Pharm - CNS Degenerative Diseases

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  • 1/20 Questions

    Which of the following drugs is a selective monoamine oxidase B inhibitor used to reduce dopamine metabolism in Parkinson's disease?

    • Levodopa
    • Benztropine
    • Selegiline
    • Phenelzine
    • Bromocriptine
    • Entacapone
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Pharm - CNS Degenerative Diseases - Quiz
About This Quiz

Central nervous system disorders are a group of neurological disorders that affect the structure or function of the brain or spinal cord. Degenerative brain diseases have an enormous impact on our aging society. Take this pharmacology test on the CNS degenerative diseases and test your knowledge on the prescribed drugs for a patient.

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  • 2. 

    Carbidopa is currently used in combination with levodopa in the treatment of Parkinson’s disease because it inhibits which of the following actions?

    • Dopamine metabolism in the striatum

    • Active transport of levodopa outside the brain

    • Conversion of dopamine into norepinephrine in the striatum

    • Peripheral biotransformation of levodopa

    • Dopamine reuptake in the striatum

    Correct Answer
    A. Peripheral biotransformation of levodopa
    Explanation
    Answer: D
    (Katzung, pp 449, Brunton, pp 534)
    Carbidopa is a DOPA decarboxylase inhibitor that cannot cross the blood brain barrier. When
    levodopa is given in combination with carbidopa the peripheral metabolism of levodopa is
    reduced, plasma levels of levodopa are higher and more levodopa is available to enter the
    brain. Indeed concomitant administration of levodopa and carbidopa may reduce the daily
    requirement of levodopa by about 75%.
    A, B, C, E) All these actions are not inhibited by carbidopa

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  • 3. 

    Which of the following statements best explains the mechanism of action of levodopa in the treatment of Parkinson’s disease?

    • Increased sensitivity of dopaminergic receptors in the striatum

    • Increased sensitivity of dopamine receptors in the substantia nigra

    • Increased availability of dopamine in the striatum

    • Inhibition of DOPA decarboxylase in the striatum

    • Inhibition of dopamine reuptake in the substantia nigra

    Correct Answer
    A. Increased availability of dopamine in the striatum
    Explanation
    Answer: C
    (Katzung, pp 448, Brunton, pp 533)
    Dopamine cannot cross the blood brain barrier an therefore has no therapeutic effects on
    parkinsonism if given into the peripheral circulation. However levodopa, the immediate
    precursor of dopamine, is readily carried across the blood brain barrier by the neutral amino
    acid transported. In the brain levodopa is biotransformed into dopamine and therefore the
    availability of dopamine in the striatum increases.
    A, B) Neither levodopa, nor dopamine can cause an increased sensitivity of dopaminergic
    receptors.
    D, E) These action would decrease, not increase, the availability of dopamine in basal ganglia.

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  • 4. 

    A 64-year-old woman with Parkinson’s disease complained that her tremor gradually worsened over the past two weeks. She has been receiving a levodopa-carbidopa combination for one years. The neurologist decided to add benztropine to the therapeutic regimen. Which of the following statement best explains why benztropine can alleviate the tremor of the patient?

    • The drug inhibits levodopa metabolism in the striatum

    • The drug inhibits the abnormally high cholinergic tone in the striatum

    • The drug activates dopaminergic receptors in the striatum

    • The drug blocks beta-2 receptors which mediate the tremor in the skeletal muscle

    • The drug activate a specific transport system that allows levodopa to enter the brain

    Correct Answer
    A. The drug inhibits the abnormally high cholinergic tone in the striatum
    Explanation
    Answer: B
    (Katzung, pp 454 , Brunton, pp 537)
    In Parkinson’s disease the loss of dopaminergic neurons results in a loss of balance that
    normally exists between acetylcholine and dopamine mediated neurotransmission
    Antimuscarinic drugs, like benztropine, seem to act by blocking muscarinic receptors in the
    striatum, so decreasing the abnormally high cholinergic tone, which results from lack of the
    inhibitory activity of dopamine. These drugs may improve tremor and rigidity but have little
    effect on bradykinesia.
    A, C, D, E) Antimuscarinic drugs do not produce these effects

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  • 5. 

    A 66-year-old man with Parkinson’s disease has been taking levodopa/carbidopa but lately the therapy was sometimes ineffective in controlling his symptoms. His neurologist prescribed another drug, to take concurrently with levodopa/carbidopa, that should enhance and prolong the effects of levodopa. Which of the following drugs was most likely prescribed?

    • Propranolol

    • Selegiline

    • Benztropine

    • Haloperidol

    • Imipramine

    • Diazepam

    Correct Answer
    A. Selegiline
    Explanation
    Answer: B
    (Katzung, pp 453, Brunton, pp 537)
    Selegiline is a selective inhibitor of MAO B that reduces the metabolism of dopamine. In this
    way it enhances and prolongs the effects of levodopa and is therefore used as an adjunct to
    levodopa in Parkinson’s disease.
    A, C) These drugs are sometimes used in Parkinson’s disease, but they do not prolong
    dopamine effects since they act on different receptors.
    D, E, F) these drugs are not effective in Parkinson’s disease.

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  • 6. 

    Co-administration of which of the following drugs with levodopa / carbidopa will increase the availability of levodopa in the brain?

    • Amantadine

    • Entacapone

    • Methyldopa

    • Benztropine

    • Bromocriptine

    • Haloperidol

    Correct Answer
    A. Entacapone
    Explanation
    Answer: B
    (Katzung, pp 453, Brunton, pp 536)
    Entacapone belongs to the class of COMT inhibitors, a new class of drugs for parkinsonism.
    These drugs are selective inhibitors of catechol-O-methyl-transferase (COMT), the enzyme that
    converts levodopa into 3-O-methyl-DOPA, a pharmacologically inactive compound. The main
    therapeutic action of entacapone is to block the peripheral conversion of levodopa into 3-omethyl-
    dopa, so increasing both the plasma half life of levodopa as well as the fraction of each
    doses that reaches the CNS.
    A, C, D, E, F) These drugs are not COMT inhibitors.

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  • 7. 

    A 77-year-old woman has been showing an increasing memory impairment and recognition deficits over the past 2 years. Recently she became disoriented and confused at night. Physical examination revealed an awake and oriented to place person with no focal neurological deficits. Her physician prescribed a drug which might help to slow the progression of her symptoms. Which of the following drugs was most likely prescribed?

    • Fluoxetine

    • Chlorpromazine

    • Donepezil

    • Amitriptyline

    • Trazodone

    Correct Answer
    A. Donepezil
    Explanation
    Answer: C
    (Katzung, pp 1011, Brunton, pp 539)
    The woman is most likely in the early stages of Alzheimer’s disease. She displayed several
    symptoms associated with dementia, including impaired reasoning (recognition deficits), loss of
    memory, confusion and disorientation. A major approach to the treatment of Alzheimer’s
    disease has involved the attempt to augment the cholinergic function in the brain, because a
    loss of cholinergic neurons is prominent in this disease. Donepezil, tacrine, rivastigmine and
    galantamine are cholinesterase inhibitors approved for treatment of AD. Donepezil selectively
    inhibits cholinesterase in the CNS with less effect on cholinesterase in peripheral tissues.
    A, B, D, E) (see explanation above)

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  • 8. 

    A 62-year-old woman with Parkinson’s disease complained of blurred vision, dry mouth, palpitations and constipation. She has been receiving a levodopa/carbidopa combination for 8 months but recently her neurologist added another drug to the therapeutic regimen. Which of the following drugs most likely caused the patient’s symptoms?

    • Benztropine

    • Selegiline

    • Bromocriptine

    • Amantadine

    • Pergolide

    • Entacapone

    Correct Answer
    A. Benztropine
    Explanation
    Answer: A
    (Katzung, pp 454, Brunton, pp 537)
    The symptoms of the patient are typical adverse effects of antimuscarinic drugs. These drugs
    (benztropine, trihexyphenidyl, etc.) are used adjunctively in parkinsonism since they may
    improve tremor and rigidity.
    B, C, D, E, F) All these drugs do not cause the set of symptoms reported by the patient.

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  • 9. 

    Damage of basal ganglia can produce either hyperkinetic or hypokinetic disorders. Which of the following statements best describes the effects of cholinergic and dopaminergic agonists on these conditions?

    • Cholinergic agonists exacerbate hyperkinetic disorders and alleviate hypokinetic disorders

    • Cholinergic agonists alleviate both hyperkinetic and hypokinetic disorders

    • Dopaminergic agonists alleviate both hyperkinetic and hypokinetic disorders

    • Dopaminergic agonists exacerbate hyperkinetic disorders and alleviate hypokinetic disorders

    • Dopaminergic agonists alleviate hyperkinetic disorders and exacerbate hypokinetic disorders

    Correct Answer
    A. Dopaminergic agonists exacerbate hyperkinetic disorders and alleviate hypokinetic disorders
    Explanation
    Answer: D
    (Katzung, pp 457, Brunton, pp 540)
    The main hypokinetic disorder related to damage of basal ganglia is parkinsonism, whereas the
    main hyperkinetic disorder related to damage of the same area is Huntington disease.
    Dopaminergic agonist and dopamine like-drugs tend to exacerbate Huntington disease, but they
    are useful drugs for the therapy of parkinsonism.
    A, B) Cholinergic agonists tend to exacerbate parkinsonism which is instead alleviated by
    antimuscarinic drugs.
    C, E) (see explanation above)

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  • 10. 
    The following table shows the relative intensities of blockade of CNS receptors of five new drugs, each of which may have potential therapeutic value. Which of the drugs is most likely to be useful in treating Parkinson’s disease? - ProProfs

    The following table shows the relative intensities of blockade of CNS receptors of five new drugs, each of which may have potential therapeutic value. Which of the drugs is most likely to be useful in treating Parkinson’s disease?

    • Drug 1

    • Drug 2

    • Drug 3

    • Drug 4

    • Drug 5

    Correct Answer
    A. Drug 5
    Explanation
    Answer: E
    (Katzung, pp 454, Brunton, pp 537)
    Drugs that block muscarinic receptors may improve tremor and rigidity of parkinsonism. In this
    disease the loss of dopaminergic neurons results in the loss of balance that normally exists
    between acetylcholine and dopamine mediated neurotransmission. It seems likely that the
    antimuscarinic agents work by blocking the transmission of cholinergic striatal neurons, thereby
    minimizing the effect of the relative increase in cholinergic sensitivity.
    A, B) Dopaminergic blockade would exacerbate, not improve, the symptoms of parkinsonism.
    C, D) Adrenergic and GABAergic blockade would have negligible effect on parkinsonism.

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  • 11. 

    A 72-year-old man, who has been suffering from Parkinson’s disease for 4 years, complained of a purplish-red mottling of the skin which began on the thighs and spread to lower legs. The eruption appeared two weeks after a new drug was added to his therapeutic regimen. A diagnosis of livedo reticularis was made. Which of the following drugs could have caused this skin eruption?

    • Levodopa

    • Carbidopa

    • Selegiline

    • Amantadine

    • Bromocriptine

    • Benztropine

    Correct Answer
    A. Amantadine
    Explanation
    Answer: D
    (Katzung, pp 454, Koda-Kimble, pp 53-24)
    Livedo reticularis can occur in up to 805 of patients taking amantadine and usually clears within
    a month after drug withdrawal. The disorder is believe to be caused by local release of
    catecholamines which causes vasoconstriction and alter the permeability of skin blood vessels.
    A, B, C, E, F) These drugs do not cause livedo reticularis.

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  • 12. 

    A 75-year-old diabetic man, suffering from Parkinson’s disease, complained of worsening of his tremor and rigidity in arms and legs. His Parkinson’s disease has been responding well to a treatment of levodopa/carbidopa and amantadine, and his diabetes has been controlled by chlorpropamide and metformin. Recently metoclopramide was prescribed to manage diabetic gastroparesis. Which of the following drugs could have triggered the worsening of the symptoms reported by the patient?

    • Chlorpropamide

    • Amantadine

    • Carbidopa

    • Metformin

    • Metoclopramide

    Correct Answer
    A. Metoclopramide
    Explanation
    Answer: E
    (Katzung, pp 1045, Koda-Kimble, pp 53-27)
    The symptoms reported by the patient point out a worsening of his Parkinson’s disease
    Metoclopramide, a prokinetic drug used to treat diabetic gastroparesis, can block D2 receptors
    in the brain, so leading to a decreased levodopa effect.
    A, B, C, D) (see explanation above)

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  • 13. 

    A 57-year-old woman recently diagnosed with Parkinson’s disease has been receiving a levodopa- carbidopa combination for three weeks. Which of the following adverse effects is most likely to occur from this treatment?

    • Blurred vision

    • Diarrhea

    • Postural hypotension

    • Bradycardia

    • Bradykinesia

    Correct Answer
    A. Postural hypotension
    Explanation
    Answer: C
    (Katzung, pp 241, Brunton, pp 169, 534)
    Postural hypotension is the most common cardiovascular adverse effect of levodopa, especially
    in the early stage of treatment. Levodopa is a prodrug and all its effects are due to dopamine.
    Postural hypotension is most likely due both to the activation of e vasodilation D1 receptors in
    the renal and mesenteric vascular bed, which leads to vasodilation and to the activation of D1
    receptors in the proximal tubule which causes inhibition of tubular sodium reabsorption, so
    increasing the diuresis.
    A) Dopamine has negligible effects on accommodation, so blurred vision is unlikely.
    B) Dopamine can activate alpha-1 receptors in the gastrointestinal system. Activation of these
    receptors in the gastrointestinal smooth muscle cause hyperpolarization and relaxation, so
    diarrhea is unlikely.
    D) Dopamine can activate beta receptor in the heart, so causing tachycardia, not bradycardia.
    E) Dopamine can cause dyskinesias, but bradykinesia is a classic symptoms of parkinsonism,
    which is in fact alleviated, not caused by levodopa.

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  • 14. 

    A 72-year-old man, recently diagnosed with Alzheimer’s disease, has been prescribed a drug which might help to slow the progression of her symptoms. Which of the following sets of adverse effects is most likely to occur from this treatment?

    • Hypertension, palpitations

    • Nausea, vomiting and diarrhea

    • Dry mouth, anhydrosis

    • Drowsiness, lethargy

    • Mydriasis, cycloplegia

    Correct Answer
    A. Nausea, vomiting and diarrhea
    Explanation
    Answer: B
    (Brunton, pp 539, Koda-Kimble pp.100-7)
    The drugs most frequently used in Alzheimer’s disease are cholinesterase inhibitors like
    donepezil, rivastigmine etc. Even if these drugs preferentially inhibit acetylcholinesterase in the
    CNS, they can cause most of the adverse effects shared by all cholinergic drugs, which are due
    to activation of cholinergic receptors. Effects affecting the gastrointestinal tract (nausea
    vomiting and diarrhea) are the most common.
    A, C, D, E) Actually these effects are caused by antimuscarinic drugs, not by cholinergic drugs.

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  • 15. 

    A 72-year-old man, suffering from Parkinson disease for 5 years, complains of a resting tremor, which at present is one of the most debilitating symptoms of his disease. He has gained improvement in rigidity, bradykinesia and posture as well as improvement in the ‘on-off’ effects with levodopa/carbidopa combination and benztropine, but he has experienced little if any improvement in tremor. Which of the following would be an appropriate therapeutic conduct for the reduction of the tremor in this patient?

    • To decrease the dose of carbidopa

    • To substitute levodopa/carbidopa with bromocriptine

    • To withdraw benztropine

    • To add propranolol to the present drug regimen

    • To start brief periods of ‘drug holidays‘ during therapy

    Correct Answer
    A. To add propranolol to the present drug regimen
    Explanation
    Answer: D
    (Katzung, pp 457, Koda-Kimble, pp 53-25)
    Parkinsonian tremor is often less responsive to dopaminergic therapy than other symptoms.
    Tremor can be worsened by peripheral factors such as catecholamine release often in
    association with stress or anxiety. Propranolol improves parkinsonian tremor in about 50% of
    patients and therefore a trial with propranolol can be appropriate for this patient.
    A, B, C, E) All these procedures would not affect the tremor of the patient.

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  • 16. 

    A 51-year-old woman presented to her doctor complaining of a unilateral rhythmic tremor, and slowing down of all movements. Her medical history was significant for two schizophrenic episodes in her late forties which had been treated with phenothiazines. On examination she showed cog wheel rigidity. A presumptive diagnosis of parkinsonism was made. Which one of the following drugs would be relatively contraindicated at the start of her therapy?

    • Amantadine

    • Benztropine

    • Bromocriptine

    • Entacapone

    • Entacapone

    Correct Answer
    A. Bromocriptine
    Explanation
    Answer: C
    (Katzung, pp 453, Koda-Kimble, pp 78-3)
    Dopaminergic drugs, like bromocriptine, levodopa, amphetamines, etc., are contraindicated, or
    should be used with caution, in patients with a history of psychosis, since they constantly
    exacerbate the symptoms of schizophrenic disorders.
    A, B, D, E) These drugs are not contraindicated in patients with a history of psychosis.

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  • 17. 

    Which of the following statements correctly pair the drugs used in parkinsonism with their appropriate mechanism of action? (Check all that apply)

    • Levodopa - inhibits dopamine metabolism in the brain

    • Benztropine - blocks central Nn cholinergic receptors

    • Selegiline - selectively inhibits MAO B

    • Amantadine - selectively inhibits catechol-O-methyl-transferase

    • Bromocriptine - activates central dopaminergic receptors

    • Entacapone - blocks central muscarinic receptors

    Correct Answer(s)
    A. Selegiline - selectively inhibits MAO B
    A. Bromocriptine - activates central dopaminergic receptors
    Explanation
    Answer: CE
    (Katzung, pp 452,453 Brunton, pp 535, 537)
    Selegiline is a selective inhibitor of MAO B (the enzyme that metabolize dopamine) so
    preventing the oxidation of dopamine to DOPAC and hydrogen peroxide. Bromocriptine is a D2
    receptor agonist.
    A) Levodopa is biotransformed into dopamine by the enzyme DOPA decarboxylase. It does not
    affect the metabolism of dopamine.
    B) Actuallybenztropine blocks central muscarinic receptors. It has negligible blocking activity on
    central Nn cholinergic receptors.
    D) In fact the mechanism of action of amantadine is still unknown, but the drug is not an
    inhibitor of catechol-O-methyl-transferase.
    F) Entacapone is a selective inhibitor of catechol-O-methyl-transferase

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  • 18. 

    A 65-year-old man presented to the hospital complaining of difficulty in writing, because of unsteadiness in his right hand, and tightness in his harms and legs. These symptoms started about one week ago. Physical examination showed a well-nourished, anxious male with a notable lack of normal changes in facial expression and with a soft, monotone voice. Tremor was present in his hands and a festinating gait was noted. A preliminary diagnosis was made and an appropriate treatment was prescribed. Which of the following drug was most likely prescribed?

    • Carbidopa

    • Entacapone

    • Benztropine

    • Pramipexole

    • Clonazepam

    • Propranolol

    Correct Answer
    A. Pramipexole
    Explanation
    Answer: D
    (Katzung, pp 452, Koda-kimble, pp 53-7)
    The patients presents with symptoms and signs typical of Parkinson’s disease. The four classic
    features of Parkinson’s disease, i.e tremor, rigidity (tightness in his harms and legs)
    bradykinesia (lack of normal changes in facial expression) and postural instability (festinating
    gait) are easily recognized. Pramipexole is a dopamine receptor agonist which is effective when
    used as monotherapy for mild parkinsonism. Dopaminergic therapy of parkinsonism is usually
    initiated with a dopamine agonist, since these drugs have a number of potential advantages
    over levodopa, including a lower incidence of response fluctuations and dyskinesias.
    A, B, C) These drugs are not currently used as monotherapy, but only in addition to levodopa
    therapy.
    E, F) These drugs are only used adjunctively to control symptoms that, in a particular patient,
    are resistant to the conventional therapy, like tremor (propranolol) or myoclonus (clonazepam).

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  • 19. 

    A 67-year-old man with Parkinson’s disease complained that recently he felt increasingly confused at times, often had vivid dreams and on occasion experienced visual hallucinations. He has been receiving a levodopa-carbidopa combination for 1 years and his disease was well controlled. Which of the following actions could be implemented to reduce the occurrence of these adverse effect?

    • To substitute levodopa with selegiline

    • To substitute levodopa with bromocriptine

    • To add benztropine to the present regimen

    • To add amantadine to the present regimen

    • To add clozapine to the present regimen

    Correct Answer
    A. To add clozapine to the present regimen
    Explanation
    Answer: E
    (Katzung, pp 451, Koda-Kimble pp 53-18)
    The symptoms of the patients are typical mental disturbances caused by levodopa and are
    more common in patients taking the drug in combination with carbidopa, presumably because
    higher levels are reached in the brain. Psychotic symptoms often respond to neuroleptic
    treatment, but classical neuroleptics are not indicated since they may cause marked worsening
    of parkinsonism, likely through the blockade of D2 receptors in the striatum. Atypical
    neuroleptics like clozapine do not block D2 receptors, do not worsen parkinsonism and are
    effective in the treatment of levodopa-induced Psychotic symptoms.
    A) Selegiline has only a minor therapeutic effect on parkinsonism when given alone, and
    therefore the substitution of levodopa with selegiline most likely would cause a worsening of the
    disease.
    B) Dopaminergic agonists like bromocriptine can cause mental disturbances very similar to
    those caused by levodopa, likely because both adverse effects have the same underlaying
    mechanism.
    C, D) Actually mental disturbances can be exacerbated, not alleviated, by concurrent
    anticholinergic or amantadine therapy.

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  • 20. 

    A 65-year-old man with Parkinson’s disease complained of periods of few minutes of complete immobility followed by a sudden switch to involuntary movements such as twitching, nodding, and jerking. The patient’s current medications included levodopacarbidopa. In order to reduce these rapid fluctuations the neurologist reduced the daily dose of levodopa-carbidopa and added another drug. Which of the following drugs was most likely prescribed?

    • Amantadine

    • Benztropine

    • Haloperidol

    • Bromocriptine

    • Fluoxetine

    Correct Answer
    A. Bromocriptine
    Explanation
    Answer: D
    (Katzung, pp 452, Koda-Kimble, pp 53-16)
    The patient is most likely suffering from the on-off phenomenon in which off periods of marked
    akinesia alternate over the course of a few hours with on periods of improved mobility and
    marked dyskinesia. These response fluctuations can be improved by adjunctive drugs which
    include dopamine agonists like bromocriptine, COMT inhibitors and in some cases selegiline.
    A, B, C, E ) These drugs are not useful to improve response fluctuations.

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  • Mar 21, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Sep 04, 2012
    Quiz Created by
    Chachelly
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