By I. Luca. University of Detroit Mercy. 2017.
LOOH CH3 •O that neutralize free radicals by donating a hydrogen atom (with its one electron) to the radical discount zocor 10mg fast delivery. Antioxidants generic zocor 10mg, therefore, reduce free radicals and are themselves oxi- H C 3 Phytyl dized in the reaction. VITAMIN E CH3 Vitamin E ( -tocopherol), the most widely distributed antioxidant in nature, is a O lipid-soluble antioxidant vitamin that functions principally to protect against lipid peroxidation in membranes (see Fig. Vitamin E comprises a num- H C Phytyl 3 O ber of tocopherols that differ in their methylation pattern. Among these, - O CH3 O tocopherol is the most potent antioxidant and present in the highest amount in L our diet (Fig. Vitamin E is an efficient antioxidant and nonenzymatic terminator of free radi- H2O cal chain reactions, and has little pro-oxidant activity. When Vitamin E donates an LOOH electron to a lipid peroxy radical, it is converted to a free radical form that is stabi- lized by resonance. If this free radical form were to act as a pro-oxidant and abstract CH3 OH Phytyl an electron from a polyunsaturated lipid, it would be oxidizing that lipid and actu- O ally propagate the free radical chain reaction. The chemistry of vitamin E is such that it has a much greater tendency to donate a second electron and go to the fully H3C O oxidized form. Vitamin E ( -tocopherol) terminates Although ascorbate (vitamin C) is an oxidation-reduction coenzyme that functions free radical lipid peroxidation by donating single in collagen synthesis and other reactions, it also plays a role in free radical defense. It is water-soluble and circulates unbound in so doing, the -tocopherol is converted to the blood and extracellular fluid, where it has access to the lipid-soluble vitamin E fully oxidized tocopheryl quinone. CAROTENOIDS Vitamin E is found in the diet in the Carotenoids is a term applied to -carotene (the precursor of vitamin A) and simi- lipid fractions of some vegetable oils and in liver, egg yolks, and cereals. It lar compounds with functional oxygen-containing substituents on the rings, such as is absorbed together with lipids, and fat mal- zeaxanthin and lutein (Fig.
CHAPTER 22 / GENERATION OF ATP FROM GLUCOSE: GLYCOLYSIS 409 Glucose 5 carbon Glucose-6-P sugars Glycerol–P 1 buy discount zocor 20 mg,3 bisphosphoglycerate Triglyceride 2 generic zocor 10 mg free shipping,3 bisphosphoglycerate Fatty acids Serine 3-phosphoglycerate Alanine Pyruvate Acetyl CoA TCA cycle Glutamate and other amino acids Fig. Compounds formed from intermediates of glycolysis are shown in blue. These pathways are discussed in subsequent chapters of the book. Dotted lines indicate that more than one step is required for the conversion shown in the figure. Because 2,3-BPG is not depleted by its role in this catalytic process, most cells need only very small amounts. REGULATION OF GLYCOLYSIS BY THE NEED FOR ATP One of the major functions of glycolysis is the generation of ATP, and, therefore, the pathway is regulated to maintain ATP homeostasis in all cells. Phosphofruc- tokinase-1 (PFK-1) and pyruvate dehydrogenase (PDH), which links glycolysis and the TCA cycle, are both major regulatory sites that respond to feedback indi- cators of the rate of ATP utilization (Fig. The supply of glucose-6-P for glycolysis is tissue dependent and can be regulated at the steps of glucose trans- port into cells, glycogenolysis (the degradation of glycogen to form glucose), or the rate of glucose phosphorylation by hexokinase isoenzymes. Other regulatory mechanisms integrate the ATP-generating role of glycolysis with its anabolic roles. All of the regulatory enzymes of glycolysis exist as tissue-specific isoenzymes, which alter the regulation of the pathway to match variations in conditions and needs in different tissues. For example, in the liver, an isoenzyme of pyruvate kinase introduces an additional regulatory site in glycolysis that contributes to the inhibi- tion of glycolysis when the reverse pathway, gluconeogenesis, is activated. Relationship between ATP, ADP, and AMP Concentrations The AMP levels within the cytosol provide a better indicator of the rate of ATP uti- lization than the ATP concentration itself (Fig. The concentration of AMP 410 SECTION FOUR / FUEL OXIDATION AND THE GENERATION OF ATP Glucose – hexokinase Glucose–6–P Fructose–6–P ATP phosphofructokinase–1 + AMP, F-2,6-bisP – ATP, citrate ADP Fructose–1,6–bis P Glyceraldehyde–3–P Pi NAD+ NADH + H+ 1,3–Bisphosphoglycerate ATP PEP pyruvate kinase + F-1,6-bisP – ATP ATP NAD+ NADH Lactate Pyruvate Pyruvate NAD+ pyruvate + ADP, Ca2+ dehydrogenase – NADH, Acetyl CoA NADH ATP Acetyl CoA Mitochondrion 5 Rest Exercise 4 Fig. Major sites of regulation in the glycolytic pathway.
After middle childhood buy zocor 40 mg amex, with a fully mature neurologic system zocor 20mg with amex, maturation to execute the concept of jumping has developed. When a child is asked to jump as far as she can, the natural general pattern, which is probably determined by dy- namic control organizing the activity around the chaotic attractor or series of attractors that are not very stable, will be used. However, if the individual wants to become a champion broad jumper, they must work on a specific pattern and be able to execute this pattern consistently within a very narrow range. This part of the activity now becomes a maturation activity around defining a specific CPG, which helps to explain why the basic pattern is seen, but also allows for refinement. Also, much more energy is required to change the basic pattern than to refine the current pattern. When considering individual pathologic problems, the neurologic aspects of the motor impairments can be separated into abnormalities of the three subsystems of motor control. These subsystems are muscle tone, motor plan- ning, and balance The variety of abnormalities in these three subsystems leads to almost all the motor problems in children with CP. Some children have impairments in only one area, such as a spastic gastrocnemius in child with a hemiplegic pattern involvement. Others, such as children with severe quadriplegic pattern involvement, have significant abnormalities in all three subsystems. Disorders of Muscle Tone Muscle tone is defined as the stiffness of the muscles or the limb as one tries to passively move the limb. This stiffness has a spring characteristic, which is stiffer with small movements than with large movements and is defined as a nonlinear response to movement. In studies using the leg drop test, a difference has been seen between an awake and alert child compared with the same child under neuromotor blockade anesthesia. In normal individuals there is less muscle tone under anesthesia than when they are awake, which strongly suggests that there is an active stiffness in the muscle that is not due to contraction induced by the motor neuron, as this stiffness is occurring with a silent elec- tromyogram (EMG) (Miller et al. In addition to nonlinear passive and active spring stiffness, tone in the limb also has a component of viscoelastic dampening, which is velocity-dependent 104 Cerebral Palsy Management resistance to movement.
This differ- ence is completely missed by many children cheap zocor 10 mg on line, families discount zocor 10 mg line, and even some vendors and therapists. Many of the wheelchairs that are heavily marketed directly to families are meant for the paraplegic spinal cord-injured population. These individuals have normal upper extremities, trunk balance, and trunk control. These patients do sliding transfers with no standing. Children and adolescents with CP almost never fit these parameters, because if they had normal or near-normal upper extremity control and normal trunk control, they would not use wheelchairs but walk with crutches or walkers. Children with Some Ambulatory Ability Childhood Needs Children who are being considered for wheelchairs but ambulate in child- hood usually ambulate with a walker; however, their ambulation is slow with high energy demands such that long-distance functional ambulation is lim- ited. Most of these children have functional bilateral upper extremities and functional, although not completely normal, trunk and head control. Most are transported by parents in normal strollers until they are 5 to 7 years old. Typically, the first wheelchair is purchased when children are between 5 and Figure 6. A common first device many 7 years of age and, because of functional upper extremities, this should be a parents obtain is the stroller base wheelchair, wheelchair that children can push if their cognitive and behavioral function which works well for rapid transport out- is such that they are responsible. If children are not responsible, then the side, such as shopping trips in early child- chair design should be such that it can be locked or not pushed by them when hood (A). At middle childhood, if the child is safe and physically able to push a wheelchair, they are sitting in the chair. This wheelchair should have swing-away or flip- a standard large wheelchair should be ob- up footrests so children can stand up out of the wheelchair.