<s docid="FBIS3-42994" num="41"> An example of a nodal substance is glucose-6-phosphate, which participates in glycolysis, glycogen synthesis, the pentose phosphate pathway, and many other transformations.</s>

<s docid="FBIS3-42994" num="42"> Another example of a nodal substance is pyruvate, with which many metabolic transformations begin or end.</s>

<s docid="FBIS3-42994" num="43"> Glucose-6-phosphate and pyruvate are related nodal substances coupled by the glycolysis metabolic pathway.</s>

<s docid="LA100889-0041" num="32"> M's doctors at the Huntington Medical Center have taken some of his white blood cells, or lymphocytes -- part of the immune system's weapons against invaders -- and mixed them with interleukin 2, a naturally occurring chemical messenger used by the body to prod the lymphocytes into renewed activity.</s>

<s docid="LA100889-0041" num="95"> As they exercised, the expected biochemical changes were documented: The store of the metabolite phosphocreatine in their muscles decreased; the synthesis of ATP, an energy-storing compound that fuels cellular activity, dropped off; the concentration of lactic acid rose; eventually the muscles no longer would contract.</s>

<s docid="LA100889-0041" num="117"> Phosphocreatine is a sensitive indicator of a depleted energy state.</s>

<s docid="LA100889-0041" num="118"> Successful treatment is also likely to be signaled by a rise in the level of inorganic phosphate since this is a breakdown product of dying cells.</s>

<s docid="LA100889-0041" num="122"> Ross suspected McArdle's syndrome, a rare genetic disease in which the muscles can't break down the sugar glycogen, used as a source of energy to fuel contraction.</s>

<s docid="FR940817-2-00229" num="17"> In addition, a series of specific transport mechanisms exist through which required nutrients (hormones, amino acids, peptides, proteins, fatty acids, etc).</s>

<s docid="FR940817-2-00229" num="18"> reach the brain (Pardridge, 1988).</s>

<s docid="FR940817-2-00229" num="22"> 2.5.3. Metabolism The central nervous system has a very high metabolic rate and, unlike other organs, the brain depends almost entirely on glucose as a source of energy and raw material for the synthesis of other molecules (Damstra and Bondy, 1980).</s>

<s docid="FR940817-2-00229" num="25"> Without glucose, nerve cells usually begin to die within minutes.</s>

<s docid="FR941222-1-00035" num="17"> In humans as much as 60 percent of aniline that is absorbed is oxidized in a dose-dependent manner to give o - and p -aminophenol, the first step in amide formation for this pathway.</s>

<s docid="FR940405-1-00043" num="22"> Nicotine is rapidly eliminated, primarily via metabolism and urinary excretion.</s>

<s docid="FR940405-1-00043" num="24"> The principle metabolic pathways of nicotine appear to involve oxidation of the pyrrolidine ring to yield nicotine-1 '-N-oxide and cotinine, the latter being the major metabolite and the precursor of many of the metabolic products of nicotine.</s>

<s docid="FR940405-1-00043" num="27"> In humans, cotinine is the major degradation product of nicotine metabolism and has a serum half-life of about 17 hours compared to two hours for the parent compound, nicotine [Exs.</s>

<s docid="FR940405-1-00043" num="28"> 4-27, 4-253].</s>

<s docid="FR940405-1-00043" num="35"> More rapid elimination of nicotine and cotinine has been attributed to the inductive effects of chronic cigarette smoking on the hepatic metabolism of many xenobiotic agents.</s>

<s docid="FR940817-2-00223" num="22"> The substance is eliminated from the bloodstream by the process of accumulation into the various sites in the body, with the liver and kidney being major sites of accumulation of toxic substances.</s>

<s docid="FR940817-2-00223" num="33"> The liver can detoxify substances like organic lead, which are excreted from the liver into the bile and then the small intestines, bypassing the blood and kidney.</s>

<s docid="FR940817-2-00223" num="34"> Lipophilic toxic substances are primarily removed from the body through feces and bile, and water-soluble metabolites are removed in the urine, through the skin, and through expiration into the air.</s>

<s docid="FR940817-2-00223" num="35"> Biotransformation is a biochemical process that converts a substance into a different chemical compound, allowing it to be excreted more easily.</s>

<s docid="FR940817-2-00223" num="36"> Substances are more easily removed if they are biotransformed into a more hydrophilic compound.</s>

<s docid="FT921-13251" num="21"> Its survival mechanisms will be alerted to an imminent famine and it will slow down the metabolism to conserve energy.</s>

<s docid="FT921-13251" num="22"> It will even prepare to use its own muscle protein as a calorie source.</s>

<s docid="FR941006-1-00106" num="25"> A. The Iron Requirements of Children and Women of Childbearing Age Iron is an essential nutrient because it is a component of blood and muscle tissue and because of its role in metabolic reactions.</s>

<s docid="FR941006-1-00106" num="27"> The compounds in the first category include hemoglobin (a component of red blood cells), myoglobin (a muscle protein), and iron-containing enzymes.</s>

<s docid="FR941006-1-00106" num="29"> Compounds in the second category are involved in the maintenance of iron homeostasis and include the storage compounds ferritin and hemosiderin.</s>

<s docid="FR941006-1-00106" num="30"> When the supply of dietary iron becomes inadequate to meet the body's needs, iron is mobilized from iron stores to maintain the production of red blood cells and to perform other essential iron-dependent functions.</s>

<s docid="LA082889-0040" num="38"> Some of the body's enzymes function as a repair system to fix the damage done by free radicals.</s>

<s docid="LA082889-0040" num="39"> Davies discovered one set of enzymes, macroxyprotheinase (MOP), salvages injured proteins.</s>

<s docid="LA082889-0040" num="40"> Another class of enzymes, phopholipases, performs a similar function with cell membranes, while yet a third group, nucleases and glycosylases, actually repair the DNA.</s>

<s docid="LA082889-0040" num="52"> Our bodies also produce enzymes, like superoxide dismutase (SOD), catalase, gluthathione peroxidase and DT diaphrorase, that neutralize free radicals by converting them to harmless chemicals.</s>

<s docid="LA031989-0012" num="114"> When a muscle has more of what is called slow myosin, it burns its fuel slower and contracts slowly.</s>

<s docid="LA031989-0012" num="116"> Fast myosin creates powerful contractions that result in explosive movements needed for a floor routine in gymnastics or a 100-meter sprint.</s>

<s docid="LA031989-0012" num="122"> Somehow, the (muscle activity) has to trigger a chemical to send a messenger to the cell to have it create the certain types of myosin.</s>

<s docid="LA031989-0012" num="130"> Bouchard's ground-breaking research is focusing on the genes associated with the transformation of energy in the muscle, particularly the genes that are involved in replenishing adenosine triphosphate, or ATP.</s>

<s docid="LA031989-0012" num="133"> The more effectively ATP is replenished, the more efficiently the human operates.</s>

<s docid="FT932-7262" num="14"> Researchers have begun to understand the biological basis of the disease, in particular the microscopic 'senile plaques' and 'neurofibrilary tangles' that are the main sign of deterioration in sufferers' brains at post-mortem examinations.</s>

<s docid="FT932-7262" num="17"> Healthy cells produce small quantities of APP (though its normal function is unknown) but in excess it may lead to toxic accumulations of beta-amyloid.</s>

<s docid="LA031590-0014" num="28"> A healthy adult can metabolize only a single ounce of pure alcohol each hour.</s>

<s docid="FT934-704" num="25"> One is when the body's metabolism is too efficient - it needs very little energy to sustain itself and therefore stores the excess as fat.</s>

<s docid="FT934-704" num="28"> When empty or full, the gut produces different hormone peptides that act on a region in the brain called hypothalamus.</s>

<s docid="FT934-704" num="31"> Excess production of certain peptides leads the feeding centre to believe the body is hungry when it has enough food.</s>

<s docid="FT934-704" num="32"> A shortage of peptides acting on the satiety centre indicates the body is not satiated when in fact it is.</s>

