Cyclical Ketogenic Diets Review

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Carbohydrates Immune Stimulating

Recent developments in glycobiology have shown that carbohydrates play an important part in diverse immunological processes such as opsonization and phagocytosis of microorganisms, and cell activation and differentiation (Table 1). Carbohydrates exert Table 1 Immunostimulating carbohydrates and their structures Table 1 Immunostimulating carbohydrates and their structures Carbohydrates

Carbohydrates And Glycobiology

7.4 Carbohydrates as Informational Molecules The Sugar Code 261 7.5 Working with Carbohydrates 267 Carbohydrates are the most abundant biomolecules on Earth. Each year, photosynthesis converts more than 100 billion metric tons of CO2 and H2O into cellulose and other plant products. Certain carbohydrates (sugar and starch) are a dietary staple in most parts of the world, and the oxidation of carbohydrates is the central energy-yielding pathway in most nonphotosynthetic cells. Insoluble carbohydrate polymers serve as structural and protective elements in the cell walls of bacteria and plants and in the connective tissues of animals. Other carbohydrate polymers lubricate skeletal joints and participate in recognition and adhesion between cells. More complex carbohydrate polymers covalently attached to proteins or lipids act as signals that determine the intracellular location or metabolic fate of these hybrid molecules, called glycoconjugates. This chapter introduces the major classes of...

Benefits of Low Glycemic Index Carbohydrates on Diabetic Control

This is the area in which there is most evidence of clinical efficacy. Two independent systematic reviews of the world evidence demonstrated the efficacy of low glycemic index diets on glycemic control in both type 1 and type 2 diabetes. Clinical studies have shown that after 3 months of a diet containing low glycemic index carbohydrates, glycemic control is improved in both type 1 and type 2 diabetes. With low glycemic diets, postprandial glucose and insulin concentrations decrease in type 2 diabetic subjects, whereas both postprandial glucose values and insulin requirements decrease in type 1 diabetic subjects. Good glycemic control and favorable lipid and fibri-nolytic profiles have also been reported in individuals with either type 1 or 2 diabetes who habitually consume low glycemic index dietary carbohydrates. It remains to be shown whether these diets bestow

Anticonvulsant Mechanisms Of The Ketogenic Diet 41 Mechanistic Criteria

Effect of dietary manipulation on electroconvulsive threshold in adult rats. Ordinate Voltage needed to produce a minimal convulsion (brief, massive flexion spasm with forelimb and jaw clonus lasting 1-3 s). Abscissa Experimental day. Animals received standard rat chow until day 0 (arrow), followed by ketogenic diet for 39 d, high carbohydrate diet for 9 d, and, finally, standard rat chow again. The threshold for a minimal convulsion remains constant at about 70 V until about 12 d on the ketogenic diet the threshold then rises steadily to a plateau. After changing to the high carbohydrate diet, minimal seizure threshold falls and more intense (maximal) seizures occur at the same stimulus intensity that previously produced minimal convulsions. Mean body weights are also plotted. (Reproduced with permission from Appleton & DeVivo, 1974.) Fig. 1. Effect of dietary manipulation on electroconvulsive threshold in adult rats. Ordinate Voltage needed to produce a minimal convulsion...

Chronic Effects of the Ketogenic Diet

Kainic-acid-treated rats normally display hyperexcitable hippocampal circuitry (Tauck & Nadler, 1985 Cronin & Dudek, 1988 Mathern et al., 1997). To determine whether the KD could ameliorate KA-induced hyperexcitability changes, we examined hippocampal slices obtained from KA-treated rats on normal and ketogenic diets. Significantly fewer CA1 population spikes were evoked by Schaffer collateral stimulation in slices from KD-fed rats than from controls, suggesting that this neuronal network is less excitable after KD treatment (Stafstrom et al., 1999b). Because slices were perfused in normal artificial cerebrospinal fluid (without ketones), this reduction in excitability is independent of ketosis, reflecting a chronic stabilizing effect of the KD. It is tempting to speculate that such long-term effects may involve membrane lipid alterations.

Classes of Carbohydrates

If healthy population groups around the world are studied, there are relatively few illustrations of toxic effects associated with carbohydrate intakes. If sufficient food is available, population groups whose diets consist mostly of carbohydrates do not suffer adverse effects. Some short-term effects such as intestinal problems and diarrhea can be attributed to marked changes in the amount or form of ingested carbohydrate, e.g., high-fiber foods. On the other hand, there are subpopulations prone to significant adverse effects associated with carbohydrates, which include individuals with abnormal tolerances or intolerances (glucose, lactose). Milk sugar intolerance is prevalent in populations from the Far and Middle East and Africa. These individuals have difficulty digesting lactose, and, when they do ingest lactose, they experience gastric distress, cramping, and diarrhea. The intolerance is because such individuals lack the enzyme lactase to break down lactose to monosaccharides...

Health Effects of Carbohydrates

Carbohydrates are stored in the human body as glycogen mainly in the liver and muscle. The human body has a limited storage capacity for carbohydrates compared to fat. The total amount of carbohydrates stored in tissues and circulating in the blood as glucose is approximately 7.56 MJ (1800 kcal). Diets high in carbohydrate ensure adequate glycogen storage available for immediate energy utilization. Carbohydrates are the preferred energy source for the human brain and have an important role in reducing protein breakdown when energy intake is inadequate. Dietary carbohydrates are absorbed in their hex-ose form (glucose, fructose, galactose) and provide 15.6 kJg-1 (3.75 kcal g-1) of energy. Although sugars and polysaccharides provide similar amounts of energy, they differ in their physiological and metabolic properties. The effects of carbohydrate-containing foods on blood glucose levels during digestion and absorption are variable, depending on the type of dietary carbohydrate....

Ketones And The Ketogenic Diet

*Ketogenic diets are described by the ratio of foods with ketogenic potential (K) versus antiketogenic potential (AK), approximated by the formula K AK F + 0.5P C + 0.1F + 0.6P , where F, P, and C are amounts, by weight, of fat, protein, and carbohydrate. Practically, KDs are usually denoted as 3 1 or 4 1. K AK > 1.5 1 is considered necessary to produce ketosis. The equation adapted from Withrow, 1980. provided mainly in the forms of heavy cream and butter, contributes about 90 of the calories. The fats in the classic KD consist of a mixture of animal and plant-derived fats fatty acids of varying chain lengths are likely to be included, but no attempt is made to specify fat type or chain length. Therefore, the classic KD likely contains an abundance of saturated fatty acids and, possibly, a relative dearth of long-chain PUFAs as discussed, this is of interest because of the roles of PUFAs in brain development and modulation of excitability. There have been attempts to formulate a KD...

Proposed Mechanism by which Dietary Carbohydrates Glycemic Index Influence Insulin Resistance

Adipocyte metabolism is central to the pathogenesis of insulin resistance and dietary carbohydrates influence adipocyte function. The previous simplistic view that insulin resistance resulted from the down-regulation of the insulin receptors in response to hyperinsulinemia is being replaced by the hypothesis that high circulating NEFA levels both impair insulin action and reduce pancreatic fi cell secretion. It is plausible that low glycemic index carbohydrates Many of the metabolic benefits associated with low glycemic index carbohydrates can be attributed to their ability to reduce adipocyte NEFA release. Low glycemic index foods have been consistently shown to reduce insulin resistance, and animal studies have shown that improvements in fat and muscle insulin sensitivity are accompanied by decreases in fatty acid synthatase activity, adipocyte size, and lipid storage. Although human studies have shown that low glycemic index diets consumed for 3 weeks increase adipocyte insulin...

Dietary Fiber Complex Carbohydrates and Health Outcomes A Need for Fiber Equivalents

In the large bowel NSPs and RS are fermented by the microflora, yielding metabolic end products, principally short-chain fatty acids (SCFAs), which may mediate some of the health benefits ascribed to the carbohydrates. Undigested protein (resistant protein) and other nondigested carbohydrates (e.g., OSs) also contribute to large bowel fermentation. These nondigested fractions contribute to dietary fiber via fermentation and could be considered in net dietary fiber intake. This problem could be overcome relatively easily by classifying them (and other non-NSP carbohydrates) as fiber equivalents in which their actions are compared against an agreed standard. This is similar to the situation with other nutrients such as vitamin A, where reti-nol equivalents include carotenoids, which are reti-nol precursors. It follows that classifications based on chemical composition alone appear to be quite inadequate if one considers as improved health and diminished disease risk as the most...

Benefits of Low Glycemic Index Carbohydrates on Cardiovascular Disease Risk Factors

High glycemic index foods induce postprandial hyperinsulinemia, which is a powerful predictor for metabolic risk factors and CVD in epidemiological studies. Both cross-sectional and prospective population studies have shown favorable lipid profiles in association with high carbohydrate diets. Initially, these benefits were attributed to a high fiber content. However, when the glycemic index is controlled for, it is the low glycemic index diets rather than high fiber content that have the greatest influence on high-density lipoprotein (HDL) cholesterol, insulin sensitivity, and fibrinolytic parameters. In a cross-sectional study on more than 2000 middle-aged subjects, the glycemic index was a stronger determinant of HDL cholesterol than any other dietary factor, be it carbohydrate or fat. In this study, the HDL cholesterol of the women whose habitual diet was within the lowest quintile for glycemic index was 0.25 mmol l higher than that for women whose dietary carbohydrate was within...

Anaerobic Degradation of Carbohydrates in Wastewater

Carbohydrates are homo- or heteropolymers of hexoses, pentoses, or sugar derivatives, which occur in soluble form or as particles, forming grains or fibers of various sizes. In some plants, starch forms grains up to 1 mm in diameter, which is 1000 times the diameter of bacteria. Starch metabolism by bacteria requires hydrolytic cleavage by amylases to form soluble monomers or dimers, since only soluble substrates can be taken up and metabolized.


The carbohydrates are a vast and diverse group of nutrients found in most foods. This group includes simple sugars (like the sugar you add to your morning coffee) and complex forms such as starches (contained in pasta, bread, cereal, and in some fruits and vegetables), which are broken down during digestion to produce simple sugars. The main function of the simple sugars and starches in the foods we eat is to deliver calories for energy. The simple sugar glucose is required to satisfy the energy needs of the brain, whereas our muscles use glucose for short-term bouts of activity. The liver and muscles also convert small amounts of the sugar and starch that we eat into a storage form called glycogen. After a long workout, muscle glycogen stores must be replenished. Both simple sugars and starches provide about 4 calories per gram (a gram is about the weight of a paper clip). Because carbohydrates serve primarily as sources of calories (and we can get calories from other...

Mechanisms of neutrophil infiltration

The first leukocytes to infiltrate a site of inflammation are neutrophil granulocytes, which sometimes begin to accumulate within minutes of induction of inflammation. A host of adhesion molecules essential for neutrophil recruitment have been identified. During its journey through the vasculature, the neutrophil makes transient contact with the vascular wall of postcapillary venules, which gives the cell a rolling motion across the endothelium. This phenomenon is dependent on L-selectin (CD62L), present on the neutrophil surface, which recognizes and binds carbohydrates on the luminal surface of the vascular endothelium. Near an inflammatory site, however, the neutrophil becomes activated, the L-selectin is shed from the surface, and now the CD lib CD 18 adhesion complex, part of the integrin family, comes into play as the neutrophil adheres firmly to the vascular wall. Next, the neutrophil migrates out of the vessel through the junction between adjacent endothelial cells, and...

Amino Acid Metabolism Amino Acid Synthesis

Microorganisms in the digestive tract can synthesize all amino acids in the presence of ammonia, sulfur, and carbohydrates. 2 All animals can synthesize tyrosine as well as the following amino acids and their carbon skeletons alanine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline, and serine. The ability to synthesize citrulline and its carbon skeleton varies among species, but arginine can be made from citrulline in all animal cells.

Principles Of Animal Nutrition And Feeding

Nutrients required for livestock, just like for humans, can be categorized into six functional or chemical classes carbohydrates, proteins, fats, minerals, vitamins, and water. All carbohydrates or saccharides are related structurally and chemically and contain the same amount of gross energy. Carbohydrates are comprised primarily of hexose (C6H1206) and pentose (C5H10O5) molecules. Tetrose and triose molecules are present in small quantities but are generally not important in animal nutrition. Carbohydrates are usually categorized as monosaccharides, disac-charides, and polysaccharides based on how many hexose and pentose molecules are linked together. Common monosaccharides, also called simple sugars, consist of glucose, fructose, and galactose. Disaccharides consist of two monosaccharides linked together with hydroxyl groups of each sugar unit. The common monosaccharides include sucrose (table sugar), maltose, and lactose. Polysaccharides have the empirical formula (C6H10O5)n and...

Posttranslational Modification

The e-N of lysine residues is also susceptible to chemical reactions within food systems. It undergoes the Maillard reaction with carbonyl groups of carbohydrates to form a series of brown and slightly bitter products. This is an integral part of the baking process when producing bread, cakes, and biscuits, although there is evidence that large quantities of some Maillard products may be toxic or carcinogenic. On the other hand, since the lysine in Maillard products is not biologically available when the food is ingested, this can seriously reduce the protein quality of heat-treated animal feedstuffs.

Biochemical Principles

All matter, whether living or non-living, is made up of atoms the atom is the smallest unit of matter capable of entering into a chemical reaction. Atoms can combine together by bonding, to form molecules, which range from the small and simple to the large and complex. The latter are known as macromolecules major cellular constituents such as carbohydrates and proteins belong to this group and it is with these that this chapter is mainly concerned (Table 2.1). In order to appreciate how these macromolecules operate in the structure and function of microbial cells however, we need to review the basic principles of how atoms are constructed and how they interact with one other.

The Substances Of Life

A useful simplification of biological organisms sometimes made by environmental engineers and scientists is to view them as catalysts for chemical reactions, such as the oxidation of ammonia or ferrous iron, or production of methane and carbon dioxide from acetic acid. Such a view hides the detailed mechanisms, including the sequence of chemical intermediates and the specific chemical nature of the catalyst. Examining these details will help us to understand more complex chemical interactions between organisms and their environment, such as biodegradation of toxic organic chemicals or the effect of chemicals on the health of organisms and ecosystems. The details of biochemistry begin with knowledge of the four most important types of chemical substances comprising living things carbohydrates, lipids, proteins, and nucleic acids. Later, in the chapters on toxicology, we consider the biochemical reactions involving xenobiotic compounds (those that are, literally, foreign to life,'' that...

The Composition Of Living Things

Four groups of compounds are of primary importance in living things carbohydrates (including sugars, starches, cellulose, and glycogen), lipids (fats and oils), proteins, and nucleic acids (which form DNA and RNA). The first three of these form the majority of cell dry weight and are important for structural material, energy metabolism, and other metabolic functions. Nucleic acids are significant in reproduction and in energy metabolism. Finally, there are many compounds that do not fit neatly into these categories or may be hybrids of two or more.

Use of Glycosyl Transferases

Of reagent to protein or by the length of reaction. It should be borne in mind that these modifications generally produce a distribution of different sugar substitution in terms of both position and number. However, the ability to vary the degree of substitution turned out to be a great advantage for probing of carbohydrate function in many biological systems that is not readily available in natural glycoproteins. This is because recognition of carbohydrates often requires multivalency (Glycoside Clustering Effect) in order to manifest its function unequivocally. Neoglycoproteins can readily provide multivalency and thus are powerful ligands for carbohydrate binding.

Antibodyantigen Intermolecular Forces

The different types of bonds occurring in the specific interaction between antigen (Ag) and antibody (Ab) molecules are all of the weak physical variety. The three different classes of bonding forces in question are (not necessarily in the order of their relative importance) 1) van der Waals or electrodynamic forces 2) hydrogen bonding or polar forces 3) electrostatic forces. Covalent bonds are not involved in Ag-Ab interactions. These physical, noncovalent forces also provide the bonds between other biological entities, such as various ligand and cell surface receptors, carbohydrates and lectins, and enzymes and their substrates. (In enzyme-substrate reactions however, covalent bonds can also occur, in addition to the three types of physical forces mentioned above.)

Examination of Glycoprotein Structure Function Relationship

Cys (in lieu of Asn) in the Fc domain and glycosylthiols of various structures to examine the effect of glycan structure on Fc receptor binding activity. Moreover, if the amino acid sequence and X-ray structure are known, one can place a Cys at different surface locations by genetic engineering, which would provide more latitude in examination of the role of carbohydrates on glycoproteins.

Test systems and approaches to cell surface antigen characterization Table

The discovery of differentiation antigens established cell surface serology as a new approach to studying general aspects of cellular differentiation, first in cells of hematopoietic origin and subsequently in other cell lineages. With recent developments in serologic, biochemical and genetic techniques and test systems, the study of cell surface differentiation has been vastly expanded and it is now possible to carry out a comprehensive survey of tissue-specific cell surface antigen display. First, hybridoma technology permits sampling of common and rare immune responses and permits rapid analysis of large numbers of monoclonal antibodies (mAbs) without the elaborate specificity controls required for complex hetero- and xenoantisera. Thus, over the past years, mAbs have been used to define hundreds of new cell surface antigens, primarily in humans and mice. Second, indirect immunofluorescence staining combined with cyto-fluorometry and cell sorting and other...

Type 2 Tindependent antigens

CD21 is associated in the B cell membrane with the CD19 signal transduction complex, and thus can generate an acti-vatory signal. In addition, B cells, macrophages and other cells express carbohydrate receptors of various kinds specificities C-type lectins (selectins, collectins) and others (e.g. galectins). These animal lectins play a role in cell adhesion, phagocytosis and cell activation as well as in interactions of cells with glycosylated serum proteins. In addition, they can recognize carbohydrates on microbial antigens, and thus probably participate in T-independent polysaccharide-specific antibody responses (e.g. the B cell signaling molecules CD23 and CD72 have C-type lectin domains. More generally, the 'adjuvant effect' of type 2 antigens is their capacity to activate accessory cells and induce cytokine secretion by such cells (phagocytes, inflammatory cells, etc.). In principle, activated bystander T cells can also participate in type 2...

Principles of Chromatography High-Performance Liquid Chromatography (HPLC) HPLC, one of the most common chromatographic techniques performed by food scientists, is an analytical technique well suited to the separation and identification of biological molecules such as proteins, nucleic acids, phenolic compounds, carbohydrates, and lipids. With the development of stationary phases with very small particles sizes and large surface areas, HPLC improves elution rates by applying high pressure to the solvent flow. The result is high resolution of a solute into its individual components in a relatively short period of time (typically between 10-60 Min). Unknown compounds are identified by comparing their retention times (that is, the amount of time required for the compound to elute from the column under specific experimental conditions) to those of known standards, either alone or in combination. The computerized systems in use today are relatively simple to use as they are largely automated and can be...

Functional and Pharmacological Components of Foods and Drinks

There is growing interest, particularly in the food and beverage industry, in developing foods and drinks with functional properties (nutraceuticals) attractive to the consumer. These include effects on behavior, such as improvements in cognitive function, mood, and physical performance. Components of interest include caffeine, herbal extracts such as ginkgo biloba and panax ginseng, micronutrients, essential fatty acids, amino-acids, and carbohydrates. There is some support for beneficial effects of these components, but they are not reviewed further here.

Blood Group Genotyping

Blood group antigens are polymorphisms of proteins and carbohydrates on the outside surface of the red blood cell (RBC) (Fig. 1) and are defined by serum alloantibodies produced in response to an immunizing event such as transfusion or pregnancy. It is the antibody that causes clinical problems in transfusion incompatibility, maternal-fetal incompatibility, and autoimmune hemolytic anemia.

Digestion and Metabolism

The lower gastrointestinal tract can also be a potentially important site affecting the bioavailability of bioactive substances found in food. In this regard, intestinal bacteria found in the large intestine can influence bioavailability. Bacteria are instrumental in the metabolic conversion of certain phytonutrients into forms that are more readily absorbed. In addition, bacteria likely play an important role in the enhancing effects of prebiotics on mineral bioavailability. Consumption of nonabsorbable carbohydrates, such as inulin, can have a positive effect on mineral absorption. A possible mechanism of this effect is that the nonabsorbable carbohydrates pass the small intestine and enter into the large intestine where they serve as a food substrate for bacteria. The metabolism of these prebiotic substances by intestinal bacteria lowers the pH of the lumen of the large intestine and may thereby

Amino Acids and Protein

In brain rapidly influences the rate of 5HT synthesis raising brain TRP concentrations increases synthesis, while lowering brain TRP decreases synthesis. Brain TRP uptake and concentrations are directly influenced by the plasma concentrations of TRP and its BBB LNAA transport competitors. The plasma concentrations of TRP and the other LNAA are readily modified by food intake, thereby linking diet to brain 5HT synthesis. Dietary proteins and carbohydrates are the food components that change brain TRP and 5HT carbohydrate ingestion increases plasma TRP, while lowering the plasma concentrations of its LNAA competitors, causing BBB TRP uptake, brain TRP concentrations, and 5HT synthesis all to increase. The ingestion of a meal containing protein raises plasma concentrations of both TRP and its LNAA competitors. As a consequence, TRP experiences no change in competition for BBB transport (and sometimes a reduction, at highprotein intakes), and brain TRP concentrations and 5HT production do...

Functionality and Limitations

The parent CDs are cyclic carbohydrates consisting of a variable number of glucopy-ranose units linked by 1,4-glycosidic bonds. The chemical structure of p-CD (Fig. 1) shows the cyclic nature and the three hydroxyl groups on each glucopyranose unit. Two of the hydroxyls are secondary alcohols and are located at the C2 and C3 positions of the glucopyranose unit. The third hydroxyl is a primary alcohol at the C6 position.

Introduction to Leukocytes

Diverse in their functions and characteristics, leukocytes do have two properties in common that utilize membrane proteins the need to adhere to other cells and the engagement of signaling pathways to carry out effector activities, including, in some cases, proliferation. Adhesion is carried out by an assortment of cell-surface proteins and carbohydrates, whose select distribution among various tissues and at different stages of cell development and differentiation regulate the migration and ultimate cellular interactions of leukocytes. Signaling is a profoundly complex process utilizing seemingly countless proteins, including those at the plasma membrane that initiate the pathway that extends through the cytoplasm to the nucleus. Lymphocytes (T-cells, B-cells) undergo a special recognition process wherein interaction of their cell-surface antigen receptors with antigen results in a signal requisite for proliferation and differentiation. In the case of...

Biomolecular Engineering Metabolic Engineering

Modification of metabolic storage products or secondary metabolic pathways, which often have relatively flexible roles in plant biology, has also been generally more successful than manipulations of primary and intermediary metabolism (DellaPenna, 2001). Thus, exploiting the full biosyn-thetic capacity of food crops requires a thorough knowledge of the metabolic routes in plants and the regulatory processes involved in plant biochemistry (Galili et al., 2001). When novel branch-points in plant metabolic pathways are introduced by genetic engineering, the introduced enzyme or enzymes must possess a sufficiently high affinity for their sub-strate(s) to compete with endogenous enzymes (Jacobsen and Khosla, 1998). In addition, the effects of novel carbohydrates, proteins, or lipids on plant physiology and development may limit the range and quantity of products that can be synthesized. The tissue and or cellular compartment in which the compound is produced may also limit accumulation of...

Energy Metabolism Of The Brain As A Whole Organ

Indeed, the oxygen consumption of the brain, which accounts for almost 20 of the oxygen consumption of the whole organism, is 160 mol per 100 g of brain weight per minute and roughly corresponds to the value determined for CO2 production. This O2 CO2 relation corresponds to what is known in metabolic physiology as a respiratory quotient of nearly 1 and demonstrates that carbohydrates, and glucose in particular, are the exclusive substrates for oxidative metabolism. This rather detailed information of whole-brain energy metabolism was obtained by using an experimental approach in which the concentration of a given substrate in the arterial blood entering the brain through the carotid artery is compared with that present in the venous blood draining the brain through the jugular vein (Kety and Schmidt, 1948). If the substrate is used by the brain, the arteriovenous (A-V) difference is positive in certain cases, the A-V difference may be negative, indicating that metabolic...

Nutritional Importance

The Food and Agriculture Organization (FAO) and the World Health Organization (WHO) expert consultation on carbohydrates use the term 'sugar' to describe monosaccharides and disaccharides. Sugars can be separated analytically from the food matrix by gas-liquid chromatography (GLC), high performance liquid chromatography, and enzymatic methods. Sugars are widely used in the food industry as sweeteners and preservatives. They improve the texture, body, palatability, and viscosity of foods and beverages.

Glucose Production by the Liver and Kidneys

It is vital that the organism synthesizes glucose for those tissues that are unable to synthesize glucose. In humans, liver glycogen stores can sustain the body for 18 h without the ingestion of dietary carbohydrates. After this period, the liver must produce glucose for transport to other organs. The liver is the main gluconeogenic contributor (90 ), while the kidney contributes gluconeogenically produced glu-

Dietary Sources and Intakes

The major sources of carbohydrates are cereals, accounting for over 50 of carbohydrate consumed in both developed and developing countries, followed by sweeteners, root crops, pulses, vegetables, fruit, and milk products. Carbohydrate and nutrient intake in general can be estimated using data from food production and balance sheets, household surveys, and individual assessments (Table 1). Figure 1 shows the trends in carbohydrate consumption by

Requirements and Recommendations

The DRIs for carbohydrate consumption of individual groups and lifestages are outlined in Table 2. These values are based on the average minimum amount of glucose needed for brain function. A UL for carbohydrates was not set because no studies have shown that excessive consumption of carbohydrates has a detrimental effect on health. Based on the dilutional effect of added sugars on micronutri-ents, the expert panel suggests a maximal intake of less than 25 of energy from added sugars. Total sugar intake can be decreased by limiting foods high in added sugars and consuming naturally occurring sugar products, like milk, dairy products, and fruit. There is insufficient evidence to support a recommendation by the IOM for the consumption of low-GI foods or the replacement of high-GI foods, like bread and potatoes. Although several studies propose adverse effects of high-GI carbohydrates and beneficial effects of low-GI foods, a recommendation on consumption of low-GI foods is a major...

Resistant Starch Definition

In 1992, a concerted action of European researchers defined resistant starch as ''the sum of starch and the products of starch degradation not absorbed in the small intestine of healthy individuals.'' This concept completely changed our understanding of the action of carbohydrates in the diet because up until the early 1980s, it was thought that starches were completely digested and absorbed in the human small intestine. Three important considerations are attached to this physiological definition. First, resistant starch is made up not only of high-molecular weight polymers but also can include dextrins, small oligosaccharides, and even glucose, all derived from digested starch that escapes absorption. Second, resistant starches reach the human large intestine where they are metabolized by the complex colonic microflora. Finally, the actual amount of resistant starch in a food (i.e., the amount reaching the colon) depends on the physiology of the individual and it may be affected by...

Oxidation of Fats and Amino Acids

The acetyl-CoAs produced then enter the Krebs cycle, where they are further oxidized. In addition, for every acetyl-CoA formed, one NADH2 and one FADH2 are formed, feeding the electron transport system production of ATP. This accounts for the high-energy yield of fats in comparison to carbohydrates.

Microbial Nutrition and Cultivation

You will recall that carbon forms the central component of proteins, carbohydrates, nucleic acids and lipids indeed, the living world is based on carbon, so it should come as no surprise that this is the most abundant element in all living cells, microbial or otherwise. Of the other macronutrients, nitrogen, oxygen, hydrogen, sulphur and phosphorus are also constituents of biological macromolecules, while the remainder (magnesium, potassium, sodium, calcium and iron in their ionised forms) are required in lesser quantities for a range of functions that will be described in due course. Micronutrients are all metal ions, and frequently serve as cofactors for enzymes.

Transphosphatidylation by Lipid Coated Phospholipase in a Water Organic Two Phase System

We have applied this system to produce some practical phospholipid derivatives having amino acids, carbohydrates, and deoxyribonucleotides, as shown in Fig. 7. The lipid-coated PLD acts as an efficient catalyst to hydrophobize the water-soluble drug, such as saccharide, amino acid, and nucleic acid, resulting from the introduction as a head group of phospholipids.

The Initiation of Protein NLinked Glycosylation in the ER

As proteins enter the ER lumen, they fold and assemble with the help of chaperone proteins. Many proteins are also co-translationally modified by the addition of carbohydrates to asparagine residues in the process of N-linked glycosylation (Figure 2). A preformed oligosac-charide, consisting of three glucoses, nine mannoses, and two N-acetylglucosamine residues (Glc3Man9GlcNAc2) is transferred to accessible asparagine residues in the tripeptide sequence asparagine-X-serine or threonine (X cannot be proline) by the oligosaccharide protein transferase complex. Subsequent modification by glyco-sidases (enzymes that remove monosaccharides) and glycosyltransferases (enzymes that add monosacchar-ides) in the ER and Golgi lead to the remodeling of the N-linked oligosaccharides. These N-linked carbohydrates help proteins fold, protect them from proteo-lytic degradation and, in some cases, are critical for modulating and mediating protein and cell interactions at the cell surface and in the...

Beneficial Effects Of Ca Storage

The rate of respiration of fresh fruits and vegetables has been shown to be reduced by low 02 or high C02 (12). The lower respiration rate indicates that CA has an inhibitory effect on the overall metabolic activities of stored commodities. A slower rate of utilization of carbohydrates, organic acids, and other reserves usually leads to prolonging the life of the produce. A slower decline in carbohydrates under CA has been reported in sugar beet, Chinese cabbage, apricots, and peaches (21,22,23). CA storage is also beneficial in the retention of ascorbic acid and amino acids in several fresh fruits and vegetables (3,22,24,25).

Synergistic Action Of Pufa

Nevertheless, there are some exciting avenues to explore, of which one is the already mentioned possible role of PUFAs in the ketogenic diet, as is covered in Chapter 17. Another aspect is the enhancement of the action of conventional drugs by nanomolar concentrations of PUFAs. This interesting phenomenon was observed at very low doses

Carbohydrate Antigens

Cornells PJ Glaudemans, Chief, Section on Carbohydrates, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA Carbohydrates, containing n asymmetric carbon atoms, can exist in 2 stereoisomeric forms. A common hexose possesses a priori four asymmetric carbon atoms (C-2, -3, -4 and -5) and thus can exist in 16 stereoisomeric forms (i.e. d-glucose, L-glucose, d-mannose, L-mannose, etc.). Each of these isomers can occur in either a six-membered (pyranose) or five-membered (furanose) ring form. When a hexose is in the ring form, the C-l aldehyde function also becomes asymmetric, and the 1-hydroxyl group can assume either the a or the (3 configuration, thereby doubling the number of possible isomers. In total, a hexose can thus occur in an oligo- or polysaccharide in 64 different ways. This enormous capability for diversity makes carbohydrates very versatile as nature's alphabet for recognition in biological events,...

Conformation in solution

Polysaccharides as well as the oligosaccharide components of glycoproteins and glycopeptides and glycolipids may be linear or branched, homo- or heteropolymer, neutral or charged. These oligo- and polysaccharides can assume tertiary (globular) structure, and in some cases the particular spacial presentation of a carbohydrate becomes critical in dictating the immunologic specificity. For instance, Jennings and associates have evidence that the capsular polysaccharide of group B streptococcus assumes a conformation in which short, sialic acid-terminated side-chains each form a hydrogen bond with an intra-chain GlcNAc nearby. That results in an immunologically specific conformation. This, even though the sialic acid itself is not a (contact) immunodetermin-ant, and apparently only functions as the vector in creating the correct conformational rigidity. However, it must be kept in mind that for carbohydrates, conformational changes on the polymeric level are easier to achieve (i.e. have...

Improvement of Plant Nutritional and Functional Quality

Human beings require a diverse, well-balanced diet containing a complex mixture of both macronutrients and micronutrients in order to maintain optimal health. Macronutrients, carbohydrates, lipids, and proteins make up the bulk of foodstuff and are used primarily as an energy source (Guzm n-Maldonado and Paredes-L pez, 1999). Modifying the nutritional composition of plant foods is an urgent worldwide health issue, as basic nutritional needs for much of the world population are still unmet (DellaPenna, 1999 Guzm n-Maldonado and Paredes-L pez, 1999 Kishore and Shewmaker, 1999 Mazur et al., 1999). Large numbers of people in developing countries exist on diets composed mainly of a few staple foods which usually present poor food quality for some macronutrients and many essential micronutri-ents (DellaPenna, 1999 Guzm n-Maldonado and Paredes-L pez, 1999 Kishore and Shewmaker, 1999 Mazur et al., 1999).

Structure And Physiology Of Angiosperms

The root is the underground portion of the sporophyte. Their main function is anchorage and absorption, but they may also be used in storage (as in carrots and potatoes). Monocots form a shallow fibrous root system. Gymnosperms and most dicots form a main root called a taproot that grows straight down. Roots of some trees have been found to penetrate 30 to 50 m into the soil. Most of the tree roots involved in absorption are in the top 15 cm and extend out beyond the crown of the tree. Roots of the corn plant (Zea mays) penetrate up to 1.5 m, and spread horizontally 1 m around the plant. The surface area of roots is greatly increased by the formation of root hairs, which grow from cells at the surface of the roots (Figure 7.3). As the plant grows, it maintains a balance between the leaf surface area and root surface area, so that water, minerals, and carbohydrates are formed in the proper proportion for growth. The roots absorb minerals by active

Protein Targeting to the Lysosome

The lysosome is a degradative compartment that contains numerous acid hydrolases that function to digest proteins, lipids, and carbohydrates. The trafficking of the majority of lysosomal enzymes to the lysosome requires mannose 6-phosphate residues on these enzymes' N-linked sugars. The mannose 6-phosphate residues are recognized by receptors in the TGN that mediate the incorporation of the new lysosomal enzymes into clathrin-coated vesicles destined for the late endosome compartment (Figure 3). These clathrin-coated vesicles move from the TGN and fuse with the late endosome, where a decrease in lumenal pH causes the lysosomal enzymes to dissociate from the mannose 6-phosphate receptors. The enzymes are then transported to the lysosome, while the receptors recycle to the TGN. Some lysosomal membrane proteins are also trafficked in clathrin-coated vesicles to the lysosome like the soluble enzymes but without the use of a mannose 6-phosphate marker, while others are transported to the...

Protein Synthesis In Nervous Tissue

Palade Experiment Secretory Pathway

In addition to the processing of carbohydrates in the Golgi, posttranslational modifications can take place in other subcellular compartments. Some protein glycosylations are modified further post-Golgi in components of the smooth endoplasmic reticulum or transport vesicles, as described later in this section. Finally, some neuropeptides (adrenocorticotropic hormone, enkephalins, etc.) are synthesized as sequence domains in large precursor proteins that must be cleaved in transit by specific proteases to form the biologically active form.

Physical And Chemical Body Composition

The main body tissues in growing animals are muscle or lean tissue, fat, visceral organs, bones, and skin. The other tissues, including nervous, lymphatic, and vascular tissue, and blood contribute less than 10 to empty body weight in growing animals and are discussed in detail elsewhere in this encyclopedia. The three main chemical constituents in the animal's empty body are water, protein, and lipid. Most of the body water and body protein is contained in muscle tissue, whereas body lipid is largely present in fat tissue. The animal's body contains only minor amounts of carbohydrates, which largely represent glycogen stores in the liver and muscle. The mineral and vitamin content in animal products is low relative to the three main chemical constituents, but animal products represent an important source of these essential nutrients for humans. Moreover, the bio-availability of nutrients in animal products is generally higher than that in plant products.

Decomposition of Organic Carbon Compounds in Natural and Manmade Ecosystems

Biological degradation of recent biomass and of organic chemicals during solid waste or wastewater treatment proceeds either in the presence of molecular oxygen by respiration, under anoxic conditions by denitrification, or under anaerobic conditions by methanogenesis or sulfidogenesis. Respiration of soluble organic compounds or of extracellularly solubilized biopolymers such as carbohydrates, proteins, fats, or lipids in activated sludge systems leads to the formation of carbon dioxide, water, and a significant amount of surplus sludge. Some ammonia and H2S may be formed during degradation of sulfur-containing amino acids or heterocyclic compounds. Oxygen must either be supplied by aeration or by injection of pure oxygen. The two process variant for oxygen supply differ mainly in their capacity for oxygen transfer and the stripping efficiency for carbon dioxide from respiration. Stripping of carbon dioxide is necessary to prevent a drop in pH and to remove heat energy. Respiration...

Processing MHC presentation

HIV-1 interactions with DC-SIGN on dendritic cells (DCs). DC-SIGN is expressed at high levels on DCs and binds to carbohydrates present on the surface of the heavily glycosylated HIV-1 envelope protein. Binding of HIV-1 to DC-SIGN-positive DCs can have multiple consequences. During a relatively short time window (hours) bound virus can be transferred to adjacent susceptible cells (short-term transfer). Certain HIV-1 isolates can also productively infect DCs via CD4 and a chemokine coreceptor. Prior engagement of DC-SIGN might augment infectious entry. Progeny virions produced from infected DCs can then be efficiently transmitted to cocultured T cells over a prolonged time period (days, long-term transfer). Finally, HIV-1 captured by DC-SIGN can be endo-cytosed and processed for MHC presentation. DC-SIGNR 11 , also termed L-SIGN (for liver SIGN) 91 , shares 77 sequence identity with DC-SIGN and is expressed by sinusoidal endothelial cells in liver (LSECs) and in lymph nodes,...

Caries Causing Bacteria

6 months of age) and continues throughout life. There is evidence to suggest that the initial colonization of a baby's teeth with cariogenic bacteria may arise by infection from the mother's mouth. The common practice of sampling the food in a baby's dish, to check that it is not too hot, using the same spoon that is to be used to feed the baby may be a particularly effective way of transferring bacteria from carer to baby. Brushing the teeth with a toothbrush will remove part, but not all, of this film and its accompanying bacterial population. Many of the bacteria present are harmless, but a number of species are capable both of metabolically converting carbohydrates to acids (acidogenic bacteria) and of continuing to be metabolically active when the local pH has become too acid for most bacteria to tolerate. It is these bacteria that cause caries.

Fermentable Carbohydrate

Starches are also classed as fermentable carbohydrates because they are partially broken down by amylase in saliva during chewing to maltose and glucose. Residues of starchy foods are frequently caught between the teeth and in the fissures of the molar teeth, where they may be broken down to sugars over long periods. Measurements of the pH of plaque following the ingestion of starches have suggested that the depression of pH may be as great as and last even longer than that produced by some sources of sugars, such as drinks, because of slow clearance. Highly processed starchy products, such Clearly, the wide range of individual dietary choices and eating habits may influence the risk of developing caries. The physical characteristics of fermentable carbohydrates will affect the rate at which they are cleared from specific sites in the dentition. Foods that are inclined to remain for long periods in stagnation sites (for example, between the teeth), such as toffees or raisins, are...

Basic Biology Mass and Energy Balance of Aerobic Biopolymer Degradation

To make soluble and insoluble biopolymers - mainly carbohydrates, proteins, and lipids - accessible for respiration by bacteria, the macromolecules must be hydro-lyzed by exoenzymes, which often are produced and excreted only after contact with respective inductors. The exoenzymes adsorb to the biopolymers and hydrolyze them to monomers or at least to oligomers. Only soluble, low molecular weight compounds (e.g., sugars, disaccharides, amino acids, oligopeptides, glycerol, fatty acids) can be taken up by microorganisms and be metabolized for energy production and cell multiplication. When carbohydrates are respired by aerobic bacteria, about one third of the initial energy content is lost as heat, and two thirds are conserved biochemically in 38 phosphoanhydride bonds of ATP. In activated sludge reactors or in wastewater treatment ponds that are not loaded with highly concentrated wastewater, wall irradiation and heat losses with the off-gas stream of aeration into the atmosphere...

Practical Approach to the Prevention of Caries

Where a tooth site is shielded from saliva (stagnation site) and oral hygiene and the availability of fluoride are insufficient it is likely that a dietary modification of sufficient magnitude could exert some influence on the final outcome. But where these protective factors are adequate it is highly unlikely that dietary variations will exert any material effect. These predictions are borne out by epidemiological observations. In most developed countries, where fluoride use is adequate, wide variations in dietary exposure to fermentable carbohydrates between individuals are not accompanied by predictable differences in caries experience.

Monosaccharides and Disaccharides

The simplest of the carbohydrates, the monosaccharides, are either aldehydes or ketones with two or more hydroxyl groups the six-carbon monosaccharides glucose and fructose have five hydroxyl groups. Many of the carbon atoms to which hydroxyl groups are attached are chiral centers, which give rise to the many sugar stereoisomers found in nature. We begin by describing the families of monosaccharides with backbones of three to seven carbons their structure and stereoisomeric forms, and the means of representing their three-dimensional structures on paper. We then discuss several chemical reactions of the carbonyl groups of monosaccharides. One such reaction, the addition of a hydroxyl group from within the same molecule, generates the cyclic forms of five- and six-carbon sugars (the forms that predominate in aqueous solution) and creates a new chiral center, adding further stereochemical complexity to this class of compounds. The nomenclature for unambiguously specifying the...

Physiology of Normal Blood Glucose Regulation

The metabolic fate of ingested glucose is determined by the interplay of multiple hormones. Insulin is of major importance in this homeostasis, but glucagon, glucocorticoids, catecholamines, and growth hormone also have significant effects that are interactive with insulin. Glucose ingested with a meal or derived from the digestion of other dietary carbohydrates is rapidly absorbed by the small intestine. It is carried first to the liver by the portal vein, where a substantial portion (30-70 ) is removed the remainder enters the peripheral circulation, where regulated insulin secretion and target tissue responses to insulin contribute to glucose clearance and control of blood glucose levels (Figure 1). Carbohydrates Glucose Carbohydrates Glucose

Malabsorption of Nutrients

Malabsorption in diarrheal illness may result from the epithelial destruction by the pathogen. Diminished nutrient absorption often begins during acute diarrhea. At this time, the body is less able to absorb needed macronutrients, including fats and proteins, as well as some carbohydrates. This is most severe in undernourished children who suffer from persistent diarrhea due to damage to the gut epithelium. When the gut is damaged, food is not properly digested or absorbed. The causes of insufficient nutrient absorption include diminished concentration of bile acids, which are used for fat absorption damaged epithelial cells, which provide the absorptive surface on the bowel and a deficiency of disaccharides due to damaged microvilli, which normally produce the needed enzymes. In symptomatic rotavirus infection, the most common cause of acute severe diarheal illness worldwide, there is a 42 decrease in the absorption of nitrogen and fat, a 48 decrease in absorption of carbohydrates,...

Drawbacks Of Sample Abuse

Unless one is handed a bottle of salad oil, it is usually necessary to consider that the lipid classes of Figure 3.1 are dispersed in some sort of food matrix. At one time, a sausage was considered one of the toughest food items on which to perform an extraction, although a chicken pot pie is a close second (Sheppard et al., 1974 Hubbard et al., 1977). Historically, analysts regarded oven drying as an essential first step in sample proximate analysis, because moisture content was needed in any event and a dry sample could be conveniently ground and homogenized. Unfortunately, the oven drying created two problems. One was that the fats or lipids might be encased in dry protein or some similar matrix that solvent could penetrate only with difficulty (Happich et al., 1984 de Koning and Mol, 1989). The second difficulty created was the potential for oxidation of polyunsaturated fatty acids. Until modern chromatographic methods were introduced, it was not appreciated that not only did...

Protein And Amino Acid Needs Of Broilers

The need for crude protein reflects a need for the amino acids needed by the broiler. Some of these amino acids, considered as nutritionally indispensable, must be present in the diet in adequate amounts. Others, considered as nutritionally dispensable, can be synthesized from other closely related amino acids or from structurally related fats or carbohydrates through the process known as transamination. Although there is not a specific requirement for crude protein per se, sufficient protein must be present to support a nitrogen pool for synthesis of the dispensable amino acids. At the present time, it is not possible to suggest a minimum crude protein level that will sustain adequate performance in broilers of different ages.

Selective Plating Media

These are formulated so that Salmonella may appear in the form of discrete colonies, whereas the growth of competing non-Salmonella microorganisms is suppressed. Non-Salmonella colonies are generaly distinguished by their ability to produce hydrogen sulfide, and to utilize one or more carbohydrates incorporated in the media. Selective media that have been used for the isolation of Salmonella include brillant green (BG), bismuth sulfite (BS), Salmonella shigella, MacConkey's, desoxycholate citrate, Hektoen enteric (HE), xylose lysine desoxycholate (XLD), and xylose lysine brillant green.

Ivtotal Fatty Acid Recovery

The objective of lipid extraction is varied. Increasingly, it develops from requests for specific information on cholesterol and fatty acids. There is thus very little reason to bother with lipid extraction. Instead, total lipid recovery may be bypassed, and the sample may be digested under nitrogen to destroy the protein food matrix. Traditionally, as in the Association of Official Analytical Chemists' (AOAC) method 18.043 (Williams, 1984), concentrated HCI was used to digest carbohydrates and so on, but in practice alcoholic alkali will do this job more efficiently (Kovacs et al., 1979).

Theoretical Bases

There is a significant genetic component to the development of obesity, and it is generally believed that some interaction of genetics and environment may predispose selected persons to gain weight. For example, one genotype may predispose someone who consumes a diet high in fat to become obese. Another genotype may predispose someone who consumes a high carbohydrate diet to become obese. The focus of a behavioral intervention incorporates modification of eating behaviors and physical activity to yield energy imbalance. Figure 1 illustrates the relationship between body weight and changes in energy intake and energy expenditure.

Hydrolysis of Cellulose by Aerobic and Anaerobic Microorganisms Biological Aspects

Glycosyl hydrolases are involved in cellulose and hemicellulose degradation by cleaving glycosidic bonds between different carbohydrates and between carbohydrates and noncarbohydrates. Endo- and exocellulases - in some organisms organized in cellulosomes - must be excreted into the medium. Cellulases are complex biocatalysts and contain a catalytic site and a substrate-binding site. The presence of a noncatalytic substrate binding site permits tight attachment to the different forms of cellulose substrate and keeps the enzyme close to its cleaving sites. Substrate binding is reversible, which allows the enzyme to 'hike' along the fibers and obtain total solubilization. Many aerobic fungi and some bacteria excrete endoglucanases that hydrolyze the amorphous region of cellulose (degradation within the chain), whereas exoglucanases hydrolyze cellulose from the ends of the glucose chains. Cel-lobiose is cleaved off by cellobiohydrolases from the nonreducing ends in the amorphous region,...

Maternal High Fat Consumption

In today's Western, more affluent society, the in utero environment is likely to be influenced by maternal nutritional insults such as excess fat consumption. There is little dispute regarding the deleterious effects of a high-fat diet. It is well documented that a diet high in fat has played a fundamental role in the prevalence of type 2 diabetes, reaching the epidemic proportions that is seen today. Both human epidemiological studies and experimental animal investigations have demonstrated clear associations between the consumption of a high-fat diet and the increasing prevalence of cardiovascular disease, insulin resistance, and type 2 diabetes. In light of this, a high-fat diet can increase the risk of a pregnant woman developing gestational diabetes. As will be discussed later, it is well established that offspring of diabetic mothers are themselves at an increased risk of developing the disease at an early age. Consumption of a high-fat diet may not only therefore cause...

Cultural Overview

Elk, deer, antelope, and smaller game were hunted, as well as bison. Blackfoot disdained fish but do eat trout. Berries, prairie turnips (an indigenous root vegetable), and camas bulbs (a lily) were significant carbohydrates in the diet, with a stew of meat. Women had the responsibility of collecting vegetable foods from carefully sustained fields, and of preparing family meals. They also tanned hides, cut and sewed clothing and tipis, made containers (mostly of hide), collected firewood, and packed and set up camps. Men had the responsibility of providing the animals to be processed, defending the nation, and learning and performing often lengthy rituals, assisted by their wives.

Fats And Oils Flavors

The isolation, separation, and identification of volatile compounds from fats and oils is difficult due to their chemical complexity, variations in concentrations and volatilities, interactions between the volatile compounds themselves, and also reactions between the volatile compounds and food components such as proteins and carbohydrates (1). The mechanisms responsible for the production of volatile flavor compounds during oxidation must be thoroughly studied and understood to improve the flavor quality of fats and oils.

Metabolism of lipids and proteins

We have concentrated so far on the metabolism of carbohydrates, but both lipids and proteins may also act as energy sources. Both are converted by a series of reactions to an intermediate compound that can then enter the pathways of metabolism we have discussed above. Proteins are a less useful source of energy than lipids or carbohydrates, but may be utilised when these are in short supply. Like lipids, they are initially hydrolysed to their constituent 'building blocks', in this case, amino acids. These then undergo the loss of an amino group (deamination), resulting in a compound that is able to enter, either directly or indirectly, the TCA cycle.

Egg Macronutrient and Micronutrient Content and Distribution

Hen eggs contain 75.8 water, 12.6 protein, 9.9 lipid, and 1.7 vitamins, minerals, and a small amount of carbohydrates (Table 2). Eggs are classified in the protein food group, and egg protein is one of the highest quality proteins available. Virtually all lipids found in eggs are contained in the yolk, along with most of the vitamins and minerals. Of the small amount of carbohydrate (less than 1 by weight), half is found in the form of glyco-protein and the remainder as free glucose.

Small size as an ecological response

Rich in macromolecules which are denser than water, including proteins ( 1300 kg m 3), carbohydrates ( 1500 kg m 3), and nucleic acids ( 1700 kg m 3). These molecules are contained within an aqueous cytosol, and the overall density of phytoplankton cells or colonies is typically > 1050 kg m 3. This may be considerably increased by the presence of dense inorganic inclusions such as polyphosphate bodies ( 2500 kg m 3) and opaline silica cell wall material ( 2600 kg m 3). Conversely, cell density can be reduced by the internal presence of low-density lipids (860 kg m 3), gas vacuoles, and the occurrence of external mucilage.

Roles of Molecular Hydrogen and Acetate During Anaerobic Biopolymer Degradation

Molecular hydrogen is produced during different stages of anaerobic degradation. In the fermentative stage, organisms such as Clostridium sp. and Eubacterium sp. produce fatty acids, CO2, and hydrogen from carbohydrates. In the acetogenic stage, acetogens such as Syntrophobacter wolinii and Syntrophomonas wolfei produce acetate, CO2, and hydrogen or acetate and hydrogen by anaerobic oxidation of propionate and n-butyrate (Mclnerney, 1988). Fermentative bacteria release molecular hydrogen even at a high H2 partial pressure and simultaneously excrete reduced products (e.g., clostridia, Ruminococcus, Eubacterium sp.). However, the release of molecular hydrogen during acetogenesis of fatty acids or of other reduced metabolites may occur only when hydrogen does not accumulate, for thermodynamic reasons. Molecular hydrogen is consumed by methanogens (Table 1.4, reaction 1) or, alternatively, by sulfate reducers (Table 1.4, reaction 2) via interspecies hydrogen transfer. In the rumen and in...

Gross and Metabolizable Energy

The traditional way of measuring the energy content of foostuffs is to use a 'bomb calorimeter' in which the heat produced when a sample of food is combusted (under high pressure of oxygen) is measured. When the food is combusted, it is completely oxidized to water, carbon dioxide, and other incompletely burned elements. The total heat liberated (expressed in kilocalories or kilojoules) represents the gross energy value or heat of combustion of the food. The heat of combustion differs between carbohydrates, proteins, and fats. There are also important differences within each category of macronutrient. The gross energy yield of sucrose, for example, is 16.5 kJg-1, whereas starch yields 17.5 kJg-1. The energy yield of butterfat is 38.5 kJg-1 and of lard 39.6 kJg-1. These values have been rounded off to give 17.3 kJg-1 for carbohydrates rich in starch and poor in sugar, 39.3 kJg-1 for average fat, and 23.6 kJg-1 for mixtures of animal and vegetable proteins.

Biosynthesis of nucleic acids

Pyrimidines have a similarly complex synthesis. The amino acids aspartate and glu-tamine are involved in the synthesis of the precursor orotic acid. Note that unlike the purines, the skeleton of pyrimidines is fully formed before association with the ribose-5-phosphate moiety, which is itself derived from glucose (see biosynthesis of carbohydrates, above).

FTIR Spectra Analysis

Our data showed a gradual disappearance of the peak at 1023 cm-1 over time with the development of herpesviruses infection (29). This spectral peak can be attributed to carbohydrates, as was previously reported (31). There was also a notable decrease in this peak in cells infected with retroviruses (Fig. 1).

Methods In Enzymology

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Basic and Applied Research

(read the message) and assemble the protein. After translation, a protein may be modified by covalent attachment of carbohydrates and lipids to particular amino acids. A molecular biologist might seek to determine the three-dimensional structure of a modified protein using techniques like X-ray diffraction and nuclear magnetic resonance.

Description And Application Of Methods Electromagnetic Radiation

Near-infrared diffuse reflectance spectra are used to predict starch, protein, oil, and moisture contents of grains and oil seeds (6) and sugars in fruit (7,8). Dry matter content of onions and potatoes, mainly carbohydrates, is determined by near infrared wavelengths (9).

Anaerobic Degradation of Neutral Fats and Lipids

Carbohydrates, proteins, fats, and biogenic oils can also be degraded anaerobical-ly under thermophilic conditions. The overall degradation scheme is the same, but the microorganism populations are different (e.g., Winter and Zellner, 1990). Thermophilic fat degradation is becoming more important in practice, since waste fat from fat separators and fat flotates of the food industry are often cofermented in agricultural biogas plants. Since, for hygienic reasons, the input material must be au-toclaved, a thermophilic process should be used, keeping the fat in a melted, soluble form for more effective metabolism. Biogas plants with cofermentation of waste fat residues are considered waste treatment systems (Chapter 11, this volume) and must be designed to meet the hygienic demands relevant to treatment of the respective waste.

Carbohydrate Digestion and Absorption

Dietary carbohydrates include monosaccharides, disac-charides, and polysaccharides. Starch is a glucose-containing polysaccharide. Amylose, which constitutes 10 to 20 of dietary starch, is a long, straight chain of a-1, 4-glucosyl units. Amylopectin, which composes 80 to 90 of dietary starch, also has the straight chain, but with some a-1, 6-branching linkages. Glycogen is similar to amylopectin with more branching linkages. Amylopectin and amylose are of plant origin, whereas glycogen is of

Fermentative Digestion And Nutrient Absorption

The herbivore depends primarily on roughages. No cell wall material of roughages is subject to hydrolysis by mammalian glandular digestive enzymes. The herbivore uses fermentative digestion to break down cell wall material by the action of bacteria and other microorganisms. In the omnivore and the carnivore, fermentative digestion also occurs in the large intestine for carbohydrates and proteins that are not digested by mammalian enzymes in the small intestine.

Anaerobic Degradation of Protein

Eral types of proteases that cleave membrane-permeable amino acids, dipeptides, or oligopeptides. In contrast to the hydrolysis of carbohydrates, which proceeds favorably at a slightly acid pH, optimal hydrolysis of proteins requires a neutral or weakly alkaline pH (McInerney, 1988). In contrast to the fermentation of carbohydrates, which lowers the pH due to volatile fatty acid formation, fermentation of amino acids in wastewater reactors does not lead to a significant pH change, due to acid and ammonia formation. Acidification of protein-containing wastewater proceeds optimally at pH values of 7 or higher (Winterberg and Sahm, 1992), and ammonium ions together with the CO2-bicarbonate-carbonate buffer system stabilize the pH. Acetogenesis of fatty acids from deamination of amino acids requires a low H2 partial pressure for the same reasons as for carbohydrate degradation. This can be maintained by a syntrophic interaction of fermentative, protein-degrading bacteria and acetogenic...

Characteristics of the organism and its antigens

It grows poorly on most ordinary culture media. Growth is, however, well supported on blood agar enriched with L-cysteine and glucose. Chocolate agar, such as used for the isolation of gonococci, also maintains the growth of F. tularensis. F. tularensis is strictly aerobic, weakly catalase-positive, and oxi-dase-negative. Carbohydrates are weakly catabolized with the production of acid but no gas. The organism has a characteristic pattern of cellular fatty acids, including long-chain (C20-C26) acids and the hydroxy acids 2-hydroxydecanoate, 3-hydroxyhexa-decanoate and 3-hydroxyoctadecanoate.

Anatomical Changes With

There are also degenerative changes that occur within the nerve cell body, including accumulation of lipid products, vacuoles, inclusions, and abnormal protein within the cytoplasm. Pigment accumulation or lipofuscin occurs at different rates within different areas of the brain. The large neurons of the precentral gyrus are particularly predisposed to lipofuscin deposits, which are composed of lipids, proteins, and carbohydrates. Neuromelanin, which results from peroxidation of the lipofuscin granules, also occurs in the neurons of the substantia nigra and locus coeruleus. Granulovascular degeneration, which results in the accumulation of cytoplasmic vacuoles, is common in aging. Lewy bodies, commonly found in Parkinson's disease, occur in a small number of healthy aged subjects, whereas colloid inclusions or fine granular material in the cisterns of rough endo-plasmic reticulum are often found in the senescent brain. Marinesco bodies, composed of fine granules and filaments in a...

Consequences of Plant Diversity on the Quality of Carbon Input

Most plant-derived carbon belongs to a small number of chemical structures. These are mainly carbohydrates, organic acids, lipids, lignin, and proteins. Some of them, such as carbohydrates, organic acids, and proteins, are preferred energy sources for soil organisms and thus less recalcitrant in soils than lignin or lipids (Gleixner et al. 2001a). In consequence, the decomposition rate of plant litter will change with litter quality (see also Hattenschwiler, Chap. 8, this Vol.) and stable plant-derived structures may accumulate in soil. Wood for example, as the most abundant plant biomass, mainly consists of cellulose and lignin (Fig. 9.2a, b). Cellulose is chemically less stable than lignin and lignin accumulates, i.e., is selectively preserved, in wood decomposition. This is well known for example for brown rot fungi (Gleixner et al. 1993). bon differs accordingly. However, not only the quality of biomass produced depends on the species composition. The amount and composition of...

Classical Pathway Figure HA30

Complex resulting in auto-activation of C1r, which in turn activates C1s. The next step is activation of C4 with the production of C4b, which avidly binds surface carbohydrates or proteins, thus complement activation is localized to a surface. Like the coagulation cascade, the large number of steps ensures amplification and offer opportunity for regulation. The C4b2a complex catalyses the central step the cleavage of C3.

Total Saturated Fat Content of Diets

Platelet aggregation and clotting activity of plasma were studied in British and French farmers, who were classified according to their intake of saturated fatty acids. A positive correlation was observed between thrombin-induced aggregation of platelet-rich plasma and the intake of saturated fatty acids. Aggregation induced by ADP or collagen, however, did not correlate with dietary saturated fat intake. In a follow-up study, a group of farmers consuming high-fat diets were asked to replace dairy fat in their diets with a special margarine rich in polyun-saturated fatty acids. Besides lowering the intake of saturated fatty acids, this intervention also resulted in a lower intake of total fat. A control group of farmers did not change their diets. After this intervention the thrombin-induced aggregation of platelet-rich plasma decreased when saturated fat intake decreased. Aggregation induced by ADP, however, increased in the intervention group. From these

Coagulation and Fibrinolysis

Saturated fatty acids can affect the plasma activity of some of these coagulation and fibrinolytic factors and thus the prethrombotic state of the blood. However, the effects of saturated fatty acids on coagulation and fibrinolytic factors in humans, unlike effects on cholesterol concentrations, have received little attention, and few well-controlled human studies have been reported. Also, regression equations derived from a meta-analysis, which predict the effects on coagulation and fibrinolytic factors of different fatty acid classes compared with those of carbohydrates, do not exist. Therefore, the reference fatty acid is dependent on the experiment discussed. In the epidemiological studies that have found associations between CHD risk and factors involved in thrombogenesis or atherogenesis, subjects were mostly fasted. Also, the effects of saturated fatty acids on cholesterol metabolism, platelet aggregation, and coagulation and fibrinolysis have been studied mainly in fasted...

Emulsion Science In The Food Industry

Food Emulsions

Most food emulsions are much more complex than the simple three-component (oil, water, and emulsifier) systems described in Section 1.2.1. The aqueous phase may contain a variety of water-soluble ingredients, including sugars, salts, acids, bases, surfactants, proteins, and carbohydrates. The oil phase usually contains a complex mixture of lipid-soluble components, such as triacylglycerols, diacylglycerols, monoacylglycerols, free fatty acids, sterols, and vitamins. The interfacial region may contain a mixture of various surface-active components, including proteins, phospholipids, surfactants, alcohols, and solid particles. In addition, these components may form various types of structural entities in the oil, water, or interfacial regions, such as fat crystals, ice crystals, protein aggregates, air bubbles, liquid crystals, and surfactant micelles. A further complicating factor is that foods are subjected to variations in their temperature, pressure, and mechanical agitation during...

Causes And Manifestations Of Food Deterioration

Microorganisms are ubiquitous living organisms that need nutrients, moisture, appropriate oxygen conditions, and favorable pH ranges to grow. Microorganisms can contaminate our food supply from the point of production or harvest until the time of consumption. Many microbial food contaminants are native to the soil or animal environment from which the food is derived, and many are added unintentionally through handling practices. The components of most foodstuffs (carbohydrates, proteins, etc) serve as ideal nutrients for the growth of microorganisms and this growth leads to potentially harmful populations of microorganisms, potentially harmful buildup of microbial metabolites, for example, toxins, enzymes, polysaccharides, or pigments, and a deterioration in food quality resulting from the metabolism of food constituents, for example, amino acid or fatty acid release from proteins or lipids. Microorganisms important to food deterioration include bacteria, yeasts, and molds. Some...

The role of dairy products in preventing dental caries

An individual's dietary and social patterns are major contributors to one's oral health. The quality of life can be greatly impacted as a result of poor oral health leaving a negative impact on self-esteem, eating ability, and social functioning (Moynihan, 2005). Several oral diseases can be linked back to poor nutrition, and as teeth deteriorate the conditions are exacerbated. Studies (Johansson et al., 1994, Norlen et al., 1993) have shown edentulous individuals are more apt to have inadequate dietary intake (high carbohydrate, high fat, low nutrient density foods) than dentate individuals. Sugars, specifically sucrose, are recognized as being a major contributor to dental caries' etiology. Other social factors such as alcohol and tobacco use, drug abuse, poor hygiene, and poor nutrition are also cited as being major contributory factors to oral diseases. Tooth surfaces are colonized by a variety of bacterial species that hydrolyze dietary carbohydrates to organic acids (Figs 7.2...

Molecular Turnover of Soil Organic Matter

In contrast to current assumptions on SOM stability, turnover times of under 1 year for the major plant-derived molecules such as stable lignin and cellulose molecules were found in agricultural soils (Gleixner et al. 1999, 2001b). This supports the idea that plant-derived carbon skeletons are neither chemically nor physically stabilized in soil in their original structure. Consequently, the influence of plant diversity on the chemistry of soil carbon will be small. No indication for specific, recoverable molecules with turnover times in the millennium range, as suggested by soil carbon models, could be found in the soils under investigation. The existence of this pool is thus in question, although 14C ages of bulk soil carbon have been found in the millennium range (Wang et al. 1996). In contrast, pyrolysis products of carbohydrates and proteins, which were only present in soil samples, had unexpectedly long turnover times of between 20 and 100 years (Fig. 9.9). These turnover times...

Additional Advances In Epilepsy Treatment That Warrant Consideration

The ketogenic diet has been used with increasing frequency in the management of childhood epilepsy. Ketones are an alternative energy source for cerebral metabolism. By severely restricting glucose and increasing fat intake, ketosis can be maintained and seizure control improved. There are several concerns about an emergency department visit that warrant mention. It is necessary to maintain ketosis and, as a result, glucose infusions should be avoided if possible, and prescriptions given should have no measurable carbohydrate content. This is most easily managed by consultation with the prescribing neurologist, associated dietician, and pharmacist. Hematuria and flank pain may be due to renal calculi. Pancreatitis is an uncommon occurrence in children on the ketogenic diet.

Effects of dehydration on cellular structures and constituents

Microbial cell structure and composition are closely dependent on the degree of hydration. The effects of dehydration on whole cells are first manifested by a volume decrease corresponding to an osmotic exchange, that can then be followed by a metabolic adaptation of cells. Placing microorganisms in low aw media results in passive and active mechanisms of adaptation. The adaptative response is mainly based on the intracellular accumulation of solutes that allows water retention in cells (Brown and Edgley, 1980, Blomberg and Adler, 1992). This response occurs at relatively high water activities (1 to 0.6, depending on cell type and growth phase) whereas cell metabolism is ineffective in more dehydrated media. The accumulation of carbohydrates and amino acids during adaptation to dryness may account for an increased thermotolerance (Piper, 1993, Benaroudj et al., 2001, C novas et al., 2001). During adaptation to dehydration, protein synthesis and phospholipid modification also occur and...

Future trends positionspecific isotope analysis PSIA

Weber et al8 reported that the average 613C o value of glycerol from a botanical origin was 4 to 5 more negative than that of carbohydrates from the same source. This depletion was related exclusively to a large depletion at the C1 position of the glycerol molecule. This PSIA was performed after degrading the glycerol with periodic acid. The stoichiometry of the reaction is such that one mole of periodic acid is required to cleave each pair of adjacent hydroxyl groups on the glycerol molecule. As a result, one mole of glycerol yields two moles of formaldehyde and one mole of formic acid.72 The formaldehyde retains the carbon isotopic signature of the C1 and C3 atoms of the parent glycerol, whereas the formic acid retains the C2 information. Weber et al. determined the 613C o value of the volatile products directly by GC-Combustion-IRMS.

Indigestible Fiber

Fiber is commonly determined as the dry matter (DM), or preferably the organic matter (OM), insoluble after extraction with a neutral detergent solvent. The NDF consists of the structural carbohydrates cellulose and hemicelluloses and potentially indigestible entities such as lignin and lignified structural carbohydrates. Conceptually, NDF can be divided into PDF and IDF. Analytically, IDF is estimated by fitting kinetic models 1'2 that describe the disappearance of NDF over digestion time. The IDF is estimated as the undigested NDF remaining when no further disappearance of NDF is detectable by the kinetic model. Alternatively, IDF is analytically defined as the undigested NDF remaining after exposure to agents of digestion for a sufficient time (6 10 days) to approximate complete digestion of PDF. 3 The PDF is analytically defined as the difference between NDF and IDF. Thus, by

Enzyme Additives For Nonruminant Animals

In the nonruminant diet, enzymes are used more as a feed treatment than as a supplement. Their purpose, principally, is to degrade indigestible or antinutritional factors (such as protease inhibitors) within the feed, to improve digestibility of poor-quality feed, or to remove inhibitors of digestion. Improvements to health are brought about by the removal of these antinutrients and by rendering poorly digestible carbohydrates into a form that is digested in the ileum, resulting in a reduction in fermentable substrate entering the large intestine. Although the enzyme may be added to the feed rather than applied as a pretreatment, the principle is the same. The enzymes act on components of the feed, not on the digestive processes of the animal or on its microflora.

Occurrence And Organoleptic Properties Of Heterocyclic Compounds In Food

Furans are mainly associated with caramel-like, sweet, fruity, nutty, meaty, and burnt odor impressions. Because of their olfactory properties, many furans are commercially important flavoring chemicals. Furans are formed in food by thermal degradation of carbohydrates and by the Maillard reaction. They are almost present in all food aromas and essential oils. The most abundant furans are 2- and 2,5-disubstituted, such as 2-methylfuran, which is found in coffee aroma. The 2-substituted furans with aldehyde, ketone, or alcohol functional groups generally have fruity aromas with the mild flavor of caramel when added in small amounts to nonalcoholic beverages and ice creams. 3-Acetyl-2,5-dimethylfuran is used in imitation nut flavors (Fig. 13).

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