By I. Anog. Spartanburg Methodist College. 2018.
The process levothroid 200mcg mastercard thyroid cancer ata guidelines,or hypothesis-testing discount 100 mcg levothroid with amex thyroid gland nodules causes, approach emphasizes qualitative aspects of neuropsy- chological functions that are founded in developmental and cognitive psychology. Champions of the process approach, most notably Edith Kaplan, promote ‘‘testing the limits’’ with patients and assessing the component processes of cognition rather than relying exclusively upon Copyright 2003 by Marcel Dekker, Inc. In other words, the process approach sees as critical ‘‘how’’ a task is solved and how the solution unfolds over time, rather than the achievement score quantifying the quality of the end-product. Although the ﬁxed battery and process approaches dominated neuropsychology initially, the ﬂexible battery has recently emerged as the most commonly used approach to neuropsychological evaluation (4). Flexible batteries beneﬁt from the strengths of the ﬁxed battery and process approaches by striving to quantify the qualitative aspects of cognition and task performance (5). In this way, the ﬂexible battery approach capitalizes on advances in cognitive neuroscience while remaining ﬁrmly grounded in psychometric theory. In addition, the ﬂexible battery approach incorpo- rates a standard battery of tests from which the clinician can tailor his or her evaluation to address particular clients needs and explore given domains of function in greater detail as desired. Many clinicians, in the tradition of Benton, will utilize a small ﬁxed battery and then elaborate this battery depending upon the referral question, the patient’s ability to cooperate with certain tasks, patient and family concerns, and presenting diagnoses. The particular components and length of a neuropsychological evaluation will vary across clinical settings, but typically include the following: Copyright 2003 by Marcel Dekker, Inc. A clinical interview and review of records to ascertain relevant biopsychosocial background information. Informal observations regarding patient behavior, cognition, and affect. The administration of psychometric tests to measure intelligence, attention and executive functions, language, learning and memory, visuospatial perception, praxis, motor and sensory-perception, mood state, quality of life, and personality/coping variables (see Table 2 for a sample of tests and the domains of functioning they evaluate). An integration of ﬁndings and recommendations into oral and/or written feedback that is provided to the patient, family, and healthcare providers THE ROLE OF NEUROPSYCHOLOGY IN THE MANAGEMENT OF PARKINSON’S DISEASE Neuropsychology provides an important contribution to the management of patients with PD. A neuropsychological evaluation delineates the nature and extent of cognitive changes, if any, and a proﬁle of relative neuropsychological strengths and weaknesses. The determination of the most probable etiology of mild and new-onset cognitive changes. Development and formulation of strategies or treatments to ameliorate the impact of cognitive deﬁcits on functioning. Guidance of the patient and family in making and requesting adaptive changes in the patient’s home, leisure, and work environments that enhance functioning and minimize handicap. Decision making about the appropriateness of medical and neurosur- gical interventions for a patient; ASSESSMENT OF COMPETENCE TO CONSENT TO TREATMENT Financial, Legal, and Placement Planning Given the noteworthy prevalence of cognitive and behavioral changes in PD, every patient would, in ideal circumstances, receive a baseline evaluation when ﬁrst diagnosed with PD. Such a baseline neuropsycholo- gical evaluation would facilitate the accurate detection and diagnosis of subsequent neurobehavioral changes and permit the evaluation of treatment effects. This, however, occurs rarely and probably reﬂects cost-effectiveness issues in a managed care environment, and the reluctance of many patients, and some physicians, to contemplate in the early disease stages the threat of Copyright 2003 by Marcel Dekker, Inc. In the absence of an early baseline evaluation, a neuropsychological evaluation in the context of cognitive morbidity relies on less accurate, probabilistic estimation of premorbid functioning to detect and estimate the extent of impairments. Accordingly, if a full evaluation is not indicated or cannot be achieved soon after diagnosis, a cognitive screening should be contemplated as an alternative. Such screening can be readily achieved in the neurologist’s ofﬁce using the Mattis Dementia Rating Scale (DRS) (6) or comparable instruments. Likewise, the administration of brief self-report measures of mood state and quality of life [e. Affective disturbances are crucial to screen for on a regular basis considering the high prevalence of anxiety and depression in patients with PD (10) and the high likelihood of these entities going undiagnosed in routine neurologic practice (11). The optimization of quality of life, from the patient’s perspective, facilitates a patient–physician collaboration and treatment adherence. A more comprehensive neuropsychological evaluation that supple- ments screening should be strongly considered under the following circumstances:. If the patient, caregiver, and/or clinician suspect changes in the patient’s ability to carry out fundamental and/or instrumental activities of living that are unlikely to be related to motor dysfunction. If there is concern regarding a possible evolving dementia related to depression, PD, Alzheimer’s disease (AD), or any other medical and/or psychiatric condition. If the neurologist suspects that brief cognitive screening tests [e.
For example cheap levothroid 50 mcg amex thyroid t3, a child with a cognitive level of 3 to 6 months will not even try to walk generic 100 mcg levothroid amex thyroid cancer explanation, even though this same child’s motor development may be such that he could walk from a motor perspective. Many of these chil- dren will slowly develop insight with stimulation to the point where they will stand up suddenly and start walking. The oldest child in whom we have seen this occur was just short of her 13th birthday. This kind of dramatic late beginning of walking never occurs if the major impairment limiting walking is in any other subsystem except the cognitive system. Balance Subsystem Balance is required for children to ambulate, and this is often the difference between independent bipedal ambulation and ambulation in a quadruped pattern with a walking aid. Balance is a complex function, in which most of the research has been reported with standing26 or sitting balance studies. Often, the transitions in movement, such as stopping and stand- ing or starting from a sitting position, are especially difficult when balance is a major impairment (Case 7. Energy Production Ambulation always requires an output of energy as fuel for the muscles. Even downhill walking, which in many mechanical systems can generate en- ergy, requires more energy than it generates with human gait. Children must have the energy available for the musculoskeletal system to use or walking is not possible or comfortable (Case 7. A typical reason for low energy supply is a walking pattern that consumes more energy than children can generate (Case 7. Another common cause is poor cardiovascular condi- tioning, which limits the amount of energy available to the musculoskeletal system. In spite of this energy-efficient gait, tion, general muscle weakness and hypotonia were noted. Although Her videotape demonstrated a gait pattern typical of there was no known diagnosis in Kimberly except hypo- hypotonia. On assessment of her energy requirements tonia, we made the presumption based on her energy use of walking, she was found to have walking velocity of that there was a deficiency in the way the muscle used en- 85 cm/s with an oxygen cost of 0. This muscle pathology, not mechanical in efficiency. She attended a regular high school, which required it in school for many months until her knee pain resolved. In middle childhood she used However, she was very unhappy in the wheelchair be- a posterior walker and was later switched to Lofstrand cause she believed she was gaining weight, felt herself be- crutches, which she used exclusively by high school. Dur- coming more deconditioned, and did not like to sit when ing high school, in the period of her adolescent growth, talking to friends who were standing. She decided to walk she developed knee pain and complained about increased with her crutches, which she did throughout high school, fatigue. An oxygen consumption test showed that she and she completed a university nursing degree walking walked with a very slow velocity of 78 cm/s with an oxy- with her crutches. As a young adult in her mid-twenties, gen cost of 0. Based on the complete analysis, there were no me- needed it. Motor Control Motor control is an extremely important aspect of developing good walking skills. Individuals with significant motor control disorders, or the inability to develop motor control, will have significant problems with gait. This aspect is discussed at length in Chapter 4 on neurologic control. Structural Stability The mechanical mobility system includes the muscles, bones, and tendons. The interaction of these structural elements is the primary focus of much of the remainder of this chapter because it is the area where the most opportunity is present to make alterations in the system to functionally improve children’s 272 Cerebral Palsy Management gait. As understanding of the mechanics of walking in individual children is gained from a clinical perspective, the defined methods of measuring the ef- fects of different subsystems also have to be understood.
In 1968 buy generic levothroid 100mcg on line thyroid dizziness, Johnston identiﬁed two types of monoamine oxidase: A and B (2) generic 50mcg levothroid amex thyroid cancer oncologist. Each has a separate afﬁnity for various catecholamines and works in different parts of the body. MAO-B is found predominantly in the human brain (3) and platelets and has an afﬁnity for dopamine and benzylamine. MAO-A is found predominantly in the intestinal tract and has an afﬁnity for serotonin and norepinephrine. Both types can oxidize tyramine, though MAO-B does so only at higher concentrations. They also showed that at low doses selegiline did not potentiate the pressor effect of tyramine also known as the ‘‘cheese effect. In autopsied brains, 10 mg of selegiline was found to be sufﬁcient to selectively inhibit 90% of MAO-B in such areas as the caudate, substantia nigra, globus pallidus, and thalamus (5). Hence, it was shown that selective MAO-B inhibitors such as selegiline could inhibit the MAO that has strong afﬁnity for the basal ganglia. This may augment the concentration of dopamine in areas in which it is deﬁcient. For over two decades MAO-B inhibitors have been used in Parkinson’s disease (PD). They were originally developed as antidepressants but were later found to have beneﬁt in patients with PD. Knoll’s study showed that selegiline, a selective nonreversible MAO-B inhibitor, lengthened the life span of rodents by 50% (6). The neuroprotective properties of MAO inhibitors were evaluated over the next two decades. There was much interest in their ability to protect neurons against neurodegenerative processes such as PD. The bulk of the scientiﬁc interest revolves around selegiline, while more recent studies have looked at rasagiline (a selective irreversible MAO-B inhibitor) and lazabemide (a selective reversible, competitive inhibitor of MAO-B). In clinical practice, selegiline is used as monotherapy or as adjunctive therapy to levodopa. MECHANISMS OF ACTION In PD there is a loss of dopaminergic neurons in the substantia nigra pars compacta. The mechanisms involved in the destruction of these cells are complex. Abnormalities found in PD include abnormal iron metabolism (7), increased free radical production (8), and decreased scavenging systems such as reduced glutathione (GSH). The latter two comprise the ‘‘oxidative stress’’ theory. Levodopa can produce free radicals, but it can also increase the rate of reduced GSH synthesis and protect against toxins such as L- buthionine sulfoximine (L-BSO) an inhibitor of GSH synthesis. There are three theories to justify the use of MAO inhibitors to slow progression of PD: oxidative stress, neurotoxicity, and potential regenerative properties of MAO-B inhibitors. Oxidative Stress Theory This theory proposes that the parkinsonian brain is under oxidative stress (10): there is an overabundance of free radicals or oxygen species in the brain causing damage to the dopaminergic cells. This skewed proportion of reactive oxygen species may be due to an increased production or a Copyright 2003 by Marcel Dekker, Inc. One pathway in the degradation of dopamine is through MAO-B or autooxidation. This degradative process can produce free radicals such as hydrogen peroxide and hydroxyl radicals that in turn may cause cellular damage. A solution is to reduce formation of these free oxygen species by inhibiting the degradation of dopamine. Selegiline slows the rate of dopamine degradation and, hence, the rate of free radical production. Selegiline also allows for an increase in GSH that helps clear free radicals from the system (8). MPTP and Neurotoxicity Studies have shown that various chemicals including dopamine, levodopa, and 6-hydroxydopamine act as neurotoxins (12,13).
They are also HGPRT can use either hypoxanthine or gua- prone to chewing off their fingers and performing other acts of self-mutilation purchase 100mcg levothroid with visa thyroid gland remedies. De Novo Pathways Fumarate Aspartate GTP In the synthesis of the pyrimidine nucleotides levothroid 200mcg fast delivery thyroid symptoms video, the base is synthesized first, and then IMP AMP it is attached to the ribose 5 -phosphate moiety (Fig. The origin of the atoms of the ring (aspartate and carbamoyl-phosphate, which is derived from carbon diox- ide and glutamine) is shown in Fig. In the initial reaction of the pathway, glu- tamine combines with bicarbonate and ATP to form carbamoyl phosphate. This reaction is analogous to the first reaction of the urea cycle, except that it uses glut- NH3 amine as the source of the nitrogen (rather than ammonia) and it occurs in the Fig. The reaction is catalyzed by carbamoyl phos- Using a combination of biosynthetic and sal- phate synthetase II, which is the regulated step of the pathway. The analogous reac- vage enzymes, the net effect is the conversion tion in urea synthesis is catalyzed by carbamoyl phosphate synthetase I, which is of aspartate to fumarate plus ammonia, with activated by N-acetylglutamate. The similarities and differences between these two the fumarate playing an anaplerotic role in the carbamoyl phosphate synthetase enzymes is described in Table 41. In the next step of pyrimidine biosynthesis, the entire aspartate molecule adds to carbamoyl phosphate in a reaction catalyzed by aspartate transcarbamoylase. The molecule subsequently closes to produce a ring (catalyzed by dihydroorotase), which is oxidized to form orotic acid (or its anion, orotate) through the actions of dihydroorotate dehydrogenase. The enzyme orotate phosphoribosyl transferase cat- alyzes the transfer of ribose 5-phosphate from PRPP to orotate, producing orotidine In bacteria, aspartate transcar- 5 -phosphate, which is decarboxylated by orotidylic acid dehydrogenase to form bamoylase is the regulated step of pyrimidine production. This is a Glutamine + CO2 + 2ATP very complex enzyme and was a model sys- tem for understanding how allosteric CPS-II enzymes were regulated. In humans, how- UTP – + PRPP ever, this enzyme is not regulated. Carbamoyl phosphate Aspartate Orotate PRPP CO2 UMP UDP UTP Glutamine RNA NH+ CTP 4 dUMP 5,10-Methylene-FH4 CDP dCMP RR FH2 dCTP dCDP dTMP DNA dTTP dTDP Fig. RR ribonucleotide reductase; stimulated by; inhibited by; FH2 and FH4 forms of folate. CHAPTER 41 / PURINE AND PYRIMIDINE METABOLISM 755 Table 41. Comparison of Carbamoyl Phosphate Synthetases Glutamine Aspartate (CPSI and CPSII) (amide N) 4 N3 5 CPS-I CPS-II CO 2 1 6 Pathway Urea cycle Pyrimidine biosynthesis 2 N Source of nitrogen NH4 Glutamine Location Mitochondria Cytosol Fig. The origin of the bases in the Activator N-Acetylglutamate PRPP Inhibitor – UTP pyrimidine ring. In mammals, the first three enzymes of the pathway (carbamoyl phosphate synthetase II, aspartate transcarbamoylase, In hereditary orotic aciduria, orotic and dihydroorotase) are located on the same polypeptide, designated as CAD. The acid is excreted in the urine last two enzymes of the pathway are similarly located on a polypeptide known as because the enzymes that convert UMP synthase (the orotate phosphoribosyl transferase and orotidylic acid dehydro- it to uridine monophosphate, orotate phos- genase activities). An amino group, derived from the amide of glu- phate decarboxylase, are defective (see Fig. Pyrimidines cannot be synthe- tamine, is added to carbon 4 to produce CTP by the enzyme CTP synthetase (this sized, and, therefore, normal growth does reaction cannot occur at the nucleotide monophosphate level). Oral administration of uridine is precursors for the synthesis of RNA (see Fig. The synthesis of thymidine used to treat this condition. Uridine, which is triphosphate (TTP) will be described in section IV. Salvage of Pyrimidine Bases pyrimidines, as both CTP and dTMP can be produced from UMP. Pyrimidine bases are normally salvaged by a two-step route. First, a relatively non- specific pyrimidine nucleoside phosphorylase converts the pyrimidine bases to their respective nucleosides (Fig. Notice that the preferred direction for this reac- tion is the reverse phosphorylase reaction, in which phosphate is being released and is not being used as a nucleophile to release the pyrimidine base from the nucleo- side. The more specific nucleoside kinases then react with the nucleosides, forming nucleotides (Table 41.
Dairy products generic levothroid 200mcg on-line thyroid symptoms upset stomach, not a part of Deria’s diet in Nigeria generic levothroid 50 mcg without a prescription thyroid and weight gain, were identified as the probable offending agent because her gastrointestinal symptoms disappeared when milk and milk products were eliminated from her diet. Ann Sulin’s fasting and postprandial blood glucose levels are frequently above the normal range in spite of good compliance with insulin therapy. Her physician has referred her to a dietician skilled in training diabetic patients in the successful application of an appropriate American Diabetes Association diet. Sulin is asked to incorporate foods containing fiber into her diet, such as whole grains (e. The dietary sugar in fruit juice and Nona Melos (no sweets) is a 7-month-old baby girl, the second child born other sweets is sucrose, a disac- to unrelated parents. Her mother had a healthy, full-term pregnancy, and charide composed of glucose and Nona’s birth weight was normal. She did not respond well to breastfeeding fructose joined through their anomeric car- and was changed entirely to a formula based on cow’s milk at 4 weeks. Nona Melos’ symptoms of pain and and 12 weeks of age, she was admitted to the hospital twice with a history of abdominal distension are caused by an screaming after feeding but was discharged after observation without a specific inability to digest sucrose or absorb fruc- diagnosis. Elimination of cow’s milk from her diet did not relieve her symptoms; tose, which are converted to gas by colonic bacteria. At 7 months she was stool sample had a pH of 5 and gave a posi- still thriving (weight above 97th percentile) with no abnormal findings on physical tive test for sugar. DIETARY CARBOHYDRATES Carbohydrates are the largest source of calories in the average American diet and usually constitute 40 to 45% of our caloric intake. The plant starches amylopectin and amylose, which are present in grains, tubers, and vegetables, constitute approx- imately 50 to 60% of the carbohydrate calories consumed. These starches are poly- saccharides, containing 10,000 to 1 million glucosyl units. In amylose, the glucosyl residues form a straight chain linked via -1,4 glycosidic bonds; in amylopectin, the -1,4 chains contain branches connected via -1,6 glycosidic bonds (see Fig. The other major sugar found in fruits and vegetables is sucrose, a disaccharide of glucose and fructose (see Fig. Sucrose and small amounts of the monosac- charides glucose and fructose are the major natural sweeteners found in fruit, honey, and vegetables. Dietary fiber, that portion of the diet that cannot be digested by Sweeteners, in the form of sucrose human enzymes of the intestinal tract, is also composed principally of plant poly- and high-fructose corn syrup saccharides and a polymer called lignan. The major dietary carbohydrate of animal origin is lac- a person in the United States consumes 65 tose, a disaccharide composed of glucose and galactose found exclusively in milk lb added sucrose and 40 lb high-fructose and milk products (see Fig. Glucose can be synthesized from many Starch blockers had been marketed amino acids found in dietary protein. Fructose, galactose, xylose, and all the other sug- many years ago as a means of los- ars required for metabolic processes in the human can be synthesized from glucose. DIGESTION OF DIETARY CARBOHYDRATES found in beans, which blocked the action of amylase. Thus, as the advertisements pro- In the digestive tract, dietary polysaccharides and disaccharides are converted to claimed, one could eat a large amount of monosaccharides by glycosidases, enzymes that hydrolyze the glycosidic bonds starch during a meal, and as long as you between the sugars. All of these enzymes exhibit some specificity for the sugar, the took the starch blocker, the starch would glycosidic bond ( or ), and the number of saccharide units in the chain. The mono- pass through the digestive track without saccharides formed by glycosidases are transported across the intestinal mucosal being metabolized. Unfortunately, this was cells into the interstitial fluid and subsequently enter the bloodstream. Undigested too good to be true, and starch blockers carbohydrates enter the colon, where they may be fermented by bacteria. Salivary and Pancreatic -Amylase combination of factors, such as inactivation of the inhibitor by the low pH in the stom- The digestion of starch (amylopectin and amylose) begins in the mouth, where ach, and an excess of amylase activity as chewing mixes the food with saliva. The salivary glands secrete approximately 1 compared with the amount of starch blocker liter of liquid per day into the mouth, containing salivary -amylase and other com- ingested. The shortened polysaccharide chains that are formed are called tised, although much more work is required to determine whether this amylase inhibitor -dextrins. Salivary -amylase may be largely inactivated by the acidity of the will be safe and effective in humans. O Starch O O Salivary and pancreatic α–amylase O O O HO O OH HO OH Maltose Isomaltose O O O O O O HO O O OH HO O O OH Trisaccharides α–Dextrins (and larger oligosaccharides) (oligosaccharides with α–1,6 branches) Fig. CHAPTER 27 / DIGESTION, ABSORPTION, AND TRANSPORT OF CARBOHYDRATES 497 The acidic gastric juice enters the duodenum, the upper part of the small intes- Amylase activity in the gut is abun- tine, where digestion continues.