NCT00362843

Protein Synthesis in the Brain of Patients With Fragile X Syndrome

Completed Last updated 8 October 2024

What this trial tests

trial testing [15-O]water in Fragile X Syndrome in 147 participants. Completed in 1 May 2020.

Timeline

22 August 2006

Primary endpoint
1 May 2020

1 May 2020

Quick facts

Lead sponsor	National Institute of Mental Health (NIMH)
Status	Completed
Study type	OBSERVATIONAL
Enrollment	147
Start date	22 August 2006
Primary completion	1 May 2020
Estimated completion	1 May 2020
Sites	1 location across United States

Drugs / interventions tested

• [15-O]water

Conditions studied

• Fragile X Syndrome — all drugs for Fragile X Syndrome →
• Healthy Volunteers — all drugs for Healthy Volunteers →

Sponsor

National Institute of Mental Health (NIMH)

Who can join

Adults 18 to 24, male only, with Fragile X Syndrome or Healthy Volunteers. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

Biosynthesis of proteins is essential for growth and continued maintenance of the entire neuron including axons, dendrites, and synaptic terminals, and it is clearly one of the important biochemical processes underlying adaptive changes in the nervous system. Studies in experimental animals with the quantitative autoradiographic L \[1 (14)C\]leucine method have demonstrated a number of the physiological and pathological conditions in which changes in regional rates of cerebral protein synthesis (rCPS) occur.

We have recently developed the first fully quantitative method for determining rCPS with positron emission tomography (PET). The PET method was adapted from the autoradiographic L \[1 (14)C\]leucine method; it uses L \[1 (11)C\]leucine as the PET tracer, dynamic scanning, and a kinetic modeling approach for quantification. This method was validated in nonhuman primates by comparison of PET measurements with those based on established biochemical and autoradiographic techniques.

The objective of the present study is to examine the degree to which changes in rCPS in human subjects can be quantified with the L \[1 (11)C\]leucine PET method. We propose three studies to be carried out sequentially. In Part I we will establish the L-\[1-(11)C\]leucine PET method in human subjects. In Part II we will measure rCPS in normal control subjects in two states: awake and under deep sedation/general anesthesia with propofol. A difference in rCPS between these two states may indicate that we can detect activity-dependent protein synthesis with the PET method. In Part III we will study subjects with fragile X syndrome. This patient group was chosen since the affected gene in fragile X syndrome codes for a protein that is thought to be a negative regulator of message translation. Thus an effect on protein synthesis may be very close to the underlying genetic abnormality in fragile X syndrome. Regionally selective increases in rCPS have been found in studies in a mouse model of this disease.

The present study will establish the sensitivity of the L \[1 (11)C\]leucine PET method to detect changes in rCPS in human subjects. A quantitative and sensitive method to measure rCPS with PET will augment the tools available for investigating the brain and its regional adaptive responses. Ultimately the method may have widespread applications, not only for the study of normal development and plasticity but also in clinical medicine, e.g., in the investigation of disorders of brain development, recovery from brain injury, and neurodegenerative diseases.

SPECIFIC AIMS

1. \<TAB\>Establish the L-\[1-(11)C\]leucine PET method for measurement of rCPS in human subjects. Evaluate the optimal scan time and the variability of the measurement in an individual.
2. \<TAB\>Determine the effect of deep sedation with propofol on rCPS in normal human subjects. We will use the \[1-(11)C\]leucine PET method to evaluate lambda, i.e., the fraction of the precursor pool for protein synthesis that is derived from arterial plasma, and rCPS in the same subjects under awake and deep sedation conditions.

I)\<TAB\>Hypothesis 1a. Deep sedation with propofol has effects on rCPS.

II)\<TAB\>Hypothesis 1b. Deep sedation with propofol has effects on values of lambda.
3. \<TAB\>Assess the sensitivity of the \[1-(11)C\]leucine PET method to detect differences in rCPS in subjects with fragile X syndrome.

I)\<TAB\>Hypothesis 3a. There are regionally selective changes in rCPS in subjects with fragile X syndrome compared with age-matched healthy controls. Regions affected include hippocampus, thalamus, hypothalamus, amygdala, and frontal and parietal cortex.

II)\<TAB\>Hypothesis 3b. In centrum semiovale, cerebellum, striatum and occipital and temporal cortex rCPS are unchanged in subjects with fragile X syndrome compared with age-matched healthy controls.

III)\<TAB\>Hypothesis 3c. Values of lambda in the brain as a whole and in the regions examined are unchanged in subjects with fragile X syndrome compared with age-matched healthy controls.

IV) Hypothesis 3d. The average rate of protein synthesis in the brain as a whole is unchanged in subjects with fragile X syndrome compared with age-matched healthy controls.

Publications & conference data

4 peer-reviewed publications reference this trial (live from Europe PMC):

1. Regional rates of brain protein synthesis are unaltered in dexmedetomidine sedated young men with fragile X syndrome: A L-[1-&lt;sup&gt;11&lt;/sup&gt;C]leucine PET study.
   Schmidt KC, Loutaev I, Quezado Z, Sheeler C, et al · · 2020 · cited 17× · PMID 32569795 · DOI 10.1016/j.nbd.2020.104978
2. Effects of shortened scanning intervals on calculated regional rates of cerebral protein synthesis determined with the L-[1-11C]leucine PET method.
   Tomasi G, Veronese M, Bertoldo A, Beebe Smith C, et al · · 2018 · cited 9× · PMID 29659612 · DOI 10.1371/journal.pone.0195580
3. Fragile X syndrome in a male with methylated premutation alleles and no detectable methylated full mutation alleles.
   Hayward B, Loutaev I, Ding X, Nolin SL, et al · · 2019 · cited 8× · PMID 31356000 · DOI 10.1002/ajmg.a.61286
4. Decreased rates of cerebral protein synthesis in conscious young adults with fragile X syndrome demonstrated by L-[1-¹¹C]leucine PET.
   Schmidt KC, Loutaev I, Burlin TV, Thurm A, et al · · 2022 · cited 5× · PMID 35350914 · DOI 10.1177/0271678x221090997