On date unavailable, commented:

None

On 2017 Apr 24, David Eidelberg commented:

We thank Dr. Black for his interest in our work. To answer his basic questions:

1. The minimum time interval between the start of the levodopa infusion and the start of O15- water PET was 60 minutes. As detailed in the original paper by Feigin et al. (Neurology 2001; 57(11): 2083-2088), scanning under infusion commences when UPDRS motor ratings are stable within 5% on two successive examinations separated by 30 minutes. The levodopa infusion is maintained at a constant rate at that point.

2. As for the test-retest cohort, these PD subjects took their usual morning PD medications on the day of the scan. They maintained their routine antiparkinsonian medication regimen during the 8-week interval between test and retest imaging. The majority of the subjects were on daily carbidopa/levodopa, though a minority took a combination of levodopa and a dopamine agonist. Unfortunately, the exact dosing at the time of the scans (performed before 2008) is not currently available.

3. All levodopa infusion subjects reported in the study were scanned according to the protocol described in Hirano et al., J Neurosci 2008; 28(16): 4201-4209.

On 2017 Apr 08, KEVIN BLACK commented:

Authors: Please tell us the time interval between the start of the levodopa infusions and the start of the [O-15]water and FDG PET acquisitions.

Also, can you provide information about carbidopa intake on the day of the study? The supplement says only that the 8 PD test-retest subjects took "their usual morning dose of oral levodopa/carbidopa." The dose of LD and of CD is not given for those subjects. The reader is referred to the Ma et al 2007 paper, but I can't find dosing information there, either (nor how many were on CD-LD only and how many were on other dopaminergic drugs). In the infusion subjects, can you clarify whether the newly enrolled subjects had the same carbidopa dosing regimen as described in the Hirano et al 2008 methods?

On 2017 Apr 08, KEVIN BLACK commented:

Authors: Please tell us the time interval between the start of the levodopa infusions and the start of the [O-15]water and FDG PET acquisitions.

Also, can you provide information about carbidopa intake on the day of the study? The supplement says only that the 8 PD test-retest subjects took "their usual morning dose of oral levodopa/carbidopa." The dose of LD and of CD is not given for those subjects. The reader is referred to the Ma et al 2007 paper, but I can't find dosing information there, either (nor how many were on CD-LD only and how many were on other dopaminergic drugs). In the infusion subjects, can you clarify whether the newly enrolled subjects had the same carbidopa dosing regimen as described in the Hirano et al 2008 methods?