue, which can also lead to weight gain or aggravate preexisting obesity. The craving for carbohydrates is caused by a desire for energy. Consuming carbohydrates produces an initial rush of energy, but then it is followed by a crash, which is sometimes known as postprandial depression (or postmeal depression), exacerbating or contributing to hypothyroid-induced depression. Even in those with normal thyroid function, depression can cause cravings for simple carbohydrates such as sugars and sweets. In the absence of overeating, some of the weight gain in hypothyroidism is bloating from constipation. Increasing fluid intake and fiber will help the problem, which we discuss more in Chapter 20.
A trial of pyridoxine, 50 mg twice a day orally can be done to rule out pyridoxine- dependent deficient seizures. If the serum and CSF glycine levels are elevated, the glycine cleavage enzyme activity should be assessed by liver biopsy in a laboratory qualified to do this test and treatment should be started with dextromethorphan, leucovorin, and sodium benzoate for nonketotic hyperglycinemia. In symptomatic treatment of the seizures, valproic acid should be avoided, because the risk of accelerating the course and a resultant fatal toxic hepatitis is very high. Other treatments of refractory, non- surgically treatable epilepsy at this age, such as adrenocorticotropic hormone or prednisone, ketogenic diet, and intravenous IgG, are unproven and may be harmful.
Seizures can be symptomatically treated with valproate (watching for carnitine deficiency) and clonazepam. There is a dearth of data as to whether measures for refractory myoclonic epilepsy--ketogenic diet, adrenocorticotropic hormone or corticosteroids, or L-5-hydroxytryptophan plus carbidopa--have been effective. Corticosteroids have been used for the myopathy and improvement has been noted,
Biological chemistry is overwhelmingly that of some 15-20 elements, which must be obtained and utilised using the flow of available energy. The main energy flow is that of sunlight managed by plants in the production of carbohydrates and oxygen. Plants, as we have seen in Chapter 8, cannot gain easy access to all the elements even for their own lifestyle, nor can they scavenge their own debris. Consequently, plant life had to be supported by better collectors and scavengers to complete the biological cycle. It was in part the complexity of higher plants that led to the additional need of reducing the complications of synthesis. We have seen that bacteria and fungi help to supply elements and some metabolites to plants and
At about age 3 months, a perfectly normal infant develops seizures--myoclonic, atypical absences, or unclassifiable--that are refractory to antiepileptic drugs. Developmental delay occurs the longer seizures are uncontrolled and the diagnosis is undiscovered, which can culminate in mental retardation and secondary microcephaly. The differential diagnosis includes any disease or condition causing refractory seizures in early infancy (see section on Menkes' disease). In this disorder, CSF glucose is 30 mg dl or lower, with a reduced CSF blood glucose ratio (about 0.33). CSF lactate is also low (0.97 mM L or less). EEGs and neuroimaging studies are normal. Treatment involves seizure control with a ketogenic diet, because the diet provides ketone bodies as an alternative source of fuel for brain metabolism. The prognosis for seizure control and normal development is excellent, with early diagnosis and treatment. It is likely that the defect becomes less consequential with age as the...
Dietary guidelines from nutrition experts, government nutrition advisories and panels, and registered dieticians have not changed in fifty years. A good diet is a balanced diet representing all food groups, based largely on plant foods, such as fruits, vegetables, legumes, and grains (also known as carbohydrates), with a balance of calories from animal-based foods, such as meats (red meat, poultry), fish, and dairy (also known as protein and fat). Nutrition research spanning the last fifty years has only confirmed these facts. What has changed in fifty years is the terminology used to define good diet, and the bombardment of information we receive about which foods affect which physiological processes in the body, such as cholesterol levels, triglycerides, blood sugar levels, and insulin. There are also different kinds of fats and carbohydrates, which
While cigarette smoking has been definitively established as the major cause of lung cancer, a number of issues remain to be investigated (Wynder and Hoffmann, 1994). Since 1975, the incidence of adenocarcinoma has greatly increased in the USA. The ratio of adenocarcinoma to squamous cell carcinoma was 1 2.3 among white males in 1969-1971, whereas it was 1 1.4 in 1984-1986. Adeno-carcinoma now exceed squamous cell carcinoma of the lung in the USA. This changing histology of cigarette smoke-induced lung cancer is due to changes in cigarette design, particularly the introduction of lower nicotine and higher -nitrosamine-containing cigarettes. There are important geographical and ethnic differences in lung cancer which require investigation. Lung cancer incidence in Japan is considerably lower than would be expected by comparison with US rates in spite of a dramatic increase in smoking. Diet may be one factor which enhances risk in the USA laboratory studies have shown that a high-fat...
There have been repeated claims in hard-to-obtain sources that Stevia extracts improve glucose tolerance in alloxan-diabetic rabbits (von Schmeling et al. 1977), and both diabetic and non-diabetic humans (Miquel 1966 Alvarez et al. 1981). In one study, it was reported that powdered leaves as a 10 addition to a high carbohydrate diet decreased blood glucose and hepatic glycogen levels in rats after four weeks (Suzuki et al. 1977). One study reported in an abstract claims a 35 drop in blood glucose in human volunteers eight hours after consumption of an extract (Oviedo et al. 1970). On the other hand, 0.5 1.0g day of Stevia extract for 56 days was without effect on blood sugar (Lee et al. 1979).
The primary role of insulin is to control the absorption of glucose from the bloodstream into cells where glucose is utilized as an energy source or converted into glycogen for storage. Insulin functions to regulate the level of glucose in blood. Carbohydrates, such as starch, taken in the diet are digested into glucose, which is transferred to the blood stream. The high level of blood glucose stimulates the pancreatic p cells to release insulin directly into blood stream. Insulin binds to insulin receptors on the surface of a cell, generating signals for movements of glucose transporters to the cell membrane. The glucose transporters aggregate into helical structures creating channels for entrance of glucose molecules into the cells.
In Chapter 16, we discussed obesity and thyroid disease and the optimal antiobesity diet, including how low-fat diets and low-carb diets measure up in the thyroid world. In this chapter, you'll find information on optimal diets while hypothyroid information on the low-iodine diet, necessary for thyroid cancer patients preparing for a thyroid scan as well as the optimal diet while hyperthyroid. Finally, you'll discover how to maintain a normal, healthy weight after you've been treated for a thyroid condition and are likely on thyroid hormone.
The major foods on which the body lives (with the exception of small quantities of substances such as vitamins and minerals) can be classified as carbohydrates, fats, and proteins. They generally cannot be absorbed in their natural forms through the gastrointestinal mucosa and, for this reason, are useless as nutrients without preliminary digestion. Therefore, this chapter discusses, first, the processes by which carbohydrates, fats, and proteins are digested into small enough compounds for absorption and, second, the mechanisms by which the digestive end products as well as water, electrolytes, and other substances are absorbed.
Dietary intake should provide sufficient energy to sustain life. The energy is measured in kilocalories (kcal) or kilojoules (kJ). The body can use carbohydrates, fat, and proteins to produce energy. The energy production from carbohydrates and proteins is about 4 kcal g (17 kJ g) and that from
Absorption from the small intestine each day consists of several hundred grams of carbohydrates, 100 or more grams of fat, 50 to 100 grams of amino acids, 50 to 100 grams of ions, and 7 to 8 liters of water. The absorptive capacity of the normal small intestine is far greater than this as much as several kilograms of carbohydrates per day, 500 grams of fat per day, 500 to 700 grams of proteins per day, and 20 or more liters of water per day. The large intestine can absorb still additional water and ions, although very few nutrients.
Absorption of Carbohydrates Essentially all the carbohydrates in the food are absorbed in the form of monosaccharides only a small fraction are absorbed as disaccharides and almost none as larger carbohydrate compounds. By far the most abundant of the absorbed monosaccharides is glucose, usually accounting for more than 80 per cent of carbohydrate calories absorbed. The reason for this is that glucose is the final digestion product of our most abundant carbohydrate food, the starches. The remaining 20 per cent of absorbed monosaccharides are composed almost entirely of galactose and fructose, the galactose derived from milk and the fructose as one of the monosaccharides digested from cane sugar.
Although there is little research on the involvement of iodine in exercise performance or recovery from exercise, iodine is essential for the maintenance of normal metabolism and for normal growth and development and, therefore, is likely to take part in various processes of importance to exercising individuals. Given iodine's key functions, it is surprising that more research has not been done in this area. Clearly, there are many questions to be answered. Strenuous activity and endurance training cause some changes in thyroid metabolism, but it is not clear whether these changes are temporary or permanent or whether they have any biological significance. In spite of the increased turnover of T4, it appears that serum levels of T4 and T3 do not change substantially, which leaves a major discrepancy in the reported observations. It is not clear how exercise can cause both decreased iodine uptake and increased thyroid turnover while serum hormone levels remain unaltered.34 Preliminary...
Nicotinic acid deficiency was found to be the causative agent of pellagra in 1937, yet the name was changed to niacin in order to prevent confusion with the tobacco derivative, nicotine. Niacin includes both nicotinic acid and nicotinamide, which form the metabolically active nicotinamide adenine dinucleotide (NAD) and NAD phosphate (NADP), an end product of tryptophan metabolism. More than 200 enzymes are dependent on NAD and NADP to carry out oxidation and reduction reactions, and these enzymes are involved in the synthesis and breakdown of all carbohydrates, lipids, and amino acids. Although niacin is endogenously produced in humans, exogenous intake is required to prevent deficiency. Niacin is found in meats, liver, fish, legumes, peanuts, enriched bread, coffee, and tea.
For gel imaging a UV light source is used for excitation in combination with a 520 nm band pass filter or a Wratten 9 longpass filter. Even though the stain binds covalently to carbohydrates, proteins can still be identified by mass spectrometry, especially, if the carbohydrate moiety is cleaved of before trypsin digestion using PNGaseF, for example, for N-linked carbohydrates.
And sodium homeostasis in animals.109,110 Biochemical changes induced by nickel deprivation in chicks, goats, pigs and rats include altered metabolism of carbohydrates, amino acids and lipids and distribution of calcium, iron and zinc.111-113 Nickel might have a function that is associated with vitamin B12 because the lack of this element inhibits the response to nickel supplementation when dietary nickel is low,114 and nickel can alleviate vitamin B12 deficiency in higher animals.115
The raise of transgenic sheep for the production of -antitrypsin has been described (Wright et al. 1991. Bio Technology 9, 830-834). Human o -antitrypsin (Ha, AT) is a glycoprotein with a molecular weight of 54 kD, consisting of 394 amino acids, with 12 carbohydrates. The protein is synthesized in the liver and secreted in the plasma with a serum concentration of 2 mg per ml. Human a,AT is a potent inhibitor of a wide range of serine proteases, a class of enzymes, if leave unchecked, can cause excessive tissue damage. Individuals deficient in the protein risk the development of emphysema.
Together, these two studies identified 200 genes as important for in vivo growth. Mutations in only 11 of these genes also decreased in vitro growth to some extent whereas the others only affected in vivo growth 81 . In vivo growth attenuating mutations were mapped to genes of a wide variety of predicted functions. Most frequent were genes involved in transport or metabolism of lipids, carbohydrates, amino acids and inorganic ions. Some mutations, for example those in genes important for disaccharide uptake, affected growth and survival during early and late stages of the infections. Others only affected survival at later stages of the infection. Mutations in the latter category demonstrated the importance of DNA repair systems for the long-term survival of M. tuberculosis in mice. These findings are in agreement with a recent study on the importance of uvrB, a gene involved in nucleotide excision repair, for virulence of M. tuberculosis 90 .
Hormonal Feedback from the Duodenum Inhibits Gastric Emptying Role of Fats and the Hormone Cholecystokinin
GIP is released from the upper small intestine in response mainly to fat in the chyme, but to a lesser extent to carbohydrates as well. Although GIP does inhibit gastric motility under some conditions, its effect at physiologic concentrations is probably mainly to stimulate secretion of insulin by the pancreas.
Insulin-dependent diabetes mellitus (IDDM, also known as type I diabetes mellitus) is an autoimmune disease resulting from destruction of the islets of Langerhans. It usually occurs in lean, young persons and is characterized by an absence of insulin secretion in response to hyperglycemia and a tendency toward ketosis. Hyperglycemia leads to deleterious secondary complications including retinopathy, neuropathy, and fll
In the past few chapters, we have pointed out that carbohydrates, fats, and proteins can all be used by cells to synthesize large quantities of adenosine triphosphate (ATP), which can be used as an energy source for almost all other cellular functions. For this reason, ATP has been called an energy currency in cell metabolism. Indeed, the transfer of energy from foodstuffs to most functional systems of the cells can be done only through this medium of ATP (or the similar nucleotide guanosine triphosphate, GTP). Many of the attributes of ATP are presented in Chapter 2. ATP Is Generated by Combustion of Carbohydrates, Fats, and Proteins. In previous chapters, we discussed the transfer of energy from various foods to ATP. To summarize, ATP is produced from 1. Combustion of carbohydrates mainly glucose, but also smaller amounts of other sugars such as fructose this occurs in the cytoplasm of the cell through the anaerobic process of glycolysis and in the cell mitochondria through the...
Including (1) increased rate of protein synthesis in most cells of the body (2) increased mobilization of fatty acids from adipose tissue, increased free fatty acids in the blood, and increased use of fatty acids for energy and (3) decreased rate of glucose utilization throughout the body. Thus, in effect, growth hormone enhances body protein, uses up fat stores, and conserves carbohydrates. therefore, increasing the concentration of fatty acids in the body fluids. In addition, in tissues throughout the body, growth hormone enhances the conversion of fatty acids to acetyl coenzyme A (acetyl-CoA) and its subsequent utilization for energy. Therefore, under the influence of growth hormone, fat is used for energy in preference to the use of carbohydrates and proteins. Ketogenic Effect of Growth Hormone. Under the influence of excessive amounts of growth hormone, fat mobilization from adipose tissue sometimes becomes so great that large quantities of acetoacetic acid are formed by the...
Abundance of energy-giving foods in the diet, especially excess amounts of carbohydrates, insulin is secreted in great quantity. In turn, the insulin plays an important role in storing the excess energy. In the case of excess carbohydrates, it causes them to be stored as glycogen mainly in the liver and muscles. Also, all the excess carbohydrates that cannot be stored as glyco-gen are converted under the stimulus of insulin into fats and stored in the adipose tissue. In the case of proteins, insulin has a direct effect in promoting amino acid uptake by cells and conversion of these amino acids into protein. In addition, it inhibits the breakdown of the proteins that are already in the cells.
The cell membrane (also called the plasma membrane), which envelops the cell, is a thin, pliable, elastic structure only 7.5 to 10 nanometers thick. It is composed almost entirely of proteins and lipids. The approximate composition is proteins, 55 per cent phospholipids, 25 per cent cholesterol, 13 per cent other lipids, 4 per cent and carbohydrates, 3 per cent. Membrane Carbohydrates The Cell Glycocalyx. Membrane carbohydrates occur almost invariably in combination with proteins or lipids in the form of gly-coproteins or glycolipids. In fact, most of the integral proteins are glycoproteins, and about one tenth of the membrane lipid molecules are glycolipids. The glyco portions of these molecules almost invariably protrude to the outside of the cell, dangling outward from the The carbohydrate moieties attached to the outer surface of the cell have several important functions (1) Many of them have a negative electrical charge, which gives most cells an overall negative surface charge...
The multiple hormone systems play a key role in regulating almost all body functions, including metabolism, growth and development, water and electrolyte balance, reproduction, and behavior. For instance, without growth hormone, a person would be a dwarf. Without thyroxine and triiodothyronine from the thyroid gland, almost all the chemical reactions of the body would become sluggish, and the person would become sluggish as well. Without insulin from the pancreas, the body's cells could use little of the food carbohydrates for energy. And without the sex hormones, sexual development and sexual functions would be absent.
Carbohydrates Are Preferred over Fats for Energy When Excess Carbohydrates Are Available. When excess quantities of carbohydrates are available in the body, carbohydrates are used preferentially over triglycerides for energy. There are several reasons for this fat-sparing effect of carbohydrates. One of the most important is the fol-lowing The fats in adipose tissue cells are present in two forms stored triglycerides and small quantities of free fatty acids. They are in constant equilibrium with each other.When excess quantities of a-glycerophosphate are present (which occurs when excess carbohydrates are available), the excess a-glycerophosphate binds the free fatty acids in the form of stored triglycerides. As a result, the equilibrium between free fatty acids and triglycerides shifts toward the stored triglycerides consequently, only minute quantities of fatty acids are available to be used for energy. Because a-glycerophosphate is an important product of glucose metabolism, the...
As discussed in Chapter 71, energy intake is balanced with energy output in healthy adults who maintain a stable body weight. About 45 per cent of daily energy intake is derived from carbohydrates, 40 per cent from fats, and 15 per cent from proteins in the average American diet. Energy output can also be partitioned into several measurable components, including energy used for (1) performing essential metabolic functions of the body (the basal metabolic rate) (2) performing various physical activities (3) digesting, absorbing, and processing food and (4) maintaining body temperature.
Water is added to the body by two major sources (1) it is ingested in the form of liquids or water in the food, which together normally add about 2100 ml day to the body fluids, and (2) it is synthesized in the body as a result of oxidation of carbohydrates, adding about 200 ml day. This provides a total water intake of about 2300 ml day (Table 25-1). Intake of water, however, is highly variable among different people and even within the same person on different days, depending on climate, habits, and level of physical activity.
Storage of glyco-gen allows the liver to remove excess glucose from the blood, store it, and then return it to the blood when the blood glucose concentration begins to fall too low. This is called the glucose buffer function of the liver. In a person with poor liver function, blood glucose concentration after a meal rich in carbohydrates may rise two to three times as much as in a person with normal liver function. 3. Synthesis of fat from proteins and carbohydrates To derive energy from neutral fats, the fat is first split Almost all the fat synthesis in the body from carbohydrates and proteins also occurs in the liver. After fat can be used for energy or converted into carbohydrates or fats. A small amount of deamination can occur in the other tissues of the body, especially in the kidneys, but this is much less important than the deamination of amino acids by the liver.
Thyroxine increases the rate of metabolism of all cells and, as a result, indirectly affects protein metabolism. If insufficient carbohydrates and fats are available for energy, thyroxine causes rapid degradation of proteins and uses them for energy. Conversely, if adequate quantities of carbohydrates and fats are available and excess amino acids are also available in the extracellular fluid, thyroxine can actually increase the rate of protein synthesis. In growing animals or human beings, deficiency of thyroxine causes growth to be greatly inhibited because of lack of protein synthesis. In essence, it is believed that thyroxine has little specific effect on protein metabolism but does have an important general effect by increasing the rates of both normal anabolic and normal catabolic protein reactions.
Figure 75-7 demonstrates the effect of protein deficiency on plasma growth hormone and then the effect of adding protein to the diet. The first column shows very high levels of growth hormone in children with extreme protein deficiency during the protein malnutrition condition called kwashiorkor the second column shows the levels in the same children after 3 days of treatment with more than adequate quantities of carbohydrates in their diets, demonstrating that the carbohydrates did not lower the plasma growth
Rapidly metabolizable carbohydrates such as glucose are generally avoided in sporulation media because they are vigorously fermented by certain saccharo-lytic species of Clostridium, resulting in considerable acid production.18'19 In fact, improved sporulation of C. perfringens has been reported by adjusting the initial pH value of the sporulation medium to 7.8 with sodium carbonate,20 which contributes to the buffering capacity of the medium.21
Recovery from exhaustive muscle glycogen depletion is not a simple matter. This often requires days, rather than the seconds, minutes, or hours required for recovery of the phosphagen and lactic acid metabolic systems. Figure 84-3 shows this recovery process under three conditions first, in people on a high-carbohydrate diet second, in people on a high-fat, high-protein diet and third, in people with no food. Note that on a high-carbohydrate diet, full recovery occurs in about 2 days. Conversely, people on a high-fat, high-protein diet or on no food at all show very little recovery even after as long as 5 days. The messages of this comparison are (1) that it is important for an athlete to have a high-carbohydrate diet before a grueling athletic event and (2) not to participate in exhaustive exercise during the 48 hours preceding the event. In addition to the large usage of carbohydrates by the muscles during exercise, especially during the early stages of...
Under abnormal conditions, the cholesterol may precipitate in the gallbladder, resulting in the formation of cholesterol gallstones, as shown in Figure 64-12. The amount of cholesterol in the bile is determined partly by the quantity of fat that the person eats, because liver cells synthesize cholesterol as one of the products of fat metabolism in the body. For this reason, people on a high-fat diet over a period of years are prone to the development of gallstones.
About 40 per cent of the calories in a typical American diet are derived from fats, which is almost equal to the calories derived from carbohydrates. Therefore, the use of fats by the body for energy is as important as the use of carbohydrates is. In addition, many of the carbohydrates ingested with each meal are converted into triglycerides, then stored, and used later in the form of fatty acids released from the triglycerides for energy. Ketosis in Starvation, Diabetes, and Other Diseases. The concentrations of acetoacetic acid, b-hydroxybutyric acid, and acetone occasionally rise to levels many times normal in the blood and interstitial fluids this condition is called ketosis, because acetoacetic acid is a keto acid. The three compounds are called ketone bodies. Ketosis occurs especially in starvation, in diabetes mellitus, and sometimes even when a person's diet is composed almost entirely of fat. In all these states, essentially no carbohydrates are metabolized in starvation and...
Anaerobic energy means energy that can be derived from foods without the simultaneous utilization of oxygen aerobic energy means energy that can be derived from foods only by oxidative metabolism. In the discussions in Chapters 67 through 69, it is noted that carbohydrates, fats, and proteins can all be oxidized to cause synthesis of ATP. However, carbohydrates are the only significant foods that can be used to provide energy without the utilization of oxygen this energy release occurs during glycolytic breakdown of glucose or glyco-gen to pyruvic acid. For each mole of glucose that is split into pyruvic acid, 2 moles of ATP are formed. However, when stored glycogen in a cell is split to pyruvic acid, each mole of glucose in the glycogen gives rise to 3 moles of ATP. The reason for this difference is that free glucose entering the cell must be phosphorylated by using 1 mole of ATP before it can begin to be split this is not true of glucose derived from glycogen because it comes from...
Caries and the Role of Bacteria and Ingested Carbohydrates. It is generally agreed that caries result from the action of bacteria on the teeth, the most common of which is Streptococcus mutans. The first event in the development of caries is the deposit of plaque, a film of precipitated products of saliva and food, on the teeth. Large numbers of bacteria inhabit this plaque and are readily available to cause caries. These bacteria depend to a great extent on carbohydrates for their food. When carbohydrates are available, their metabolic systems are strongly activated and they multiply. In addition, they form acids (particularly lactic acid) and proteolytic enzymes. The acids are the major culprit in causing caries because the calcium salts of teeth are slowly dissolved in a highly acidic medium. And once the salts have become absorbed, the remaining organic matrix is rapidly digested by the prote-olytic enzymes. Because of the dependence of the caries bacteria on carbohydrates for...
Apart from vitamins and trace elements, plant foods such as fruits, vegetables and cereals contain many bioactive compounds with antigenotoxic properties. Since these constituents do not belong to the classes of proteins, fats or carbohydrates, they are often called non-nutrients, microconstituents, phytochemicals or phytoprotectants. Exogenous antigenotoxins of plant origin can be roughly categorized as follows
Carbohydrates and Fats Act as Protein Sparers. When the diet contains an abundance of carbohydrates and fats, almost all the body's energy is derived from these two substances, and little is derived from proteins. Therefore, both carbohydrates and fats are said to be protein sparers. Conversely, in starvation, after the carbohydrates and fats have been depleted, the body's protein stores are consumed rapidly for energy, sometimes at rates approaching several hundred grams per day rather than the normal daily rate of 30 to 50 grams. Methods for Determining Metabolic Utilization of Proteins, Carbohydrates, and Fats Respiratory Quotient Is the Ratio of CO2 Production to O2 Utilization and Can Be Used to Estimate Fat and Carbohydrate Utilization. When carbohydrates are metabolized with oxygen, exactly one carbon dioxide molecule is formed for each molecule of oxygen consumed. This ratio of carbon dioxide output to oxygen usage is called the respiratory quotient, so the respiratory...
Hypokalaemic periodic paralysis is a disorder of episodic weakness in which a myotonia is not seen. These patients are generally hypokalaemic during an attack and attacks can be precipitated by lowering K+ with administration of glucose and insulin. Furthermore, these attacks can be precipitated by stress, fatigue and rest after vigorous exercise. Dietary precipitants include high carbohydrate meals and salt load. Hyperkalaemic periodic paralysis is transmitted as an autosomal dominant trait although frequent sporadic cases can be seen. Patients K+ levels during hypokalaemia generally remain above 2 mM. K+ levels below 2 mM during an attack of weakness in a sporadic case raises the possibility of thyrotoxic hypokalaemic periodic paralysis, a non-Mendelian form of the disorder which is seen only during periods of thyrotoxicosis (Ptacek 1998). The episodic weakness in patients with hyperkalaemic periodic paralysis, paramyotonia congenita and hypokalaemic periodic paralysis all benefit...
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. Use of Hydrogen to Synthesize Fat the Function of Nicotinamide Adenine Dinucleotide Phosphate. The hydrogen released during the pentose phosphate cycle does not combine with NAD+ as in the glycolytic pathway but combines with nicotinamide adenine dinucleotide phosphate (NADP+), which is almost identical to NAD+ except for an extra phosphate radical, P. This difference is extremely significant, because only hydrogen bound with NADP+ in the form of NADPH can be...
Some patients may be helped by sleeping with the head of the bed elevated 15 to 30 cm (the reverse Trendelenburg position) to avoid supine hypertension and decrease nocturnal natriuresis and volume depletion. This maneuver alone may reduce postural hypotension in the morning. To reduce postprandial hypotension, patients should eat smaller, low-carbohydrate meals more frequently and drink strong coffee. Finally, custom-fitted elasticized garments (a Jobst or Barton-Carey leotard) may reduce venous pooling in the legs.
By far, the major portion of the ATP formed in the cell, about 95 per cent, is formed in the mitochondria. The pyruvic acid derived from carbohydrates, fatty acids from lipids, and amino acids from proteins are eventually converted into the compound acetyl-CoA in the matrix of the mitochondrion. This substance, in turn, is further dissoluted (for the purpose of extracting its energy) by another series of enzymes in the mitochondrion matrix, undergoing dissolution in a sequence of chemical reactions called the citric acid cycle, or Krebs cycle. These chemical reactions are so important that they are explained in detail in Chapter 67. much slower chemical reactions break down carbohydrates, fats, and proteins and use the energy derived from these to form new ATP. More than 95 per cent of this ATP is formed in the mitochondria, which accounts for the mitochondria being called the powerhouses of the cell.
Saliva plays a crucial role in the digestion of carbohydrates and fats through two main enzymes. Ptyalin is an a-amylase in saliva that cleaves the internal a-1,4-glyco-sidic bonds of starches to yield maltose, maltotriose, and a-limit dextrins. This enzyme functions at an optimal pH of 7, but rapidly denatures when exposed to a pH less than 4, such as when in contact with the acidic secretions of the stomach. Up to 75 of the carbohydrate content in a meal, however, is broken down by the enzyme within the stomach. This is due to the fact that a significant portion of an ingested meal remains unmixed within the oral region, and thus there is a delay in the mixture of gastric juices with the food bolus. Starch digestion is not slowed in the absence of ptyalin because pancreatic amylase is identical to salivary amylase and is thus able to break down all carbohydrates when in the small intestine. The salivary glands of the tongue produce lingual lipase, which functions to break down...
Age 50 years familial history of prostate cancer high serum testosterone high-fat diet high red meat consumption population geographical background (highest incidences in Canada and northwest Europe) prostatitis, genetic polymorphisms (e.g. in SRD5A2, gene for steroid 5-reductase) low micronutrient levels (e.g. selenium, carotenoids, vitamin D)
Pancreatic secretion contains multiple enzymes for digesting all of the three major types of food proteins, carbohydrates, and fats. It also contains large quantities of bicarbonate ions, which play an important role in neutralizing the acidity of the chyme emptied from the stomach into the duodenum. The pancreatic enzyme for digesting carbohydrates is pancreatic amylase, which hydrolyzes starches, glyco-gen, and most other carbohydrates (except cellulose) to form mostly disaccharides and a few trisaccharides.
According to microscopical studies the pre-treatments with calcium chloride and crystallized sucrose as well as with CaCl2 and PME in a vacuum influence the microstructure of strawberry tissues. These pre-treatments especially affect pectin, protein, lignin and structural carbohydrates in the vascular tissue and cortex when compared to the untreated reference samples. The use of a vacuum appears to make the cortex and pitch absorb the pre-treatment solutions more efficiently thus improving the stabilization particularly of pectin and structural carbohydrates (Suutarinen, 2002). Micrographs of the strawberry cortical and vascular tissues of the untreated reference and the CaCl2- and PME-treated strawberries in a vacuum after pectin staining, are shown in Fig. 16.2 (Suutarinen et al., 2000). Firmness of thawed strawberries pretreated with CaCl2 and PME in a vacuum is more than twice as high as that of other pre-treated or untreated berries (Fig. 16.3) (Suutarinen et al., 2002a).
Near infrared (NIR) spectroscopy which can avoid the complexity of sensor contact and associated handling problems (Delwiche et al, 1996) has recently been studied as a means of evaluating the texture of intact apples by Cho et al., 1996, Onda et al., 1996, Sohn and Cho, 2000, Lu et al, 2000 and Park et al, 2002 plums by Onda et al., 1996 pear by Sirisomboon, 2001 sweet cherries by Lu, 2001. As described by Robert and Cadet (1998), the spectral information obtained in the NIR spectral region corresponds to the harmonics and combinations of the fundamental vibrations observed in the mid-infrared. These absorptions are of lower intensity and are less well-resolved, and they contain only part of the information content available in the mid-infrared region. The NIR spectra of carbohydrates can be split into two distinct and characteristic parts the first part corresponds to the 1100-1800 nm wavelength region, and this is characteristic of the first and second harmonics of the OH and C-H...
Children affected with classic McArdle's disease (myophosphorylase deficiency) initially show decreased stamina and easy fatigability. Although onset usually occurs in childhood, neonatal presentations have been reported. Severe cramping pain, usually in the distal skeletal muscles, develops after exercise and is often associated with renal impairment. In adolescence and adulthood, patients may develop persistent weakness and moderate loss of muscle bulk. Patients with Hers' disease have no specific neurological or muscle findings but display varying degrees of growth retardation, hypoglycemia, ketosis, and hepatomegaly. In Tarui's disease, motor development is normal during the first decade, but decreased muscle exercise tolerance, myoglobulinuria, and easy fatigability develop in childhood. An unusual infantile syndrome characterized by limb weakness, seizures, cortical blindness, and corneal opacifications occurs microscopic studies reveal typical findings of neuron axonal...
Thiamine deficiency (beriberi) causes decreased utilization of pyruvic acid and some amino acids by the tissues, but increased utilization of fats. Thus, thiamine is specifically needed for the final metabolism of carbohydrates and many amino acids. The decreased utilization of these nutrients is responsible for many debilities associated with thiamine deficiency. Thiamine Deficiency Causes Lesions of the Central and Peripheral Nervous Systems. The central nervous system normally depends almost entirely on the metabolism of carbohydrates for its energy. In thiamine deficiency, the utilization of glucose by nervous tissue may be decreased 50 to 60 per cent and is replaced by the utilization of ketone bodies derived from fat metabolism. The neuronal cells of the central nervous system frequently show chromatolysis and swelling during thiamine deficiency, changes that are characteristic of neuronal cells with poor nutrition. These changes can disrupt communication in many portions of the...
The nonfat, water-soluble nutrients absorbed from the gut (such as carbohydrates and proteins) are transported in the portal venous blood to the same liver sinusoids. Here, both the reticuloendothelial cells and the principal parenchymal cells of the liver, the hepatic cells, absorb and store temporarily from one half to three quarters of the nutrients. Also, much chemical intermediary processing of these nutrients occurs in the liver cells.We discuss these nutritional functions of the liver in Chapters 67 through 71. Almost all of the fats absorbed from the intestinal tract are not carried in the portal blood but instead are absorbed into the intestinal lymphatics and then conducted to the systemic circulating blood by way of the thoracic duct, bypassing the liver.
Endogenous iodine-containing thyroid hormones L-thyroxine and L-triiodothyronine are produced by the thyroid gland, which exhibits pronounced metabolic control over practically every cell in the body using the two mentioned iodine-containing hormones. By controlling the rate of oxidative cellular processes, these hormones take part in regulation of growth and development of the organism, formation of bone marrow and bone tissue they affect activity of the CNS, cardiovascular system, gastrointestinal tract, metabolism of carbohydrates, fats, and proteins they have an effect on regulation of body temperature, muscle activity, water-electrolyte balance, and reproduction, playing an extremely important role in normal physical and mental development. Unlike many other hormones, they exhibit a diffusive effect on the whole organism, not on individual organs.
Intake of carbohydrates, fats, and proteins provides energy that can be used to perform various body functions or stored for later use. Stability of body weight and composition over long periods requires that a person's energy intake and energy expenditure be balanced. When a person is overfed and energy intake persistently exceeds expenditure, most of the excess energy is stored as fat, and body weight increases conversely, loss of body mass and starvation occur when energy intake is insufficient to meet the body's metabolic needs. Because different foods contain different proportions of proteins, carbohydrates, fats, minerals, and vitamins, appropriate balances must also be maintained among these constituents so that all segments of the body's metabolic systems can be supplied with the requisite materials. This chapter discusses the mechanisms by which food intake is regulated in accordance with the body's metabolic needs and some of the problems of maintaining balance among the...
Thiamin (vitamin B1) as a component of the coenzyme thiamin pyrophosphate (TPP), is important in energy metabolism. Thiamin is also needed for optimal neuromuscular functioning. Reportedly some athletes are marginally thiamin deficient. The need for thiamin is generally proportional to the caloric intake, especially when the diet is high in carbohydrates. Athletes may require more thiamin than sedentary individuals. Additional research is needed on the thiamin needs of physically active individuals. No UL exists for thiamin.7 Niacin, as a component of the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), is needed for adenosine triphosphate (ATP) production from all the energy-yielding nutrients. Niacin deficiency impairs glycolysis and respiratory metabolism. Compromised niacin status in the athletic or general population does not seem to influence aerobic exercise performance. Supplementation with nicotinic acid reduces the...
Almost all the carbohydrates of the diet are either large polysaccharides or disaccharides, which are combinations of monosaccharides bound to one another by condensation. This means that a hydrogen ion (H+) has been removed from one of the monosaccharides, and a hydroxyl ion (-OH) has been removed from the next one. The two monosaccharides then combine with each other at these sites of removal, and the hydrogen and hydroxyl ions combine to form water (H2O). When carbohydrates are digested, the above process is reversed and the carbohydrates are converted into monosaccharides. Specific enzymes in the digestive juices of the gastrointestinal tract return the hydrogen and hydroxyl ions from water to the polysaccharides and thereby separate the monosaccharides from each other. This process, called hydrolysis, is the following (in which R -R' is a disaccharide)
The classic picture of botulism is the acute onset of a flaccid descending paralysis with clear sensorium, no fever and no paresthesias. The rarity of foodborne and wound botulism makes them easily confused with other diseases. Routine laboratory studies, including the cereobrospinal fluid, are normal in botulism unless dehydration or starvation ketosis are present. EMG may demonstrate a defect in neuromuscular transmission, and the typical finding in food-borne and wound botulism is facilitation (potentiation) of the elicited muscle action potential at high frequency (50 Hz) stimulation. In infant botulism a characteristic pattern, known by the acronym BSAP (brief, small, abundant motor-unit action potentials), is present only in clinically weak muscles.
The basic principles of cellular metabolism, discussed in Chapters 67 through 72, apply to cardiac muscle the same as for other tissues, but there are some quantitative differences. Most important, under resting conditions, cardiac muscle normally consumes fatty acids to supply most of its energy instead of carbohydrates (about 70 per cent of the energy is derived from fatty acids). However, as is also true of other tissues, under anaerobic or ischemic conditions, cardiac metabolism must call on anaerobic glycolysis mechanisms for energy. Unfortunately, glycolysis consumes tremendous quantities of the blood glucose and at the same time forms large amounts of lactic acid in the cardiac tissue, which is probably one of the causes of cardiac pain in cardiac ischemic conditions, as discussed later in this chapter.
As with the bucket filling with water, the energy that drives all these proteins ultimately comes from the sun (with the exception of some bacteria that obtain their energy from inorganic compounds). Solar energy is captured within the cells of plants, where it is guided to produce sugars from carbon dioxide and water. The light energy is effectively converted into a different form of energy, stored in the chemical bonds of the sugar molecules. The chemical energy and components in the sugars are then channelled in all sorts of different directions, by other types of protein in the plant, to make molecules such as carbohydrates, fats and more proteins. These products are in turn essential for sustaining animal life when an animal eats a plant, the energy and chemical components of the plant are channelled by the animal's proteins to make its own carbohydrates, fats and proteins. In other words, the energy that drives the internal reactions of animals comes from the food they eat,...
The seasonal affective disorder develops during autumn and winter and remits in spring and summer, at which time there may even be mild hypomania. In the winter a DSPS pattern develops, associated with depression, an increase in appetite, particularly for carbohydrates, weight gain, fatigue and reduction in physical activity.
Protein glycosylation is a common post-translational modification where carbohydrates are covalently attached to seryl or threonyl residues (O-linked glycosylation) or asparagyl residues (N-linked glycosylation). It has significant effects on protein folding, stability, and structure and consequently affects protein function 95 . Glycoproteins are prevalent in the plasma membrane, secreted proteins, and proteins present in body fluids (e.g., blood, serum, cerebrospinal fluid, saliva, and breast milk) and play a vital role in biological processes such as molecular recognition and inter- and intra-cellular signaling. Several approaches to characterize glycoproteins have been used successfully, including fast atom bombardment, MALDI, and ESI using a wide variety of mass analyzers. However, the identification of glycopeptides in complex mixtures as encountered in proteomic studies still remains a challenge due to the poor ionization efficiency and rapid degradation of glycopeptides. Many...
Staining occurs via the interaction of plant tannins with both proteins and carbohydrates. Arginine, histidine, lysine, and tryptophan residues of proteins bind electrostatically to carboxylic and phenolic groups of tannins. This class of pigments chelate certain metal ions at a pH above the pKa of one or more of the substituent phenolic groups,94 and this induces a hypsochromic shift in staining.
In S. rebaudiana leaves using near infrared reflectance spectroscopy (Nishiyama et al. 1992). Gradually, analytical methods have evolved for stevioside, rebaudioside and their sweet analogues, decomposition products, and metabolites that do not require chemical derivatization. For example, this can be achieved by HPLC for the S. rebaudiana sweet glycosides using amino (NH2) columns, which are usually used in the analysis of carbohydrates (e.g. Makapugay et al. 1984 Mauri et al. 1996).
Treatment of HSV-1 infected Vero cells with retinoic acid did not reduce the production of viral glycoproteins, even when the production of infectious virus particles was inhibited by 1,000-fold. Envelope glycoproteins are a constituent of all enveloped viruses and inhibition of their synthesis would have been one possible mechanism for vitamin A dependent reduction in viral infectivity. Studies done using labeled carbohydrates however, suggest that retinoic acid treatment interferes with the processing of carbohydrates attached to enveloped virus proteins. These studies indicate that the maintenance of adequate vitamin A levels in breast milk could help to reduce the severity of enveloped virus infections in infants when a vaccine is not available.
In order for breast milk oligosaccharides to operate systemically, they need to be absorbed to have a systemic effect at other surfaces, for example the endothelium. Intact breast milk oligosaccharides have been demonstrated in the urine only of those premature infants who have been breast fed when compared to formula fed premature infants. 13C stabile isotope studies revealed that in-vivo labelled lactose given to mothers was incorporated into oligosaccharides which were taken up by the infant as indicated by the occurrence of complex 13C labelled carbohydrates with partial identity with breast milk oligosaccharides from mothers 1.
The chemical composition of Spirulina has been analyzed since 1970, showing high protein concentration, 60-70 of its dry weight, whose nutritive value is related to the quality of amino acid. Spirulina contains essential amino acids, including leucine, isoleucine and valine. It also contains a relative high concentration of provitamin A, vitamin Bi2 and j-carotene. Spirulina have 4-7 lipids, essential fatty acids as linolenic and y -linolenic acid,27 and m-3 and m-6 polyunsaturated fatty acids.28 Cyanobacteria and algae possess a wide range of colored compounds, including carotenoids, chlorophyll, and phycobiliproteins. C-phycocyanin is the principal phycobiliprotein.29 A selenium-containing phycocyanin has been isolated from S. platensis.30 S. platensis contains about 13.5 carbohydrates, the
The pharmacokinetics and pharmacodynamics of Spirulina in humans have not been thoroughly investigated. However, the proteins, lipids, and carbohydrates in Spirulina are digested, absorbed, and metabolized by the humans upon oral consumption. Spirulina can be consumed at a dose of 3-20 g day without manifestation of any adverse effects.91 Studies on the acute, subchronic, and chronic toxicity and mutagenicity of Spirulina have revealed no specific body or organ toxicity or genotoxicity.92,93 Studies in animals fed with large quantities of Spirulina have shown that the alga is neither toxic nor causes adverse health effects.94 Dietary ingestion of very high levels of Spirulina during pregnancy has not caused any fetal abnormalities or birth defects.95 Independent feeding tests have shown no toxic or adverse effects in the humans, rats, pigs, and chickens.92,96,97 Feeding experiments with rats conducted in Japan have revealed no acute or chronic toxicity or reproductive toxicity of...
Spirulina adds to the list of the most enriched nutrient foods currently known. The alga is rich in all the three broad categories of essential nutrients including mac-ronutrients (proteins, lipids, and carbohydrates), minerals such as zinc, magnesium, calcium, iron, managanese, selenium, micronutrients, provitamin A (j-carotene), riboflavin, cyanocobalamin, -tocopherol, a-linoleic acid, the most potent antioxidant enzyme, SOD, phytopigments including chlorophyll and the characteristic phycobilin pigments88,89 in an greater bioavailable state. The typical phycobilin pigments of Spirulina include C-phycocyanin and allophycocyanin. The pigments,
The liver performs many different functions yet is also a discrete organ, and many of its functions interrelate with one another. This becomes especially evident in abnormalities of the liver, because many of its functions are disturbed simultaneously. The purpose of this chapter is to summarize the liver's different functions, including (1) filtration and storage of blood (2) metabolism of carbohydrates, proteins, fats, hormones, and foreign chemicals (3) formation of bile (4) storage of vitamins and iron and (5) formation of coagulation factors.
Debris forming nutrients for other species, groups of chemotypes, managing energy and element capture differently. Though to some degree they exchanged products, even genes, this is hardly an organised system of cells, but it is believed that these prokaryotes can be attracted by sources of food to form very loose colonies , that is by sensing the presence of other cells or of debris of other prokaryotes they can become cooperative in the ecosystem. Unicellular eukaryotes, split into fungi and plant-like chemotypes which appeared next (we discuss animals in Section 9.11), can manage more activities within single cells than prokaryotes, but many of these organisms rely upon some bacteria for basic food, limiting the need for synthesis. They are able to detect food, environmental features, other organisms in their environment and they sense the environment in a more advanced way but note that they rely on incorporated bacteria, organelles, for energy, and even for iron metabolism....
The normal concentration of growth hormone in the plasma of an adult is between 1.6 and 3 ng ml in a child or adolescent, it is about 6 ng ml. These values often increase to as high as 50 ng ml after depletion of the body stores of proteins or carbohydrates during prolonged starvation.
Islandlike molecules of proteins and carbohydrates extend through the entire membrane. Because of this composition, the membrane can selectively absorb or act as a barrier to various chemical compounds. Thus it regulates the cell's activities and interactions with its surroundings. Most cell functions depend on chemical reactions. Food molecules taken into cells through the membrane are broken down to provide the chemicals and energy needed to synthesize other molecules. When nutrients proteins, fats, and carbohydrates are carried to cells by the blood, they must pass through the plasma membrane. The membrane's bilayered structure helps make this absorption possible. The membrane also allows hormones (such as insulin), oxygen, and other important chemicals to pass into or leave the cell.
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