By K. Tuwas. Texas Southern University. 2018.
Four studies evaluated the effectiveness of exercise in combination with other interventions in preventing falls buy cheap unisom 25mg on-line. Four studies investigated the effect of exercise in women only14 buy generic unisom 25mg line,18–20 and one included men only unisom 25mg visa. Eight studies included people aged 60 to 70 years cheap unisom 25 mg without prescription,13 generic unisom 25mg with visa,16–20 generic 25 mg unisom with visa,22,23 and in one study participants were aged 80 years and older. In five studies, the exercise intervention was delivered to a group,13,18–20,23 and in another four studies exercises were carried out in the home. Length of monitoring of falls varied from three to 25 months. Intention to treat analysis was stated in six studies. In one study effectiveness continued for a second year. A wide variety of exercise interventions have been tried using different exercise frequencies, intensities, and duration periods. Studies successfully lowering falls have used strength and balance retraining, endurance training, and Tai Chi. A meta-analysis of the seven FICSIT exercise trials suggests balance may be more effective in lowering falls risk than the other exercise components. It is probable that exercise would have had the greatest effect on balance in this multiple intervention study. Four successful programmes have required the participants to exercise regularly against resistance using either therabands or weights. The authors consider the following factors contribute to the success of the programme. Definitions of exercise compliance differed, and two studies failed to report exercise monitoring and compliance. One trial reported 27% (31 of 116) of participants from the original sample still carrying out exercise sessions at least three times a week at two years. Programmes offering both approaches may enhance compliance. Adverse effects Six studies addressed adverse events. There were no significant differences in severe soreness, bruising and fatigue between participants receiving physical therapy and those receiving friendly visits. Robertson et al26 reported that one person fell while exercising according to instructions. Ten participants (6⋅5%) reported self limiting musculoskeletal symptoms in one home based programme, which the investigators attributed to the exercises. Study factors diminishing benefit Six studies reported no change in falls following the exercise intervention. Several studies used exercise of inadequate intensity to modify falls risk factors and this was shown by the lack of 143 Evidence-based Sports Medicine change in intermediate variables. Exercise may be less effective in fall prevention when there are other significant risk factors for falls present that are not influenced by exercise. For example, in a younger sample of men and women on psychotropic drugs, exercise was less effective in reducing falls than in older, frailer populations. While intermediate outcomes improve in frail institutionalised elderly following high intensity strength training,40 falls may not decrease because other risk factors may not improve.
Tyramine induces the release of norepinephrine from storage vesi- SAM Oxidation cles 25 mg unisom with mastercard, which leads to potentially life-threaten- SAH ing hypertensive episodes discount 25 mg unisom with visa. When it was real- COMT ized that MAO existed in two forms buy 25mg unisom fast delivery, selective irreversible inhibitors were devel- CH3O oped cheap unisom 25 mg with amex; examples include clorgyline for MAO- OH – A unisom 25 mg visa, and deprenyl for MAO-B unisom 25 mg. Deprenyl has HO CH COO been used to treat Parkinson’s disease (which is caused by a lack of dopamine, 3–Methoxy–4–hydroxymandelic acid which is also inactivated by MAO). Deprenyl, (Vanillylmandelic acid, VMA) however, is not an antidepressant. This led to the development 3-methoxy-4-hydroxymandelic acid is the final product. These compounds are excreted in of the third generation of MAO inhibitors, the urine. MAO monoamine oxidase; COMT catechol O-methyltransferase; SAM which are reversible inhibitors of the S-adenosylmethionine; SAH S-adenosylhomocysteine. Moclobemide is a specific, reversible inhibitor of MAO-A and is effective as an antidepressant. REGULATION OF TYROSINE HYDROXYLASE of the reversible nature of the drug, the “cheese” effect is not observed, because as Efficient regulatory mechanisms coordinate the synthesis of catecholamine neuro- tyramine levels increase, they displace the transmitters with the rate of firing. Tyrosine hydroxylase, the first committed step drug from MAO, and the tyramine is safely and rate-limiting enzyme in the pathway, is regulated by feedback inhibition that is inactivated. Tyrosine hydroxylase is inhibited by free cytosolic catecholamines that compete at the binding site on the enzyme for the pterin cofactor (tetrahydrobiopterin, BH4; see Chapter 39). Depolarization of the nerve terminal activates tyrosine hydroxylase. Depolariza- tion also activates a number of protein kinases (including protein kinase C, protein 2 kinase A [the cAMP-dependent protein kinase] and CAM kinases [Ca -calmod- ulin–dependent kinases]) that phosphorylate tyrosine hydroxylase. These activation steps result in an enzyme that binds BH4 more tightly, making it less sensitive to end-product inhibition. In addition to these short-term regulatory processes, a long-term process involves alterations in the amounts of tyrosine hydroxylase and dopamine -hydroxylase present in nerve terminals. When sympathetic neuronal activity is increased for a prolonged period, the amounts of mRNA coding for tyrosine hydroxylase and dopamine -hydroxylase are increased in the neuronal perikarya (the cell body of the neuron). The increased gene transcription may be the result of phos- phorylation of CREB (cAMP response element binding protein; see Chapter 26) by 892 SECTION EIGHT / TISSUE METABOLISM protein kinase A or by other protein kinases. CREB then binds to the CRE (cAMP response element) in the promoter region of the gene (similar to the mechanism for the induction of gluconeogenic enzymes in the liver). The newly synthesized enzyme molecules are then transported down the axon to the nerve terminals. The concentration of dopamine decarboxylase in the terminal does not appear to change in response to neuronal activity. Metabolism of Serotonin The pathway for the synthesis of serotonin from tryptophan is very similar to the path- way for the synthesis of norepinephrine from tyrosine (Fig. The first enzyme of the pathway, tryptophan hydroxylase, uses an enzymic mechanism similar to that of tyrosine and phenylalanine hydroxylase and requires BH4 to hydroxylate the ring structure of tryptophan. The second step of the pathway is a decarboxylation reaction + CH2 CH NH3 Nicotinamide moiety COO– of NAD(P) N H Tryptophan O2 BH4 tryptophan hydroxylase H2O BH2 HO + CH2 CH NH3 COO– N H 5–Hydroxytryptophan PLP CO2 DOPA decarboxylase HO + CH2 CH2 NH3 MAO-A N NH3 O H HO CH2 C H Serotonin Acetyl CoA N CoASH 5-hydroxyindole- O acetaldehyde HO CH CH NH C CH NAD+ 2 2 3 NADH N O H HO CH C O– N-Acetyl Serotonin 2 SAM N SAH H O 5-hydroxyindole CH3O acetic acid CH2 CH2 NH C CH3 N H Melatonin Fig. CHAPTER 48 / METABOLISM OF THE NERVOUS SYSTEM 893 catalyzed by the same enzyme that decarboxylates DOPA. Serotonin, like the cate- Evan Applebod was placed on cholamine neurotransmitters, can be inactivated by MAO. Redux, which increased the secre- tion of serotonin. Serotonin has The neurotransmitter melatonin is also synthesized from tryptophan (see been implicated in many processes, including Fig. Melatonin is produced in the pineal gland in response to the light–dark mood control and appetite regulation.