Sex correction improves the accuracy of clinical dopamine transporter imaging

Background In clinical diagnostic imaging, dopamine transporter (DAT) SPECT scans are commonly evaluated using automated semiquantitative analysis software. Age correction is routinely implemented, but usually no sex correction of DAT binding is performed. Since there are sex differences in presynaptic dopaminergic function, we investigated the effect of DAT sex correction in a sample of healthy volunteers who underwent brain [123I]-FP-CIT SPECT. Methods Forty healthy elderly individuals (21 men and 19 women) underwent brain [123I]-FP-CIT SPECT, and each subject was examined clinically for motor and non-motor parkinsonian symptoms and signs. Regional specific DAT binding ratios (SBR = [ROI-occ]/occ) were calculated using age correction, and the results were compared to those in normal databases with and without sex correction. The level of regional abnormality was set at 2 standard deviations below the mean values of the reference databases. Results In the analysis without sex correction, compared to the mean ratio of the reference database, ten healthy individuals (8 men and 2 women) had abnormally low DAT binding ratios, and four individuals (3 men and 1 woman) had borderline low DAT binding ratios in at least one striatal region. When sex correction was implemented, the ratio of one individual was abnormal, and the ratio of one individual was borderline (both males). There were no clinically significant differences in motor or non-motor symptoms between healthy volunteers with abnormal and normal binding. Conclusions A considerable number of elderly healthy male subjects can be interpreted to be dopaminergically abnormal if no sex correction of DAT binding is performed. Sex differences in striatal dopaminergic function should be taken into account when DAT imaging is used to assist clinical diagnostics in patients with suspected neurological disorders.

Age-Related Alterations in DTI Metrics in the Human Brain—Consequences for Age Correction

Background: Over the life span, the diffusion metrics in brain MRI show different, partly nonlinear changes. These age-dependent changes also seem to exhibit regional differences with respect to the brain anatomy. The age correction of a study cohort's diffusion metrics might thus require consideration of age-related factors.Methods: Diffusion tensor imaging data sets were acquired from 219 healthy participants at ages between 19 and 81 years. Fractional anisotropy (FA), mean diffusivity (MD), and axial and radial diffusivity (AD and RD, respectively) maps were analyzed by a tract of interest-based fiber tracking approach. To describe diffusion metrics as a function of the participant age, linear splines were used to perform curve fitting in 21 specific tract systems covering different functional areas and diffusion directions.Results: In the majority of tracts, an interpolation with a change of alteration rate during adult life described the diffusion properties more accurately than a linear model. Consequently, the diffusion properties remained relatively stable until a decrease (of FA) or increase (of MD, AD, and RD) started at a region-specific time point, whereas a uniform change of diffusion properties was observed only in a few tracts. Single tracts, e.g., located in the cerebellum, remained nearly unaltered throughout the ages between 19 and 81 years.Conclusions: Age corrections of diffusion properties should not be applied to all white matter regions and all age spans in the same way. Therefore, we propose three different approaches for age correction based on fiber tracking techniques, i.e., no correction for areas that do not experience age-related changes and two variants of an age correction depending on the age range of the cohort and the tracts considered.

Revision of the human’s occupations chronologies at the Senegalese and Mauritania sites by using marine reservoir ages corrections

The prehistoric settlement of the west coast of the Senegalese-Mauritanian basin is established from archaeological remains and coal samples collected, sometimes in a stratigraphic context. However, the chronology issued, in the Before Present (BP) age, does not take into account the taphonomic context of the sites and the local reservoir age. Therefore, this article revisits the chronologies obtained based on the 14C literature and dating(s) acquired. Changes in time and duration of human occupancy of the area are shorter or longer depending on adequate yields of local reservoir age (Ndeye, 2008), which is a relevant element for marine samples. Thus, the archaeological implications observed with the reservoir effect are the rejuvenation or ageing of the dates, the age of the sites, the duration of occupation prehistoric or historical sites studied. Using the calibration programmes, it is noted that for the site of Senegal (Khant), without taking into account the reservoir effect, the human occupation is a priori, from the fifth millennium (Ancient Neolithic) to the third millennium BC (Middle Neolithic). However, if this marine reservoir effect is applied, the chronological periodisation goes from the fourth millennium to the first millennium. For the Mauritanian sites, the reservoir age correction is necessary for the Chami site while for the Tintan site is not required. Therefore, the calibrated archaeological chronologies obtained after the application of the marine reservoir effect are more relevant.

MARINE RESERVOIR AGE CORRECTION FOR THE ANDAMAN BASIN

ABSTRACTMarine reservoir age is an important component for correction in radiocarbon (14C) dating of marine and coastal samples. 14C concentration in pre-bomb marine samples of known age are used to derive marine reservoir age of a region. Annually banded coral from Landfall island in the northern Andaman has been analyzed for its 14C concentration during the pre-bomb period 1948–1951. 14C age and reservoir effect (∆R) are reported for these pre-bomb coral samples from the northern Andaman region. The mean 14C age of 331 ± 61 yr BP was obtained for the period 1948–1951 with an average reservoir age correction of –138 ± 61 yr. This reservoir age correction is lowest reported from the northern Indian Ocean. ∆R value of the northern Andaman and the Bay of Bengal appears lower than that of southern Andaman. The ∆R values obtained using mollusk shells and coral from the Andaman region shows large variability. The lower reservoir age correction for the Landfall Island situated in the northern part of the Andaman archipelago, could result due to freshwater flux and reduced upwelling in the region.

Projecting effectiveness after ending a randomized controlled trial: a two-state Markov microsimulation model

ObjectiveTo investigate the behavior of restricted mean survival time (RMST) and designs of a two-state Markov microsimulation model through a 2 × 4 × 2 full factorial experiment.MethodBy projecting patient-wise 15-year-post-trial survival, we estimated life-year-gained between an intervention and a control group using data from the Cardiovascular Outcomes for People Using Anticoagulation Strategies Study (COMPASS). Projections considered either in-trial events or post-trial medications. They were compared based on three factors: (i) choice of probability of death, (ii) lengths of cycle, and (iii) usage of half-a-cycle age correction. Three-way analysis of variance and post-hoc Tukey's Honest Significant Difference test compared means among factors.ResultsWhen both in-trial events and post-trial study medications were considered, monthly, quarterly, or semiannually were not different from one other in projected life-year-gained. However, the annual one was different from the others: mean and 95 percent confidence interval 252.2 (190.5–313.9) days monthly, 251.8 (192.0–311.6) quarterly, 249.1 (189.7–308.5) semiannually, and 240.8 (178.5–303.1) annually. The other two factors also impacted life-year-gained: background probability (269.1 [260.3–277.9] days projected with REACH-based-probabilities, 227.7 [212.6–242.8] with a USA life table); half-a-cycle age correction (245.5 [199.0–292] with correction and 251.4 [209.1–293.7] without correction). When not considering post-trial medications, only the choice of probability of death appeared to impact life-year-gained.ConclusionFor a large trial or cohort, to optimally project life-year-gained, one should consider using (i) annual projections, (ii) life table probabilities, (iii) in-trial events, and (iv) post-trial medication use.

Preliminary Test of the EA-AGE3 System for 14C Measurement of CaCO3 Samples and Coral-Based Estimation of Marine Reservoir Correction in the Ogasawara Islands, Northwestern Subtropical Pacific

ABSTRACTWe conducted a preliminary test of the coupled system of an elemental analyzer and the automated graphitization equipment Ionplus AGE3 (EA-AGE3 method) for accelerator mass spectrometry radiocarbon (AMS 14C) measurements of CaCO3 samples, by comparing with the conventional method where the samples are hydrolyzed in phosphoric acid and resulting CO2 gas is manually graphitized in a vacuum line (HPA method). The samples used in the test were the IAEA C2 travertine, fossil and modern corals from the Ryukyu Islands and the Ogasawara Islands, respectively (both are located in the northwestern subtropical Pacific). Results indicate that, relative to the HPA method, the EA-AGE3 method tends to cause an increase of ~0.4–0.5 pMC with more widely scattered data. This is presumably due to 14C contamination in the EA (the most likely cause seems to be a memory effect of 14C); this effect could be reduced by careful optimization of conditions and procedures in the EA process. The 14C data of pre-bomb annual bands (1931–1949 AD) in the modern Ogasawara coral obtained by the HPA method were used to estimate the marine reservoir 14C-age correction (ΔR) of this region; it ranges from –109 yr to –28 yr with the mean value with standard deviation of –81 ± 29 yr.

Modeled and Measured Carbon Isotopic Composition and Petrographically Estimated Binder-Aggregate Ratio—Recipe for Binding Material Dating?

ABSTRACTThis paper presents the results of radiocarbon (14C) dating of bulk mortars and reports an attempt of implementation of the knowledge about the isotopic fractionation, based on δ13C measurements, to make the age correction for mortars, together with verification of such correction based on the percentage estimation of carbonate components, namely binder and aggregate. To evaluate the variability of isotopic fractionation during CO2 absorption by mortar, dependent on the climatic and environmental conditions, and the type of mortar, the δ13C measurements have been performed for the mortars from Sussita (Golan Heights). Such measurements were also made for fragments of natural carbonate rocks and for mortars produced in the laboratory from the same substrate. We propose the recipe for mortars age estimation.

The Cantonese Hearing in Noise Test for Children

The aim of this study was to develop a children's version of the Cantonese Hearing in Noise Test (CHINT-C). This was accomplished in two stages. First, a total of 120 sentences understood by children aged 6-7 years were selected from the original pool of CHINT sentences and were grouped into 12 lists, each containing 10 sentences composed of 10 characters. Following this, 260 primary and secondary school children, with ages ranging from 6 to 17 years, and 21 adults of age 18 or older were administered the CHINT-C to determine its reliability/validity, normative data, and age-specific correction factors. The result showed good interlist reliability, and test–retest reliability for the CHINT-C. The speech perception skills assessed using the CHINT-C do not reach adult level until after 11-13 years of age. Correction factors were established that could be used to determine age-specific norms for the evaluation of speech intelligibility of children in various sound fields.